The SAMI Galaxy Survey: global stellar populations on the size–mass plane

Abstract

We present an analysis of the global stellar populations of galaxies in the SAMI Galaxy Survey. Our sample consists of 1319 galaxies spanning four orders of magnitude in stellar mass and includes all morphologies and environments. We derive luminosityweighted, single stellar population equivalent stellar ages, metallicities and alpha enhancements from spectra integrated within one effective radius apertures. Variations in galaxy size explain the majority of the scatter in the age-mass and metallicitymass relations. Stellar populations vary systematically in the plane of galaxy size and stellar mass, such that galaxies with high stellar surface mass density are older, more metal-rich and alpha-enhanced than less dense galaxies. Galaxies with high surface mass densities have a very narrow range of metallicities, however, at fixed mass, the spread in metallicity increases substantially with increasing galaxy size (decreasing density). We identify residual correlations with morphology and environment. At fixed mass and size, galaxies with late-type morphologies, small bulges and low Sérsic n are younger than early-type, high n, high bulge-to-total galaxies. Age and metallicity both show small residual correlations with environment; at fixed mass and size, galaxies in denser environments or more massive halos are older and somewhat more metal rich than those in less dense environments. We connect these trends to evolutionary tracks within the size-mass plane.

HST/WFC3 grism observations of z ∼ 1 clusters: evidence for evolution in the mass–size relation of quiescent galaxies from post-starburst galaxies

“…In further support of this conclusion, Fagioli et al (2016) found that large quiescent field galaxies with 10.5 < Log(M * /M ) < 11 at 0.2 < z < 0.8 were composed of younger stellar populations than smaller quiescent field galaxies within the same stellar mass range. Similar results to this one have also been found by Delaye et al (2014), Gargiulo et al (2017), Scott et al (2017), Williams et al (2017), Zahid & Geller (2017) and Wu et al (2018). van der Wel et al (2014) however did observe a decrease in the number density of compact quiescent galaxies with a much larger sample of field galaxies between 0 < z < 2, concluding that minor mergers drive the observed growth in the average size of quiescent galaxies with decreasing redshift.…”

The VIRUS-P Exploration of Nearby Galaxies (VENGA): the stellar populations and assembly of NGC 2903’s bulge, bar, and outer disc

“…The authors found that seven out of the seven gas-phase metallicity indicators exhibit solar and super-solar values in the central region of NGC 2903, even reaching 0.4 dex above so-lar values. It is interesting to note that other radial gradient studies in the low redshift regime (e.g., González Delgado et al 2015;Scott et al 2017) show that the median stellar metallicity trend for galaxies with similar morphology and similar mass to NGC 2903 have slighty below solar stellar metallicity values. This may however be an effect of lower spatial sampling that would drive the average metallicity down.…”

Supernovae and their host galaxies – VI. Normal Type Ia and 91bg-like supernovae in ellipticals

“…According to Taylor et al, this relation provides an estimate of the stellar mass-to-light ratio (M * /Li) to a 1σ accuracy of ∼ 0.1 dex. In addition, to estimate average host galaxy stellar metallicities, we use the Gallazzi et al (2006) correlation between stellar mass of E-S0 galaxy and log(Z * /Z⊙) as determined from about 26000 SDSS galaxies (see also Scott et al 2017, for early-type/high mass galaxies):…”