Семинар 159 – 31 августа 2020 г.


Ольга Сильченко

Презентация

2008.08092 CGM$^{2}$ I: The Extent of the Circumgalactic Medium Traced by Neutral Hydrogen

Matthew C. Wilde, Jessica K. Werk, Joseph N. Burchett, J. Xavier Prochaska, Kirill Tchernyshyov, Todd M. Tripp, Nicolas Tejos, Nicolas Lehner, Rongmon Bordoloi, John M. O'Meara, Jason Tumlinson

Published 2020-08-18, 30 pages, 14 figures. Submitted to ApJ, Comments welcome

We present initial results from the \textit{COS and Gemini Mapping theCircumgalactic 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 havingstellar 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 thresholdof \NHI$>10^{14} $cm$^{-2}$ is $\gtrsim 0.5$ within 1.5 virial radii ($R_{\rmvir} \sim R_{200m}$). We examine the \ion{H}{1} kinematics and find that themajority of absorption lies within $\pm$ 250 km s$^{-1}$ of the galaxy systemicvelocity. We examine \ion{H}{1} covering fractions over a range of impactparameters to infer a characteristic size of the CGM, $R^{14}_{\rm CGM}$, as afunction of galaxy mass. $R^{14}_{\rm CGM}$ is the impact parameter at whichthe 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-massgalaxies, $M_{\star} < 10^{9.2} M_{\odot}$, show a smaller physical scale$R^{14}_{\rm CGM} = 177_{-65}^{+70}$ kpc and extend to $R^{14}_{\rm CGM} \simeq1.6R_{\rm vir}$. Our analysis suggests that using $R_{\rm vir}$ as a proxy forthe characteristic radius of the CGM likely underestimates its extent.