Article

THE PAN-STARRS1 MEDIUM-DEEP SURVEY: THE ROLE OF GALAXY GROUP ENVIRONMENT IN THE STAR FORMATION RATE VERSUS STELLAR MASS RELATION AND QUIESCENT FRACTION OUT TO<i>z</i>∼ 0.8

Lihwai LinInstitute of Astronomy & Astrophysics, Academia Sinica, Taipei 106, Taiwan, R.O.C.; [email protected]Hung-Yu JianDepartment of Physics, National Taiwan University, Taipei 106, Taiwan, R.O.CS. FoucaudDepartment of Earth Sciences, National Taiwan Normal University, N°88, Tingzhou Road, Sec. 4, Taipei 11677, Taiwan, R.O.CP. NorbergInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKR. G. BowerInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKShaun ColeInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKP. Arnalte-MurInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKChin-Wei ChenInstitute of Astronomy & Astrophysics, Academia Sinica, Taipei 106, Taiwan, R.O.C.; [email protected]Jean CouponDepartment of Astronomy, University of Geneva, ch. d'Ecogia 16, CH-1290 Versoix, SwitzerlandBau-Ching HsiehInstitute of Astronomy & Astrophysics, Academia Sinica, Taipei 106, Taiwan, R.O.C.; [email protected]S. HeinisDepartment of Astronomy, University of Maryland, MD 20742, USAS. PhlepsMax-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, D-85748 Garching, GermanyWenping ChenGraduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan, R.O.CChien‐Hsiu LeeMax-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, D-85748 Garching, GermanyW. S. BurgettInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAK. C. ChambersInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAL. DenneauInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAP. W. DraperInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKH. FlewellingInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAK. W. HodappInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAM. E. HuberInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAN. KaiserInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAR. P. KudritzkiInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAE. A. MagnierInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAN. MetcalfeInstitute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UKP. A. PriceDepartment of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USAJ. TonryInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAR. J. WainscoatInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USAC. WatersInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

2014en

ABI

Abstract

Using a large optically selected sample of field and group galaxies drawn from the Pan-STARRS1 Medium-Deep Survey (PS1/MDS), we present a detailed analysis of the specific star formation rate (SSFR)—stellar mass (M *) relation, as well as the quiescent fraction versus M * relation in different environments. While both the SSFR and the quiescent fraction depend strongly on stellar mass, the environment also plays an important role. Using this large galaxy sample, we confirm that the fraction of quiescent galaxies is strongly dependent on environment at a fixed stellar mass, but that the amplitude and the slope of the star-forming sequence is similar between the field and groups: in other words, the SSFR-density relation at a fixed stellar mass is primarily driven by the change in the star-forming and quiescent fractions between different environments rather than a global suppression in the star formation rate for the star-forming population. However, when we restrict our sample to the cluster-scale environments (M > 1014 M ☉), we find a global reduction in the SSFR of the star-forming sequence of 17% at 4σ confidence as opposed to its field counterpart. After removing the stellar mass dependence of the quiescent fraction seen in field galaxies, the excess in the quiescent fraction due to the environment quenching in groups and clusters is found to increase with stellar mass, although deeper and larger data from the full PS1/MDS will be required to draw firm conclusions. We argue that these results are in favor of galaxy mergers to be the primary environment quenching mechanism operating in galaxy groups whereas strangulation is able to reproduce the observed trend in the environment quenching efficiency and stellar mass relation seen in clusters. Our results also suggest that the relative importance between mass quenching and environment quenching depends on stellar mass—the mass quenching plays a dominant role in producing quiescent galaxies for more massive galaxies, while less massive galaxies are quenched mostly through the environmental effect, with the transition mass around 1-2 × 1010 M ☉ in the group/cluster environment.

Identifiers

DOI: 10.1088/0004-637x/782/1/33

Citations and references

Cited by 20 references

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