Participants List and Contributions
Contribution: Oral
Title: Do massive neutron stars end as invisiable dark energy objects?
Author(s): Ahmad A. Hujeirat
Abstract: Astronomical observations reveal a gap in the mass spectrum of relativistic objects: neither black holes nor neutron stars having masses in the range of 2 - 5$\,\MSun$ have ever been observed. Based on the solution of the TOV equation modified to include a universal scalar field $\cal{H},$ we argue that all moderate and massive neutron stars should end invisible dark energy objects (DEOs). Triggered by the $\cal{H}-$baryonic matter interaction, a phase transition from normal compressible nuclear matter into an incompressible quark-superfluid is shown to occur at roughly $3$ times the nuclear density. At the transition front, the scalar field is set to inject energy at the maximum possible rate via a non-local interaction potential $V_\phi = a_0 r^2 + b_0.$ This energy creates a global confining bag, inside which a sea of freely moving quarks is formed in line with the asymptotic freedom of quantum chromodynamics. The transition front, $r_f,$ creeps from inside-to-outside to reach the surface of the object on the scale of Gyrs or even shorter, depending on its initial compactness. Having $r_f$ reached $R_\star,$ then the total injected dark energy via $V_\phi $ turns NSs into invisible DEOs. While this may provide an explanation for the absence of stellar BHs with $M_{BH}\leq 5 \MSun$ and NSs with $M_{NS}\geq 2 \MSun$, it also suggests that DEOs might have hidden connection to dark matter and dark energy in cosmology.
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Contribution: Oral
Title: New tetrads in Riemannian geometry and new ensuing results in group theory, gauge theory and fundamental physics, in particle physics, general relativity and astrophysics.
Author(s): Alcides Garat
Abstract: A new technique is presented in order to build tetrads in four-dimensional Lorentzian spacetimes. These tetrads have special useful properties in general relativity, astrophysics and also particle physics. A new fundamental result is proved in group theory using these tetrads. The group SO(2) (spatial rotations) is isomorphic to the group SO(1;1) (boosts) plus two kinds of discrete transformations. One of them is not Lorentzian. That is, a compact group is isomorphic to a non-compact group plus two different kinds of discrete transformations (A. Garat, Tetrads in geometrodynamics, J. Math. Phys. 46, 102502 (2005) and (A. Garat, Tetrads in Yang-Mills geometrodynamics, Gravitation and Cosmology, (2014) Vol. 20 No. 1, pp. 116-126. Pleiades Publishing Ltd.) The electromagnetic local gauge group is proved to be isomorphic to the local group of transformations of these particular kind of tetrads. Therefore, establishing a concrete link between internal and spacetime local groups of transformations. These new tetrads also diagonalize the electromagnetic stress-energy tensor for non-null electromagnetic fields, any stress-energy tensor, in a general, covariant and local way. These new tetrads also introduce maximum simplification in the Einstein-Maxwell differential equations, and introduce maximum simplification in the expression of the electromagnetic field itself, in any curved four-dimensional Lorentzian spacetime, allowing for the identification of its degrees of freedom in two local scalars. These tetrads introduce simplification in spacetime evolution algorithms, specially in astrophysical situations related, for example, to neutron stars (A. Garat, Euler observers in geometrodynamics, Int. J. Geom. Meth. Mod. Phys., Vol. 11 (2014), 1450060). This new tetrad can be applied and introduce simplification in the analysis of astrophysical relativistic problems where vorticity is present through the Carter-Lichnerowicz equation (A. Garat, Covariant diagonalization of the perfect fluid stress-energy tensor, Int. J. Geom. Meth. Mod. Phys., Vol. 12 (2015), 1550031).
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Title: Monte Carlo simulation of 3-D Hamiltonian systems with dynamical interaction in axisymmetric gravitational potential
Author(s): Ali Taani and Juan Carlos
Abstract: Observational access to the Neutron Star (NS) properties provides one of the only means to unveil the physical properties of the matter at ultra-high densities and form an active area of research. This paper, is describing the distribution of positions, orbits and velocities of the simulated isolated old NS population (≥ 1 Gyr) in the Galaxy. The Miyamoto-Nagai and Paczy´nski Galactic potentials were superimposed on the axisymmetric potentials under the influence of different birth velocity distributions. We further perform Monte Carlo simulations for their distributions with different initial conditions. The overall system velocity combines with the original velocity within the Galaxy, with no preferred directions.We applied the Poincar´e section method to study the nature and distribution of old NSs orbits, 3-D trajectories and their 2-D projections which obtained from simulations. We study also their simple periodic orbits, characteristics and stability through the perturbation over time and the dynamical interaction with the gravitational potential in 3-D Hamiltonian systems. The inspection of the maximal asymptotic Lyapunov exponent allows the dynamical characterisation of an orbit, and it turns out that the several prototypical orbits and their behaviors are nearly the same as the regular orbits with two degrees of freedom. The Poincar´e section method clearly shows also that there are 2-D invariant tori and invariant curves (islands) around stable periodic orbits (as quasi-periodic orbits associated with regular motion) that bound to the surface of 3-D tori in a 3-D Hamiltonian system, this graphical treatment shows fundamental constraints in term of deviation vectors and time evolution. The regularity of several prototypical orbits offer the means to identify phase space regions with localized motions and to determine their environment, because they can occupy significant parts of phase-space depending on the potential. This is of particular importance in Galactic Dynamics. In addition, the strong gravitational forces which can also create runaways that be produced by a supernovae, perturb the initial binary fractions and also the mass fractions via the
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Contribution: Oral
Title: Effect of magnetic field in Quark Stars
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Contribution: Oral
Title: Anisotropic Bianchi Type I Cosmological Model in f(R) gravity
Author(s): B.Mishra
Abstract: Anisotropic cosmological models are investigated in the frame work of $f(R)$ gravity in the metric formalism. Plane symmetric models are considered to incorporate anisotropy in the expansion rates along different spatial directions. The anisotropy in expansion rates are assumed to be maintained throughout the cosmic evolution. Two accelerating models are constructed by considering different functional forms for $f(R)$. The viability of these models are tested through a stability analysis.
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Contribution: Poster
Title: Low Energy KN Interaction in the Fock-Tani Formalism
Author(s): Bruna Cesira Folador, Daniel Tavares da Silva, Dimiter Hadjimichef
Abstract: The Fock-Tani formalism is a first principle method to obtain effective interactions from microscopic Hamiltonians. Originally derived for meson-meson or baryon-baryon scatttering, we present the correponding equations for meson-baryon scattering. In particular we shall obtain the low energy cross-sections for the $K^{-}+p\to \Lambda+\eta$ channel.
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Contribution: Oral
Title: Frequency tracking noise of b gravitational wave detector Niobe
Author(s): Carlos Frajuca
Abstract: This work studies the influence of the frequency tracking noise of the Niobe gravitational wave (GW) detector. The University of Western Australia operated the GW detector Niobe at Perth, Australia. It was a resonant-mass bar detector made of niobium operating at a temperature of 5 K. It was sensitive around the frequency of 700 Hz and had a burst sensitivity of h~ 7 x 10-19 with a long term operation from 1993 to early 1998. It had the lowest observed noise temperature. Using the characteristics of the detector, NIOBE should had reached a much better sensitivity that the one measure. It seems that the noise introduced in the system by the frequency tracking device was not taken into at the time, this noise gives a value of ~ 2.5 x 10-18 m/(Hz) -1/2, what is the value that limited the detector sensitivity to the one measured.
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Contribution: Poster
Title: Pushing the Limits of General Relativity Beyond the Big Bang Singularity
Author(s): C.A. Zen Vasconcellos and Dimiter Hadjimichef
Abstract: General relativity suggests an universe in which as we follow time backwards, the hotter and the more dense it was, and the more rapidly it was expanding. And that, 13.7 billion years ago, in the extreme gravitational regime, density, temperature and the universe expansion rate would start off as infinite. This represents a drastic consequence of general relativity, the possibility that space and time may exhibit spacetime singularities, i.e., a point in the fabric of space time in which all physical laws are indistinguishable from one another and where space and time are no longer interrelated realities, but merge indistinguishably and cease to have any independent meaning. This prediction may represent undoubtedly a failure of general relativity in the sense that one can not expect that its classical description shall remain valid at the extreme physical conditions near a spacetime singularity. The presence of a singularity in the early universe would impose a limitation to our understanding of the cosmos and of gravity. The presence of a singularity results in infinite value of the scalar Ricci. The theory thus loses its character of predictability, making it impossible to impose initial conditions. These extreme conditions of the initial state of the universe are very far from our experimental possibilities and presently theoretical models allow only speculations about the avoidance of physical singularities or about the physical conditions that circumvented this drastic consequence of general relativity. The main speculations in this regard explore the possibility that the primordial spacetime singularity of the universe may have been avoided through quantization effects of gravitation or by a combination of effects associated with some sort of unification of general relativity and quantum field theory. Speculations aside, in this study we follow an analytical line in which we apply the tools of singular semi-Riemannian geometry to push the limits of general relativity beyond the Big Bang singularity.
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Contribution: Poster
Title: The QCD phase-diagram obtained from NJL and extended-NJL models for quark and hadron phases
Author(s): Clebson Abati Graeff, Débora Perez Menezes
Abstract: Abstract: We analyse the hadron/quark-gluon-plasma phase transition described by the Nambu-Jona-Lasinio (NJL) model [quark phase] and the extended Nambu-Jona-Lasinio model (eNJL) [hadron phase]. While the original formulation of NJL model is not capable of describing hadronic properties due to its lack of confinement, it can be extended with a scalar-vector interaction so it exhibits this property, the so-called eNJL model. As part of this analysis, we obtain the equations of state within the SU(2) versions of both models for for the hadron and the quark phases, and determine the binodal surface.
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Contribution: Poster
Title: Submergence and re-difussion of magnetic field post core-collapse
Author(s): Cristian G. Bernal
Abstract: I revisit the hyperaccretion phase, in the core-collapse supernova scenario, when a reverse shock is formed few moments after the explosion. We focus our study on the complex dynamics present in the system when strong accretion allows depositing large amounts of matter onto the stellar surface and we follow their consequences. We carry out magnetohydrodynamic numerical simulations of the hypercritical regime, using the AMR Flash method.
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Title: Quadrupole of a composite mass otimization in very high speed using FEM
Author(s): Daniel Coppede, Paulo Roberto Murger Nogueira, Carlos Frajuca
Abstract: A experiment to measure the velocity of gravity is been planning. In order to achieve a reasonable signal in the detector, a very massive quadrupole mass is put to rotate at a very high rotation speed. In order to maximize the signal, the product mass and rotation radius squared much be as higher as possible. This work test a composite mass-quadrupole geometries in Finite Element Modeling with the goal to maximize the signal.
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Contribution: Oral
Title: Constraints on the braneworld from compact stars
Author(s): R. González Felipe, D. Manreza Paret, A. Pérez Martínez
Abstract: According to the braneworld idea, ordinary matter is confined on a 3-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman-Oppenheimer-Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.
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Contribution: Poster
Title: Dark Matter in a Bimetric Portal
Author(s): Dimiter Hadjimichef
Abstract: One of the great mysteries in current physics is the nature of dark matter. Originally discovered as a form of "unseen" matter that modified the dynamics of galactic clusters. Today dark matter is extensively studied in astrophysics and in particle physics. Arguments are brought forward to consider a form dark matter, manifested as a broken local dual symmetry of a bimetric spin-2 theory in the Fierz representation.
