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

Bielby, Richard M; Fumagalli, Michele; Fossati, Matteo; Rafelski, Marc; Oppenheimer, Benjamin; Cantalupo, Sebastiano; Christensen, Lise; Fynbo, JPU; Lopez, Sebastian; Morris, Simon L; D’Odorico, Valentina; Peroux, Celine

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


Richard M Bielby

Matteo Fossati

Marc Rafelski

Benjamin Oppenheimer

Sebastiano Cantalupo

Lise Christensen

JPU Fynbo

Sebastian Lopez

Valentina D’Odorico

Celine Peroux


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.


Bielby, R. M., Fumagalli, M., Fossati, M., Rafelski, M., Oppenheimer, B., Cantalupo, S., …Peroux, C. (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), 5336-5356.

Journal Article Type Article
Acceptance Date Feb 15, 2020
Online Publication Date Mar 3, 2020
Publication Date Apr 30, 2020
Deposit Date Mar 3, 2020
Publicly Available Date Mar 3, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 493
Issue 4
Pages 5336-5356


Accepted Journal Article (7.6 Mb)

Copyright 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.

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