http://arxiv.org/abs/2305.05698
We present the first statistical detection of cool, neutral gas in the outskirts of low-z galaxy clusters using a sample of 3191 z $\approx$0.2 background quasar – foreground cluster pairs with a median cluster mass of $\sim 10^{14.2}$ M_sun by cross-matching the Hubble Spectroscopic Legacy Archive quasar catalog with optically- and SZ-selected cluster catalogs. We detect significant Lya, marginal CIV, but no OVI absorption in the median stacked spectra with rest-frame equivalent widths (REWs) of 0.043$\pm$0.006A, 0.020$\pm$0.007A, and <0.006A (3$\sigma$) for our sample with a median impact parameter ($\rho_{cl}$) of $\approx$5 Mpc (median $\rho_{cl}$/$R_{500}$ $\approx$7 ). The Lya REW shows a declining trend with increasing $\rho_{cl}$ ($\rho_{cl}$ / $R_{500}$) which is well explained by a power-law with a slope of -0.74 (-0.60). The covering fractions measured for Lya, CIV and OVI in cluster outskirts are significantly lower compared to the circumgalatic medium (CGM). We find that the CGM of galaxies residing in cluster outskirts is considerably deficient in neutral gas compared to their field counterparts. This effect is more pronounced for galaxies that are closer to cluster centers or that are in massive clusters. We argue that the cool gas detected in cluster outskirts arises from the circumgalactic gas stripped from cluster galaxies and to large-scale filaments feeding the clusters with cool gas.
S. Mishra, S. Muzahid, S. Dutta, et. al.
Thu, 11 May 23
22/55
Comments: 17 pages, 4 tables, 9 figures. Submitted to MNRAS