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WHAT SETS THE SIZES OF THE FAINTEST GALAXIES?
Brasseur, Crystal M.1; Martin, Nicolas F.1; Maccio, Andrea V.1; Rix, Hans-Walter1; Kang, Xi2
2011-12-20
Source PublicationASTROPHYSICAL JOURNAL
Volume743Issue:2
AbstractWe provide a comprehensive description and offer an explanation for the sizes of the faintest known galaxies in the universe, the dwarf spheroidal (dSph) satellites of the Milky Way and Andromeda. After compiling a consistent data set of half-light radii (r(1/2)) and luminosities, we describe the size-luminosity relation of dSphs by a log-normal distribution in r(1/2) with a mean size that varies as a function of luminosity. Accounting for modest number statistics, measurement uncertainties, and surface brightness limitations, we find that the size-luminosity relations of the Milky Way and Andromeda dSph populations are statistically indistinguishable and also very similar: their mean sizes at a given stellar luminosity differ by no more than 30%. In addition, we find that the mean size, slope, and scatter of this log-normal size description of Local Group dSphs match onto the relation of more massive low-concentration galaxies. This suggests that the stellar sizes of dSphs are ultimately related to their overall initial baryonic angular momentum. To test this hypothesis, we perform a series of high-resolution N-body simulations that we couple with a semi-analytic model of galaxy formation. These predict the same mean size and slope as observed in dSph satellites. At the same time, these models predict that the size-luminosity distributions for satellite galaxies around similar host halos must be similar providing a natural explanation as to why the size distributions of Milky Way and Andromeda satellites are similar. Although strong rotation is currently not observed in dSphs, this may well be consistent with our angular-momentum-based explanation for their sizes if the disks of these galaxies have become sufficiently stirred through tidal interaction.
KeywordGalaxies: Dwarf Galaxies: Structure Local Group
WOS HeadingsScience & Technology ; Physical Sciences
DOI10.1088/0004-637X/743/2/179
WOS KeywordDARK-MATTER HALOES ; MILKY-WAY SATELLITES ; KECK/DEIMOS SPECTROSCOPIC SURVEY ; DWARF SPHEROIDAL GALAXIES ; LOCAL GROUP ; ELLIPTIC GALAXIES ; STRUCTURAL-PROPERTIES ; SEMIANALYTICAL MODEL ; LUMINOSITY FUNCTION ; DISK GALAXIES
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000298178400081
Citation statistics
Cited Times:35[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/15982
Collection南极天文中心
Affiliation1.Max Planck Inst Astron, D-69117 Heidelberg, Germany
2.Purple Mt Observ, Nanjing 210008, Peoples R China
Recommended Citation
GB/T 7714
Brasseur, Crystal M.,Martin, Nicolas F.,Maccio, Andrea V.,et al. WHAT SETS THE SIZES OF THE FAINTEST GALAXIES?[J]. ASTROPHYSICAL JOURNAL,2011,743(2).
APA Brasseur, Crystal M.,Martin, Nicolas F.,Maccio, Andrea V.,Rix, Hans-Walter,&Kang, Xi.(2011).WHAT SETS THE SIZES OF THE FAINTEST GALAXIES?.ASTROPHYSICAL JOURNAL,743(2).
MLA Brasseur, Crystal M.,et al."WHAT SETS THE SIZES OF THE FAINTEST GALAXIES?".ASTROPHYSICAL JOURNAL 743.2(2011).
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