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Contribution: Poster
Title: Energy spectrum of cosmic ray nuclei
Author(s): Eak raj Paudel
Abstract: The energy spectrum is heavily dominated by light nuclei . It has been found that the lower energy cosmic ray flux is maximum than higher energy cosmic ray flux for all types of nuclei under study. The relationship between magnetic rigidity and flux value is also developed in this work. The magnetic rigidity R of a particle is a measure of its resistance to a magnetic force that deflects the particle from straight line trajectory.
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Contribution: Poster
Title: A vibration isolation and cooldown system for the mirrors of the laser interferometric gravitational-wave detectors
Author(s): Elvis Camilo Ferreira, Marcio Constancio Jr, Odylio Denys Aguiar, Allan Douglas dos Santos Silva
Abstract: The direct detection of gravitational waves (GW) by the LIGO (Laser Interferometric Gravitational-Wave Observatory) inaugurated the GW astronomy. The investigation of astrophysical objects and systems by GW requires very high sensitivity detectors, due to the relatively very small wave amplitudes. Therefore, it is necessary to reduce the effect of the detector noise sources. Therefore, we developed for the LIGO Voyager mirrors a vibration isolation and cooldown system using a Multi-Nested Pendula (MNP) with Geometric Anti-Springs. We present some results of the experimental tests of the MNP with GAS, and thermal simulations to cool the interferometer mirrors down.
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Contribution: Oral
Title: Neutrino-nucleus cross sections for studies of supernova neutrinos
Author(s): E. Ydrefors, W. Almosly, J. Suhonen, T. Frederico
Abstract: Neutrinos produced by supernovae provide very important information regarding both the dynamics of supernova explosions and of elementary properties of neutrinos, such as neutrino flavor conversions, etc. From the astrophysical point of view, knowledge about neutrino-nucleus reactions is crucial for applications such as nucleosynthesis of heavy nuclei Neutrinos interact with matter only through the weak interactions. Therefore, Earth-bound neutrino experiments based on charged-current and/or neutral-current neutrino-nucleus scattering can be used to detect supernova neutrinos. Theoretical estimates of the cross sections for neutrino-induced interactions on nuclei are crucial for the interpretation of the results from future neutrino experiments. Additionally, nuclear-weak interactions play a crucial role in supernova explosions. In this contribution we discuss results from recent calculations [1,2,3] of neutrino-nucleus cross sections for nuclei which are of interest for the detection of supernova neutrinos. We discuss the influence of the nuclear structure on the cross sections, as well as challenges and future aspects of the aforementioned calculations. [1] E. Ydrefors, J. Suhonen and Y. M. Zhao, Neutrino-nucleus scattering off $^{136}, Phys. Rev. C 91 (2015) 014307. [2] W. Almosly, et al , Theoretical estimates of supernova-neutrino scattering off the stable even-even lead isotopes: charged-current reactions, submitted to Phys. Rev. C. [3] W. Almosly, et al, Charged-current neutino and antineutrino scattering off 116 Cd described by Skyrme forces, Phys. Rev. C 89 (2014) 024308.
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Contribution: Poster
Title: QCD dynamics of proton-proton scattering at cosmic-ray energies
Author(s): Emerson Gustavo de Souza Luna
Abstract: We present an eikonal model in which the energy dependence of the proton-proton total cross section is obtained from the QCD using a formulation compatible with analyticity and unitarity constraints. More precisely, the behavior of the total cross section is derived from the parton model using standard QCD cross sections for elementary parton-level processes, updated sets of quark and gluon distribution functions and physically-motivated cutoffs which restrict the elementary processes to semihard ones. We discuss the behavior of the scattering amplitude at very high energies within the QCD-based formalism and show that the AUGER and Telescope Array results for the proton-proton total cross section are well described by our eikonal model.
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Contribution: Oral
Title: DUNE: next generation of precise measurements in neutrino sector
Author(s): Ernesto Kemp for the collaboration DUNE
Abstract: The last decade was remarkable for neutrino physics. In particular, the phenomenon of neutrino flavor oscillations has been firmly established by a series of independent measure-ments using solar, atmospheric, reactor and accelerator neutrino beams. All parameters of the neutrino mixing matrix are now known, and we have the elements to plan a judicious exploration of new scenarios that are opened by these recent advances. It is time to go further with precise measurements to test the 3-neutrino paradigm and important questions like the neutrino mass hierarchy and CP asymmetry in the lepton sector. Within this context the future long-baseline experiments are considered to be a fundamental tool to deepen our knowledge of electroweak interactions. The Deep Underground Neutrino Experiment – DUNE will detect a broad-band neutrino beam from Fermilab in an underground massive Liquid Argon Time-Projection Chamber at an L/E of about 10ˆ3 km / GeV to reach good sensitivity for CP-phase measurements and the determination of the mass hierarchy. The dimensions and the depth of the Far Detector also create an excellent opportunity to look for rare signals like proton decay to study violation of baryonic number, as well as supernova neutrino bursts, broadening the scope of the experiment to astrophysics and associated impacts in cosmology. In this presentation, we will discuss the physics motivations and the main experimental features of the DUNE project required to reach its scientific goals.
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Contribution: Poster
Title: Topics on noncommutative cosmology
Author(s): Everton M. C. Abreu
Abstract: In this work we will analyze some issues concerning noncommutative cosmology such as inflation, black holes and wormholes. We will see that some ideas like the age of the Universe and the radius of a black hole can be altered. The wormholes discussed here have a rotational throat, and the angular momentum is also altered thanks to the noncommutative feature of the space. However, it is important to stress that the physics of these objects and concepts suffer no modification in a noncommutative space-time background. For example, the accelerated characteristic of the Universe as well as the breaking of the energy rules by the wormholes are not modified, as well known.
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Contribution: Poster
Title: Gravitoelectromagnetism revisited: The Lense and Thirring equations from a generalized Helmholtz theorem for time-varying vector fields
Author(s): F. T. Dalmolin
Abstract: Among the results of the Einstein's General Relativity there are the so famous Gravitoelectromagnetism equations, so named because of the great similarity with the Maxwell's equations of electromagnetism. In general relativity, these equations are derived from the pioneering work of Lense and Thirring thatthrough a linearization of Einstein's field equations for a rotating body could get a generalization of the contribution of gravitomagnetic field. However, it is known from literature that the equations have a serious problem of divergence, which leads to violation of the unicity of the fields. In this work we start from the Helmholtz theorem for time-varying vector fields in order to obtain the Lense and Thirring equations by a more general way, supported on a mathematical theorem. Finally we discuss the results.
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Contribution: Oral
Title: A new approach to the thermal evolution of neutron stars
Author(s): Rodrigo Negreiros, Stefan Schramm and Fridolin Weber
Abstract: In the work we continue our research of the thermal evolution of rotating neutron stars. We have previously calculated the thermal evolution of neutron stars undergoing spin-down, focusing on the effects that a dynamic composition change may have on the cooling. We havel also calculated the thermal evolution of rotating neutron stars (with a constant frequency) under the full effect of general relativity. The work presented here is the culmination of these two studies, in which we show, for the first time, the thermal evolution of rotating neutron stars that are undergoing spin-down (or up). We self-consistently calculate the evolution of the structure of the star during its spin-down, coupled to the thermal evolution of the object. In such manner, we are able to see how the dynamical composition together with the structure and metric composition affect the thermal evoluion of such objects. This work opens the possibility for the investigation of several scenarios, forbidden by the traditional "frozen-in" cooling calculations, such as thermal evolution of accreting neutron stars, whose composition changes due to the addition of mass and heat.
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Contribution: Poster
Title: Stability of charged white dwarfs
Author(s): Geanderson A. Carvalho, José Domingo Arbañil Vela, Rubens M. Marinho jr, Manuel Malheiro
Abstract: Recently were discovered superluminous type Ia Supernovae [1] [2] in which some authors suggest that their progenitors have a mass that exceed the Chandrasekhar mass limit. In view of this we follow the idea that a net charge distribution can generate theoretically white dwarfs with a mass that significantly exceed the Chandrasekhar mass limit [3]. In this work we did a better estimative of the effect of a net charge distribution in a general relativistic context being more carefully about the effects of the net charge to the Equation of State (EoS) for White Dwarfs and how this net charge distribution is related to mass distribution in such stars. Finally we use Tolman-Oppenheimer-Volkoff equation to find a mass-radius relation for these stars and we use radial oscillations equations to study their stability using general relativity. The conclusions about this work are still object of discussion. [1] D. A. Howell et al., Nature (London) 443, 308 (2006). [2] R. A. Scalzo et al., Astrophys. J. 713, 1073 (2010). [3] H. Liu et al., Phys. Rev. D 89, 104043 (2014).
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Contribution: Poster
Title: Magnetized Neutron Stars
Author(s): Gibran Henrique de Souza, Ernesto Kemp, Cecilia Chirenti
Abstract: Here we solve numerically the relativistic Grad-Shafranov equation, that describes the vector potential behavior, for a typical neutron star having as equation of state the matter described by Akmal, Pandharipande and Ravenhall (APR2).
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Contribution: Poster
Title: Mimetic Dark Matter in Pseudo-complex General Relativity
Author(s): Guilherme Lorenzatto Volkmer, Dimiter Hadjimichef
Abstract: We investigate the dark matter problem in the context of Pseudo-complex General Relativity. A form of gravitational dark matter has recently been studied, the mimetic dark matter, which is a scalar tensor extension for gravity where the conformal degree of freedom is isolated in a covariant way. For such, we perform a combination of both approaches to reveal non trivial results even in the absence of matter. Solutions for different scenarios and possible interpretations are presented.
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Contribution: Poster
Title: A Model of the Braking Index of Pulsars
Author(s): Heitor Oliveira de Oliveira, Rubens de Melo Marinho Jr and Nadja Simão Magalhães
Abstract: In this work we present our proposal of a model for pulsars' rotation frequency decay by modifying an assumption of the canonical model. Starting from the model of spin powered pulsars, where the electromagnetic energy is provided by the rotational energy, we explore the influence of the variation of the star radius on the value of the braking index considering a theoretical model. We find that the braking index gets smaller as the star radius increases, also implying a higher moment of inertia. This contribution does not alter the emission of magnetic dipole energy but reduces the star's angular velocity and consequently, the frequency of the light pulses of the pulsar, as is observed. We tested our model with data of seven pulsars with observed braking indices, obtaining good results.
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Title: Piercing the Vainshtein screen with anomalous gravitational wave speed: Constraints on modified gravity from binary pulsars
Author(s): J. Beltran, F. Piazza and Hermano Velten
Abstract: By using observations of the Hulse-Taylor pulsar we constra in the gravitational wave (GW) speed to the level of 10^{-2}. We apply this result to scalar-tensor theories that generalize Galileon 4 and 5 models, which display anomalous propagation speed and cou pling to matter for GWs. We argue that this effect survives conventional screening due to the p ersistence of a scalar field gradient inside virialized overdensities, which effectively “pierces” the Vainshtein screening. In specific branches of solutions, our result allows to directly constrain the co smological couplings in the effective field theory of dark energy formalism. [PRL 116, 061101 (2016) ]
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Contribution: Oral
Title: Self-Mgnetization of the Fermi gas
Author(s): H. Pérez Rojas et al.
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Contribution: Poster
Title: Temperature Noise Profile of Mario Schenberg GW Detector
Author(s): Ivana F. Cunha, R. M. Marinho Jr.
