Zfire: Similar stellar growth in hα-emitting cluster and field galaxies at z ∼ 2

Kim Vy H. Tran, Leo Y. Alcorn, Glenn G. Kacprzak, Themiya Nanayakkara, Caroline Straatman, Tiantian Yuan, Michael Cowley, Romeel Davé, Karl Glazebrook, Lisa J. Kewley, Ivo Labbé, Davidé Martizzi, Casey Papovich, Ryan Quadri, Lee R. Spitler, Adam Tomczak

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We compare galaxy scaling relations as a function of environment at z ∼ 2 with our ZFIRE survey12 where we have measured Hα fluxes for 90 star-forming galaxies selected from a mass-limited (log(Mz.astModot) > 9) sample based on ZFOURGE.13 The cluster galaxies (37) are part of a confirmed system at z=2.095 and the field galaxies (53) are at 1.9 < z < 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), galaxy size (reff ), SFR surface density (σ(H star)), and stellar age distributions. The only difference is that at fixed stellar mass, the Hα-emitting cluster galaxies are log(reff ) ∼ 0.1 larger than in the field. Approximately 19% of the Hα-emitters in the cluster and 26% in the field are IR-luminous (LIR > 2>× 1011 L⊙). 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)=±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) 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.

Original languageEnglish (US)
Article number101
JournalAstrophysical Journal
Issue number2
StatePublished - Jan 10 2017


  • galaxies: evolution
  • galaxies: star formation
  • galaxies: starburst

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'Zfire: Similar stellar growth in hα-emitting cluster and field galaxies at z ∼ 2'. Together they form a unique fingerprint.

Cite this