Quasar-Galaxy Clustering through Projected Galaxy Counts at z=0.6-1.2

TL;DR

This study measures how galaxies cluster around quasars at redshifts 0.6 to 1.2, revealing stronger clustering at higher redshifts and associations with specific quasar and galaxy properties, informing galaxy evolution models.

Contribution

It provides the first detailed measurement of quasar-galaxy clustering dependence on quasar and galaxy properties at these redshifts.

Findings

Clustering amplitude increases with redshift.

Stronger clustering for quasars with more massive black holes.

Quasars correlate more with blue galaxies than red ones.

Abstract

We investigate the spatial clustering of galaxies around quasars at redshifts from 0.6 to 1.2 using the photometric data from Sloan Digital Sky Survey (SDSS) Stripe 82. The quasar and galaxy cross-correlation functions are measured through the projected galaxy number density n(r_p) on scales $0.05<r_p<20 h^-1 Mpc around quasars for a sample of 2300 quasars from Schneider et al. (2007). We detect strong clustering signals at all redshifts, and find that the clustering amplitude increases significantly with redshift. We examine the dependence of the quasar-galaxy clustering on quasar and galaxy properties and find that the clustering amplitude is significantly larger for quasars with more massive black holes, or with bluer colors, while the dependence on quasar luminosity is absent. We also show that quasars have a stronger correlation amplitude with blue galaxies than with red galaxies. We finally discuss the implication of our finding.