Wide Field Multiband Imaging of Low Redshift Quasar Environments

TL;DR

This study investigates the large-scale environments of low-redshift quasars using multiband imaging, finding that their galaxy clustering properties are consistent with typical galaxy environments and that nuclear activity does not correlate with large-scale environment.

Contribution

It provides the first detailed multiband clustering analysis of low-redshift quasars, revealing that their large-scale environments are similar to normal galaxies and are not directly linked to nuclear activity.

Findings

Galaxy clustering around quasars is consistent with normal galaxy environments.

The bias of galaxies around quasars varies with wavelength but does not correlate with AGN properties.

Nuclear activity appears independent of large-scale galaxy environment.

Abstract

We present photometry of the large scale environments of a sample of twelve broad line AGN with $0.06 < z < 0.37$ from deep images in the SDSS $u$, $g$, $r$, and $i$ filters taken with the 90Prime prime focus camera on the Steward Observatory Bok Telescope. We measure galaxy clustering around these AGN using two standard techniques: correlation amplitude (B$_{gq}$) and the two point correlation function. We find average correlation amplitudes for the 10 radio quiet objects in the sample equal to (9$\pm$18, 144$\pm$114, -39$\pm$56, 295$\pm$260) Mpc$^{1.77}$ in ($u$, $g$, $r$, $i$), all consistent with the expectation from galaxy clustering. Using a ratio of the galaxy-quasar cross-correlation function to the galaxy autocorrelation function, we calculate the relative bias of galaxies and AGN, $b_{gq}$. The bias in the $u$ band, $b_{gq}=3.08\pm0.51$ is larger compared to that calculated in the other bands, but it does not correlate with AGN luminosity, black hole mass, or AGN activity via the luminosity of the [OIII] emission line. Thus ongoing nuclear accretion activity is not reflected in the large scale environments from $\sim$10 h$^{-1}$ kpc to $\sim$0.5 h$^{-1}$ Mpc and may indicate a non-merger mode of AGN activity and/or a significant delay between galaxy mergers and nuclear activity in this sample of mostly radio quiet quasars.