MUSE analysis of gas around galaxies (MAGG) – III. The gas and galaxy environment of z = 3–4.5 quasars

Abstract

We present a study of the environment of 27 z = 3 − 4.5 bright quasars from the MUSE Analysis of Gas around Galaxies (MAGG) survey. With medium-depth MUSE observations (4 hours on target per field), we characterise the effects of quasars on their surroundings by studying simultaneously the properties of extended gas nebulae and Lyα emitters (LAEs) in the quasar host haloes. We detect extended (up to ≈100 kpc) Lyα emission around all MAGG quasars, finding a very weak redshift evolution between z = 3 and z = 6. By stacking the MUSE datacubes, we confidently detect extended emission of C iv and only marginally detect extended He ii up to ≈40 kpc, implying that the gas is metal enriched. Moreover, our observations show a significant overdensity of LAEs within 300 $\rm km~s^{-1}$ from the quasar systemic redshifts estimated from the nebular emission. The luminosity functions and equivalent width distributions of these LAEs show similar shapes with respect to LAEs away from quasars suggesting that the Lyα emission of the majority of these sources is not significantly boosted by the quasar radiation or other processes related to the quasar environment. Within this framework, the observed LAE overdensities and our kinematic measurements imply that bright quasars at z = 3 − 4.5 are hosted by haloes in the mass range $\approx 10^{12.0}-10^{12.5}~\rm M_\odot$.

Metal-enriched halo gas across galaxy overdensities over the last 10 billion years

“…We have presented a study of the correlation between low-and high-ionization metal-enriched gaseous haloes traced by Mg II and C IV absorption, respectively, and galaxy properties and environment characterized by overdensities at z < 2. We have utilized two large galaxy surveys in quasar fields, MAGG (Dutta et al 2020;Lofthouse et al 2020;Fossati et al 2021) and QSAGE (Bielby et al 2019;Stott et al 2020), for this study. MAGG, a MUSE optical IFU survey with an FoV of ≈1 × 1 arcmin 2 in 28 z QSO ≈ 3-4 quasar fields, and QSAGE, an HST NIR grism survey with an FoV of ≈1.5 × 1.5 arcmin 2 in 12 z QSO ≈ 1-2 quasar fields (8 of which have MUSE observations), are both 'blind' (i.e.…”

“…In this work, we study gaseous haloes up to z ≈ 2 with a systematic focus on the galaxy environment, taking advantage of the large and complete galaxy surveys that are becoming available now in quasar fields. In particular, we use data from two large, independent surveys -the MUSE Analysis of Gas around Galaxies (MAGG; Dutta et al 2020;Lofthouse et al 2020;Fossati et al 2021) survey and the Quasar Sightline and Galaxy Evolution (QSAGE; Bielby et al 2019;Stott et al 2020) survey. The structure of this paper is as follows.…”

APEX at the QSO MUSEUM: molecular gas reservoirs associated with $z\sim$3 quasars and their link to the extended Ly$α$ emission

“…The halo gas, known as circumgalactic medium (CGM, e.g., Tumlinson et al 2017), has been studied around quasars mostly targeting the cool phase both in absorption (e.g., Hennawi et al 2006;Prochaska et al 2013;Farina et al 2013Farina et al , 2014Lau et al 2018) and in emission (e.g., Heckman et al 1991;Bunker et al 2003;Farina et al 2019;Fossati et al 2021). While the absorption technique usually relies on only one background sightline per foreground halo to provide statistical information on the physical properties of the CGM of quasars, studies of the CGM in emission are currently able to map the quasar CGM around individual systems.…”

“…The seminal papers by Rees (1988) and Haiman & Rees (2001), predicted that gas surrounding quasars reprocesses the impinging strong UV radiation as Ly𝛼 emission. Current studies routinely report extended Ly𝛼 emission, with ∼ 200 quasars surveyed to date at 2 < 𝑧 < 4 (e.g., Husband et al 2015;Fumagalli et al 2016;Borisova et al 2016;Arrigoni Battaia et al 2019a;Cai et al 2019;O'Sullivan et al 2020;Mackenzie et al 2021;Fossati et al 2021). The bulk of the extended emission traces gas on a few tens of kpc near the quasars, while large-scale structures extending to 𝑅 80 kpc are seen at lower surface brightness (SB Ly𝛼 ∼ 10 −18 erg s −1 cm −2 arcsec −2 ).…”

“…On top of this, there are large uncertainties on the ionizing radiation that impinges on the surrounding gas, because quasars are expected to be anisotropic, intermittent sources with different degrees of obscuration. These uncertainties hamper the physical interpretation of properties of the emitting gas (e.g., density 𝑛 H , metallicity; Fossati et al 2021).…”