In pursuit of giants

II. Evolution of dusty quiescent galaxies over the last six billion years from the hCOSMOS survey

¹ National Centre for Nuclear Research, Pasteura 7, 02-093 Warsaw, Poland
e-mail: darko.donevski@ncbj.gov.pl
² SISSA, Via Bonomea 265, 34136 Trieste, Italy
³ IFPU – Institute for fundamental physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
⁴ Department of Astronomy and Physics, Saint Mary’s University, 923 Robie Street, Halifax, NS B3H 3C3, Canada
⁵ Canada Research Chair in Astronomy and Astrophysics, Tier II, Canada
⁶ Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
⁷ INAF – Osservatorio di Astrofisica e Scienza dello Spazio, Via Gobetti 93/3, 40129 Bologna, Italy
⁸ INAF – OAPD, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁹ Department of Astronomy, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL, USA
¹⁰ Cosmic Dawn Center (DAWN), Rådmandsgade 64, 2200 Copenhagen, Denmark
¹¹ Institute for Astronomy, Royal Observatory, University of Edinburgh, Edinburgh EH9 3HJ, UK
¹² Department of Physics & Astronomy, University of the Western Cape, Robert Sobukwe Rd, Bellville 7535, South Africa
¹³ Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
¹⁴ Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
¹⁵ Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
¹⁶ CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
¹⁷ Max-Planck-Institute für Astrophysik, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany

Received: 2 February 2023
Accepted: 10 July 2023

Abstract

The physical mechanisms that link the termination of star formation in quiescent galaxies and the evolution of their baryonic components, stars, and the interstellar medium (ISM; dust, gas, and metals) are poorly constrained beyond the local Universe. In this work, we characterise the evolution of the dust content in 545 quiescent galaxies observed at 0.1 < z < 0.6 as part of the hCOSMOS spectroscopic redshift survey. This is, to date, the largest sample of quiescent galaxies at intermediate redshifts for which the dust, stellar, and metal abundances are consistently estimated. We analyse how the crucial markers of a galaxy dust life cycle, such as specific dust mass (M_dust/M_⋆), evolve with different physical parameters, namely gas-phase metallicity (Z_gas), time since quenching (t_quench), stellar mass (M_⋆), and stellar population age. We find morphology to be an important factor in the large scatter in M_dust/M_⋆ (∼2 orders of magnitude). Quiescent spirals exhibit strong evolutionary trends of specific dust mass with M_⋆, stellar age, and galaxy size, in contrast to the little to no evolution experienced by ellipticals. When transitioning from solar to super-solar metallicities (8.7 ≲ 12 + log(O/H)≲9.1), quiescent spirals undergo a reversal in M_dust/M_⋆, indicative of a change in dust production efficiency. By modelling the star formation histories of our objects, we unveil a broad dynamical range of post-quenching timescales (60 Myr < t_quench < 3.2 Gyr). We show that M_dust/M_⋆ is highest in recently quenched systems (t_quench < 500 Myr), but its further evolution is non-monotonic, as a consequence of different pathways for dust formation, growth, or removal on various timescales. Our data are best described by simulations that include dust growth in the ISM. While this process is prevalent in the majority of galaxies, for ∼15% of objects we find evidence of additional dust content acquired externally, most likely via minor mergers. Altogether, our results strongly suggest that prolonged dust production on a timescale of 0.5 − 1 Gyr since quenching may be common in dusty quiescent galaxies at intermediate redshifts, even if their gas reservoirs are heavily exhausted (i.e. cold gas fraction < 1 − 5%).