MUSE searches for galaxies near very metal-poor gas clouds at z ~ 3: New constraints for cold accretion models

Michele Fumagalli*, Sebastiano Cantalupo, Avishai Dekel, Simon L. Morris, John M. O'Meara, J. Xavier Prochaska, Tom Theuns

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

We report on the search for galaxies in the proximity of two very metal-poor gas clouds at z ~ 3 towards the quasar Q0956+122. With a 5-hour Multi-Unit Spectroscopic Explorer (MUSE) integration in a ~500 × 500 kpc2 region centred at the quasar position, we achieve a ≥ 80 per cent complete spectroscopic survey of continuum-detected galaxies with mR ≤ 25 mag and Lyα emitters with luminosity LLyα ≥ 3 × 1041 erg s-1. We do not identify galaxies at the redshift of a z ~ 3.2 Lyman limit system (LLS) with log Z/Z = -3.35 ± 0.05, placing this gas cloud in the intergalactic medium or circumgalactic medium of a galaxy below our sensitivity limits. Conversely, we detect five Lyα emitters at the redshift of a pristine z ~ 3.1 LLS with log Z/Z≤-3.8, while~0.4 sources were expected given the z~3Lyα luminosity function. Both this high detection rate and the fact that at least three emitters appear aligned in projection with the LLS suggest that this pristine cloud is tracing a gas filament that is feeding one or multiple galaxies. Our observations uncover two different environments for metal-poor LLSs, implying a complex link between these absorbers and galaxy haloes, which ongoing MUSE surveys will soon explore in detail. Moreover, in agreement with recent MUSE observations, we detected a ~90 kpc Lyα nebula at the quasar redshift and three Lyα emitters reminiscent of a 'dark galaxy' population.

Original languageEnglish
Pages (from-to)1978-1988
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume462
Issue number2
DOIs
StatePublished - 21 Oct 2016

Bibliographical note

Publisher Copyright:
© 2016 The Authors.

Keywords

  • Galaxies: formation
  • Galaxies: haloes
  • Galaxies: high-redshift
  • Intergalactic medium
  • Quasars: absorption lines
  • Quasars: individual: Q0956+122

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