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Into the Lyα jungle : exploring the circumgalactic medium of galaxies at z ∼ 4 − 5 with MUSE.

Bielby, Richard M. and Fumagalli, Michele and Fossati, Matteo and Rafelski, Marc and Oppenheimer, Benjamin and Cantalupo, Sebastiano and Christensen, Lise and Fynbo, J.P.U. and Lopez, Sebastian and Morris, Simon L. and D’Odorico, Valentina and Peroux, Celine (2020) 'Into the Lyα jungle : exploring the circumgalactic medium of galaxies at z ∼ 4 − 5 with MUSE.', Monthly notices of the Royal Astronomical Society., 493 (4). pp. 5336-5356.


We present a study of the galaxy environment of 9 strong H I+C IV absorption line systems (16.2 < log(N(HI)) < 21.2) spanning a wide range in metallicity at z ∼ 4 − 5, using MUSE integral field and X-Shooter spectroscopic data collected in a z ≈ 5.26 quasar field. We identify galaxies within a 250 kpc and ±1000 km s−1 window for 6 out of the 9 absorption systems, with 2 of the absorption line systems showing multiple associated galaxies within the MUSE field of view. The space density of Lyα emitting galaxies (LAEs) around the H I and C IV systems is ≈10 − 20 times the average sky density of LAEs given the flux limit of our survey, showing a clear correlation between the absorption and galaxy populations. Further, we find that the strongest C IV systems in our sample are those that are most closely aligned with galaxies in velocity space, i.e. within velocities of ±500 km s−1. The two most metal poor systems lie in the most dense galaxy environments, implying we are potentially tracing gas that is infalling for the first time into star-forming groups at high redshift. Finally, we detect an extended Lyα nebula around the z ≈ 5.26 quasar, which extends up to ≈50 kpc at the surface brightness limit of 3.8 × 10−18 erg s−1 cm−2 arcsec−2. After scaling for surface brightness dimming, we find that this nebula is centrally brighter, having a steeper radial profile than the average for nebulae studied at z ∼ 3 and is consistent with the mild redshift evolution seen from z ≈ 2.

Item Type:Article
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:15 February 2020
Date deposited:03 March 2020
Date of first online publication:03 March 2020
Date first made open access:03 March 2020

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