Abstract: Gravitational waves (GW) were foresee by Einstein in his general theory of relativity. They have been detected for the fist time by the LIGO collaboration in September 15, 2015. They are ripples in space-time produced always when masses are accelerated asymmetrically. They interact weakly with matter so that only catastrophic events in the Universe can be detected. It is possible to detect a GW by monitoring the normal mode of oscillations of a resonant mass. The Brazilian Mario Schenberg detector is such kind of detector in spherical format. Due to the weakness of the GW arriving at the detector, many kinds of noise become important. One of them is the noise temperature. Therefore is important to characterize the noise temperature of a detector in order to estimate the probability that a candidate signal is not a noise. In this work, using the data from a October and November, 2015 of the Schenberg's detector commissioning run, we present the Gaussian noise distribution for short burst signals.
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Title: Observing relativistic effects near compact objects with MIRAX
Author(s): João Braga
Abstract: The observation of X rays coming from the inner regions of the accretion flow onto compact objects like neutron stars and black holes is a powerful tool to probe general relativistic effects. Precise timing of the X-ray flux can unveil frequencies associated with motion under Kerr metric like Lense-Thirring precession, Bardeen-Peterson effect and periastron precession. Spectral fitting can provide important information about the spin of black holes thought the determination of the radius of the innermost stable circular orbit (ISCO) of the accretion disk. Distorted emission lines can also probe the transverse Doppler shift and the gravitational redshift. In this work we shot the contribution that the MIRAX mission will be able to make toward measuring these effects on Galactic X-ray binaries and supermassive black holes in Active Galactic Nuclei.
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Title: Inside real neutron stars: observations and theory of pulsar crusts/magnetospheres
Author(s): J.E. Horvath
Abstract: We review in this talk the issue of pulsar timing irregularities, generally tied to the existence of superfluid components in the (solid) crust of the star. We show how these data is useful to characterize and constrain this crust, and also how non-standard torques may be required to fully explain the trajectories of pulsars in the ${\dot{P}}-P$ plane, with possible consequences for the existence of magnetars.
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Contribution: Oral
Title: Three-body heavy meson decays with final state interactions and CP violation
Author(s): J.H. Alvarenga Nogueira and T. Frederico
Abstract: The formation of CP violation (CPV) constrained by CPT invariance is affected by resonances and final state interactions (FSI). Starting from the CPT constraint, a generalized CP asymmetry formula including resonances and FSI is computed without the three-body FSI contribution. A simple B decay model is elaborated with the $\rho$ and $f_0$(980) resonances plus a non resonant background including the $\pi\pi \to KK$ coupled amplitude. Performing the fit of the CP asymmetry for one charmless three-body $B^\pm$ decay channel the formula presents fair agreement with the high statistics LHCb data in the mass region below 1.6 GeV and we obtain as outcome a coupled decay channel for the channel asymmetry. The model is extended to study the CP violation in the high mass energy region. The CPV occurring in this sector of the phase space could be associated with the final state interaction coupling the pair of light pseudo-scalars to double charm B decay channels. We also discuss the three body final state interaction (FSI) contribution to B decay within a light-front framework, considering S-wave interactions decomposed in isospin states. The convergence of the rescattering series can be checked computing terms in an incrasing perturbative order.
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Contribution: Oral
Title: Dormant Black Holes
Author(s): J.A. de Freitas Pacheco
Abstract: Supermassive black holes in the center of galaxies can be in a dormant state, that is not accreting matter. These black holes manifest from time to time an electromagnetic or gravitational activity by tidally disrupting nearby stars or by capturing compact objects like neutron stars or stellar black holes. I discuss these processes providing the expected rate of gravitational wave signals and the light curve for tidal events.
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Contribution: Oral
Title: The effect of the anisotropy on the stability of strange stars
Author(s): José D. V. Arbañil and Manuel Malheiro
Abstract: The influence of the anisotropy in the equilibrium and stability of strange stars is investigated through the numerical solution of the hydrostatic equilibrium equation and the radial oscillation equation, both modified from their original version to include these effects. Two different kinds of local anisotropic equations of state are considered. One that is nonnull at the star's surface and other one that is null on it, namely, $\sigma_s=0$ and $\sigma_s\neq0$. When $\sigma_s=0$, we found that in strange stars the central energy density used to reach the maximum mass value is the same used to determine the zero frequency of oscillation, indicating of this way that the maximum mass marks the onset of the instability. In turn, when $\sigma_s\neq0$, the maximum mass point and the zero frequency of oscillation are derived from the same central energy density only in a sequence of stars with the same value $\sigma_s$. I.e., in a sequence of equilibrium configurations with the same value of $\sigma_s$, the regions constituted by stable and unstable configurations against radial oscillations can be determined always by the conditions $dM/d\rho_c>0$ and $dM/d\rho_c<0$, respectively.
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Contribution: Poster
Title: Gamma ray bursts and stellar evolution
Author(s): Kauan Dalfovo Marquez, Débora Peres Menezes
Abstract: Gamma ray bursts are distinguished mainly by their duration and the energies released and they are known as soft (SGRBs) and long (LGRBs) gamma ray bursts. The total nergy released in the first few hundred seconds is of the order of $10^{50}$ erg, which is two or three orders of magnitude smaller than seen in LGRBs. Not long ago it was proposed that LGRBs can be a manifestation of a phase change in the interior of a neutron star, causing a conversion of a hadronic star into a quark star. Recent observational results, as the existence of 2 $M_\odot$ neutron stars with relatively small radii, have constrained relativistic equations of state (EOS) from more than two hundred to about 3 dozens. The energetics of the LGBRs will be revisited and only accepted EOS will be used. The results will be confronted with the results of the released energy in LGRBs.
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Contribution: Oral
Title: White Dwarf Stars
Author(s): S. O. Kepler
Abstract: We study the white dwarf mass and distance distribution, and the discovery of a normal mass white but devoided of any H,He and C.
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Title: Statical properties of CMB B-mode polarisation
Author(s): L. Santos, Y. R. Hu, K. Wang and W. Zhao
Abstract: The next target of cosmic microwave background (CMB) experiments is the detection of the primordial B-mode polarisation signal generated by gravitational waves (GWs) in the early universe, as predicted by inflationary models. However, GWs are not the only source of B-mode polarisation in CMB: weak gravitational lensing of the CMB photons due to large-scale structure along the line of sight converts part of E-mode polarisation into B-mode component. In addition, foreground residuals can mimic CMB B-mode polarisation and must be studied in detail. Moreover, in a realistic point of view, the CMB B-map must be generated from partial sky maps due to Galactic contaminations even in the case of satellite surveys. The incomplete sky coverage leads to the so called E-to-B leakage that increases the uncertainty of the estimated primordial B-mode signal. Therefore, considering the LCDM model, the total B-mode map is then a non-Gaussian field due to different contaminations t o the gaussian primordial signal. For non-gaussian fields, in addition to the power spectrum, other statistics must considered, as for example the Minkowski Functionals (MFs). We will use the MF as a tool to study the imprint of different components in the total B-mode map, especially the E-to-B leakage.
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Contribution: Oral
Title: Cosmicmagnetism in alternative theories of gravity
Author(s): Garcia de Andrade
Abstract: The present status of cosmic magnetism is briefly reviwed and new results presented based on the works of K Bamba and myself with special enphases of cosmoc magnetic seeds and dynamos in torsion cosmology.
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Contribution: Poster
Title: Detonation Wave by Hadron-Quark Phase Transition into Compact Stars
Author(s): Luis Gustavo de Almeida, Hilário A. Rodrigues, Sérgio B. Duarte
Abstract: In this work we present an effective description of the detonation wave formation in hadronic matter inside a protoneutron star core. We have used a simplified two shell model where the inner shell medium is initially composed of a small lump of strange quark matter surrounded by a thick outer shell composed of hadronic matter. We have used an equation of state (EOS) based on Relativistic Mean Field Theory with the coupling parameter set NL3 to describe the nuclear phase and a Virial expansion to describe the subnuclear phase. We used the MIT bag model to describe the strange quark matter. The hadron-quark phase transition actually induces highly non equilibrium modes, which may become a detonation process (faster) or a burning process (slower). The main purpose of the work is to study the formation of a remnant quark star and the possibility of mass ejection caused by the hadron-quark phase transition. We have found that the total amount of ejected mass is dependent on the bag model constant used in the strange matter description.
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Contribution: Oral
Title: Luminosity Function statistics applied in GRB samples
Author(s): L. J. Rangel Lemos, C. L. Bianco, R. Ruffini
Abstract: The luminosity function (LF) statistics applied in data of GRBs detected by GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We produced, by LF statistics, the GRB predicted distributions of: peak flux N(Fpk), redshift N(z) and peak luminosity N(Lpk). We also used differents GRB rates. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with more then 250 GRBs with known redshifts. We estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy.
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Title: Total, Elastic and Single Diffractive Cross Sections for LHC energies in Miettinen-Pumplin Model
Author(s): Mairon Melo Machado, Magno Valério Trindade Machado
Abstract: In this contribution we provide predictions for total, elastic and single diffractive cross sections calculated to proton-proton collision at LHC energies (in centre-of-mass energy 0,9 TeV, 7 TeV, 8 TeV and 14 TeV) considering the framework from the Miettinen-Pumplin model. Such an approach has correctly described the data available at Fermilab-Tevatron energies. Our predictions are based on E811 and CDF sigma_tot and sigma_el data, which gives about 10% of the total cross sections for the diffractive cross sections in all range of energies, and it is in agreement with the CERN-ATLAS Collaboration experimental result.
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Contribution: Poster
Title: THE MIRAX MISSION: SIMULATIONS OF BACKGROUND AND IMAGING RECONSTRUCTION
Author(s): Manuel Castro, João Braga, Flávio D'Amico, Ana Penacchioni, Rodrigo Sacahui
Abstract: The MIRAX mission will be the first Brazilian-led mission focused on the study of the X and gamma-ray emission from astrophysical sources. The mission will conduct a deep, high resolution survey of the Galactic plane in order to measure the black hole vs neutron star populations and study high energy time domain astrophysics of compact objects. The mission is planned to be launched into a near-equatorial circular 650-km orbit. The instruments on board will be hit by particles coming from all directions. These interactions will produce an intense background that affects the instrument’s sensitivity and imaging capabilities. In this work, we will present the results of detailed simulations using the package GEANT4, that allows us to study the radiation detected by the experiment by tracking each kind of particle into the instrument. We considered five background sources at the expected orbit: cosmic diffuse Gamma-ray radiation, albedo gamma-ray photons, Galactic cos mic rays (GCR), trapped protons and neutrons. For each radiation field we have simulated its spectral and angular distributions, and simulated the interaction of the particles with the instrument's geometry in order to calculate its contribution and effects in the imaging reconstruction when astrophysical sources are observed.
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Contribution: Oral
Title: Ansatz for dense matter equation of state
Author(s): Marcelo D. Alloy (UFSC), Débora P. Menezes (UFSC) e Manuel Malheiro (ITA)
Abstract: Recently, two massive pulsars were observed, PSR J1614-2230 and PSR J0348+0432, causing excitement between theorists. The first one was observed in 2010 with mass (1.97 ± 0.04) solar masses and the second one was observed in 2013 with mass (2.01 ± 0.04) solar masses. The maximum mass of a neutron star is a very important constraint in the description of dense matter. In this work, we assume that the equation of state is given by p=Ae^c+Be, where p is the pressure, e is the energy density, and A, B and C are free parameters that we vary in order to satisfy both the TOV equations and the baryonic density restricted to theoretical and observational constraints.
