We use medium and highresolution spectroscopy of close pairs of quasars to analyze the circumgalactic medium (CGM) surrounding 32 damped Ly
We present an analytic model for the cool,
 Award ID(s):
 2044303
 NSFPAR ID:
 10516760
 Publisher / Repository:
 The Astrophysical Journal
 Date Published:
 Journal Name:
 The Astrophysical Journal
 Volume:
 956
 Issue:
 2
 ISSN:
 0004637X
 Page Range / eLocation ID:
 92
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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Abstract α absorption systems (DLAs). The primary quasar sightline in each pair probes an intervening DLA in the redshift range 1.6 <z _{abs}< 3.5, such that the secondary sightline probes absorption from Lyα and a large suite of metalline transitions (including Oi , Cii , Civ , Siii , and Siiv ) in the DLA host galaxy’s CGM at transverse distances 24 kpc ≤R _{⊥}≤ 284 kpc. Analysis of Lyα in the CGM sightlines shows an anticorrelation betweenR _{⊥}and Hi column density (N _{HI}) with 99.8% confidence, similar to that observed around luminous galaxies. The incidences of Cii and Siii withN > 10^{13}cm^{−2}within 100 kpc of DLAs are larger by 2σ than those measured in the CGM of Lyman break galaxies (C_{f}(N _{CII}) > 0.89 and ). Metallicity constraints derived from ionic ratios for nine CGM systems with negligible ionization corrections and ${\mathrm{C}}_{f}({N}_{\mathrm{Si}\mathrm{II}})={0.75}_{0.17}^{+0.12}$N _{HI}> 10^{18.5}cm^{−2}show a significant degree of scatter (with metallicities/limits across the range ), suggesting inhomogeneity in the metal distribution in these environments. Velocity widths of C $2.06\lesssim \mathrm{log}Z/{Z}_{\odot}\lesssim 0.75$iv λ 1548 and lowionization metal species in the DLA versus CGM sightlines are strongly (>2σ ) correlated, suggesting that they trace the potential well of the host halo overR _{⊥}≲ 300 kpc scales. At the same time, velocity centroids for Civ λ 1548 differ in DLA versus CGM sightlines by >100 km s^{−1}for ∼50% of velocity components, but few components have velocities that would exceed the escape velocity assuming dark matter host halos of ≥10^{12}M _{⊙}. 
Abstract We present
CloudFlex , an opensource tool for predicting absorptionline signatures of cool gas in galaxy halos with smallscale structure. Motivated by analyses of ∼10^{4}K material in hydrodynamical simulations of turbulent, multiphase media, we model cool gas structures as complexes of cloudlets sampled from a powerlaw distribution of mass with velocities drawn from a turbulent velocity field. The user may specify $\propto {m}_{\mathrm{cl}}^{\alpha}$α , the lower limit of the cloudlet mass distribution ( ), and several other parameters that set the mass, size, and velocity distribution of the complex. This permits investigation of the relation between these parameters and absorptionline observables. As a proofofconcept, we calculate the Mg ${m}_{\mathrm{cl},\mathrm{min}}$ii λ 2796 absorption induced by the cloudlets in background quasistellar object (QSO) spectra. We demonstrate that, at fixed metallicity, the covering fraction of sight lines with equivalent widthsW _{2796}< 0.3 Å increases significantly with decreasing , cloudlet number density ( ${m}_{\mathrm{cl},\mathrm{min}}$n _{cl}), and complex size. We then use this framework to predict the haloscaleW _{2796}distribution around ∼L ^{*}galaxies. We show that the observed incidences ofW _{2796}> 0.3 Å sight lines with impact parameters 10 kpc <R _{⊥}< 50 kpc in projected QSO–galaxy studies are consistent with our model over much of parameter space. However, they are underpredicted by models with and ${m}_{\mathrm{cl},\mathrm{min}}\ge 100{M}_{\odot}$n _{cl}≥ 0.03 cm^{−3}, in keeping with a picture in which the inner cool circumgalactic medium (CGM) is dominated by numerous lowmass cloudlets (m _{cl}≲ 100M _{⊙}) with a volume filling factor ≲1%. When used to model absorptionline data sets built from multisight line and/or spatially extended background probes,CloudFlex enables detailed constraints on the size and velocity distributions of structures comprising the photoionized CGM. 
