Research Accomplishments

Dr. Storchi Bergmann’s main area of research has been the investigation of starburst and nuclear activity in galaxies – the building blocks of the Universe. Starburst and nuclear activity sample important phases in the evolution of galaxies. Luminous starbursts probe vigorous episodes of star formation which lead to the growth of galaxies − and in particular, of their central bulges. Active Galactic Nuclei (hereafter AGN) probe the phases in which supermassive black holes (hereafter SMBH) − now known to be present in the nuclei of most galactic bulges − are actively accreting mass. The study and characterization of these phases and their relation − as we now know that the masses of the nuclear SMBH are proportional to those of the corresponding galactic bulges − are fundamental for the understanding of galaxy evolution.

PhD: Dr. Storchi Bergmann was hired by IF-UFRGS when she had just finished her Masters Dissertation. After a couple of years observing in the local and national observatories, when she published a few papers on stellar and galaxy photometry, she had the opportunity to use the telescopes of the Cerro Tololo Interamerican Obsevatory (CTIO), in Chile, to obtain spectra of active galaxies for her PhD Thesis, under the supervision of Dr. Miriani Pastoriza. The main topic of the thesis was on the determination of the chemical abundance of the gas around AGN. They concluded that the emitting gas has an enhanced abundance of Nitrogen, and thus was the result of many previous generations of stars, within which it is synthesized and released to the insterstellar medium through supernova explosions. The resulting three papers have been cited over 120 times. At CTIO she participated of the first observations of the supernova 1987A; because of this work, together with Dr. Pastoriza, she was the subject of an article in the New York Times.

Pos-doc 1: After the PhD, she did post-doctoral studies at the University of Maryland, Washington DC (US), in a collaboration with Dr. Andrew S. Wilson, studying rings of star-formation around AGN as well as conical mass outflows from AGN. Besides mapping the gas excitation and kinematics in the outflow, they showed that the emission properties were consistent with the presence of an obscuring torus around the AGN at the apex of the cone. 7 papers were published with circa 700 citations to them.

Pos-doc 2: At the same epoch, she began a profitable collaboration with Drs. Anne Kinney and Daniella Calzetti at the Space Telescope Science Institute (STScI), Baltimore, MD (US), collecting spectral energy distributions of star-forming, active and normal galaxies which gave origin to a number of studies: (1) the derivation of an extragalactic reddening law for starburst galaxies (the famous Calzetti law, in two papers with almost 2000 citations); (2) the relation between stellar and gaseous metallicity in star-forming galaxies (2 papers with more than 300 citations); (3) the building of spectral templates which are now used in most observatories as templates for the calculation of exposure times (paper with more than 500 citations); (4) a database of UV-optical spectra of nearby quiescent and active galaxies, recoverable from the homepage of STScI.

By the end of the 1990’s, she began studies of the stellar population in the nuclear region of active galaxies, which led to the conclusion that there is an excess of intermediate age (108 stellar population in the circumnuclear region (inner kpc) of AGN when compared with non-active galaxies. An evolutionary scenario was proposed in which interactions with companion galaxies send gas inwards, triggering episodes of star-formation followed by the onset of nuclear activity. She wrote more than 15 papers on this topic (citations close to 1000), in another profitable collaboration with Dr. Roberto Cid Fernandes.

Her discovery of a transient accretion disk around the LINER nucleus of the galaxy NGC1097 led to a number of studies which showed how an accretion disk around a nuclear supermassive black hole evolves with time, revealing also the structure of the accretion flow: a hot “ion torus” in the inner rim of the disk surrounded by a flatter structure where spiral arms can develop. Radiation from the inner hot torus ionizes the outer part of the flat disk driving line emission, which has a varying double- peaked profile, confirming that its origin is a flattened and inclined structure with an asymmetric emission (the spiral arm). She has observed the corresponding double-peaked profiles in the Balmer emission lines of NGC1097 and other LINER nuclei. 7 papers published on this topic generated about 500 citations.

Recent studies (beginning circa 2006) include the search for signatures of gas transfer to the nuclear region of active galaxies, a necessary process to allow the formation of the accretion disk which in turn feeds the supermassive black hole. Although predicted, gas inflows are seldom observed due to the presence of outflows from the AGN which dominate the gas emission. She has mapped both inflows and outflows within the inner few hundred parsecs of AGN using HST imaging and Integral Field Spectroscopy (IFS), mostly using the Gemini telescopes. The IFS product is a data cube which provides both spatial (x and y axes) and spectral information (z axis), corresponding to thousands of spectra to characterize the region around AGN. The data analysis is sophisticated and time-consuming, and Dr. Storchi Bergmann’s group (students and collaborators) is considered a worldwide reference group in the application of this technique to map the gas kinematics and excitation around AGN. She has published 20 papers using this technique in the last 5 years, having accumulated already circa 400 citations to these papers. Although finding that outflows are indeed ubiquitous, new original results include the observation of resolved inflows in the inner ten to hundred of parsecs of about 1/3 of the sample observed so far. Other recent product of the analysis of the data cubes is the mapping of the distribution of the stellar population in the vicinity of AGN.

