Fumagalli, M. and Cantalupo, S. and Dekel, A. and Morris, S. L. and O'Meara, J. M. and Prochaska, J. X. and Theuns, T. (2016) 'MUSE searches for galaxies near very metal-poor gas clouds at z~3 : new constraints for cold accretion models.', Monthly notices of the Royal Astronomical Society., 462 (2). pp. 1978-1988.
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 ∼ 3 Lyα 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.
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|Publisher Web site:||http://dx.doi.org/10.1093/mnras/stw1782|
|Publisher statement:||This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||18 July 2016|
|Date deposited:||31 August 2016|
|Date of first online publication:||25 July 2016|
|Date first made open access:||31 August 2016|
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