ZFIRE: similar stellar growth in hα-emitting cluster and field galaxies at z ∼ 2
- George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States)
- Swinburne University of Technology, Hawthorn, VIC 3122 (Australia)
- Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)
- Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)
- Department of Physics and Astronomy, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109 (Australia)
- University of the Western Cape, Bellville, Cape Town, 7535 (South Africa)
- Department of Astronomy, University of California, Berkeley, CA 95720 (United States)
- Department of Physics, University of California, Davis, CA 95616 (United States)
We compare galaxy scaling relations as a function of environment at z∼2 with our ZFIRE survey{sup 12} where we have measured Hα fluxes for 90 star-forming galaxies selected from a mass-limited (log(M{sub ⋆}/M{sub ⊙})>9) sample based on ZFOURGE.{sup 13} The cluster galaxies (37) are part of a confirmed system at z = 2.095 and the field galaxies (53) are at 1.9<2.4; all are in the COSMOS legacy field. There is no statistical difference between Hα-emitting cluster and field populations when comparing their star formation rate (SFR), stellar mass (M{sub ⋆}), galaxy size (r{sub eff}), SFR surface density (Σ(Hα{sub star})), and stellar age distributions. The only difference is that at fixed stellar mass, the Hα-emitting cluster galaxies are log(r{sub eff}) ∼ 0.1 larger than in the field. Approximately 19% of the Hα emitters in the cluster and 26% in the field are IR-luminous (L{sub IR} > 2 × 10{sup 11} L{sub ⊙}). Because the luminous IR galaxies in our combined sample are ∼5 times more massive than the low-IR galaxies, their radii are ∼70% larger. To track stellar growth, we separate galaxies into those that lie above, on, or below the Hα star-forming main sequence (SFMS) using ΔSFR(M{sub ⋆}) = ±0.2 dex. Galaxies above the SFMS (starbursts) tend to have higher Hα SFR surface densities and younger light-weighted stellar ages than galaxies below the SFMS. Our results indicate that starbursts (+SFMS) in the cluster and field at z∼2 are growing their stellar cores. Lastly, we compare to the (SFR–M{sub ⋆}) relation from Rhapsody-G cluster simulations and find that the predicted slope is nominally consistent with the observations. However, the predicted cluster SFRs tend to be too low by a factor of ∼2, which seems to be a common problem for simulations across environment.
- OSTI ID:
- 22869538
- Journal Information:
- Astrophysical Journal, Vol. 834, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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