The size distribution of galaxies in the Sloan Digital Sky Survey

Abstract

abridged: We use a complete sample of about 140,000 galaxies from the Sloan Digital Sky Survey (SDSS) to study the size distribution of galaxies and its dependence on their luminosity, stellar mass, and morphological type. The large SDSS database provides statistics of unprecedented accuracy. For each type of galaxy, the size distribution at given luminosity (or stellar mass) is well described by a log-normal function, characterized by its median $\bar{R}$ and dispersion $\sigma_{\ln R}$. For late-type galaxies, there is a characteristic luminosity at $M_{r,0}\sim -20.5$ (assuming $h=0.7$) corresponding to a stellar mass $M_0\sim 10^{10.6}\Msun$. Galaxies more massive than $M_0$ have $\bar{R}\propto M^{0.4}$ and $\sigma_{\ln R}\sim 0.3$, while less massive galaxies have $\bar{R}\propto M^{0.15}$ and $\sigma_{\ln R}\sim 0.5$. For early-type galaxies, the $\bar{R}$ - $M$ relation is significantly steeper, $\bar{R}\propto M^{0.55}$, but the $\sigma_{\ln R}$ - $M$ relation is similar to that of late-type galaxies. Faint red galaxies have sizes quite independent of their luminosities.Comment: 42 pages, 18 figures, 2 tables; replaced with the version accepted by MNRA

Formation of disc galaxies in preheated media: a preventative feedback model

“…This over-prediction is not surprising because we only attempt to model disk galaxies, and ignore angular momentum loss, which is expected in spheroidal galaxies formed mainly through mergers (e.g. Shen et al 2003). This over-prediction leaves room for angular momentum loss possibly happening in reality.…”

“…For the observational data, we only show the mean relation between the half mass radius and stellar mass, as the scatter in the relation is not a focus of the model. Those observational data include Shen et al (2003) and Dutton et al (2007) for local galaxies, and Dutton et al (2011), Ichikawa, Kajisawa & Akhlaghi (2012, and van der Wel et al (2014) for galaxies in a range of redshift from z = 0 to 2. The upper panels show the predictions of Model-EJ.…”

The size evolution of star-forming and quenched galaxies in the IllustrisTNG simulation

“…The main differences between these observational studies are as follows. (2014) perform two-dimensional fits to the whole galaxy image, while Shen et al (2003) perform one-dimensional fits on azimuthally averaged annuli. This is shown by Bernardi et al (2014) to be responsible for their steeper slopes at high masses with respect to Shen et al (2003).…”

“…Galaxy size is a basic observational property that is found to significantly vary with galaxy mass, color or star-formation activity, and redshift (Shen et al 2003;Ferguson et al 2004;Trujillo et al 2006;Elmegreen et al 2007;Williams et al 2010;Mosleh et al 2012;Ono et al 2013;van der Wel et al 2014;Lange et al 2015). These dependencies encode important information on the formation processes of galaxies of different types.…”

The metal enrichment of passive galaxies in cosmological simulations of galaxy formation

“…Since the original spectra were measured in 1.5 arcsec radius fibre aperture in SDSS, we correct the observed metallicities from aperture values to mean global values assuming a uniform metallicity gradient, d log Z/d log r = −0.15, based on Rawle et al (2010) and by using the redshift of each galaxy. We here assume that the light profile in each galaxy follows an r 1/4 raw and the median size-mass relation for early-type galaxies by Shen et al (2003). The corrected median MZR is shown by the solid line in Fig.…”