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ZFIRE: Similar Stellar Growth in Hα-emitting Cluster and Field Galaxies at z ~ 2

Research output: Contribution to journalArticle

  • 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

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Original languageEnglish
Pages (from-to)101
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 5 Jan 2017


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}({M}\star /{M}⊙ )> 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}\star ), galaxy size ({r}{eff}), SFR surface density (Σ({{H}}{α }{star})), and stellar age distributions. The only difference is that at fixed stellar mass, the Hα-emitting cluster galaxies are {log}({r}{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}{IR} > 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}\star ) = ±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}\star ) 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.

    Research areas

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

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