2021 journal article

CGM(2) I: The Extent of the Circumgalactic Medium Traced by Neutral Hydrogen

ASTROPHYSICAL JOURNAL, 912(1).

By: M. Wilde*, J. Werk*, J. Burchett*, J. Prochaska*, K. Tchernyshyov*, T. Tripp*, N. Tejos*, N. Lehner* ...

co-author countries: Chile 🇨🇱 Japan 🇯🇵 United States of America 🇺🇸
Source: Web Of Science
Added: May 10, 2021

Abstract We present initial results from the Cosmic Origins Spectrograph (COS) and Gemini Mapping the Circumgalactic Medium (CGMCGM ≡ CGM 2 ) survey. The CGM 2 survey consists of 1689 galaxies, all with high-quality Gemini-GMOS spectra, within 1 Mpc of 22 z ≲ 1 quasars, all with a signal-to-noise ratio of ∼10 Hubble Space Telescope/COS G130M+G160M spectra. For 572 of these galaxies with stellar masses 10 7 M ⊙ &lt; M ⋆ &lt; 10 11 M ⊙ and z ≲ 0.5, we show that the H i covering fraction above a threshold of N HI &gt; 10 14 cm −2 is ≳0.5 within 1.5 virial radii ( R vir ∼ R 200m ). We examine the H i kinematics and find that the majority of absorption lies within ±250 km s −1 of the galaxy systemic velocity. We examine H i covering fractions over a range of impact parameters to infer a characteristic size of the CGM, <?CDATA ${R}_{\mathrm{CGM}}^{14}$?> , as a function of galaxy mass. <?CDATA ${R}_{\mathrm{CGM}}^{14}$?> is the impact parameter at which the probability of observing an absorber with N HI &gt;10 14 cm −2 is &gt;50%. In this framework, the radial extent of the CGM of M ⋆ &gt; 10 9.9 M ⊙ galaxies is <?CDATA ${R}_{\mathrm{CGM}}^{14}={346}_{-53}^{+57}$?> kpc or <?CDATA ${R}_{\mathrm{CGM}}^{14}\simeq 1.2{R}_{\mathrm{vir}}$?> . Intermediate-mass galaxies with 10 9.2 &lt; M ⋆ / M ⊙ &lt; 10 9.9 have an extent of <?CDATA ${R}_{\mathrm{CGM}}^{14}={353}_{-50}^{+64}$?> kpc or <?CDATA ${R}_{\mathrm{CGM}}^{14}\simeq 2.4{R}_{\mathrm{vir}}$?> . Low-mass galaxies, M ⋆ &lt; 10 9.2 M ⊙ , show a smaller physical scale of <?CDATA ${R}_{\mathrm{CGM}}^{14}={177}_{-65}^{+70}$?> kpc and extend to <?CDATA ${R}_{\mathrm{CGM}}^{14}\simeq 1.6{R}_{\mathrm{vir}}$?> . Our analysis suggests that using R vir as a proxy for the characteristic radius of the CGM likely underestimates its extent.