Massive quiescent galaxies at z ∼3: A comparison of selection, stellar population, and structural properties with simulation predictions

Peter Lustig, Veronica Strazzullo, Rhea Silvia Remus, Chiara D'eugenio, Emanuele Daddi, Andreas Burkert, Gabriella De Lucia, Ivan Delvecchio, Klaus Dolag, Fabio Fontanot, Raphael Gobat, Joseph J. Mohr, Masato Onodera, Maurilio Pannella, Annalisa Pillepich

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We study stellar population and structural properties of massive log (M*/M⊙) > 11 galaxies at z ≈ 2.7 in the Magneticum and IllustrisTNG hydrodynamical simulations and GAEA semi-analytic model. We find stellar mass functions broadly consistent with observations, with no scarcity of massive, quiescent galaxies at z ≈ 2.7, but with a higher quiescent galaxy fraction at high masses in IllustrisTNG. Average ages of simulated quiescent galaxies are between ≈0.8 and 1.0 Gyr, older by a factor ≈2 than observed in spectroscopically confirmed quiescent galaxies at similar redshift. Besides being potentially indicative of limitations of simulations in reproducing observed star formation histories, this discrepancy may also reflect limitations in the estimation of observed ages. We investigate the purity of simulated UVJ rest-frame colour-selected massive quiescent samples with photometric uncertainties typical of deep surveys (e.g. COSMOS). We find evidence for significant contamination (up to 60 per cent) by dusty star-forming galaxies in the UVJ region that is typically populated by older quiescent sources. Furthermore, the completeness of UVJ-selected quiescent samples at this redshift may be reduced by ≈ 30 per cent due to a high fraction of young quiescent galaxies not entering the UVJ quiescent region. Massive, quiescent galaxies in simulations have on average lower angular momenta and higher projected axis ratios and concentrations than star-forming counterparts. Average sizes of simulated quiescent galaxies are broadly consistent with observations within the uncertainties. The average size ratio of quiescent and star-forming galaxies in the probed mass range is formally consistent with observations, although this result is partly affected by poor statistics.

Original languageEnglish
Pages (from-to)5953-5975
Number of pages23
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - 1 Feb 2023


  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: star formation
  • galaxies: structure


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