Mon. Not. R. Astron. Soc., 485, 796-818 (2019/May-1)
The formation and evolution of low-surface-brightness galaxies.
MARTIN G., KAVIRAJ S., LAIGLE C., DEVRIENDT J.E.G., JACKSON R.A., PEIRANI S., DUBOIS Y., PICHON C. and SLYZ A.
Abstract (from CDS):
Our statistical understanding of galaxy evolution is fundamentally driven by objects that lie above the surface-brightness limits of current wide-area surveys (µ ∼ 23 mag arcsec–2). While both theory and small, deep surveys have hinted at a rich population of low-surface-brightness galaxies (LSBGs) fainter than these limits, their formation remains poorly understood. We use Horizon-AGN, a cosmological hydrodynamical simulation to study how LSBGs, and in particular the population of ultra-diffuse galaxies (UDGs; µ > 24.5 mag arcsec–2), form and evolve over time. For M*>108 M☉, LSBGs contribute 47, 7, and 6 per cent of the local number, mass, and luminosity densities, respectively (∼85/11/10 per cent for M*>107 M☉). Today's LSBGs have similar dark-matter fractions and angular momenta to high-surface-brightness galaxies (HSBGs; µ < 23 mag arcsec–2), but larger effective radii (x2.5 for UDGs) and lower fractions of dense, star-forming gas (more than x6 less in UDGs than HSBGs). LSBGs originate from the same progenitors as HSBGs at z > 2. However, LSBG progenitors form stars more rapidly at early epochs. The higher resultant rate of supernova-energy injection flattens their gas-density profiles, which, in turn, creates shallower stellar profiles that are more susceptible to tidal processes. After z ∼ 1, tidal perturbations broaden LSBG stellar distributions and heat their cold gas, creating the diffuse, largely gas-poor LSBGs seen today. In clusters, ram-pressure stripping provides an additional mechanism that assists in gas removal in LSBG progenitors. Our results offer insights into the formation of a galaxy population that is central to a complete understanding of galaxy evolution, and that will be a key topic of research using new and forthcoming deep-wide surveys.
© The Author(s) 2019. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Galaxies: evolution - formation - dwarf - structure
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