CGM$^{2}$ I: The Extent of the Circumgalactic Medium Traced by Neutral Hydrogen. (arXiv:2008.08092v3 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Wilde_M/0/1/0/all/0/1">Matthew C. Wilde</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Werk_J/0/1/0/all/0/1">Jessica K. Werk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burchett_J/0/1/0/all/0/1">Joseph N. Burchett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prochaska_J/0/1/0/all/0/1">J. Xavier Prochaska</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tchernyshyov_K/0/1/0/all/0/1">Kirill Tchernyshyov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tripp_T/0/1/0/all/0/1">Todd M. Tripp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tejos_N/0/1/0/all/0/1">Nicolas Tejos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lehner_N/0/1/0/all/0/1">Nicolas Lehner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bordoloi_R/0/1/0/all/0/1">Rongmon Bordoloi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+OMeara_J/0/1/0/all/0/1">John M. O&#x27;Meara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tumlinson_J/0/1/0/all/0/1">Jason Tumlinson</a>

We present initial results from the textit{COS and Gemini Mapping the
Circumgalactic Medium} (mbox{CGMCGM} $equiv$ CGM$^{2}$) survey. The CGM$^{2}$
survey consists of 1689 galaxies, all with high-quality Gemini GMOS spectra,
within 1 Mpc of twenty-two $z lesssim 1$ quasars, all with S/N$sim$10
{emph{HST/COS}} G130M$+$G160M spectra. For 572 of these galaxies having
stellar masses $10^{7} M_{odot} < M_{star} < 10^{11} M_{odot}$ and $z
lesssim 0.5$, we show that the ion{H}{1} covering fraction above a threshold
of NHI$>10^{14} $cm$^{-2}$ is $gtrsim 0.5$ within 1.5 virial radii ($R_{rm
vir} sim R_{200m}$). We examine the ion{H}{1} kinematics and find that the
majority of absorption lies within $pm$ 250 km s$^{-1}$ of the galaxy systemic
velocity. We examine ion{H}{1} covering fractions over a range of impact
parameters to infer a characteristic size of the CGM, $R^{14}_{rm CGM}$, as a
function of galaxy mass. $R^{14}_{rm CGM}$ is the impact parameter at which
the probability of observing an absorber with NHI $>$ 10$^{14}$ cm$^{-2}$ is
$>$ 50%. In this framework, the radial extent of the CGM of $M_{star} >
10^{9.9} M_{odot}$ galaxies is $R^{14}_{rm CGM} = 346^{+57}_{-53}$ kpc or
$R^{14}_{rm CGM} simeq 1.2R_{rm vir}$. Intermediate-mass galaxies with
$10^{9.2} < M_{star}/M_{odot} < 10^{9.9}$ have an extent of $R^{14}_{rm CGM}
= 353^{+64}_{-50}$ kpc or $R^{14}_{rm CGM} simeq 2.4R_{rm vir}$. Low-mass
galaxies, $M_{star} < 10^{9.2} M_{odot}$, show a smaller physical scale
$R^{14}_{rm CGM} = 177_{-65}^{+70}$ kpc and extend to $R^{14}_{rm CGM} simeq
1.6R_{rm vir}$. Our analysis suggests that using $R_{rm vir}$ as a proxy for
the characteristic radius of the CGM likely underestimates its extent.

We present initial results from the textit{COS and Gemini Mapping the
Circumgalactic Medium} (mbox{CGMCGM} $equiv$ CGM$^{2}$) survey. The CGM$^{2}$
survey consists of 1689 galaxies, all with high-quality Gemini GMOS spectra,
within 1 Mpc of twenty-two $z lesssim 1$ quasars, all with S/N$sim$10
{emph{HST/COS}} G130M$+$G160M spectra. For 572 of these galaxies having
stellar masses $10^{7} M_{odot} < M_{star} < 10^{11} M_{odot}$ and $z
lesssim 0.5$, we show that the ion{H}{1} covering fraction above a threshold
of NHI$>10^{14} $cm$^{-2}$ is $gtrsim 0.5$ within 1.5 virial radii ($R_{rm
vir} sim R_{200m}$). We examine the ion{H}{1} kinematics and find that the
majority of absorption lies within $pm$ 250 km s$^{-1}$ of the galaxy systemic
velocity. We examine ion{H}{1} covering fractions over a range of impact
parameters to infer a characteristic size of the CGM, $R^{14}_{rm CGM}$, as a
function of galaxy mass. $R^{14}_{rm CGM}$ is the impact parameter at which
the probability of observing an absorber with NHI $>$ 10$^{14}$ cm$^{-2}$ is
$>$ 50%. In this framework, the radial extent of the CGM of $M_{star} >
10^{9.9} M_{odot}$ galaxies is $R^{14}_{rm CGM} = 346^{+57}_{-53}$ kpc or
$R^{14}_{rm CGM} simeq 1.2R_{rm vir}$. Intermediate-mass galaxies with
$10^{9.2} < M_{star}/M_{odot} < 10^{9.9}$ have an extent of $R^{14}_{rm CGM}
= 353^{+64}_{-50}$ kpc or $R^{14}_{rm CGM} simeq 2.4R_{rm vir}$. Low-mass
galaxies, $M_{star} < 10^{9.2} M_{odot}$, show a smaller physical scale
$R^{14}_{rm CGM} = 177_{-65}^{+70}$ kpc and extend to $R^{14}_{rm CGM} simeq
1.6R_{rm vir}$. Our analysis suggests that using $R_{rm vir}$ as a proxy for
the characteristic radius of the CGM likely underestimates its extent.

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