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Contribution: Oral
Title: Gravitational waves in running vacuum cosmologies
Author(s): D.A. Tamayo, J.A.S. Lima, M.E.S. Alves, J.C.N. de Araujo
Abstract: We investigate the cosmological production of gravitational waves for a non- singular flat cosmology driven by a decaying vacuum energy density. The model studied can be interpreted as a particular case of the class recently discussed by Perico et al. (Phys. Rev. D 88, 063531, 2013) which is termed complete in the sense that the cosmic evolution occurs between two extreme de Sitter stages (early and late time de Sitter phases). The gravitational wave equation is derived and its time-dependent part numerically integrated since the primordial de Sitter stage. The transition from the early de Sitter to the radiation phase is smooth (no exit problem) and the generated spectrum of gravitons is compared with the standard calculations where an abrupt transition is assumed. It is found that the stochastic background of gravitons is very similar to the one predicted by the cosmic concordance model plus inflation except for the higher frequencies (f ~ 100 kHz). This remarkabl e signature of a decaying vacuum cosmology combined with the proposed high frequency gravitational wave detectors of improved sensitivity may provide in the future a crucial test for inflationary mechanisms.
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Contribution: Poster
Title: Dark Energy: Evidences, Interpretations and Models
Author(s): Maria Luiza Cescato
Abstract: We examine the experimental evidences that give us confidence in the existence of a dark energy component to the total energy density in cosmology. These evidences are presented in chronological order, from the first indications and confirmations as a “discovery” up to the more recent ones. Parallel to this presentation we consider a variety of possible interpretations of the data. Different models for the explanation of the dark energy density component, proposed in the literature, are described and compared, trying to emphasize differences, similarities and pointing out their successes and difficulties.
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Contribution: Oral
Title: Braneworld scenarios from deformed defect chains
Author(s): Mariana Chinaglia, Alex de Bernardini, Roldão da Rocha.
Abstract: Novel braneworld scenarios supported by warp factors driven by a single extra dimension are obtained from deformed one-dimensional lump-like solutions known a priori. Through a novel ansatz, the internal energy structure, the braneworld warp factor, and the quantum mechanical analogue problem, as well as the associated zero mode solutions, are straightforwardly derived by means of an analytical procedure. The results allow one to identify thick brane solutions that support internal structures and that can hold the (3 + 1)-dimensional gravity.
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Contribution: Poster
Title: Regge phenomenology at LHC energies
Author(s): C. A. S. Bahia, M. Broilo, E. G. S. Luna
Abstract: Regge theory is presently a valued tool in the investigation of the main features of soft hadronic interactions and an important guide in the search of a fundamental theory for soft processes based upon QCD. At high energies the Pomeron plays a crucial part in describing the soft interactions. In the light of LHC data we perform a detailed analysis of proton-proton and antiproton-proton forward scattering data, and obtain extrema bounds for the soft Pomeron intercept using both eikonal and Born-level amplitudes. In our analysis we investigate the effects of exponential and power-like forms for the elastic Pomeron-proton vertex. In order to improve the large $b$ region we incorporate the nearest $t$-channel singularity of the Pomeron trajectory, namely the two-pion loop. WE give predictions for proton-proton total cross section at Tevatron, LHC, and cosmic-ray energies.
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Contribution: Poster
Title: Simplified thermal evolution of proto-hybrid stars
Author(s): Mauro Mariani, Milva Orsaria, Héctor Vucetich
Abstract: We study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. We also discuss the strange quark matter stability in the quark matter phase. Furthermore, we analyze the astrophysical properties of hot and cold hybrid stars, considering the recent constraint on maximum mass given by the pulsars PSR J1614-2230 and PSR J1614-2230. We obtain cold hybrid stars with maximum masses >2M_Sun and analyze, in a simplified way, different stages of hot hybrid stars as a first approximation to the cooling evolution of neutron stars with quark matter cores.
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Contribution: Poster
Title: The generalized expression for symmetry energy in a class of nonliner relativistic nuclear models
Author(s): Moisés Razeira and Cesar A. Z. Vasconcellos
Abstract: The symmetry energy play an important role in nuclear astrophysics, ranging from structure of nuclei to neutron stars physics. In this work we have derived a simple semi-analitc expression for the symmetry energy in an frame work of generalized derivative coupling model for dense nuclear matter. We have investigated the density dependence of symmetry energy for highly asymmetric nuclear matter with explicit inclusion of the scalar isovector meson.
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Title: Dimensionally compactified Chern-Simon theory in 5D as a gravitation theory in 4D
Author(s): Ivan Morales, Bruno Neves, Zui Oporto, Olivier Piguet
Abstract: We propose a gravitation theory in 4 dimensional space-time obtained by compacting to 4 dimensions the five dimensional topological Chern-Simons theory with the gauge group SO(1,5) or SO(2,4) -- the de Sitter or anti-de Sitter group of 5-dimensional space-time. In the resulting theory, torsion, which is solution of the field equations as in any gravitation theory in the first order formalism, is not necessarily zero. However, a cosmological solution with zero torsion exists, which reproduces the Lambda-CDM cosmological solution of General Relativity. Attempts to find realistic solutions with spherical symmetry are also considered. Finally, ways of quantizing the theory are discussed.
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Contribution: Oral
Title: Neutrino decay and seasonal effect
Author(s): Renan Picoreti, Marcelo Moraes Guzzo, Pedro Cunha de Holanda, Orlando Luis Goulart Peres
Abstract: We consider the possibility of solar neutrino decay as a sub-leading effect on their propagation between production and detection. Using current oscillation data, we set a new lower bound to the neutrino lifetime. Also, we show how seasonal variations in the solar neutrino data can give interesting additional information about neutrino lifetime
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Contribution: Poster
Title: Quadrupole Mass otimization in very high speed using FEM
Author(s): Paulo Roberto, Murger Nogueira, Carlos Frajuca
Abstract: An experiment to measure the velocity of gravity is been planning. In order to achieve a reasonable signal in the detector, a very massive quadrupole mass is put to rotate at a very high rotation speed. in order to maximize the signal, the mass much be as higher as possible. This work test mass-quadrupole geometries in Finite Element Modeling with the goal to maximize the signal
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Contribution: Oral
Title: ON PAIR INTABILITY SUPERNOVAE EXPLOSION AND GAMMA-RAY BURSTS
Author(s): P. CHARDONNET, A. BARANOV, V. CHECHETKIN, A. FILINA, M. POPOV and N. SMIRNOVA
Abstract: The enigma of cosmic gamma-ray bursts is tool to understand how a star ends his life with this magnificent firework. The standard fireball scenario developed during many years has provided a possible explanation of this phenomena. The aim of this presentation is simply to explore a new possible interpretation; by developing a coherent scenario inside the global picture of stellar evolution, as a missing link of stellar evolution. At the basis of our scenario is the fact that maybe we have not fully understood how the core of a pair instability supernovae explode. In such a way, we have proposed a new paradigm assuming that the core of such massive star, instead of doing a symmetrical explosion, is completely fragmented in hot spots of burning nuclear matter. We have tested our scenario using some observational data like GRB spectra, light curves, Amati relation and GRB-SN connection, and for each set of data we have proposed a possible physical interpretation. We have also suggested some possible tests of this scenario by measurements at high redshift.
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Title: Thermodynamics of nonsingular bouncing universes
Author(s): Pedro C. Ferreira, Diego Pavón
Abstract: Homogeneous and isotropic, nonsingular, bouncing world models are designed to evade the initial singularity at the beginning of the cosmic expansion. Here, we study the thermodynamics of the subset of these models governed by general relativity. Considering the entropy of matter and radiation and considering the entropy of the apparent horizon to be proportional to its area, we argue that these models do not respect the generalized second law of thermodynamics, also away from the bounce.
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Contribution: Poster
Title: Tsallis statistics and hadronic matter
Author(s): Débora Peres Menezes and Pedro Henrique Goulart Cardoso
Abstract: In this work we intend to get physical properties of quark stars using the MIT bag model to obtain the equations of state and the Tolman-Oppenheimer-Volkoff for the profile of star. The proposal is to replace the Fermi-Dirac statistics used to describe the fermi gas in the Mit bag model, by Tsallis statistics. We seek with this non-additive statistics, but extensive for complex systems, get new results related to the profile of a possible quarks star and compare them with observational data.
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Contribution: Oral
Title: Pseudo-Complex General Relativity
Author(s): Peter O. Hess
Abstract: I will present the present status of the pseudo-complex General Relativity. It will be shown that it contains many known theories with a minimal length. Retricting to its simplest form, an energy-momentum tensor is added at the right hand side of the Einstein equations, representing a dark energy, related to vacuum fluctuations. We use a phenomenological ansatz for the denisty and discuss observable consequences.
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Contribution: Oral
Title: Kaluza-Klein cosmological model in f(R; T) gravity with domain walls
Author(s): Pradyumn Kumar Sahoo
Abstract: We have investigated the physical behavior of ve dimensional Kaluza-klein cosmological model in frame work of f(R; T) theory of gravity in presence of domain walls. Here R is the Ricci scalar and T is the trace energy tensor. To determine the solution of field equation we consider the special law of variation parameter proposed by Berman [1] that yields a constant deceleration parameter. Some physical properties of the model are discussed.
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Contribution: Oral
Title: Application of Modern Neutron Star Equations of State in the study of SGRs and AXPs Properties
Author(s): Rafael C. R. de Lima; Jaziel G. Coelho; Diego L. Cáceres; Jorge A. Rueda; and Remo Ruffini
Abstract: We show that nine of the twenty three soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs), namely the 40% of the entire observed population of sources, can be described as canonical pulsars driven by the rotational energy of a neutron star (NS), for which we give the possible range of masses. We also show that if the blackbody component in soft X-rays is due to the surface temperature of the NS, then two more sources become explainable as rotation-powered NSs, leading to a 50% of the population explainable as ordinary pulsars. We show that, within these sources, we find the SGRs/AXPs with observed radio emission as well as the ones possibly associated with supernova remnants, reinforcing a natural explanation for these sources as ordinary pulsars. Assuming on the other hand an alternative model in which SGR/AXPs are rotation-powered white dwarfs (WDs), we show that the entire population can be explained within this scenario. We give tight bounds for the masses, radii, and magnetic field of the WD by requesting the gravitational and rotational stability of the star.
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Contribution: Oral
Title: Testing anomalous diffusion models for simulation of initial density fluctuation spectra in hierarchical large scale structure formation
Author(s): Reinaldo R. Rosa, Fernando A. Oliveira, M.A.P. Baroni, Julio C.G. de Freitas and Diego H. Stalder
Abstract: It is already known that structure formation was predominately at superhorizon scales during the inflation era and so must be treated by general relativity. However, in specific periods when dissipation becomes significant, the influence of fluctuation to structure formation is of subhorizon scales, and can be described by a non relativistic approximation. In this framework, the hypothesis of non-Gaussian stochastic processes has become important in the study of the structure formation in hierarchical scenarios. In this work we present the application of anomalous diffusion models (especially KPZ-equation and equivalent automata) to simulate density fluctuation spectra in the Lambda-CDM cosmology. The models are tested in the following ways: fluctuation maps are generated serving as initial conditions in large-scale structure formation. The anomalous diffusion spectra are validated based on the statistical properties of voids and filaments obtained for low redshifts (z < 1).
