- Este evento já passou.
Seminários de Astronomia: Post-starburst galaxies and the origin of galaxy bimodality — David Maltby (University of Nottingham).
12 de julho de 2017:12:30 - 13:30
Despite decades of study, we still do not fully understand why some massive galaxies
abruptly switch off their star formation in the early Universe, and what causes their rapid
transition to the red sequence. Post-starburst galaxies (PSBs) are key to understanding this
transition phase, as they represent systems in which a major burst of star formation was rapidly
quenched within the last Gyr. Recently, a photometric PCA technique has identified over 900
candidate PSBs in the UKIDDS Ultra Deep (UDS) field at redshifts 0.5 to 2. In this talk, I will
present spectroscopic verification of this technique and demonstrate that ~80% of the
photometrically-selected PSB candidates show spectral signatures characteristic of this
population. I will also present results on the morphological structure of these galaxies,
obtained from a combination of deep ground- and space-based imaging (UDS UKIRT-WFCAM
and CANDELS HST-ACS/WFC3). Using both 2D-Sersic modelling and an independent isophotal
analysis, I will show that PSB galaxies at high redshift (z above 1) are surprisingly compact and
spheroidal, while at lower redshifts they are more extended and disc-dominated. I will also
discuss what these results can tell us about the potential quenching mechanisms operating in
this important transitional population at different epochs.