The GOGREEN Survey: A deep stellar mass function of cluster galaxies at 1.0
galaxies in 11 galaxy clusters at 1.0<z<1.4, drawn from the Gemini Observations
of Galaxies in Rich Early Environments (GOGREEN) survey. Based on more than 500
hours of Gemini/GMOS spectroscopy, and deep multi-band photometry taken with a
range of observatories, we probe the SMFs down to a stellar mass limit of
10^9.7 Msun (10^9.5 Msun for star-forming galaxies). At this early epoch, the
fraction of quiescent galaxies is already highly elevated in the clusters
compared to the field at the same redshift. The quenched fraction excess (QFE)
represents the fraction of galaxies that would be star-forming in the field,
but are quenched due to their environment. The QFE is strongly mass dependent,
and increases from ~30% at Mstar=10^9.7 Msun, to ~80% at Mstar=10^11.0 Msun.
Nonetheless, the shapes of the SMFs of the two individual galaxy types,
star-forming and quiescent galaxies, are identical between the clusters and the
field – to high statistical precision. Yet, along with the different quiescent
fractions is the total galaxy SMF environmentally dependent, with a relative
deficit of low-mass galaxies in the clusters. These results are in stark
contrast with findings in the local Universe, and thus require a substantially
different quenching mode to operate at early times. We discuss these results in
the light of several popular quenching models.
We study the stellar mass functions (SMFs) of star-forming and quiescent
galaxies in 11 galaxy clusters at 1.0<z<1.4, drawn from the Gemini Observations
of Galaxies in Rich Early Environments (GOGREEN) survey. Based on more than 500
hours of Gemini/GMOS spectroscopy, and deep multi-band photometry taken with a
range of observatories, we probe the SMFs down to a stellar mass limit of
10^9.7 Msun (10^9.5 Msun for star-forming galaxies). At this early epoch, the
fraction of quiescent galaxies is already highly elevated in the clusters
compared to the field at the same redshift. The quenched fraction excess (QFE)
represents the fraction of galaxies that would be star-forming in the field,
but are quenched due to their environment. The QFE is strongly mass dependent,
and increases from ~30% at Mstar=10^9.7 Msun, to ~80% at Mstar=10^11.0 Msun.
Nonetheless, the shapes of the SMFs of the two individual galaxy types,
star-forming and quiescent galaxies, are identical between the clusters and the
field – to high statistical precision. Yet, along with the different quiescent
fractions is the total galaxy SMF environmentally dependent, with a relative
deficit of low-mass galaxies in the clusters. These results are in stark
contrast with findings in the local Universe, and thus require a substantially
different quenching mode to operate at early times. We discuss these results in
the light of several popular quenching models.
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