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Contribution: Oral
Title: GRBs, Crab Nebula and Active Galactic Nuclei
Author(s): Remo Ruffini
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Contribution: Oral
Title: Chiral symmetry restoration for quark matter with a chiral imbalance: agreement with lattice results
Author(s): Ricardo L. S. Farias, D. C. Duarte, G. Krein and R. O. Ramos
Abstract: There has been recently an increased interest in the study of how a chiral imbalance of right-handed and left-handed quarks can influence the phase diagram of quantum chromodynamics (QCD). There are many good reasons for this interest. For instance, the nontrivial nature of the vacuum of non-Abelian gauge theories in general, and of QCD in particular, allows for the existence of topological solutions like instantons and sphalerons. A chirality imbalance is expected to occur in event-by-event in heavy-ion collision experiments (C and CP violations). When these effects are associated with a magnetic field, they can induce an electric current due to the chirality imbalance, an effect dubbed the chiral magnetic effect (CME) in the literature. The effects of a chiral imbalance in the phase diagram of QCD can be studied in the grand canonical ensemble by the introduction of a chiral chemical potential mu_5 in the QCD Lagrangian density. It is intriguing that models that h ave been very successful in describing many features predicted by universality arguments and lattice simulations for the chiral transition in QCD at nonzero T and mu, have difficulties in reproducing, even at a qualitative level, recent lattice results for the chiral critical transition temperature T_c at finite mu_5. We show how a simple scheme of rewriting a divergent momentum integral can reconcile conflicting results obtained for the chiral critical transition line between some effective models for Quantum Chromodynamics (QCD) and recent lattice results, when in the presence of a chiral imbalance. Our results show an increasing critical temperature for chiral symmetry restoration as a function of the chiral chemical potential mu_5. This result is consistent with recent lattice results and also with some other more involved analytical and numerical nonperturbative studies.
Contribution: Poster
Title:
Neutral pion pole mass calculation in a strong magnetic field: Lattice QCD versus NJL model
Author(s):
Ricardo L. S. Farias, Sidney S. Avancini, Marcus Benghi Pinto, William R. Tavares, Varese S. Timóteo
Abstract:
The $\pi_0$ neutral meson pole mass is calculated in a strongly magnetized medium using the
SU(2) Nambu-Jona-Lasinio model within the random phase approximation (RPA) at zero temperature
and zero baryonic density. We employ a magnetic field dependent coupling $G(eB)$ fitted
to reproduce lattice QCD results for the quark condensates. Divergent quantities are handled with a magnetic
field independent regularization scheme in order to avoid unphysical oscillations. A comparison
between the running and the fixed couplings reveals that the former produces results much closer to the
predictions from recent lattice calculations. In particular, we find that the $\pi_0$ meson mass systematically
decreases when the magnetic field increases while the scalar mass remains almost constant.
We also investigate how the magnetic background influences other mesonic properties such as
$f_{{\pi}_0}$ and $g_{\pi_0 q q}$. The results obtained
in this work seem to indicate that the use of a running coupling within a robust theoretical framework,
such as the RPA-MFIR, turns the simple NJL into
a useful tool to investigate magnetized quark matter.
Contribution: Poster
Title:
Exploring Hot QCD in Magnetic Fields
Author(s):
Ricardo L. S. Farias, Varese S. Timóteo, Sidney S. Avancini, Marcus Benghi Pinto, Gastão I. Krein
Abstract:
The investigation of the effects produced by a magnetic field in the phase diagram of strongly interacting matter became a subject of great interest in recent years. The recent motivation stems mainly from the fact that strong magnetic fields may be produced in noncentral heavy-ion collisions. Strong magnetic fields are also present in magnetars and might have played an important role in the physics of the early universe. At zero temperature, the great majority of effective models for Quantum Chromodynamics (QCD) are in agreement with respect to the occurrence of the phenomenon of magnetic catalysis (MC), which refers to the increase of the chiral order parameter represented by the (light) quark condensates with the strength of the magnetic field. On the other hand, at finite temperature such models fail to predict the inverse magnetic catalysis (IMC), an effect discovered by lattice QCD (LQCD) simulations, in that the pseudo-critical temperature for chiral symmetry restoration decreases as B increases. In this work we will present recent results where we advocate that the phenomenon of inverse magnetic catalysis of chiral symmetry in
QCD predicted by lattice simulations can be reproduced within the
Nambu--Jona-Lasinio model if the coupling~$G$ of the model decreases
with the strength $B$ of the magnetic field and temperature~$T$. The
thermo-magnetic dependence of $G(B,T)$ is obtained by fitting recent
lattice QCD predictions for the chiral transition order parameter. Different
thermodynamic quantities of magnetized quark matter evaluated with a
$G(B, T)$ are compared with the ones obtained at constant coupling $G$.
The model with a $G(B,T)$ predicts a more dramatic chiral transition as
the field intensity increases. In addition, the pressure and magnetization
always increase with $B$ for a given temperature. Being parametrized by
four magnetic field dependent coefficients and having a rather simple exponential
thermal dependence our accurate ansatz for the running coupling can be easily
implemented to improve typical model applications to magnetized quark matter.
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Contribution: Poster
Title: Existence of cold quark matter in Nature: models and observations
Author(s): Rodrigo Alvares de Souza, Jorge Horvath
Abstract: The main goal of this work is the study of cold quark matter in neutron stars from phase transitions of hadronic matter to quark matter. To describe the hadronic phase in this work we studied the SWRDP model, which considers hyperons and the effects of many-body forces simulated by the nonlinear selfcoupling and the meson-meson contributions. The matter of quarks was described by two approaches: the QCD Mean Field Theory (MFTQCD) and QCD Infrared Extension (QCDIRE). The approach used to make the connection between hadronic matter and the cold quark matter was a first order phase transition using the Maxwell construction. Next, the hybrid state equations were integrated using the Tolman-Oppenheimer-Volkoff equations and obtained maximum masses for some sets of parameters that are in agreement with observations of pulsars PSR J1614–2230 (M=1.97±0.04 M¯) and PSR J0348+0432 (M=2.01±0.04 M¯).
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Contribution: Oral
Title: The Cherenkov Telescope Array: Unveiling the Gamma Ray Universe
Author(s): Rodrigo Nemmen (IAG/USP), on behalf of the CTA Consortium
Abstract: Gamma-ray astronomy allows synergies between Astrophysics, Particle Physics and Cosmology. The Cherenkov Telescope Array (CTA) is an international initiative to build the next-generation ground-based gamma-ray observatory which will be composed of hundreds of Cherenkov telescopes and will have a factor of 5-10 improvement in sensitivity in the 100-GeV to 10-TeV range, with a large energy coverage from a few tens of GeV to a few hundreds of TeV. CTA will consist of two arrays — one in the Canarias Island in the North and another in Chile in the South Hemisphere — and will provide a deep insight into the non-thermal high-energy Universe and its particle accelerators. In this talk, I will briefly present the major design concept of CTA, its vast science case and the Brazilian participation in the consortium.
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Contribution: Oral
Title: A new approach to the thermal evolution of neutron stars
Author(s): Rodrigo Negreiros, Stefan Schramm and Fridolin Weber
Abstract: In the work we continue our research of the thermal evolution of rotating neutron stars. We have previously calculated the thermal evolution of neutron stars undergoing spin-down, focusing on the effects that a dynamic composition change may have on the cooling. We havel also calculated the thermal evolution of rotating neutron stars (with a constant frequency) under the full effect of general relativity. The work presented here is the culmination of these two studies, in which we show, for the first time, the thermal evolution of rotating neutron stars that are undergoing spin-down (or up). We self-consistently calculate the evolution of the structure of the star during its spin-down, coupled to the thermal evolution of the object. In such manner, we are able to see how the dynamical composition together with the structure and metric composition affect the thermal evoluion of such objects. This work opens the possibility for the investigation of several scenarios, forbidden by the traditional "frozen-in" cooling calculations, such as thermal evolution of accreting neutron stars, whose composition changes due to the addition of mass and heat.
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Contribution: Oral
Title: Anisotropies detected by Pierre Auger Observatory in the Ultra-High Energy Cosmic Rays Sky
Author(s): Rogerio M. de Almeida, The Pierre Auger Collaboration
Abstract: The study of anisotropies in the flux of high-energy cosmic rays carries major clues to understanding their origin. The Pierre Auger Collaboration, in operation since 2004, is the largest cosmic ray observatory in the world. We review their recent results related to anisotropies in the arrival directions of ultra-high energy cosmic rays. We present searches for dipolar and quadrupolar anisotropies in different energy ranges spanning four orders of magnitude. For the highest energy cosmic rays, with energies above the predicted GZK cutoff, we present an update of the search for correlations between their arrival directions and the positions of active galactic nuclei from the Véron-Cetty and Véron catalog. We also examine the correlation of arrival directions with other populations of nearby extragalactic objects. Finally, we report the results of a blind search for localized excess fluxes and for self-clustering of arrival directions at angular scales up to 30 degrees and for different energy thresholds between 40 EeV and 80 EeV.
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Title: Many-body Forces in the Equation of State of Magnetized Neutron Stars
Author(s): R. O. Gomes, B. Franzon, V. Dexheimer, S. Schramm, C. A. Z. Vasconcellos
Abstract: We describe nuclear matter inside stars in a new relativistic mean field formalism that takes many-body forces into account, by means of a field dependence of the nuclear interaction coupling constants. The presence of the magnetic fields generates a Landau quantization on the energy levels of the charged particles and also an anisotropy in the components of the energy-momentum tensor. Finally, we introduce the magnetic fields in the strutucture of stars by solving the Einstein-Maxwell equations self-consistently. This solutions lead to stationary and axi-symmetric stellar models, in which a poloidal magnetic field is assumed. Hence, the matter is considered to be under a static density dependent magnetic field, reaching intensities of the order of $10^{18}\,G$ at the center of the stars. We conclude that magnetic fields affect significantly the particles population of the stars, but only the effects on the strucuture of stars have strong influence on the global properties, as maximum masses and deformation, of these objects.
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Contribution: Poster
Title: Bayesian inference applied to pulsars' models
Author(s): Rubens M. Marinho Jr., Nadja S. Magalhaes, Heitor Oliveira, Márcio E.S. Alves, Jaziel G. Coelho, Rodolfo Valentim
Abstract: There are strong evidences that pulsars are rotating magnetized neutron stars emitting electromagnetic radiation in a wide range of wavelengths. The variation of the angular frequency is an observational evidence that their rotation energy decreases. However, it is well known that the canonical model for magnetic dipole radiation cannot precisely explain the energy loss. There is a variety of models trying to explain the phenomenon, such as the energy loss due to the emission of gravitational radiation, quantum vacuum friction and interaction of the magnetic field with the plasma surrounding the star, and/or also the variation of the magnetic field, angle inclination and the moment of inertia, etc. Moreover, the equations that describe the phenomenon are functions of the mass-radius relation of the neutron star and so far it is not known which Equation of State (EoS) for nuclear matter should be used to describe the star's interior. The goal of this work is to apply Bayesian inference through BIC ({\it Bayesian Information Criterion}) to select among different theoretical models and EoS those that better fit known pulsar data for the rate of decrease of angular velocity versus the angular velocity itself. After selecting the model, we also find the posterior distribution and the best fit for some relevant parameters of the pulsar like the mass and the magnetic field.
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Contribution: Poster
Title: Thermal Instability of Radiative Plasma with Finite Electron Inertia and Finite Larmor Radius corrections for Molecular Cloud Formation in Interstellar medium (ISM)
Author(s): Sachin Kaothekar
Abstract: We study the effects of finite ion Larmor radius (FLR) corrections, finite electron inertia and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effects of finite electrical resistivity, thermal conductivity and permeability for molecular cloud formation and structure formation in interstellar medium (ISM). A general dispersion relation is derived using the normal mode analysis method with the help of relevant linearized perturbation equations of the problem. The wave propagation is discussed for longitudinal and transverse directions to the external magnetic field and the conditions of modified thermal instabilities and stabilities are discussed in different cases. We find that the thermal instability criterion is get modified. The finite electrical resistivity removes the effect of magnetic field and viscosity of the medium removes the effect of FLR from the condition of radiative instability. Numerical cal culation shows stabilizing effect of heat-loss function, FLR corrections and viscosity of the medium and destabilizing effect of electrical resistivity and finite electron inertia on the thermal instability. Our results are helpful in understanding the process of molecular cloud formation in interstellar medium (ISM).
