Circumgalactic medium of quasar host galaxies at 0.4 ⩽ z ⩽ 0.8 probed by strong Mg II absorption

Abstract

Using a sample of 166 projected quasar pairs, we investigate the influence of active galactic nuclei on the circumgalactic medium of the quasar host galaxies probed using strong Mg II absorption (i.e. W2796 ≥ 1 Å) at impact parameters (D) <100 kpc. The foreground quasars are restricted to the redshift range 0.4 ≤ z ≤ 0.8 and have median bolometric luminosity and stellar mass of 1045.1 erg s−1 and 1010.89M , respectively. We report detections of Mg II absorption in 29 cases towards the background quasar and in four cases along the line of sight to the foreground quasars. We do not find any difference in the distribution of W2796 and covering fraction (fc) as a function of D between quasar host galaxies and control sample of normal galaxies. These results are different from what has been reported in the literature, possibly because (i) our sample is restricted to a narrow redshift range, (ii) comparative analysis is carried out after matching the galaxy parameters, (iii) we focus mainly on strong Mg II absorption, and (iv) our sample lacks foreground quasars with high bolometric luminosity (i.e. Lbol > 1045.5 erg s−1). Future studies probing luminous foreground quasars, preferably at lower impact parameters and higher equivalent width sensitivity, are needed to consolidate our findings.