Braving the Storm: Quantifying Diskwide Ionized Outflows in the Large Magellanic Cloud with ULLYSES
Abstract The Large Magellanic Cloud (LMC) is home to many H
ii regions, which may lead to significant outflows. We examine the LMC’s multiphase gas (T ∼10^{45}K) in Hi , Sii , Siiv , and Civ using 110 stellar sight lines from the Hubble Space Telescope’s Ultraviolet Legacy Library of Young Stars as Essential Standards program. We develop a continuum fitting algorithm based on the concept of Gaussian process regression and identify reliable LMC interstellar absorption overv _{helio}= 175–375 km s^{−1}. Our analyses show diskwide ionized outflows in Siiv and Civ across the LMC with bulk velocities of ∣v _{out, bulk}∣ ∼ 20–60 km s^{−1}, which indicates that most of the outflowing mass is gravitationally bound. The outflows’ column densities correlate with the LMC’s star formation rate surface densities (Σ_{SFR}), and the outflows with higher Σ_{SFR}tend to be more ionized. Considering outflows from both sides of the LMC as traced by Civ , we conservatively estimate a total outflow rate of and a massloading factor of ${\stackrel{\u0307}{M}}_{\mathrm{out}}\gtrsim 0.03\phantom{\rule{0.25em}{0ex}}{M}_{\odot}{\mathrm{yr}}^{1}$η ≳ 0.15. We compare the LMC’s outflows with those detected in starburst galaxies and simulation predictions, and find a universal scaling relation of over a wide range of starforming conditions (Σ_{SFR}∼ 10^{−4.5}–10^{2} $\mid {v}_{\mathrm{out},\phantom{\rule{0.33em}{0ex}}\mathrm{bulk}}\mid \propto {\mathrm{\Sigma}}_{\mathrm{SFR}}^{0.23}$M _{⊙}yr^{−1}kpc^{−2}). Lastly, we find that the outflows are corotating with the LMC’s young stellar disk and the velocity field does not seem to be significantly impacted by external forces; we thus speculate on the existence of a bow shock leading the LMC, which may have shielded the outflows from ram pressure as the LMC orbits the Milky Way. 
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Abstract The circumgalactic medium (CGM) plays a vital role in the formation and evolution of galaxies, acting as a lifeline between galaxies and the surrounding intergalactic medium. In this study, we leverage a unique sample of quasar pairs to investigate the properties of the CGM with absorption line tomography. We present a new sample of mediumresolution Keck/ESI, Magellan/MagE, and VLT/XSHOOTER spectra of 29 quasar pairs at redshift 2 <
z < 3. We supplement the sample with additional spectra of 32 pairs from the literature, creating a catalog of 61 quasar pairs with angular separations between 1.″7 and 132.″9 and projected physical separations (r _{⊥}) between 14 kpc and 887 kpc. We construct a catalog of 906 metalline absorption doublets of Civ (λλ 1548, 1550) with equivalent widths ranging from 6 m Å ≤W _{r,1550}≤ 2053 m Å. The bestfit linear model to the logspace equivalent width frequency distribution ( ) of the sample yields coefficients of $\mathrm{log}f({W}_{r})=m\mathrm{log}({W}_{r})+b$m = −1.44 ± 0.16 andb = −0.43 ± 0.16. To constrain the projected extent of Civ , we calculate the transverse autocorrelation function. The flattening of the autocorrelation function at lowr _{⊥}provides a lower limit for the coherence length of the metal enriched CGM—on the order of 200h ^{−1}comoving kpc. This physical size constraint allows us to refine our understanding of the metals in the CGM, where the extent of Civ in the CGM depends on gas flows, feedback, timescale of metal injection and mixing, and the mass of the host galaxies.