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Contribution: Oral
Title: Dark Matter Search with the ATLAS Detector
Author(s): Sergey Burdin for ATLAS Collaboration
Abstract: Dark Matter comprises approximately 27% of the universe yet little is known about its properties. Dark matter particles, if produced by the LHC, will leave a distinct signature of significant missing transverse energy (MET). Recent results from ATLAS utilising the MET signature found in association with a variety of probes will be presented.
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Contribution: Poster
Title: Noether symmetry of f-essence cosmologies
Author(s): Myrzakul Shynaray
Abstract: We discuss the Noether Symmetry Approach in the framework of f-essence cosmology showing that the functional form of the R function, where R is the Ricci scalar, can be determined by the presence of symmetries. Besides, the method allows to find out exact solutions due to the reduction of cosmological dynamical system and the presence of conserved quantities. Some specific cosmological models are worked out. A cosmological model where a fermion field is non-minimally coupled with the gravitational field is studied. By applying Noether symmetry the possible functions for the potential density of the fermion field and for the coupling are determined. Cosmological solutions are found showing that the non-minimally coupled fermion field behaves as an inflaton describing an accelerated inflationary scenario, whereas the minimally coupled fermion field describes a decelerated period, behaving as a standard matter field.
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Contribution: Poster
Title: Growth of matter perturbations to constrain dark energy models with Gauss-Bonnet coupling
Author(s): Stefani Dorado, Juan Carlos Bueno
Abstract: In this work we investigate the evolution of matter density perturbations in a class of f(R) gravity models for dark energy, where kinetic and Gauss-Bonnet (GB) couplings are considered. The latter has the advantage of not giving rise to evolution equations higher than second order. Our study is made in the weak coupling limit and assuming slow-roll of the dark energy field in order to obtain the corresponding effective gravitational constant. Finally, we constrain the values of the GB coupling by using the observational data on the growth function and growth index (γ) of matter perturbations.
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Contribution: Oral
Title: Quest for potentials in the quintessence scenario
Author(s): Tetsuya Hara
Abstract: The time variation of the equation of state $w$ for quintessence scenario with a scalar field as dark energy is studied up to the third derivative ($d^3w/da^3$) with respect to the scale factor $a$, in order to predict the future observations and specify the scalar potential parameters with the observables. The third derivative of $w$ for general potential $V$ is derived and applied to several types of potentials. They are the inverse power-law ($V=M^{4+\alpha}/Q^{\alpha}$), the exponential ($V=M^4\exp{(\beta M/Q)}$), the cosine ($V=M^4(\cos (Q/f)+1)$) and the Gaussian types ($V=M^4\exp(-Q^2/\sigma^2)$), which are prototypical potentials for the freezing and thawing models. If the parameter number for a potential form is $ n$, it is necessary to find at least for $n+2$ independent observations to identify the potential form and the evolution of the scalar field ($Q$ and $ \dot{Q} $). Such observations would be the values of $ \Omega_Q, w, dw/da. \cdots $, and $ dw^n/da^n$. Since four of the above mentioned potentials have two parameters, it is necessary to calculate the third derivative of $w$ for them to estimate the predict values. If they are tested observationally, it will be understood whether the dark energy could be described by the scalar field with this potential. Numerical analysis for $d^3w/da^3$ are made under some specified parameters in the investigated potentials. It becomes possible to distinguish the freezing and thawing modes by the accurate observing $dw/da$ and $d^2w/da^2$ in some parameters.
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Contribution: Oral
Title: The 4MOST Spectroscopic Survey
Author(s): Th. Boller
Abstract: I present the science goals expected from the upcoming 4MOST spectroscopic mission, covering tens of Millions GAIA and Millions of eROSITA AGNs and Clusters with the first light expected in 2020. The survey strategy and optimization based on intensive simulations we are presently carrying out will also be discussed.
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Contribution: Oral
Title: In medium nucleon
Author(s): T. Frederico, W. R. B. de Araújo, J. P. B. C. de Melo, K. Suzuki
Abstract: We study the in-medium nucleon electromagnetic form factor within a light-front model. The quarks within the nucleon has an effective mass in the nuclear medium changed by the scalar mean-field, from the coupling of the quarks to the scalar and vector mesons, as in the example of the QMC models.
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Contribution: Oral
Title: Phase Transitions in Dense Matter
Author(s): V. Dexheimer
Abstract: First order phase transitions (PTs) with more than one globally conserved charge, so-called non-congruent PTs, have characteristic differences compared to congruent PTs (e.g., dimensionality of phase diagrams, location and properties of critical points and endpoints). We investigate the non-congruence of the nuclear liquid-gas PT at sub-saturation densities and the deconfinement PT at high densities and/or temperatures in Coulomb-less models, relevant for heavy ion collisions, neutron stars, proto-neutron stars and compact star mergers.
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Contribution: Oral
Title: Minkowski space approch to the relativistic bound state spectrum
Author(s): Vitor Gigante, Cristian Gutierrez, Tobias Frederico, Giovanni Salmè, Michelle Viviani and Lauro Tomio
Abstract: The Nakanishi integral representation of the Bethe-Salpeter amplitude is used in order to derive a workable framework for bound states, solutions of the homogeneous Bethe-Salpeter Equation, in Minkowski space. The projection onto the null-plane of the homogeneous Bethe-Salpeter Equation is used to derive an equation for the Nakanishi weight function for bound states. We study the bound state of two spinless bosons with the interaction given by an exchanging scalar bosons in ladder+cross-ladder approximation, used to obtain the spectrum and structure of the excited states. The unique feature of the method is to access the valence light-front wave function. Its three-dimensional structure is explored in detail for the ground and excited states, by calculating the valence momentum distribution amplitude and the impact parameter space representation of the valence state. Resorting to the analytic structure of the Nakanishi integral representation for the valence wave function, we analysed the equality between the transverse momentum amplitudes computed within Minkowski and Euclidean frameworks, and the leading exponential fall-off appearing in the impact parameter space wave function was derived.
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Contribution: Oral
Title: (Anti-) de Sitter Charged Black Hole in Higher-Derivative Gravity
Author(s): Wei-Liang Qian, Kai Lin, Elcio Abdalla and Alan B. Pavan
Abstract: In this paper, static charged black hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Schwarzschild (Anti-) de Sitter solution, while the second group is intrinsically different from a Schwarzschild (Anti-) de Sitter solution even when the charge and the cosmological constant become zero. We also discuss the quasinormal modes of the black hole spacetime.
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Contribution: Oral
Title: Preferred axis in cosmology
Author(s): Wen Zhao, Larissa Santos
Abstract: The foundation of modern cosmology relies on the so-called cosmological principle which states a homogeneous and isotropic distribution of matter in the universe on the large scale. However, recent observations, such as the temperature anisotropy of cosmic microwave background (CMB) radiation, the motion of galaxies in the universe, the polarization of quasars and the acceleration of the cosmic expansion, indicate preferred directions of the sky. If these directions have a cosmological origin, the cosmological principle would be violated, and modern cosmology should be reconsidered. In this paper, by considering the preferred axis in the CMB parity violation, we find that it coincide with the preferred axes in CMB quadrupole and CMB octopole, and they all align with the direction of the CMB kinematic dipole. In addition, the preferred directions in the velocity flows, quasar alignmen, anisotropy of the cosmic acceleration, the handedness of spiral galaxies, and the angular distribution of the fine-structure constant are also claimed to be aligned with the CMB kinematic dipole. Since CMB dipole was confirmed to be caused by the motion of our local group of galaxies relative to the reference frame of the CMB, the coincidence of all these preferred directions hits that these anomalies have a common origin, which is not cosmological or due to a gravitational effect. The systematical or contaminative errors in observation or in data analysis, which can be directly related to the motion of our local group of galaxies, can play an important role in explaining the anomalies.
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Contribution: Oral
Title: Atmospheric Tidal Effects on Cosmic Ray Shower Production
Author(s): H. Takai
Abstract: Elementary particle production by cosmic rays in the Earth's atmosphere is a well understood process. High energy cosmic rays collide with the elemental constituents of the atmosphere producing a shower of particles. The multiplicity, species distribution, and their energy spectra are a function of the incident cosmic ray energy and type. The point of production and flux measured at various altitudes depends on the atmospheric density profile as function of altitude. Using data of muon flux collected for the past eight years, and atmospheric data from various sources, we study the close relationship between the atmospheric conditions and particle production. Atmospheric tidal effects are clearly observed in our data as seasonal and daily modulation of the muon flux. We will present the results of the analysis and discuss the importante of including a detailed description of the atmosphere in interpreting data from experiments searching for non standard model particles.
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Contribution: Oral
Title: Recent Babar Results on Time-Reversal and CP Asymmetries
Author(s): The BABAR Collaboration: J.P. Lees, et al. (287 collaboration authors)
Abstract: We present a selection of recent results on time and CP asymmetries measured with the BaBar detector. They include measurement of T and CP asymmetries in the B0-B0bar mixing process using inclusive dilepton samples, a test of CPT symmetry using B0 decays to c cbar K0, and a Dalitz plot analysis of the charmless decay B+ -> Ks pi+ pi0, where the first evidence of direct CP violation in the B+ -> K*+pi0 decay has been seen. We also present a measurement of the parameter sin2beta of the Unitarity Triangle in B0 -> D0 h0 decays, which makes use of the combined data sets of the BaBar and Belle experiments.
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Contribution: Oral
Title: Excitation wave magnetohydrodynamic (MHD) by waves
Author(s): Adam S. Gontijo and Oswaldo D. Miranda
Abstract: Relativistic magnetohydrodynamics (MHD) plays an important role in high-energy astrophysics. In events like the $\gamma$-Ray Bursts (GRBs), relativistic plasmas and strong magnetic fields are believed to be involved in the extraction of energy from the central objects. These plasmas, according to the fireball model, consisting of electron-positron pair, radiation and baryonic matter. The latter acquires the greater part of the explosion energy, reaching Lorentz factors on the order $10^2 - 10^3$. The most promising progenitor to generate a GRB short (less than 2 sec) is merger binary systems (NS-NS and NS-BH). Such sistems produce significant amount of gravitational waves (GW) and are candidates to be detected by ground detectors (eg, Advanced LIGO, in the range $10 Hz - 1 kHz$). We review the excitation mechanism of MHD wave modes in a strongly magnetized plasma surrounding the source of gravitational radiation before the merger of neutron stars; assuming that the gravitational wave is weak, we linearize the GR-MHD equations and find the analytical solutions. In particular, it is shown that the magnetosonic modes are coupled to the polarization $ + $ gravitational wave and the Alfvén mode, polarization $ \times $. Such a coupling for a NSs binary system near \textit{merger}, was studied at work Moortgat (2006). The author found that the higher amount of gravitational wave emission occurs in the frequency $\omega_{g}\sim 1$kHz and he calculated the energy deposited in the plasma through interaction of the GW polarizations with MHD wave modes. We consider the formalism adopted by Moortgat (2006) to derive the equations that describe the interaction, but now considering \textit{spiral} phase from a minimum frequency ($\omega_ {g}\sim 300\rm{Hz}$) for effective interaction to the frequency of the last stable orbit system ($ \omega_{g}\sim 1.5 \rm {kHz}$). In particular, we show that the amount of energy GW dissipated into the plasma and associated with the Alfvén mode during\textit {spiral} phase, can be as high as $10^{40}\rm{J}$.
