SUPERDENSE GALAXIES AND THE MASS–SIZE RELATION AT LOW REDSHIFT

By B. Poggianti, R. Calvi, D. Bindoni, M. D’Onofrio, A. Moretti, T. Valentinuzzi, G. Fasano, J. Fritz, G. Lucia, B. Vulcani and 3 more. 2012

140 citations recorded by the source corpus.

We search for massive and compact galaxies (superdense galaxies, hereafter SDGs) at z = 0.03–0.11 in the Padova-Millennium Galaxy and Group Catalogue, a spectroscopically complete sample representative of the general field population of the local universe. We find that compact galaxies with radii and mass densities comparable to high-z massive and passive galaxies represent 4.4% of all galaxies with stellar masses above 3 × 1010 M☉, yielding a number density of 4.3 × 10−4 h3 Mpc−3. Most of them are S0s (70%) or ellipticals (23%), are red, and have intermediate-to-old stellar populations, with a median luminosity-weighted age of 5.4 Gyr and a median mass-weighted age of 9.2 Gyr. Their velocity dispersions and dynamical masses are consistent with the small radii and high stellar mass estimates. Comparing with the WINGS sample of cluster galaxies at similar redshifts, the fraction of SDGs is three times smaller in the field than in clusters, and cluster SDGs are on average 4 Gyr older than field SDGs. We confirm the existence of a universal trend of smaller radii for older luminosity-weighted ages at fixed galaxy mass. As a consequence, the median mass–size relation shifts toward smaller radii for galaxies with older stars, but the effect is much more pronounced in clusters than in the field. Our results show that, on top of the well-known dependence of stellar age on galaxy mass, the luminosity-weighted age of galaxies depends on galaxy compactness at fixed mass and, for a fixed mass and radius, on environment. This effect needs to be taken into account in order not to overestimate the evolution of galaxy sizes from high to low z. Our results and hierarchical simulations suggest that a significant fraction of the massive compact galaxies at high z have evolved into compact galaxies in galaxy clusters today. When stellar age and environmental effects are taken into account, the average amount of size evolution of individual galaxies between high and low z is mild, a factor ∼1.6.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/59d490542e706e0e6e532d3205db8237ba55f612

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In Astronomy and Astrophysics

1. P. V. van Dokkum
2. P. Hopkins
3. M. Franx
4. L. Hernquist
5. D. M. Alexander
6. R. Dav'e
7. I. Labbé
8. F. Walter

In Instrumentation

1. P. V. van Dokkum
2. M. Franx
3. G. Brammer
4. I. Labbé
5. M. Kriek
6. P. Oesch
7. P. Hopkins
8. C. Conroy

Citations in the corpus

• FORMING COMPACT MASSIVE GALAXIES (2015, background): “…that all massive galaxies in the present-day Universe had a compact progenitor (van Dokkum et al. 2008, 2014; Franx et al. 2008; Newman et al. 2012; Poggianti et al. 2013; Belli, Newman, & Ellis 2014a); however, the vast majority of com- 1 Department of Astronomy, Yale University, New Haven, CT…”
• AN ALMA SURVEY OF SUBMILLIMETER GALAXIES IN THE EXTENDED CHANDRA DEEP FIELD SOUTH: THE REDSHIFT DISTRIBUTION AND EVOLUTION OF SUBMILLIMETER GALAXIES (2013, methodology): “First, we consider the mass-weighted stellar ages of the PM2GC ellipticals, calculated with a spectrophotometric model that finds the combination of SSP synthetic spectra that best-fits the observed spectroscopic and photometric features of each galaxy (Poggianti et al. 2013).”
• Size evolution of normal and compact galaxies in the EAGLE simulation (2015, background): “The EAGLE simulation appears to reproduce many aspects of the observable Universe, in particular, the stellar mass distribution and sizes of galaxies in the local Universe.”
• 3D-HST+CANDELS: THE EVOLUTION OF THE GALAXY SIZE–MASS DISTRIBUTION SINCE z = 3 (2014, unknown): “…2kpc) exists within present-day clusters, with a number density comparable to that of higher-redshift early-type galaxies (Valentinuzzi et al. 2010; Poggianti et al. 2013); tension with the absence of such galaxies in the Sloan Digital Sky Survey (SDSS) remains (Trujillo et al. 2009; Taylor et…”