Clustering, host halos, and environment of z ~ 2 galaxies as a function of their physical properties
2014
Using a sample of 25 683 star-forming and 2821 passive galaxies at z ~ 2, selected in the
COSMOS field following the BzK color criterion, we study the hosting halo mass and
environment of galaxies as a function of their physical properties. Spitzer
and Herschel allow us to obtain accurate star formation rate
estimates for starburst galaxies. We measure the autocorrelation and cross-correlation
functions of various galaxy subsamples and infer the properties of their hosting halos
using both a halo occupation model and the linear bias at large scale. We find that
passive and star-forming galaxies obey a similarly rising relation between the halo and
stellar mass. The mean host halo mass of star-forming galaxies increases with the star
formation rate between 30 M⊙ yr-1 and 200 M⊙ yr-1, but flattens for higher
values, except if we select only main-sequence galaxies. This reflects the expected
transition from a regime of secular coevolution of the halos and the galaxies to a regime
of episodic starburst. We find similar large-scale biases for main-sequence, passive, and
starburst galaxies at equal stellar mass, suggesting that these populations live in halos
of the same mass. However, we detect an excess of clustering on small scales for passive
galaxies and showed, by measuring the large-scale bias of close pairs of passive galaxies,
that this excess is caused by a small fraction (~16%) of passive galaxies being hosted by massive halos
(~3 ×
1013 M⊙) as satellites.
Finally, extrapolating the growth of halos hosting the z ~ 2 population, we show
that M⋆ ~
1010 M⊙ galaxies at
z ~ 2 will
evolve, on average, into massive (M⋆ ~
1011 M⊙), field galaxies in the
local Universe and M⋆ ~
1011 M⊙ galaxies at
z = 2 into
local, massive, group galaxies. We also identify two z ~ 2 populations which
should end up in today’s clusters: massive (>M⋆ ~
1011 M⊙), strongly star-forming
( > 200
M⊙ yr-1), main-sequence galaxies, and
close pairs of massive, passive galaxies.
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