The dependence of star formation activity on environment and stellar mass at z∼ 1 from the HiZELS-Hα survey

By D. Sobral, P. Best, I. Smail, James E. Geach, M. Cirasuolo, T. Garn, G. Dalton. 2010

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This paper presents an environment and stellar mass study of a large sample of star-forming Hα emitters at z= 0.84 from the High-z Emission Line Survey (HiZELS), over 1.3 deg2 split over two fields (COSMOS and UKIDSS UDS). By taking advantage of a truly panoramic coverage of a wide range of environments, from the field to a rich cluster, it is shown that both stellar mass and environment play crucial roles in determining the properties of star-forming galaxies. Specific star formation rates (sSFRs) decline with stellar mass in all environments, and the fraction of Hα star-forming galaxies declines sharply from ≈40 per cent for galaxies with masses around 1010M⊙ to effectively zero above 1011.5M⊙, confirming that mass-downsizing is generally in place by z∼ 1. The fraction of star-forming galaxies is also found to fall sharply as a function of local environmental density from ≈40 per cent in the field to approaching zero at rich group/cluster densities. When star formation does occur in such high density regions, it is found to be mostly dominated by potential mergers and, indeed, if only non-merging star-forming galaxies are considered, then the environment and mass trends are even stronger and are qualitatively similar at all masses and environments, respectively, as in the local Universe. The median SFR of Hα emitters at z= 0.84 is found to increase with density for both field and intermediate (group or cluster outskirts) densities; this is clearly seen as a change in the faint-end slope of the Hα luminosity function from steep (α≈-1.9), in poor fields, to shallow (α≈-1.1) in groups and clusters. Interestingly, the relation between median SFR and environment is only found for low- to moderate-mass galaxies (with stellar masses below about 1010.6M⊙), and is not seen for the most massive star-forming galaxies. Overall, these observations provide a detailed view over a sufficiently large range of mass and environment to reconcile previous observational claims: stellar mass is the primary predictor of star formation activity at z∼ 1, but the environment, while initially enhancing the median SFR of (lower mass) star-forming galaxies, is ultimately responsible for suppressing star formation activity in all galaxies above surface densities of 10-30 Mpc-2 (group and cluster environments).

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/5d502bba46395e576d890fbbaf5375204ec7c3ef

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Citations in the corpus

A new multifield determination of the galaxy luminosity function at z = 7-9 incorporating the 2012 Hubble Ultra-Deep Field imaging (2012, background): “Amongst these the three most important are new ultra-deep z′−band imaging obtained with Suprime-Cam on Subaru which reaches a depth of z′ = 26.5 (5σ; 1.8′′diameter apertures), new ultra-deep VLT+HAWK-I Y−band observations of the UDS CANDELS region obtained as part of the HUGS programme (P.I. A. Font”
THE GEMINI CLUSTER ASTROPHYSICS SPECTROSCOPIC SURVEY (GCLASS): THE ROLE OF ENVIRONMENT AND SELF-REGULATION IN GALAXY EVOLUTION AT z ∼ 1 (2011, background): “This independence of SFR on galaxy mass is also seen in the HiZELS narrow-band Hα survey at z ∼ 0.84 (Sobral et al. 2011), and is most likely a co-incidence of the overall process of galaxy quenching as a function of stellar mass and redshift and the particular redshift range considered here.”
On the evolution and environmental dependence of the star formation rate versus stellar mass relation since z ∼ 2 (2013, methodology): “For example, Sobral et al. (2011) used Hα emitters sample atz = 0.8 selected from HiZELS to show higher median SFRs (by a factor of ∼2–3) in high-density environment compared to low-density environment.”
The properties of the star-forming interstellar medium at z = 0.84-2.23 from HiZELS : mapping the internal dynamics and metallicity gradients in high-redshift disc galaxies. (2012, methodology): “…deep archival multiwavelength imaging from rest-frame ultraviolet (UV) to mid-infrared bands (see Sobral et al. 2010 for references) and follow Sobral et al. (2011) to perform a full SED χ2 fit using the Bruzual & Charlot (2003) population synthesis models but including the thermally…”
A HIGHLY CONSISTENT FRAMEWORK FOR THE EVOLUTION OF THE STAR-FORMING “MAIN SEQUENCE” FROM z ∼ 0–6 (2014, methodology): “See also Sobral et al. (2011) for more discussion on this issue.”
Star formation at z=1.47 from HiZELS: an Hα+[O ii] double-blind study* (2011, methodology): “These photometric redshifts were used in Sobral et al. (2010, 2011).”
A large Hα survey at z = 2.23, 1.47, 0.84 and 0.40: the 11 Gyr evolution of star-forming galaxies from HiZELS (2012, background): “In addition, Sobral et al. (2011) found that at z = 0.84 the faint-end slope of the luminosity function (α) is strongly dependent on the environment, with the Hα luminosity function being much steeper in low density regions and much shallower in the group/cluster environments.”