Clustering of Mg ii absorption line systems around massive galaxies: an important constraint on feedback processes in galaxy formation

Abstract

We use the latest version of the metal line absorption catalogue of Zhu & Ménard (2013) to study the clustering of MgII absorbers around massive galaxies (∼ 10 11.5 M ⊙ ), quasars and radio-loud AGN with redshifts between 0.4 and 0.75. Clustering is evaluated in two dimensions, by binning absorbers both in projected radius and in velocity separation. Excess MgII is detected around massive galaxies out to R p = 20 Mpc. At projected radii less than 800 kpc, the excess extends out to velocity separations of 10,000 km s −1 . The extent of the high velocity tail within this radius is independent of the mean stellar age of the galaxy and whether or not it harbours an active galactic nucleus. We interpret our results using the publicly available Illustris and Millennium simulations. Models where the MgII absorbers trace the dark matter particle or subhalo distributions do not fit the data. They overpredict the clustering on small scales and do not reproduce the excess high velocity separation MgII absorbers seen within the virial radius of the halo. The Illustris simulations which include thermal, but not mechanical feedback from AGN, also do not provide an adequate fit to the properties of the cool halo gas within the virial radius. We propose that the large velocity separation MgII absorbers trace gas that has been pushed out of the dark matter halos, possibly by multiple episodes of AGN-driven mechanical feedback acting over long timescales.

Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

“…Furthermore, the velocity dispersion scaling is in rough agreement with Nielsen et al (2015Nielsen et al ( , 2016 who characterized the galaxy-absorber relative velocity around blue and red galaxies using high-resolution spectra of quasars. The existence of broad components in the velocity distributions of Mg absorbers around massive red galaxies is in agreement with the results of Kauffmann et al (2017), who proposed that the large velocity separation Mg absorbers trace gas that has been pushed out of the dark matter haloes by multiple episodes of AGN-driven mechanical feedback acting over long time-scales.…”

“…The distribution of velocity separations between galaxies and absorbers allows the kinematics of cold gas around galaxies to be investigated (Tremonti et al 2007). For example, the clustering of Mg systems around BOSS LRGs (M ★ ∼ 10 11.5 M ) shows an excess of Mg up to 𝑅 𝑝 = 20 Mpc, as well as relative velocities of Δv ∼ 10000 km s −1 within a projected distance of 800 kpc (Kauffmann et al 2017). The implication is that cool circumgalactic gas can originate in either supernovae or supermassive black hole driven outflows, as well as due to infall and accretion.…”

MUSE Analysis of Gas around Galaxies (MAGG) – I: Survey design and the environment of a near pristine gas cloud at z ≈ 3.5

“…the Sloan Digital Sky Survey, York et al 2001, or the Galaxy And Mass Assembly survey, Driver et al 2011) that, supplemented by follow-up spectroscopy of quasars in the optical and UV, allow for detailed studies of the CGM in absorption as a function of galaxies properties in emission (including mass, star formation rates, and luminosity), and their environment (e.g. Tumlinson et al 2013;Stocke et al 2013;Bordoloi et al 2014;Finn et al 2016;Kauffmann et al 2017;Heckman et al 2017). These studies reveal the ubiquitous presence of a multiphase, enriched, and kinematically-complex CGM surrounding every galaxy, containing a significant baryonic mass that is comparable to, or even in excess of, the mass of baryons locked in stars.…”

Kinematics of MgII Absorbers from the Redshift-space Distortion Around Massive Quiescent Galaxies

“…This sharp truncation explains the missing of FOG effect in the RSD of MgII absorbers, and can not be reproduced simply by reducing the velocity dispersion of the cool clouds (as will be demonstrated later in § 5). We note that Kauffmann et al (2017) also measured the redshift-space cross-correlation function between the CMASS LRGs and MgII absorbers. However, they used a different method of generating random catalogues, a different estimator than Equation 1, and a different binning, so it is difficult to make direct comparison between Figure 4 and their results.…”

“…than adequate for comparing the LOS velocity dispersion of the MgII absorbers to that of the dark matter (see e.g., Huang et al 2016), but for a more stringent test of cloud kinematic models we need to explicitly model the redshift-space galaxy-absorber crosscorrelation functions (Lanzetta et al 1998;Chen et al 2005;Ryan-Weber 2006;Wilman et al 2007;Chen & Mulchaey 2009;Tejos et al 2012;Borthakur et al 2016). Recently, Kauffmann et al (2017) measured the redshift-space cross-correlation between the LRGs and MgII absorbers, but focused mostly on the large velocity tail, where they found significant discrepancy between the observations and hydrodynamic simulations at large Δ𝑧. In this paper, we will first reconstruct the 3D spatial distribution of cool clouds from the observed projected LRG-MgII cross-correlation function, and then infer the velocity distribution from the observed RSD of MgII absorbers around LRGs.…”