Measuring the luminosity and virial black hole mass dependence of quasar-galaxy clustering at z ~ 0.8

TL;DR

This study investigates how quasar clustering at z ~ 0.8 depends on luminosity and black hole mass by measuring galaxy overdensities around quasars, finding no significant dependence on either property.

Contribution

It introduces a method using photometrically selected galaxies to measure quasar-galaxy clustering, providing new insights into the relationship between quasar properties and their host environments.

Findings

No significant increase in clustering with luminosity.

Clustering amplitude shows no strong dependence on black hole mass.

Quasar luminosity varies widely within similar dark matter halo masses.

Abstract

We study the dependence of quasar clustering on quasar luminosity and black hole mass by measuring the angular overdensity of photometrically selected galaxies imaged by WISE about z $\sim$ 0.8 quasars from SDSS. By measuring the quasar-galaxy cross-correlation function and using photometrically selected galaxies, we achieve a higher density of tracer objects and a more sensitive detection of clustering than measurements of the quasar autocorrelation function. We test models of quasar formation and evolution by measuring the luminosity dependence of clustering amplitude. We find a significant overdensity of WISE galaxies about z $\sim$ 0.8 quasars at 0.2--6.4 h$^{-1}$ Mpc in projected comoving separation. We find no appreciable increase in clustering amplitude with quasar luminosity across a decade in luminosity, and a power-law fit between luminosity and clustering amplitude gives an exponent of $-$0.01 $\pm$ 0.06 (1 $\sigma$ errorbar). We also fail to find a significant relationship between clustering amplitude and black hole mass, although our dynamic range in true mass is suppressed due to the large uncertainties in virial black hole mass estimates. Our results indicate that a small range in host dark matter halo mass maps to a large range in quasar luminosity.