Over the years, Dr. Storchi Bergmann has participated of many Scientific Committees of Conferences, as well as in Time Allocation Committees of Observatories, such as the Hubble Space Telescope, the European Southern Observatory and the Gemini Observatory. As a Professor, besides having taught many courses, one important contribution was the creation of a discipline at UFRGS which is a success among both science and non-science majors, called: “Exploring the Universe: from Quarks to Quasars”, which has an enrollment of more than 200 students per semester.

Dr. Storchi Bergmann has advised during her career 10 MSc and 10 PhD students, as well as 5 post- docs and more than 20 undergraduate students. Their PhD student have been finding positions at prestigious Institutes all over the world, such as the Space Telescope Science Institute, Goddard Space Flight Center, US Naval Observatory, Gemini Observatory (two permanent and two post-doctoral positions). A few are Professors at Universities, and one is now working for the company Petrobras.

She is member of the Brazilian Academy of Sciences since 2009, has received the Elsevier/Scopus prize for her volume of publications and number of citations in 2010 and in 2011 has been nominated member of the Academy of Sciences of the Developing World (TWAS).

Postgraduate and Postdoc Students

PhD students (in progress):

Janaína Nascimento – Galáxias ativas e Starburst em 3 dimensões
Astor Schonell Jr. – Co-evolução de Galáxias e Buracos Negros Supermassivos.

PhDs completed:

Guilherme dos Santos Couto – Relação entre estruturas nucleares e os processos de inflow e outflow em núcleos ativos de galáxias.
Jáderson Schimoia – A natureza da emissão em duplo pico de galáxias ativas.
Daniel Drehmer – Buracos Negros Supermassivos no Centro de Galáxias: Efeitos na Cinemática Estelar. Data da defesa: ***
David Sanmartim – População Estelar e Cinemática em Quasares Post-Starburst Data da defesa da tese: Agosto de 2013. Atualmente realiza estágio de Pós-Doutorado no Exterior (CNPq) junto ao telescópio SOAR.
Allan Schnorr Müller – Alimentação do Buraco Negro Supermassivo no Núcleo de Galáxias Ativas. Data da defesa: 20/06/2013. Coorientação: Prof. Dr. Fabricio Ferrari. Atualmente realiza pós-doutorado no exterior, junto ao Max-Planck Institute of Extraterrestrial Physic, Garching, Alemanha.
Rodrigo Nemmen da Silva – Acreção a Buracos Negros Supermassivos no Universo Presente. Data da defesa: 18/06/2009. Atualmente é professor contratado do Instituto Astronômico e Geofísico da Universidade de São Paulo, SP.
Rogemar André Riffel – Mapeamento “tridimensional” do entorno dos buracos negros supermassivos em galáxias Seyfert.Data da defesa: 27/03/2008. Atualmente é professor contratado da Universidade Federal de Santa Maria, RS.
Fausto Kuhn Berenguer Barbosa – Cinemática Bi-dimensional da Região Nuclear de Galáxias Seyfert. Data da defesa: 18/01/2007. Atualmente é professor contratado do Instituto Federal de Educação da Restinga, RS.
Daniel Iunes Raimann – População estelar em galáxias ativas versus não ativas: o papel das novas gerações de estrelas. Data da defesa: 27/08/2004. Atualmente é professor na Universidade do Estado de Santa Catarina (UDESC).
Henrique Aita Fraquelli – O gás ionizado em galáxias ativas. Data da defesa: 24/06/2002. Atualmente trabalha na Petrobrás, RJ.
Henrique Roberto Schmitt – O estudo do contínuo e da região de linhas de galáxias Seyfert: implicações ao modelo unificado. Data da defesa: 23/03/1998. Atualmente trabalha no Observatório Naval dos Estados Unidos.
Cláudia Winge – Estudo da variabilidade óptica de uma amostra de galáxias com núcleo ativo. Data da defesa: 23/06/1995. Co-Orientação: Miriani Griselda Pastoriza.

Postdoc researchers:

Dinalva Aires Sales (em andamento) – A estrutura interna de galáxias com emissão megamaser de OH.
Tibério Borges Vale (concluído) – Bolsista de Pós-doutorado CNPq de Agosto/2010 a Março/2012.
Rodrigo Nemmen (concluído) – Atlas de Cubos de Dados.
Rogemar Riffel (concluído) – Atlas de Cubos de Dados.
Joao R. S. Leão (concluído) – Discos estelares nucleares.
Roberto Cid Fernandes (concluído) – Populações Estelares em Galáxias Ativas.

Other students and collaborators:

Patricia Figueiró Spinelli – Aluna de mestrado, dissertação: Caracterização das Regiões Circumnucleares de Galáxias Seyfert 1 versus Seyfert 2 no ultravioleta próximo, 2007.
Tibério Borges Vale – Pós-doutor de 08/2010 a 03/2012, atualmente professor na Universidade Federal Fluminense.
João R. S. Leão – 2007.
Roberto Cid Fernandes – Pós-doutor, atualmente professor titular da UFSC.