Narrow associated QSO absorbers: clustering, outflows and the line-of-sight proximity effect

TL;DR

This study examines the distribution and origins of narrow CIV and MgII quasar absorption lines, revealing quasar-driven outflows, their extent, and differences between radio-loud and radio-quiet quasars using SDSS DR3 data.

Contribution

It provides new insights into the clustering, outflows, and intrinsic absorption features of quasars, highlighting the impact of quasars on their surrounding gas and the differences based on radio activity.

Findings

Quasars destroy absorbers within ~300kpc (CIV) and ~800kpc (MgII).

Over 40% of CIV absorbers near quasars are intrinsic, not due to clustering.

Intrinsic outflows extend up to ~12,000km/s and are present in both radio-loud and radio-quiet quasars.

Abstract

Using data from the Sloan Digital Sky Survey data release 3 (SDSS DR3) we investigate how narrow (<700km/s) CIV and MgII quasar absorption line systems are distributed around quasars. The CIV absorbers lie in the redshift range 1.6 < z < 4 and the MgII absorbers in the range 0.4<z<2.2. By correlating absorbers with quasars on different but neighbouring lines-of-sight, we measure the clustering of absorbers around quasars on comoving scales between 4 and 30Mpc. The observed comoving correlation lengths are r_o~5h^-1Mpc, similar to those observed for bright galaxies at these redshifts. Comparing with correlations between absorbers and the quasars in whose spectra they are identified then implies: (i) that quasars destroy absorbers to comoving distances of ~300kpc (CIV) and ~800kpc (MgII) along their lines-of-sight; (ii) that >40% of CIV absorbers within 3,000km/s of the QSO are not a result of large-scale clustering but rather are directly associated with the quasar itself; (iii) that this intrinsic absorber population extends to outflow velocities of order 12,000km/s; (iv) that this outflow component is present in both radio-loud and radio-quiet quasars; and (v) that a small high-velocity outflow component is observed in the MgII population, but any further intrinsic absorber component is undetectable in our clustering analysis. We also find an indication that absorption systems within 3,000km/s are more abundant for radio-loud than for radio-quiet quasars. This suggests either that radio-loud objects live in more massive halos, or that their radio activity generates an additional low-velocity outflow, or both.