The rich galactic environment of a H₂-absorption-selected quasar

Abstract

We present the first Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of a quasar featuring a proximate molecular absorption system, SDSS J125917.31+030922.5. The proximate damped absorption acts as a natural coronagraph, removing the quasar emission over sim 40 AA in wavelength, and allows us to detect extended emission without the necessity of subtracting the quasar emission. This natural coronagraph permits the investigation of the quasar environment down to its inner regions ($r < 20$ kpc), where galaxy interactions or feedback processes should have the most noticeable effects. Our observations reveal a dense environment, with a highly asymmetric emission within $2"$ ($ 15$ kpc), possibly shaped by a companion galaxy, and a southern extension of the nebulae to about 50 kpc, with rotation-like kinematic signature. The width of the emission is broadest closer to the quasar, indicating perturbed kinematics as expected if interactions and significant gas flows are present. The foreground absorbing system itself is redshifted by $ $400 km/s relative to the background quasar, and therefore is likely arising from gas moving toward the quasar. Finally two additional emitters are detected with $>10\ significance at 96 and 223 kpc from the quasar, making this field overdense relative to other similar observations of quasars at $z 3$. Our results support the hypothesis that quasars with proximate neutral and molecular absorption trace rich environments where galaxy interactions are at play and motivates further studies of quasars to shed light on feeding and feedback processes.