Coronal Gas in Magellanic-Analog Dwarfs: Insights from the \textsc{HESTIA} Simulations (2504.15237v1)

Abstract: We characterize the warm circumgalactic medium (CGM) of a dwarf galaxy pair with properties similar to the Magellanic Clouds in the \textsc{Hestia} cosmological simulations. The system consists of a massive dwarf ($M_{\rm halo} \sim 10^{11.5} M_{\odot}$) and a lower-mass companion ($M_{\rm halo} \sim 10^{10} M_{\odot}$), dynamically evolving in isolation before infall into a Milky Way-mass halo. The massive dwarf hosts a warm coronal gas envelope with a temperature of $T \sim 3 \times 10^5$ K, consistent with expectations for virialized CGM in dwarf halos. Tidal interactions produce a neutral gas stream that extends over $\sim 150$ kpc, with an \ion{H}{1} mass of $M_{\rm HI} \sim 10^8 M_{\odot}$, similar to the Magellanic Stream. Furthermore, in the \textsc{Hestia} simulation suite, we find that coronal gas is ubiquitous in all halos with $M_{\rm halo} > 10^{11} M_{\odot}$, implying that massive dwarfs generically develop extended gaseous envelopes prior to accretion. This result has significant implications for the survival of neutral tidal structures, and suggests that current and future high-ion UV absorption-line observations are indicative of warm coronae surrounding LMC-mass dwarfs, independent of their environment.