Abstract
We study the statistical distribution of satellites around star-forming and
quiescent central galaxies at 1<z<3 using imaging from the FourStar Galaxy
Evolution Survey (ZFOURGE) and the Cosmic Assembly Near-IR Deep Extragalactic
Legacy Survey (CANDELS). The deep near-IR data select satellites down to
$łog(M/M_ødot)>9$ at z<3. The radial satellite distribution around centrals
is consistent with a projected NFW profile. Massive quiescent centrals,
$łog(M/M_ødot)>10.78$, have $\sim$2 times the number of satellites compared
to star-forming centrals with a significance of 2.7$\sigma$ even after
accounting for differences in the centrals' stellar-mass distributions. We find
no statistical difference in the satellite distributions of intermediate-mass
quiescent and star-forming centrals, $10.48<łog(M/M_ødot)<10.78$. Comparing
to the Guo2011 semi-analytic model, the excess number of satellites indicates
that quiescent centrals have halo masses 0.3 dex larger than star-forming
centrals, even when the stellar-mass distributions are fixed. We use a simple
toy model that relates halo mass and quenching, which roughly reproduces the
observed quenched fractions and the differences in halo mass between
star-forming and quenched galaxies only if galaxies have a quenching
probability that increases with halo mass from $\sim$0 for
$łog(M_h/M_ødot)\sim$11 to $\sim$1 for $łog(M_h/M_ødot)\sim$13.5. A single
halo-mass quenching threshold is unable to reproduce the quiescent fraction and
satellite distribution of centrals. Therefore, while halo quenching may be an
important mechanism, it is unlikely to be the only factor driving quenching. It
remains unclear why a high fraction of centrals remain star-forming even in
relatively massive halos.
Users
Please
log in to take part in the discussion (add own reviews or comments).