期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 485, 期 1, 页码 796-818出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stz356
关键词
Galaxies: evolution; formation; dwarf; structure
资金
- STFC [ST/N504105/1, ST/N002512/1, ST/R504786/1]
- Worcester College Oxford
- Adrian Beecroft
- Oxford Martin School
- STFC
- Beecroft Fellowship
- ERC [670193]
- Large Facilities Capital Fund of BIS
- French ANR [ANR-13-BS05-0005]
- European Research Council (ERC) [670193] Funding Source: European Research Council (ERC)
- STFC [ST/M007073/1, ST/M006948/1, ST/R001014/1, ST/T001569/1, ST/T001348/1, ST/T001550/1, ST/R001006/1, ST/M007006/1, ST/M007065/1, ST/S002529/1, ST/T001372/1, ST/R00689X/1, ST/R002363/1, ST/R000832/1, ST/M007618/1, ST/R001049/1, ST/P002307/1, ST/N002512/1] Funding Source: UKRI
Our statistical understanding of galaxy evolution is fundamentally driven by objects that lie above the surface-brightness limits of current wide-area surveys (mu similar to 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; mu > 24.5 mag arcsec(-2)), form and evolve over time. For M-* > 10(8) M-circle dot, LSBGs contribute 47, 7, and 6 per cent of the local number, mass, and luminosity densities, respectively (similar to 85/11/10 per cent for M-* > 10(7) M-circle dot). Today's LSBGs have similar dark-matter fractions and angular momenta to high-surface-brightness galaxies (HSBGs; mu < 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 similar to 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.
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