Observational signatures of a warped disk associated with cold-flow accretion

Abstract

We present MUSE observations of the field of the quasar Q0152−020 whose spectrum shows a Lyman limit system (LLS) at redshift z abs = 0.38, with a metallicity Z 0.06 Z ⊙ . The low ionization metal lines associated with the LLS present two narrow distinct absorption components with a velocity separation of 26 km s −1 . We detect six galaxies within 600 km s −1 from the absorption redshift; their projected distances from the quasar sightline range from 60 to 200 kpc. The optical spectra of five of these galaxies exhibit prominent nebular emission lines, from which we deduce extinctioncorrected star formation rates in the range SFR = 0.06-1.3 M ⊙ yr −1 , and metallicities between 0.2 Z ⊙ and Z ⊙ . The sixth galaxy is only detected in the stellar continuum. By combining our data with archival Keck/HIRES spectroscopy of the quasar and HST/WFPC2 imaging of the field, we can relate absorption line and galaxy kinematics; we conclude that the LLS is most likely associated with the galaxy closest to the quasar sight-line (galaxy "a"). Our morphokinematic analysis of galaxy "a" combined with the absorption line kinematics supports the interpretation that one of the absorption components originates from an extension of the stellar disk of galaxy "a", while the other component may arise in accreting gas in a warped disk with specific angular momentum ∼ 3 times larger than the specific angular momentum of the galaxy halo. Such warped disks are common features in hydrodynamical simulations of cold-flow accretion onto galaxies; the data presented here provide observational evidence in favour of this scenario.

MUSE-ALMA haloes V: physical properties and environment of z ≤ 1.4 H i quasar absorbers

“…For the redshift determination, we used Mg iiλ2796; in case of multiple components, we used the strongest one to measure the central wavelength. We limited the sample to systems with redshift z < 1.4, so that the [O ii] emission line is within the MUSE wavelength coverage, resulting in a list of 14 Mg ii absorbers, of which some have been presented elsewhere: Q0152z038 (Rahmani et al 2018a), Q0152z078 (Rahmani et al 2018b), Q1130z031 (Péroux et al 2019) and Q2131z042 (Péroux et al 2017). We used VPFIT 1 v10.0 to fit the Voigt profiles to unsaturated metal absorption lines.…”

“…Integral-field spectroscopy with instruments like SIN-FONI (Eisenhauer et al 2003), MUSE (Bacon et al 2006) or OSIRIS (Larkin et al 2006), make it possible to obtain spectra of many sources in the field-of-view and efficiently classify galaxies associated with absorbers. Combined with highresolution UV spectroscopy of quasars, these studies have revealed relevant features interpreted as galactic outflows (Schroetter et al 2016;Rahmani et al 2018b;Schroetter et al 2019), warped accretion discs (Rahmani et al 2018a) and galactic fountains (Bouché et al 2016). Alongside the detection of kinematic traces of gas inflows and outflows, new studies detected multiple galaxies associated with one absorber (Bielby et al 2017;Péroux et al 2017;Klitsch et al 2018;Nielsen et al 2018;Péroux et al 2019;Muzahid et al 2019).…”

MusE GAs FLOw and Wind (MEGAFLOW) II. A study of gas accretion around z ≈ 1 star-forming galaxies with background quasars

“…Among those, Ho et al (2017) demonstrated the existence of co-rotating structures at z ≈ 0.2 in a sample of half-dozen galaxies, a step forward from the individual analyses of Bouché et al (2013) and Bouché et al (2016) Progress in sample size has been slow in spite of decades of research with galaxy-quasar pairs, as studies investigating the connections between the host galaxy kinematics and the low-ionization absorption line kinematics were limited to ∼ 50 pairs (see Kacprzak 2017, for a recent review). Less than half of these have orientations favourable to study extended gas disks (accretion cases) (Barcons et al 1995;Steidel et al 2002;Chen et al 2005;Kacprzak et al 2010Kacprzak et al , 2011Bouché et al 2013Bouché et al , 2016Ho et al 2017;Rahmani et al 2018).…”

MusE GAs FLOw and Wind (MEGAFLOW) IV. A two sightline tomography of a galactic wind

“…Bouché et al 2012;Kacprzak et al 2014;Muzahid et al 2015;Schroetter et al 2015Schroetter et al , 2016Schroetter et al , 2019Rahmani et al 2018b;Martin et al 2019) and the extended gas accretion disks (e.g. Steidel et al 2002;Chen et al 2005;Kacprzak et al 2010Kacprzak et al , 2011bBouché et al 2013Bouché et al , 2016Ho et al 2017;Rahmani et al 2018a;Zabl et al 2019), respectively.…”