Downsizing of Star Formation Measured from the Clustered Infrared Background Correlated with Quasars

TL;DR

This study measures the clustering of dusty star-forming galaxies around quasars across different redshifts, revealing a downsizing trend in the dark matter haloes hosting these galaxies from high to low redshift.

Contribution

It introduces a halo model analysis of Herschel-SPIRE data to quantify the evolution of dark matter halo masses hosting dusty star-forming galaxies in quasar environments.

Findings

Dark matter halo mass decreases from ~10^13.8 M_sun at z~2.2 to ~10^10.7 M_sun at z~0.7.

Evidence of downsizing in the halo masses of star-forming galaxies.

Results are consistent with other measurements of star-forming and sub-millimeter galaxies.

Abstract

Powerful quasars can be seen out to large distances. As they reside in massive dark matter haloes, they provide a useful tracer of large scale structure. We stack Herschel-SPIRE images at 250, 350 and 500 microns at the location of 11,235 quasars in ten redshift bins spanning $0.5 \leq z \leq 3.5$. The unresolved dust emission of the quasar and its host galaxy dominate on instrumental beam scales, while extended emission is spatially resolved on physical scales of order a megaparsec. This emission is due to dusty star-forming galaxies clustered around the dark matter haloes hosting quasars. We measure radial surface brightness profiles of the stacked images to compute the angular correlation function of dusty star-forming galaxies correlated with quasars. We then model the profiles to determine large scale clustering properties of quasars and dusty star-forming galaxies as a function of redshift. We adopt a halo model and parameterize it by the most effective halo mass at hosting star-forming galaxies, finding $\log(M_\mathrm{eff}/M_{\odot}) = 13.8^{+0.1}_{-0.1}$ at $z=2.21-2.32$, and, at $z=0.5-0.81$, the mass is $\log(M_\mathrm{eff}/M_{\odot}) = 10.7^{+1.0}_{-0.2}$. Our results indicate a downsizing of dark matter haloes hosting dusty star-forming galaxies between $0.5 \leq z \leq 2.9$. The derived dark matter halo masses are consistent with other measurements of star-forming and sub-millimeter galaxies. The physical properties of dusty star-forming galaxies inferred from the halo model depend on details of the quasar halo occupation distribution in ways that we explore at $z>2.5$, where the quasar HOD parameters are not well constrained.