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

Alexander Beckett, Simon L. Morris, Michele Fumagalli, Rich Bielby, Nicolas Tejos, Joop Schaye, Buell Jannuzi, Sebastiano Cantalupo

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


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 ≈ 1 projected quasar triplet. With full Ly α 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 100-1000 kpc scales. We search for H i absorption systems occurring at the same redshift (within 500 km s-1) in multiple sightlines, finding with >99.9 per cent 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(H i) > 1014 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 H i 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 O vi at the same redshift.

Original languageEnglish (US)
Pages (from-to)2574-2602
Number of pages29
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Sep 1 2021


  • Galaxies: formation
  • Intergalactic medium
  • Large-scale structure of Universe
  • Quasars: absorption lines

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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