Galaxies Probing Galaxies in PRIMUS. II. The Coherence Scale of the Cool Circumgalactic Medium

Rubin, Kate H. R.; Diamond‐Stanic, Aleksandar M.; Coil, Alison L.; Crighton, Neil H. M.; Stewart, Kyle R.

doi:10.3847/1538-4357/aad566

Cited by 36 publications

(33 citation statements)

References 152 publications

(249 reference statements)

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“…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.…”

Section: Direct Comparison With Quasar and Galaxy Surveysmentioning

confidence: 44%

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

López

Tejos

Barrientos

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present spatially-resolved echelle spectroscopy of an intervening Mg ii-Fe ii-Mg i absorption-line system detected at z abs = 0.73379 toward the giant gravitational arc PSZ1 G311. 65-18.48. The absorbing gas is associated to an inclined disk-like starforming galaxy, whose major axis is aligned with the two arc-segments reported here. We probe in absorption the galaxy's extended disk continuously, at ≈ 3 kpc sampling, from its inner region out to 15× the optical radius. We detect strong (W 2796 0 > 0.3Å) coherent absorption along 13 independent positions at impact parameters D = 0-29 kpc on one side of the galaxy, and no absorption at D = 28-57 kpc on the opposite side (all de-lensed distances at z abs ). We show that: (1) the gas distribution is anisotropic; (2) W 2796 0 , W 2600 0 , W 2852 0 , and the ratio W 2600 0 /W 2796 0 , all anti-correlate with D; (3) the W 2796 0-D relation is not cuspy and exhibits significantly less scatter than the quasar-absorber statistics; (4) the absorbing gas is co-rotating with the galaxy out to D 20 kpc, resembling a 'flat' rotation curve, but at D 20 kpc velocities decline below the expectations from a 3D disk-model extrapolated from the nebular [O ii] emission. These signatures constitute unambiguous evidence for rotating extra-planar diffuse gas, possibly also undergoing enriched accretion at its edge. Arguably, we are witnessing some of the long-sought processes of the baryon cycle in a single distant galaxy expected to be representative of such phenomena.

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Section: Direct Comparison With Quasar and Galaxy Surveysmentioning

confidence: 44%

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

López

Tejos

Barrientos

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…In recent years, there has been increasing attention given to understanding the physics and chemistry of CGM gas as a function of galaxy properties, e.g. environment (Johnson, Chen & Mulchaey 2015;Burchett et al 2016;Nielsen et al 2018), mass and star formation rate (Adelberger et al 2005b;Chen et al 2010;Tumlinson et al 2011;Rakic et al 2012;Johnson et al 2017;Rubin et al 2018), and cosmic epoch (Hafen et al 2019;Hummels et al 2019;Nelson et al 2019). In large part, the increased focus on the CGM is attributable to a growing appreciation that diffuse gas outside of galaxies is a laboratory where many of the most important, but poorly understood, baryonic processes can be observed and tested.…”

mentioning

confidence: 99%

The Keck Baryonic Structure Survey: using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at z ∼ 2

Chen

Steidel

Hummels

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present new measurements of the spatial distribution and kinematics of neutral hydrogen in the circumgalactic and intergalactic medium surrounding star-forming galaxies at z ∼ 2. Using the spectra of ≃ 3000 galaxies with redshifts 〈z〉 = 2.3 ± 0.4 from the Keck Baryonic Structure Survey, we assemble a sample of more than 200,000 distinct foreground-background pairs with projected angular separations of 3″ − 500″ and spectroscopic redshifts, with 〈zfg〉 = 2.23 and 〈zbg〉 = 2.57 (foreground, background redshifts, respectively.) The ensemble of sightlines and foreground galaxies is used to construct a 2-D map of the mean excess H i$\rm Ly\alpha$ optical depth relative to the intergalactic mean as a function of projected galactocentric distance ($20 {\,\, \lesssim \,\,}D_{\rm tran}/{\rm pkpc} {\,\, \lesssim \,\,}4000$) and line-of-sight velocity. We obtain accurate galaxy systemic redshifts, providing significant information on the line-of-sight kinematics of H i gas as a function of projected distance Dtran. We compare the map with cosmological zoom-in simulation, finding qualitative agreement between them. A simple two-component (accretion, outflow) analytical model generally reproduces the observed line-of-sight kinematics and projected spatial distribution of H i. The best-fitting model suggests that galaxy-scale outflows with initial velocity vout ≃ 600 km s−1 dominate the kinematics of circumgalactic H i out to Dtran ≃ 50 kpc, while H i at Dtran ≳ 100 kpc is dominated by infall with characteristic $v_{\rm in} {\,\, \lesssim \,\,}$ circular velocity. Over the impact parameter range $80 {\,\, \lesssim \,\,}D_{\rm tran}/{\rm pkpc} {\,\, \lesssim \,\,}200$, the H i line-of-sight velocity range reaches a minimum, with a corresponding flattening in the rest-frame $\rm Ly\alpha$ equivalent width. These observations can be naturally explained as the transition between outflow-dominated and accretion-dominated flows. Beyond Dtran ≃ 300 pkpc (∼1 cMpc), the line of sight kinematics are dominated by Hubble expansion.

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“…Nonetheless, recent studies have used additional, novel techniques to place constraints on the physical scales of structures in the CGM. Rubin et al (2018) analyzed the CGM of 27 star-forming galaxies along spatially resolved background-galaxy lines of sight to determine that the coherence scale of Mg II absorbers is >1.9 kpc. Specifically, cold gas clouds either are >2 kpc in radius themselves or represent collections of much smaller clouds with similar properties.…”

Section: Cold Cloud Sizesmentioning

confidence: 99%

The Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium

Butsky

Fielding

Hayward

et al. 2020

ApJ

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Large reservoirs of cold (∼10 4 K) gas exist out to and beyond the virial radius in the circumgalactic medium (CGM) of all types of galaxies. Photoionization modeling suggests that cold CGM gas has significantly lower densities than expected by theoretical predictions based on thermal pressure equilibrium with hot CGM gas. In this work, we investigate the impact of cosmic-ray physics on the formation of cold gas via thermal instability. We use idealized three-dimensional magnetohydrodynamic simulations to follow the evolution of thermally unstable gas in a gravitationally stratified medium. We find that cosmic-ray pressure lowers the density and increases the size of cold gas clouds formed through thermal instability. We develop a simple model for how the cold cloud sizes and the relative densities of cold and hot gas depend on cosmic-ray pressure. Cosmic-ray pressure can help counteract gravity to keep cold gas in the CGM for longer, thereby increasing the predicted cold mass fraction and decreasing the predicted cold gas inflow rates. Efficient cosmic-ray transport, by streaming or diffusion, redistributes cosmicray pressure from the cold gas to the background medium, resulting in cold gas properties that are in between those predicted by simulations with inefficient transport and simulations without cosmic rays. We show that cosmic rays can significantly reduce galactic accretion rates and resolve the tension between theoretical models and observational constraints on the properties of cold CGM gas.

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Galaxies Probing Galaxies in PRIMUS. II. The Coherence Scale of the Cool Circumgalactic Medium

Cited by 36 publications

References 152 publications

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

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

The Keck Baryonic Structure Survey: using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at z ∼ 2

The Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium

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