The first catalogue of spectroscopically confirmed red nuggets at z ∼ 0.7 from the VIPERS survey

Abstract

Context. Red nuggets are a rare population of passive compact massive galaxies thought to be the first massive galaxies that formed in the Universe. First found at z ∼ 3, they are even less abundant at lower redshifts, and it is believed that with time they mostly transformed through mergers into today's giant ellipticals. The red nuggets that managed to escape this fate can serve as unique laboratories to study the early evolution of massive galaxies. Aims. In this paper we aim to make use of the unprecedented statistical power of the VIMOS Public Extragalactic Redshift Survey to build the largest up-to-date catalogue of spectroscopically confirmed red nuggets at the intermediate redshift 0.5 < z < 1.0. Methods. Starting from a catalogue of nearly 90 000 VIPERS galaxies we selected sources with stellar masses M star > 8×10 10 M ⊙ and effective radii R e < 1.5 kpc. From these sources we selected red passive galaxies with old stellar populations based on colour-colour NUVrK diagram, star formation rate values, and verification of their optical spectra. Results. Verifying the influence of the limit of the source compactness on the selection, we found that the sample size can vary by up to two orders of magnitude, depending on the chosen criterion. Using one of the most restrictive criteria with additional checks on their spectra and passiveness, we spectroscopically identified only 77 previously unknown red nuggets. The resultant catalogue of 77 red nuggets is the largest such catalogue built based on the uniform set of selection criteria above the local Universe. The number density calculated on the final sample of 77 VIPERS passive red nuggets per comoving Mpc 3 increases from 4.7×10 −6 at z ∼ 0.61 to 9.8 × 10 −6 at z ∼ 0.95, which is higher than values estimated in the local Universe, and lower than the values found at z > 2. It fills the gap at intermediate redshift.Conclusions. A catalogue of red nuggets presented in this paper is a golden sample for future studies of this rare population of objects at intermediate redshift. In addition to covering a unique redshift range and careful selection of galaxies, the catalogue is spectroscopically identified.

CEERS Key Paper. IV. A Triality in the Nature of HST-dark Galaxies

“…Such systems are classically called quiescent galaxies. We note that rather than the term quiescent, it may be more adequate at early epochs to talk about dormant galaxies; since the universe itself is not much older than those ages, there is no time to be quiescent (in the same way used to talk about other galaxy populations at lower redshifts, such as red nuggets; Costantin et al 2020;Tortora et al 2020;;Lisiecki et al 2023) but these early galaxies may reignite and rejuvenate in their future evolution (Pérez-González et al 2008a;Fumagalli et al 2014;Tacchella et al 2022b;Woodrum et al 2022).…”

The isolated dark matter-poor galaxy that ran away

“…Given that almost the entirety of its stellar component is ∼9 Gyr old and it has largely remained unchanged since its formation, the galaxy can represent an example of a so-called relic galaxy (Ferré-Mateu et al 2015). Observationally confirmed relics (also known as red nuggets) are typically more massive than our example galaxy (Lisiecki et al 2023), but this assumption may be due to bias.…”

The massive relic galaxy NGC 1277 is dark matter deficient

“…Cleaner nuggets can be studied at intermediate and high z (e.g. Damjanov et al 2009Damjanov et al , 2013Damjanov et al , 2014van Dokkum et al 2009;Auger et al 2011;Stockton et al 2014;Hsu et al 2014;Saulder et al 2015;Oldham et al 2017;Charbonnier et al 2017;Buitrago et al 2018;Scognamiglio et al 2020;Spiniello et al 2021a,b;Lisiecki et al 2023;D'Ago et al 2023), but the price to pay is to suffer cosmological dimming and poor angular resolution.…”