The relationship between gas and galaxies at z < 1 using the Q0107 quasar triplet

We study the distribution and dynamics of the circumgalactic and intergalactic medium using a dense galaxy survey covering the field around the Q0107 system, a unique z approximate to 1 projected quasar triplet. With full Ly alpha coverage along all three lines-of-sight from z = 0.18 to z = 0.73, more than 1200 galaxy spectra, and two MUSE fields, we examine the structure of the gas around galaxies on 100-1000kpc scales. We search for Hi absorption systems occurring at the same redshift (within 500kms(-1)) in multiple sightlines, finding with >99.9 percent significance that these systems are more frequent in the observed quasar spectra than in a randomly distributed population of absorbers. This is driven primarily by absorption with column densities N(Hi) > 10(14)cm(-2), whilst multi-sightline absorbers with lower column densities are consistent with a random distribution. Star-forming galaxies are more likely to be associated with multi-sightline absorption than quiescent galaxies. HST imaging provides inclinations and position angles for a subset of these galaxies. We observe a bimodality in the position angle of detected galaxy-absorber pairs, again driven mostly by high-column-density absorbers, with absorption preferentially along the major and minor axes of galaxies out to impact parameters of several hundred kpc. We find some evidence supporting a disc/outflow dichotomy, as Hi absorbers near the projected major axis of a galaxy show line-of-sight velocities that tend to align with the rotation of that galaxy, whilst minor-axis absorbers are twice as likely to exhibit Ovi at the same redshift.

Automated summary

This study examines the distribution and dynamics of the circumgalactic and intergalactic medium around the Q0107 system, finding that high-column-density absorbers significantly impact the structure and position of galaxy absorber pairs. Star-forming galaxies are more likely to be associated with multi-sightline absorption.