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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20180725T103000
DTEND;TZID=Atlantic/Canary:20180725T113000
UID:iactalks-1191
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1191
CREATED:2018-07-25T10:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY: Galaxies in the low-surface-brightness Universe - the new frontier
  in galaxy evolution studies
DESCRIPTION: Galaxies in the low-surface-brightness Universe - the new fron
 tier in galaxy evolution studies\nDr. Sugata Kaviraj\n\nA new era of obser
 vational surveys that are both deep and wide is poised  to revolutionise o
 ur understanding of galaxy evolution, by enabling,  for the first time, st
 atistical studies of the low-surface-brightness  (LSB) Universe. While lar
 gely inaccessible in past wide-area surveys  like the SDSS (due to their l
 ack of depth), the uncharted LSB regime  holds the key to a complete under
 standing of galaxy evolution. While  small, deep surveys and new instrumen
 ts have long hinted at the  existence of a rich population of LSB galaxies
  below the  surface-brightness limits of surveys like the SDSS, the mechan
 isms that  create these galaxies remain unexplored. We use, Horizon-AGN, a
   cosmological hydrodynamical simulation to study how and why  low-surface
 -brightness galaxies (LSBGs;  mu > 23 mag arcsec^-2), and  in part
 icular, the recently studied population of ultra-diffuse  galaxies, form a
 nd evolve over time. For stellar masses greater than  10^7  MSun, LSB
 Gs contribute 85, 10 and 11 per cent of the local number,  mass and lumino
 sity densities respectively. When controlled for stellar  mass, today's LS
 BGs have similar dark-matter fractions and angular  momenta to their high-
 surface-brightness (HSB) counterparts but larger  (x 2.5) effective radii 
 and lower (< 5% vs 30%) star-forming gas  fractions. Interestingly, LSB
 Gs originate from the same progenitors as  HSB systems at high redshift (z
 ~3). However, LSBG progenitors form stars  more rapidly at early epochs. T
 he higher resultant supernova energy  injection flattens their gas-density
  profiles which, in turn, creates  shallow stellar profiles that are more 
 susceptible to tidal processes.  After z~1, harassment and tidal heating s
 teadily expand LSBG stellar  distributions and quench star formation by he
 ating cold gas, creating  the population of diffuse, gas-poor LSB systems 
 seen today. In clusters,  ram-pressure stripping provides an additional me
 chanism that assists in  gas removal in LSBG progenitors. The study of LSB
 Gs will be one of most  exciting advances in galaxy evolution in the comin
 g years. This study  offers insights into the demographics and properties 
 of a population of  galaxies that will have a transformational impact on o
 ur understanding  of galaxy evolution.
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