Adding to the RESOLVE and ECO Gas in Galaxy Groups (G3) initiative, we examine possible drivers of group-integrated HI-to-halo mass ratios ($M_{ \rm HI,grp}/M_{ \rm halo}$) and group X-ray emission, including group halo mass ($M_{ \rm halo}$), virialization as probed by crossing time ($t_{ \rm cross}$), presence of active galactic nuclei (AGN), and group-integrated fractional stellar mass growth rate (FSMGR$_{ \rm grp}$). G3 groups span $M_{ \rm halo}=10^{ 11-14.5}\,M_\odot$ with comprehensive HI and AGN information, which we combine with X-ray stacking of ROSAT All-Sky data. We detect hot gas emission exceeding AGN and X-ray binary backgrounds confidently for $M_{ \rm halo}=10^{ 12.6-14}\,M_\odot$ and unambiguously for $M_{ \rm halo}>10^{ 14}\,M_\odot$, reflecting an inverse dependence of $M_{ \rm\,HI,grp}/M_{ \rm halo}$ and hot gas emission on halo mass. At fixed halo mass, $M_{ \rm\,HI,grp}/M_{ \rm halo}$ transitions to greater spread below $t_{ \rm cross}\sim2$ Gyr. Dividing groups across this transition, lower-$t_{ \rm cross}$ groups show elevated X-ray emission compared to higher-$t_{ \rm cross}$ groups for $M_{ \rm halo}>10^{ 13.3}\,M_\odot$, but this trend reverses for $M_{ \rm halo}=10^{ 12.6-13.3}\,M_\odot$. Additionally, AGN-hosting halos below $M_{ \rm halo}\sim10^{ 12.1}\,M_\odot$ exhibit a broad, $\sim$0.25 dex deep valley in $M_{ \rm HI,grp}/M_{ \rm halo}$ compared to non-AGN-hosting halos with correspondingly reduced FSMGR$_{ \rm grp}$. When diluted by non-AGN-hosting halos, this valley becomes shallower and narrower, falling roughly between $M_{ \rm halo}=10^{ 11.5}\,M_\odot$ and $M_{ \rm halo}=10^{ 12.1}\,M_\odot$ in the overall $M_{ \rm\,HI,grp}/M_{ \rm\,halo}$ vs. $M_{ \rm halo}$ relation. We may also detect a second, less easily interpreted valley at $M_{ \rm halo}\sim10^{ 13}\,M_\odot$. Neither valley matches theoretical predictions of a deeper valley at or above $M_{ \rm halo}=10^{ 12.1}\,M_\odot$.
Categories: astro-ph.GA