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Contribution: Poster
Title: Quark-hadron phase transition in proto-neutron stars cores based on a non-local NJL model
Author(s): G. Malfatti, G. Contrera, M. Orsaria and F. Weber
Abstract: We study the QCD phase diagram using a non-local SU(3) NJL model with vector interactions among quarks. We analyze the thermodynamic quantities such as entropy and specific heat and the influence of vector interactions in the phase transition process. Theoretical studies show that vector interactions stiffen the equation of state of cold hybrid stars. By considering electric charge neutrality and baryon number conservation, we build the equation of state for the core regions of proto-neutron stars and discuss the astrophysical implications of considering this non-local quark model.
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Contribution: Oral
Title: Time variability of NS-LMXBs as oscillation modes of relativistic axisymmetric tori: implications for constraining the parameters of neutron stars
Author(s): M. G. B. de Avellar, L. Rezzolla, O. Porth, Z. Younsi
Abstract: There have been many efforts to explain the dynamical mechanisms and models for the origin and phenomenology of the quasi-periodic oscillations (QPOs) seen in the X-ray light curves of low-mass X-ray binaries. Up to now, none of the models on the market can address all the frequencies observed in the power density spectrum of the light curve. However, new light is shed on the problem through sophisticated simulations of accretion flows onto compact objects. We perform several hydrodynamic simulations of non-self gravitating relativistic axisymmetric thick tori around the neutron star in the low-mass X-ray binary 4U 1636-53 and show how the observed oscillation modes triggered by different velocity perturbations give rise to a set of variability features similar to what we see in the observational X-ray data, in particular in the case of the kiloHertz QPOs. We compare the simulated and the observational relations between the upper and lower kiloHertz QPOs frequencies to probe the inner regions of the system, potentially constraining the mass and radius of the neutron star.
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Contribution: Poster
Title: Exploring the BEC-BCS crossover in a cold and magnetized two color QCD
Author(s): Dyana C. Duarte, P. G. Allen, R. L. S. Farias, Pedro H. A. Manso, Rudnei O. Ramos, and N. N. Scoccola
Abstract: There are many motivations to study the phase structure of quantum chromodynamics (QCD), related to investigations of the relativistic heavy ion collisions, compact stars and the early universe. Moreover, the QCD phase diagram remains poorly understood, despite the many efforts dedicated to its description in recent years. Further motivated by the fact that strong magnetic fields may be produced in noncentral heavy-ion collisions, investigations of the effects produced by a magnetic field in the phase diagram of strongly interacting matter became a subject of great interest in recent years. Due to fermion sign problem, the implementation on lattice of the QCD phase diagram studies at finite temperature and densities, then many low energy effective models, such as quark-meson model and chiral perturbation theory are used to study the phase diagram of strongly interacting matter. It is expected that a crossover from Bose-Einstein Condensation (BEC) to Bardeen-Cooper-S hriffer condensation (BCS) for diquarks at finite baryon density. This crossover may happen when the coupling constant of the attractive interations increases, or changing the charge number through the increase of the chemical potential, at small temperature. In this work we study the BEC-BCS crossover for a two color Nambu–Jona-Lasinio (NJL) model with diquark interactions in the presence of an external magnetic field, devoting special attention to different regularization schemes used in the literature. We verify the influence of this field in the phase diagrams, for both critical chemical potentials (first for BEC phase transition and then for BEC-BCS crossover) at zero temperature. Additionally, we use a method that makes a full separation of the finite magnetic contributions of the divergencies, the Magnetic Field Independent Regularization (MFIR) to show that unphysical oscillations that usually appears when using common regularization schemes completely disappear.
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Contribution: Oral
Title: The first harmonic of cyclotron line in Be/X-ray binary pulsar Cep X-4
Author(s): Gaurava K. Jaisawal and Sachindra Naik
Abstract: We present broad-band spectral properties of the high mass X-ray binary pulsar Cep X-4 during its outburst in 2014 July. The 1-70 keV energy spectrum, obtained from Suzaku observation of the pulsar was described with several continuum models such as partial covering Negative and Positive power-law with Exponential cut-off (NPEX), high-energy cut-off power-law and CompTT models along with a cyclotron absorption line at $\sim$28 keV and 6.4 and 6.9 keV iron emission lines. An additional absorption like feature was detected in the pulsar spectrum at $\sim$45 keV. This feature was seen in a model independent manner. We identified this additional feature as the first harmonic of the fundamental cyclotron line at 28 keV. The energy ratio between first cyclotron harmonic and fundamental line was found to be lower (1.7) than the conventional factor of 2, indicating that the line forming regions are at different heights or viewed at larger angles. The fundamental and fir st cyclotron harmonic line parameters show a significant variation with pulse phase of the pulsar which can be explained as the effects of the viewing angle or the role of complicated magnetic field of the neutron star.
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Contribution: Poster
Title: Delayed Thermalization in Thermonuclear Supernovae
Author(s): Elvis do A. Soares, Takeshi Kodama, João R. T. de Mello Neto
Abstract: Numerical models of Type Ia supernovae (SNe Ia) have been extensively applied to test general ideas about possible explosion mechanisms. Regardless of the exact details of the mechanism, these supernovae are driven by thermonuclear runaway from nuclear reactions of carbon and oxygen within a white dwarf, therefore called thermonuclear supernovae. Many simulations of thermonuclear supernova assume instantaneous thermalization of the burning matter within a large domain of fluid elements used. However, we expect the appearance of transient processes such as convection currents, vortices, and other collective motions on smaller scales, which can delay thermodynamics equilibrium in the burning material. To simulate these effects in a simple one-dimensional hydrodynamical calculation, we introduce a time delay in the hydrodynamic equations and show that such effects could have a significant influence on the evolution of the supernova explosion and nucleosynthesis.
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Contribution: Poster
Title: Heuristic approach on anomalous apsidal precession of planets
Author(s): Abraao J. S. Capistrano, Joice A. M. Penagos, Manuel S. Alarcon
Abstract: We investigate the anomalous planets precession in the nearly-newtonian gravitational regime. Using a non-standard expression for the perihelion advance from the Weyl conformastatic vacuum solution as a model, we describe the anomalous movement in planets precession as compared to different observational data from Ephemerides of the Planets and the Moon (EPM2008 and EPM2011) and the Planetary and Lunar Ephemeris (INPOP10a). As a first approximation, we use heuristic methodology obtaining a very close results to observations.
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Contribution: Poster
Title: Magnetic suspension with motorization to measure the speed of gravity
Author(s): Henrique Linares, Carlos Frajuca, Givanildo Alves dos Santos, Franscisco Yastami Nakamoto
Abstract: This work aims to design a magnetic suspension for an experiment to measure gravity’s velocity. Such device must rotate two objects symmetrically with the greatest mass and largest radius as possible, at the speed of 500,000 rpm, which means this device falls into the high-speed machines category. The guidelines and solutions proposed in this paper constitute a contribution to this class of engineering problems and were based on an extensive literature search, contacts with experts, the tutor’s and author's experience, as well as on experimental results. The main solution proposed is a hybrid bearing that combines a radial passive magnetic bearing with an axial sliding bearing, here called MPS (Magnetic Passive and Sliding) bearing.
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Contribution: Poster
Title: Dark Spinor field in inflationary cosmology
Author(s): Thiago Vinícius Moreira Guimarães, Saulo Henrique Pereira
Abstract: The theory of inflation was introduced by Alan Guth as a necessary ingredient at the very early universe and then developed into a full working model by Linde, Albrecht and Eteinhardt [1], and it remains the leading paradigm for the very early universe. It naturally solves the cosmological flatness problem, absence of magnetic monopoles, horizons problem and also is consistent with high precision measurements of the cosmic microwave background radiation. Numerous models of inflation have been proposed in the literature, each adding new features to the predictions of a scale invariant spectrum derived from single-field slow-roll inflation. Structure formation must also be consistent with the inflation theory. In the present work we analyze a model in which the inflation is not driven by a standard scalar-field, as currently proposed by most of models. The analysis was carried out by considering that inflation is due to a dark spinor field [2], acting something like a scalar field, but with a much more rich structure. More precisely, we show that a new class of dark spinor field in curved background with torsion is a viable alternative model for scalar driven inflation and leads to a slow-roll parameter very similar to the ones of the single-scalar-field models. Moreover, the solutions for the new inflaton field and for the scale factor evolution have the expected behavior and can also predict the expected mass for the inflaton, under some considerations. The numerical analysis for different potentials shows a good agreement with the standard model of inflation, which makes dark spinors as a good candidate to the inflaton field.
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Contribution: Poster
Title: Cosmic Censorship in a Kantowsky-Sachs spacetime.
Author(s): Patricia Carvalho, B. Terezon, M. Campos
Abstract: The Kantowski-Sachs (KS) model presents somewhat different features from models that usually populate the Bianchi classification, i.e., the model is resulting from the product of a sphere with a line (R3 x R), and can be described as a spatially homogeneous, isotropic model, that does not permit a simple transitive group of motions. From the cosmological point of view, the KS universe with a positive cosmological term (that the more plausible interpretation is considering as the vacuum energy of the all fields in the cosmic fluid) can admit an inflationary phase during which occur the isotropization process, and , naturally, the shear decays exponentially. However, if we are dealing with a cosmological model or if we treat the gravitational collapsing process, in the truth, both studies can to be considered as the two sides of the same coin. Much has already been published considering cosmological KS- models, however, our intend in this work is analyze the cosmi c censorship conjecture in an anisotropic collapsing process, with for some different contents in the material side of the Einstein field equations, with or without an interaction with a vacuum energy component.
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Contribution: Poster
Title: Delta resonance coupling with Walecka’s mesons - Implications to Stellar Matter EoS
Author(s): William Silva Gomes, José Carlos T. de Oliveira, Hilário Rodrigues, and Sérgio Barbosa Duarte
Abstract: In this work we have obtained the equation of state to the highly asymmetric dense stellar matter, using the nonlinear Walecka model in the mean field approximation. We discussed the implication of changes in coupling constant of the delta baryonic resonance on the observable of the neutron star. A detailed analysis of the equation of state and of the baryonic effective mass in respect to changes in the delta coupling constants is carried out. We focus attention on a new aspect observed for pressure when varying the baryonic density of the medium; a first order phase transition like a liquid-gas phase transition was observed for an acceptable range of delta coupled constant values. We have explored the implication of this aspect for the neutron star structure and their maximum masses.
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Contribution: Oral
Title: Recent Advances in Conformal Gravity
Author(s): James G. O'Brien, Spasen Charkov, Modestas Stulge
Abstract: In recent years, significant advances have been made in alternative gravitational theories. Although MOND remains the leading candidate amongst the alternative models, Conformal Gravity has been studied by Mannheim and O'Brien to solve the rotation curve problem without the need for dark matter. Recently, Mannheim, O'Brien and Chaykov have begun solving other gravitational questions in conformal gravity. In this presentation, we first review Conformal Gravity. Second, we highlight the new work of Conformal Gravity's application to random motions of clusters (the original Zwicky problem), gravitational bending of light, gravitational lensing and a very recent survey of dwarf galaxy rotation curves (bringing the total count of rotation curves fit by conformal gravity to over 200). We will show in each case that conformal gravity can provide an accurate explanation and prediction of the data without the need for dark matter. Coupled with the fact that Conformal Gravity is a fully re-normalizable metric theory of gravity, these results help to push conformal gravity onto a competitive stage against other alternative models.
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Contribution: Poster
Title: Investigating the prompt photon production at the LHC energies.
Author(s): G. Sampaio dos Santos and M. V. T. Machado
Abstract: We investigate the rapidity and transverse momentum distributions of the prompt photon production at the LHC energies considering the color dipole approach. We compare the predictions from distinct models for the dipole cross section, where parton saturation models at high energies are expected to be important at the forward rapidities in pp and pA collisions at the LHC.
