Nature versus nurture: relic nature and environment of the most massive passive galaxies at $z<0.5$

Abstract

Relic galaxies are thought to be the progenitors of high-redshift red nuggets that for some reason missed the channels of size growth and evolved passively and undisturbed since the first star formation burst (at $z>2$). These local ultracompact old galaxies are unique laboratories for studying the star formation processes at high redshift and thus the early stage of galaxy formation scenarios. Counterintuitively, theoretical and observational studies indicate that relics are more common in denser environments, where merging events predominate. To verify this scenario, we compared the number counts of a sample of ultracompact massive galaxies (UCMGs) selected within the third data release of the Kilo Degree Survey, that is, systems with sizes $R_{\mathrm{e}}<1.5\mathrm{kpc}$ and stellar masses $M_{\star }>8\times 10^{10}{\mathrm{M}}_{\odot }$, with the number counts of galaxies with the same masses but normal sizes in field and cluster environments. Based on their optical and near-infrared colors, these UCMGs are likely to be mainly old, and hence representative of the relic population. We find that both UCMGs and normal-size galaxies are more abundant in clusters and their relative fraction depends only mildly on the global environment, with denser environments penalizing the survival of relics. Hence, UCMGs (and likely relics overall) are not special because of the environment effect on their nurture, but rather they are just a product of the stochasticity of the merging processes regardless of the global environment in which they live.

Accepted for publication on Astronomy & Astrophysics Letters, 6 pages, 1 figure

References in corpus (8)

• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• Radial variations in the stellar initial mass function of early-type galaxies
• Superdense massive galaxies in the Nearby Universe
• The initial mass function of a massive relic galaxy
• From blue star-forming to red passive: galaxies in transition in different environments
• A cooperative approach among methods for photometric redshifts estimation: an application to KiDS data
• Evolution of central dark matter of early-type galaxies up to z ~ 0.8
• The last 6 Gyr of dark matter assembly in massive galaxies from the Kilo Degree Survey

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