Linking gas and galaxies at high redshift: MUSE surveys the environments of six damped Lyα systems at z ≈ 3

• Published in: Monthly notices of the Royal Astronomical Society Vol. 487; no. 4; pp. 5070 - 5096
• Main Authors: Mackenzie, Ruari, Fumagalli, Michele, Theuns, Tom, Hatton, David J, Garel, Thibault, Cantalupo, Sebastiano, Christensen, Lise, Fynbo, Johan P U, Kanekar, Nissim, Møller, Palle, O’Meara, John, Prochaska, J Xavier, Rafelski, Marc, Shanks, Tom, Trayford, James
• Format: Journal Article
• Language: English
• Published: Oxford University Press (OUP): Policy P - Oxford Open Option A 21.08.2019
• Subjects: Sciences of the Universe; galaxies: formation; intergalactic medium; Astrophysics - Astrophysics of Galaxies; galaxies: evolution; quasars: absorption lines; galaxies: high-redshift
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stz1501

ABSTRACT We present results from a survey of galaxies in the fields of six z ≥ 3 damped Lyman α (Lyα) systems (DLAs) using the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT). We report a high detection rate of up to ${\approx } 80{{\ \rm per\ cent}}$ of galaxies within 1000 km s−1 from DLAs and with impact parameters between 25 and 280 kpc. In particular, we discovered five high-confidence Lyα emitters associated with three DLAs, plus up to nine additional detections across five of the six fields. The majority of the detections are at relatively large impact parameters (>50 kpc) with two detections being plausible host galaxies. Among our detections, we report four galaxies associated with the most metal-poor DLA in our sample (Z/Z⊙ = −2.33 ± 0.22), which trace an overdense structure resembling a filament. By comparing our detections with predictions from the Evolution and Assembly of GaLaxies and their Environments (EAGLE) cosmological simulations and a semi-analytic model designed to reproduce the observed bias of DLAs at z > 2, we conclude that our observations are consistent with a scenario in which a significant fraction of DLAs trace the neutral regions within haloes with a characteristic mass of $M_{\rm h} \approx 10^{11}-10^{12}~\rm M_\odot$, in agreement with the inference made from the large-scale clustering of DLAs. We finally show how larger surveys targeting ≈25 absorbers have the potential of constraining the characteristic masses of haloes hosting high-redshift DLAs with sufficient accuracy to discriminate between different models.