2023 journal article
CGM(2) + CASBaH: The Mass Dependence of H I Ly alpha-Galaxy Clustering and the Extent of the CGM
ASTROPHYSICAL JOURNAL, 948(2).
open access via doi.org (publisher)
Source: Web Of Science
Added: June 19, 2023
Abstract We combine data sets from the CGM2 and CASBaH surveys to model a transition point, R cross, between circumgalactic and intergalactic media (CGM and IGM, respectively). In total, our data consist of 7244 galaxies at z < 0.5 with precisely measured spectroscopic redshifts, all having impact parameters of 0.01–20 comoving Mpc from 28 QSO sightlines with high-resolution UV spectra that cover H i Lyα. Our best-fitting model is a two-component model that combines a 3D absorber–galaxy cross-correlation function with a simple Gaussian profile at inner radii to represent the CGM. By design, this model gives rise to a determination of R cross as a function of galaxy stellar mass, which can be interpreted as the boundary between the CGM and IGM. For galaxies with 108 ≤ M ⋆/M ⊙ ≤ 1010.5, we find that R cross(M ⋆) ≈ 2.0 ± 0.6R vir. Additionally, we find excellent agreement between R cross(M ⋆) and the theoretically determined splashback radius for galaxies in this mass range. Overall, our results favor models of galaxy evolution at z < 0.5 that distribute T ≈ 104K gas to distances beyond the virial radius.