Size distribution of galaxies in SDSS DR7: Weak dependence on halo environment

Abstract

Using a sample of galaxies selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and a catalog of bulge-disk decompositions, we study how the size distribution of galaxies depends on the intrinsic properties of galaxies, such as concentration, morphology, specific star formation rate (sSFR), and bulge fraction, and on the large-scale environments in the context of central/satellite decomposition, halo environment, the cosmic web: cluster, filament, sheet and void, as well as galaxy number density. We find that there is a strong dependence of the luminosity- or mass-size relation on the galaxy concentration, morphology, sSFR and bulge fraction. Compared with late-type (spiral) galaxies, there is a clear trend of smaller sizes and steeper slope for early-type (elliptical) galaxies. Similarly, galaxies with a high bulge fraction have smaller sizes and steeper slopes than those with a low bulge fraction. Fitting formulae of the average luminosity- and mass-size relations are provided for galaxies with these different intrinsic properties. Examining galaxies in terms of their large scale environments, we find that the mass-size relation has some weak dependence on the halo mass and central/satellite segregation for galaxies within mass range 9.0 ≤ log M ∗ ≤ 10.5, where satellites or galaxies in more massive halos have slightly smaller sizes than their counterparts, while the cosmic web and local number density dependence of the mass-size relation is almost negligible.