Metal line emission from galaxy haloes at z ≈ 1

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 $\rm M_*$ ≈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 kpc 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 ≈2 − 3 and more radially extended by a factor of ≈1.3 at 1.0 < 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.

The Cosmic Ultraviolet Baryon Survey: Empirical Characterization of Turbulence in the Cool Circumgalactic Medium

“…Similarly, VSF measurements have also been reported for QSO host halos on scales from 10 kpc to ≈60 kpc based on lineemitting nebulae discovered around luminous QSOs (Chen et al 2023). However, detections of line-emitting nebulae around typical galaxies or galaxy groups remain extremely rare beyond the nearby Universe (e.g., Chen et al 2019;Dutta et al 2023) and even for extreme systems like QSO nebulae and intracluster medium the ground-based seeing imposes a limit on the smallest scale one can probe with IFS observations. Extending VSF studies to the CGM around galaxies representative of the field population on scales below 1 kpc requires a different approach.…”

The MUSE Ultra Deep Field (MUDF). V. Characterizing the Mass–Metallicity Relation for Low-mass Galaxies at z ∼ 1–2

“…We present the differences between the measured metallicities for individual sources and the values predicted by the MZR using our best-fit value of γ for each galaxy in order to control for SFR in Figure 11, with the points color coded based on whether the galaxies reside in isolated (black) or group (gold) environments. We used our group catalog developed in Dutta et al (2023) to separate galaxies by environment, where the catalog was obtained by running a friends-of-friends algorithm on the galaxy sample with reliable redshifts using linking lengths of 400 kpc in the transverse spatial direction and 400 km s −1 in the line-of-sight velocity direction.…”

Discovery of Optically Emitting Circumgalactic Nebulae around the Majority of UV-luminous Quasars at Intermediate Redshift

“…However, the diffuse nature and cool-warm temperature range (T ≈ 10 4 -10 6 K) of the IGM/CGM around typical galaxies make emission observations difficult with current facilities except in the very local Universe (e.g., Chynoweth et al 2008;Lokhorst et al 2022) and rare cases with unusually high surface brightness. Consequently, emission observations of the IGM/ CGM often rely on deep, coadded observations averaging over hundreds to thousands of galaxies (e.g., Wisotzki et al 2016;Dutta et al 2023;Guo et al 2023aGuo et al , 2023b.…”

“…Recent IFS-enabled discoveries at lower redshifts of z < 1.5 revealed the potential for studies of ≈30-100 kpc-scale CGM nebulae observed in emission in nonresonant, rest-frame optical lines (e.g., [O II], Hβ, and [O III]) and resonant near-UV (NUV) lines (e.g., Mg II) around quasars (Johnson et al 2018;Helton et al 2021;Johnson et al 2022;Dutta et al 2023;Epinat et al 2024;Liu et al 2024), galaxy groups (Epinat et al 2018;Chen et al 2019;Leclercq et al 2022;Dutta et al 2023;Epinat et al 2024), and galaxies with evidence of recent bursts of star formation (Rupke et al 2019;Burchett et al 2021;Zabl et al 2021). The joint morphological and kinematic analysis of the nebulae combined with deep galaxy surveys enabled by IFSs provide direct insights into the origins of the gas, including interactions, accretion, and outflows.…”