MAGiiCAT V. ORIENTATION OF OUTFLOWS AND ACCRETION DETERMINE THE KINEMATICS AND COLUMN DENSITIES OF THE CIRCUMGALACTIC MEDIUM

Abstract

We investigate the dependence of gas kinematics and column densities in the Mg II-absorbing circumgalactic medium on galaxy color, azimuthal angle, and inclination to trace baryon cycle processes. Our sample of 30 foreground isolated galaxies at 0.3 < z gal < 1.0, imaged with the Hubble Space Telescope, are probed by background quasars within a projected distance of 20 < D < 110 kpc. From the high-resolution (∆v 6.6 km s −1 ) quasar spectra, we quantify the extent of the absorber velocity structure with pixel-velocity twopoint correlation functions. Absorbers with the largest velocity dispersions are associated with blue, face-on (i < 57 • ) galaxies probed along the projected minor axis (Φ ≥ 45 • ), while those with the smallest velocity dispersions belong to red, face-on galaxies along the minor axis. The velocity structure is similar for edge-on (i ≥ 57 • ) galaxies regardless of galaxy color or azimuthal angle, for red galaxies with azimuthal angle, and for blue and red galaxies probed along the projected major axis (Φ < 45 • ). The cloud column densities for face-on galaxies and red galaxies are smaller than for edge-on galaxies and blue galaxies, respectively. These results are consistent with biconical outflows along the minor axis for star-forming galaxies and accreting and/or rotating gas, which is most easily observed in edge-on galaxies probed along the major axis. Gas entrained in outflows may be fragmented with large velocity dispersions, while gas accreting onto or rotating around galaxies may be more coherent due to large path lengths and smaller velocity dispersions. Quiescent galaxies may exhibit little-to-no outflows along the minor axis, while accretion/rotation may exist along the major axis.

Slicing the cool circumgalactic medium along the major axis of a star-forming galaxy at z = 0.7

“…In Paper I, we found a similar situation toward RCS2032727−132623. These cases strongly suggest that the scatter in W quasar 0 is not intrinsic to the CGM but rather dominated by the heterogeneous halo population, in which gas extent and smoothness is a function of host-galaxy intrinsic properties Chen et al 2010;Nielsen et al 2013bNielsen et al , 2015Rubin et al 2018c) and orientation (Nielsen et al 2015). It should therefore not be a surprise that quasar-galaxy samples exhibit more scatter than the present case.…”

High Angular Momentum Halo Gas: A Feedback and Code-independent Prediction of LCDM

“…For example, kinematic studies of some Lyα nebulae suggest rotational velocities and inflow rates consistent with those expected for these inspiraling streams (Martin et al 2014;Prescott et al 2015). Similarly, absorption line studies are beginning to emphasize the bimodal distribution of absorption detections, where detections along the galaxy's minor axis tend to show absorption properties consistent with outflowing gas, while detections roughly along the galaxy's major axis demonstrate properties (such as corotational inflow) that are consistent with inspiraling cold streams (Kacprzak et al 2010(Kacprzak et al , 2012a(Kacprzak et al , 2012bBouché et al 2012Bouché et al , 2013Crighton et al 2013;Nielsen et al 2015;Bouché et al 2016;Ho et al 2017).…”

“…There is even indication that local extended H I disks may be environmentally dependent on the galaxy's filamentary environment (Courtois et al 2015). At moderate redshift (z∼0.5-1.5), numerous absorption line studies of the circumgalactic medium of galaxies have begun to emphasize the bimodal properties of absorbers, where absorption along the galaxy's major axis tends to show high angular momentum (co-rotating) inflow, and absorption along the galaxy's minor axis shows observational signatures of outflow (Kacprzak et al 2010(Kacprzak et al , 2012a(Kacprzak et al , 2012bBouché et al 2012Bouché et al , 2013Crighton et al 2013;Nielsen et al 2015;Bouché et al 2016;Diamond-Stanic et al 2016;Ho et al 2017). At higher redshift (z∼2-3), kinematic studies of Lyα "blobs" have observed large-scale rotation consistent with high angular momentum cold gas accretion (Martin et al 2014;Prescott et al 2015).…”

Gas Accretion and Angular Momentum

“…Furthermore, Cour-tois et al (2015) also indicated that local extended H I disks may be dependent on the galaxy's filamentary environment, suggesting there may be a fundamental distinction between the angular momentum content of filamentary accretion versus isotropic accretion. At moderate redshift (z ∼ 0.5-1.5) there are a growing number of absorption line studies of the circumgalactic medium of galaxies that have begun to emphasize the bi-modal properties of absorbers (Kacprzak et al, 2010(Kacprzak et al, , 2012aBouché et al, 2012Bouché et al, , 2013Crighton et al, 2013;Nielsen et al, 2015;Diamond-Stanic et al, 2016;Bouché et al, 2016;Bowen et al, 2016), where absorbers along a galaxy's major axis tends to show higher angular momentum inflows that are roughly corotating with the galactic disk and absorbers along a galaxy's minor axis tend to instead show observational signatures of outflowing gas. Increasingly, a number of absorption system observations seem to be in agreement with models that include massive, extended structures with inflowing disk-like kinematics (e.g., Bouché et al, 2016;Bowen et al, 2016) At higher redshift (z ∼ 2-3) kinematic studies of Lyα "blobs" have observed large scale rotation that seems consistent with high angular momentum cold gas accretion (Martin et al, 2014;Prescott et al, 2015), and there have also been recent detections of massive protogalactic gaseous disks that are kinematically linked to gas inflow along a cosmic filaments (Martin et al, , 2016.…”