Arcila-Osejo, Liz Maria; Sawicki, Marcin, 1969-; Arnouts, Stephane; Golob, Anneya; Moutard, Thibaud; Sorba, Robert (Oxford University PressRoyal Astronomical Society, 2019-04-29)
We introduce the largest to date survey of massive quiescent galaxies at redshift ζ ∼ 1.6. With these data, which cover 27.6 deg<sup>2</sup>, we can find significant numbers of very rare objects such as ultra-massive quiescent galaxies that populate the extreme massive end of the galaxy mass function, or dense environments that are likely to become present-day massive galaxy clusters. In this paper, the first in a series, we apply our gζK<sub>s</sub> adaptation of the BζK</span> technique to select our ζ ∼ 1.6 galaxy catalogue and then study the quiescent galaxy stellar mass function with good statistics over M⋆ ∼ 10<sup>10.2_</sup>10<sup>11.7</sup> M<sub>⊙</sub> – a factor of 30 in mass – including 60 ultra-massive ζ ∼ 1.6 quiescent galaxies with M<sub>⋆</sub> > 10<sup>11.5</sup> M<sub>⊙</sub>. We find that the stellar mass function of quiescent galaxies at ζ ∼ 1.6 is well represented by the Schechter function over this large mass range. This suggests that the mass-quenching mechanism observed at lower redshifts must have already been well established by this epoch, and that it is likely due to a single physical mechanism over a wide range of mass. This close adherence to the Schechter shape also suggests that neither merging nor gravitational lensing significantly affects the observed quenched population. Finally, comparing measurements of <strong>M<sup>∗</sup> </strong>parameters for quiescent and star-forming populations (ours and from the literature), we find hints of an offset (<strong>M<sup>∗</sup><sub>SF</sub>>M</strong><sub><strong>∗PE</strong></sub>), which could suggest that the efficiency of the quenching process evolves with time....