The MUSE Ultra Deep Field (MUDF). II. Survey design and the gaseous properties of galaxy groups at 0.5 < z < 1.5

Abstract

We present the goals, design, and first results of the MUSE Ultra Deep Field (MUDF) survey, a large programme using the Multi Unit Spectroscopic Explorer (MUSE) instrument at the ESO Very Large Telescope. The MUDF survey is collecting ≈ 150 hours on-source of integral field optical spectroscopy in a 1.5 × 1.2 arcmin 2 region which hosts several astrophysical structures along the line of sight, including two bright z ≈ 3.2 quasars with close separation (≈ 500 kpc). Following the description of the data reduction procedures, we present the analysis of the galaxy environment and gaseous properties of seven groups detected at redshifts 0.5 < z < 1.5, spanning a large dynamic range in halo mass, log(M h /M ) ≈ 11 − 13.5. For four of the groups, we find associated Mg ii absorbers tracing cool gas in high-resolution spectroscopy of the two quasars, including one case of correlated absorption in both sightlines at distance ≈ 480 kpc. The absorption strength associated with the groups is higher than what has been reported for more isolated galaxies of comparable mass and impact parameters. We do not find evidence for widespread cool gas giving rise to strong absorption within these groups. Combining these results with the distribution of neutral and ionised gas seen in emission in lower-redshift groups, we conclude that gravitational interactions in the group environment strip gas from the galaxy haloes into the intragroup medium, boosting the cross section of cool gas and leading to the high fraction of strong Mg ii absorbers that we detect.

MUSE Analysis of Gas around Galaxies (MAGG) – II: metal-enriched halo gas around z ∼ 1 galaxies

“…Wide-field optical integral field unit (IFU) spectrographs like the Multi Unit Spectroscopic Explorer (MUSE; Bacon et al 2010) at the Very Large Telescope (VLT) have revolutionized the study of CGM by enabling efficient and sensitive spectroscopic surveys complete down to a given flux limit around quasar sightlines (e.g. Fumagalli et al 2016Fumagalli et al , 2017Schroetter et al 2016;Mackenzie et al 2019;Zabl et al 2019;Fossati et al 2019b;Lofthouse et al 2020;Muzahid et al 2020). Such type of surveys allows a more complete characterization of the smallscale galaxy environment, a complete (flux limited) analysis of the CGM-galaxy connection up to 250 kpc from the quasar sightlines, and enables studies of CGM to lower mass galaxies (M * <10 10 M ) at z ≥ 1.…”

The data processing pipeline for the MUSE instrument

“…All of them used the MUSE pipeline to process the raw data, or directly used datacubes made available by ESO through their Phase 3 process 37 . While most publications used the pipeline as described above (Krajnović et al 2015;Guérou et al 2016;Husser et al 2016;Roth et al 2018), others tried to improve sky subtraction or background uniformity in different ways (e.g., Borisova et al 2016;Urrutia et al 2019;Fossati et al 2019), often using the external ZAP-tool (Zurich Atmosphere Purge, Soto et al 2016) to improve sky residuals. This tool was integrated into the ESO MUSE Reflex workflow to improve accessibility for users.…”

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

“…As in previous analyses of MUSE data (e.g. Fumagalli et al 2017b;Mackenzie et al 2019;Lofthouse et al 2019;Fossati et al 2019), we conduct a redshift survey of galaxies detected in the continuum together with a search for line emitters in the cube. 18 19 20 21 22 23 24 25 26 27 28 29 30 31 33 34 36 37 38 39 41 42 43 44 45 46 47 48 49 50 52 53 54 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 80 81 82 84 86 87 89 90 91 92 93 95 96 97 98 99 100 101 103 104 105 106 107 108 110 111 112113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 129 130 131 132 133 ...…”

“…Evidence of inhomogeneous enrichment is indeed building up at lower redshifts (e.g. Fumagalli et al 2011a;Mackenzie et al 2019;Lofthouse et al 2019;Fossati et al 2019), and it is thus not surprising to find hints of similar inhomogeneity at these higher redshifts, where the time available for enriched pockets to grow is limited. When compared to the eagle simulated data, we find in our observations a significant fraction of upper limits at impact parameters of > 100 kpc, consistent with the predictions from simulation.…”

“…Bergeron & Boisse 1986;Møller & Warren 1998;Kacprzak et al 2010), dedicated MUSE surveys are beginning to uncover greater numbers of associations with galaxy groups at low redshifts (e.g. Péroux et al 2017;Bielby et al 2017aBielby et al , 2019Fossati et al 2019) as well as similarly complex environments traced by Lyα emitters (LAEs) at 3 z 4 (e.g. Fumagalli et al 2016bFumagalli et al , 2017bMackenzie et al 2019;Lofthouse et al 2019).…”