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Contribution: Oral
Title: Stellar Structure Models of Deformed Neutron Stars
Author(s): Omair Zubairi, Fridolin Weber
Abstract: Traditional stellar structure models of non-rotating neutron stars work under the assumption that these stars are perfect spheres. This assumption of perfect spherical symmetry is not correct if the matter inside neutron stars is described by an anisotropic model for the equation of state. Certain classes of neutron stars such as Magnetars and neutron stars which contain color-superconducting quark matter cores are expected to deformed making them oblong spheroids. In this work, we examine the stellar structure of these deformed neutron stars by deriving the stellar structure equations in the framework of general relativity. By using a non-isotropic equation of state model, we solve these structure equations numerically in two dimensions. We calculate stellar properties such as masses and radii along with pressure and energy-density profiles and investigate any changes from standard spherical models.
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Contribution: Oral
Title: Hybrid stars in the framework of NJL models
Author(s): Gustavo A. Contrera, Milva G. Orsaria, Ignacio F. Ranea-Sandoval and Fridolin Weber
Abstract: The discovery of the two-solar mass neutron stars J1614-2230 ($1.97 \pm 0.04 M_\odot$) and J0348+0432 ($2.01 \pm 0.04 M_\odot$) allows the possible existence of deconfined quarks in the cores of neutron stars. We compute the equation of state of the matter in the cores of hybrid stars for hadronic matter, treated in the non linear relativistic mean-field approximation and quark matter, represented by three-flavor local and non-local Nambu$-$Jona-Lasinio (NJL) models with repulsive vector interactions. The transition of hadronic to quark matter (mixed phase) is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to $2.1-2.4 M_\odot$ may contain a mixed phase in their cores, if global charge conservation is considered through the Gibbs conditions. However, if the Maxwell condition is considered, the appearance of a pure quark matter core e ither destabilizes the star immediately (typically for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (usually for local NJL models). Our study also indicates that neutron stars with masses of around $1.4\, M_\odot$ would not contain deconfined quark matter. Very good agreement with the thermal evolution established for the neutron star in Cassiopeia A (Cas A) is obtained for one of our models, if the protons in the core are strongly paired, the repulsion among the quarks is mildly repulsive, and the mass of Cas A has a canonical value of $1.4\, M_\odot$.
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Contribution: Oral
Title: Quark matter under strong magnetic fields in chiral quark models
Author(s): V. Pagura, D. Gomez Dumm, S. Noguera and N.N. Scoccola
Abstract: The influence of intense magnetic fields on the properties of quark matter is investigated using a SU(2)f non-local chiral quark model.
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Contribution: Poster
Title: Nonlinear Walecka model for neutron stars
Author(s): Débora Peres Menezes, Daniel Castro Romão
Abstract: In this undergraduate work we seek to investigate the effects of different sets of parameters and variations of the Walecka model in describing the bulk properties of a neutron star. The variations in the equation of state, applied incrementally, are such as different proton fractions and beta stability, the addition of leptons, charge neutrality and the inclusion of nonlinear terms to the Lagrangian. For the star properties we use the Tolman-Oppenheimer-Volkoff equation.
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Contribution: Oral
Title: Nucleosynthesis in strange star mergers
Author(s): L. Paulucci, J. E. Horvath, O. Benvenuto
Abstract: The possible existence of deconfined matter in the cores of neutron stars has been studied for over three decades without a firm indication either for or against this proposition. Analysis mostly rely on the comparison of mass-radius curves obtained for different compositions with observational data on the mass of the most massive objects of this kind accurately determined. Nevertheless, there are other possibilities for indirectly studying the internal composition of this class of compact objects, e.g, analyzing cooling behavior, X-ray bursts, supernova's neutrinos. We present calculations on the expected nucleosynthesis spectra for the strange star-strange star merger scenario as means to test the strange quark matter hypothesis and its realization inside such objects. This would result very different from the typical r-process nucleosynthesis expected in neutron star mergers since the high temperature deconfinement of strange matter would produce large amounts of neutrons and protons and the mass buildup would proceed in a Big-Bang nucleosynthesis like scenario with a slightly higher neutron to proton ratio. Results are then evaluated for its viability as an explanation for the observables, mainly the elemental abundances and light curve.
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Contribution: Poster
Title: New look at black holes: Existence of universal horizons
Author(s): Kai Lin, Goldoni, M. F. da Silva and Anzhong Wang
Abstract: In this paper, we study the existence of universal horizons in a given static spacetime and find that the test khronon field can be solved explicitly when its velocity becomes infinitely large, at which point the universal horizon coincides with the sound horizon of the khronon. Choosing the timelike coordinate aligned with the khronon, the static metric takes a simple form, from which it can be seen clearly that the metric is free of singularity at the Killing horizon, but becomes singular at the universal horizon. Applying such developed formulas to three well-known black hole solutions, the Schwarzschild, Schwarzschild–anti–de Sitter, and Reissner-Nordström, we find that in all these solutions universal horizons exist and are always inside the Killing horizons. In particular, in the Eddington-Finkelstein and Painleve-Gullstrand coordinates, in which the metrics are not singular when crossing both of the Killing and universal horizons, the peeling-off behavior of the khronon is found only at the universal horizons, whereby we show that the values of surface gravity of the universal horizons calculated from the peeling-off behavior of the khronon match with those obtained from the covariant definition given recently by Cropp, Liberati, Mohd and Visser.
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Contribution: Oral
Title: On Dirac Equation and Angular Momentum of Axially
Author(s): Mohamed Fouad Mourad
Abstract: In this paper, we re interested in studying the teleparallel version of axially symmetric, uniformly rotating spacetime for two different sets of tetrad fields. For these sets, we obtained the expressions for the torsion vector, torsion axial-vector and the angular momentum in stationary axisymmetric space-time solutions. We found that the obtained expressions of torsion axial-vector and the angular momentum are, in general quite different in both two sets of tetrad fields. In addition, when the functions of the space time are only dependent of r or z, the torsion vectors vanish only in r or z direction while axial-vectors vanish only on z or r direction respectively. Finally, the vector part connected with Dirac spin which has been evaluated as well.
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Contribution: Oral
Title: The low-temperature astrophysical HD-cooling function
Author(s): Renat A. Sultanov
Abstract: Energy transfer collisions between H2 and HD molecules, where H is hydrogen and D is deuterium, is of fundamental importance for the astrochemistry of the early Universe [1] and the interstellar medium [2]. HD represents the second most abundant primordial molecule after H2 and plays a significant role in the cooling of the primordial gas. The abundance of deuterium is low relative to hydrogen, i.e. n(D)/n(H) ≈ 0.00001, however the HD/H2 ratio can be enhanced by an approximate factor of ~100 due to chemical fractionation, for example, through the following chemical reactions: H2 + D+ → HD + H+ or H2 + D → HD + H. It has been shown, that in the framework of the standard cosmological model the radiation temperature is higher than the matter temperature and molecules become a heating source for the gas. At higher temperatures H2 molecules dominate the heating, however HD molecules dominate the kinetic process at lower temperatures [1]. In addition, the HD molecule is especially important due to its permanent dipole moment and lower rotational constant. It makes the molecule to be an efficient coolant at lower temperatures: T < 100 K. Knowledge of the rotational-vibrational excitation and de-excitation thermal rate constants in the molecular HD + H/H2 low energy collisions is of significant importance in understanding and modeling of the energy balance within primordial gas. Therefore, in this work we carry out a pure quantum-mechanical calculation of the non-reactive scattering processes HD + H2 and HD + H. We compute their rotational energy transfer cross-sections and thermal rate coefficients at low temperatures of astrophysical interest. The most recent H3 and H4 potential energy surfaces have been used with some important modifications because of the symmetry break in the target - HD instead of H2 [3]. A quantum-mechanical close-coupling approach has been applied [3]. After these careful calculations, one can carry out a new estimation of the astrophysical HD-cooling function at different temperatures and astrophysical conditions.
[1] A. Dalgarno and R. McCray, 1972, Ann. Rev. Astron. Astrophys. 10, 375.
[2] C. M. Coppola, L. Lodi and J. Tennyson 2011, Mon. Not. R. Astron. Soc., 415, 487.
[3] R.A. Sultanov, D. Guster, and S.K. Adhikari, 2016, J. Phys. B: At. Mol. Opt. Phys., 49, 015203.
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Contribution: Oral
Title: Isospin Effects in the Neutron Star Crust
Author(s): Stefan Schramm, Rana Nandi
Abstract: The properties of the neutron star crust are crucially important for many physical processes occurring in the star. For instance, the crustal transport coefficients define the temperature evolution of accreting stars after bursts, which can be compared to observation. Furthermore, the structure of the inner crust can modify the neutrino transport through the matter considerably, significantly impacting the dynamics of supernova explosions. As the neutron star environment is highly isospin asymmetric, we perform a study of the inner crust, and in particular, the dependence of the pasta phase on the isospin properties of the nuclear interactions. To this end we developed an efficient computer code to simulate the inner and outer crust using molecular dynamics techniques. I will present numerical results with regard to the pasta phase, varying the isospin parameters of the interactions. Results with regard to the nature of the transition from inner crust to the neutron star core will be given and discussed as well.
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Contribution: Poster
Title: The Exclusive photoproduction of Upsilon(1S,2S,3S) in pp and pA collisions for LHC energies
Author(s): F. N. Köpp, M. B. Gay Ducati
Abstract: In this work, we presented the exclusive photoproduction of Upsilon(1S,2S,3S) in pp and pA reactions at the LHC energies for Ultra Peripheral Collisions(UPC). We used the dipole formalism and the following dipoles models: GBW, CGC and b-CGC. One of the main reasons to study this process is related to gluon distribution at low-x. It is well known that at low-x, the gluon distribution shows a divergence and it is not occurs in nature. One way to treat this problem is using the dipole formalism that is characterised by a saturation effect in order to avoid the gluon distribution divergence. The dipole formalism has shown a good agreement with the experimental data since HERA and with recent data released by LHCb for processes involving PSI(1S,2S), Upsilon(1S), Rho for UPC in pp.
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Contribution: Poster
Title: The pT-distribution to the exclusive photoproduction of J/psi and psi(2S) in pp and AA collisions at LHC energies.
Author(s): S. Martins, M. B. Gay Ducati
Abstract: The exclusive photoproduction of heavy vector mesons allows us to analyse hard-diffractive process from perturbative quantum chromodynamics (QCD). In other words, we have the opportunity to investigate the QCD nature of the pomeron, a fundamental object of physical diffractive, described by linear evolution equation BFKL. At high energy, it is expected a transition between the regime described by the linear dynamics, governed by DGLAP and BFKL, and the non-linear dynamics, where the recombination of partons (mainly gluons) becomes important. In this last case, the phase-space parton density reaches a limit in the hadron wave function, characterizing the saturation phenomenum. In this work, the theoretical framework considered in the analysis is the light-cone dipole formalism, where the photon-target interaction amplitude can be written as a convolution between the overlap of the photon-meson wave functions and the dipole-target cross section. Using different phenomenological models, we calculate the transverse momentum distribution in central rapidity for the mesons J/psi and psi(2S) in ultra-peripheral collisions proton-proton and Lead-Lead at 13 TeV and 5.5 TeV, respectively.
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- Abraão Jessé Capistrano de Souza - Universidade Federal da Integração Latino Americana (UNILA), Brazil
- Adam Smith Gontijo Brito de Assis - Instituto Nacional de Pesquisas Espaciais (INPE), Brazil
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