Abstract
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.
Original language | English |
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Pages (from-to) | 101 |
Journal | Astrophysical Journal |
Volume | 834 |
Issue number | 2 |
DOIs | |
Publication status | Published - 5 Jan 2017 |
Keywords / Materials (for Non-textual outputs)
- galaxies: evolution
- galaxies: starburst
- galaxies: star formation