Metal line emission from galaxy haloes at <i>z</i> ≈ 1
Rajeshwari Dutta, Matteo Fossati, Michele Fumagalli, Mitchell Revalski, Emma K. Lofthouse, Dylan Nelson, Giulia Papini, Marc Rafelski, Sebastiano Cantalupo, Fabrizio Arrigoni Battaia, Pratika Dayal, A. Longobardi, Céline Péroux, Laura Prichard, J. X. Prochaska
Abstract
ABSTRACT We present a study of the metal-enriched halo gas, traced using Mg ii and [O ii] emission lines, in two large, blind galaxy surveys – the MUSE (Multi Unit Spectroscopic Explorer) Analysis of Gas around Galaxies (MAGG) and the MUSE Ultra Deep Field (MUDF). By stacking a sample of ≈600 galaxies (stellar masses $M_*$ ≈ 106–12 $\rm M_\odot$), we characterize for the first time the average metal line emission from a general population of galaxy haloes at 0.7 ≤ z ≤ 1.5. The Mg ii and [O ii] line emission extends farther out than the stellar continuum emission, on average out to ≈25 and ≈45 kpc, respectively, at a surface brightness (SB) level of 10−20 $\rm erg\, s^{-1}\, cm^{-2}\, arcsec^{-2}$. The radial profile of the Mg ii SB is shallower than that of the [O ii], suggesting that the resonant Mg ii emission is affected by dust and radiative transfer effects. The [O ii] to Mg ii SB ratio is ≈3 over ≈20–40 kpc, also indicating a significant in situ origin of the extended metal emission. The average SB profiles are intrinsically brighter by a factor of ≈2–3 and more radially extended by a factor of ≈1.3 at 1.0 &lt; z ≤ 1.5 than at 0.7 ≤ z ≤ 1.0. The average extent of the metal emission also increases independently with increasing stellar mass and in overdense group environments. When considering individual detections, we find extended [O ii] emission up to ≈50 kpc around ≈30–40 per cent of the group galaxies, and extended (≈30–40 kpc) Mg ii emission around two z ≈ 1 quasars in groups, which could arise from outflows or environmental processes.