2022ApJ...927..228Q

Dwarf galaxies are missing nearly all of their baryons and metals from the stellar disk, which are presumed to be in a bound halo or expelled beyond the virial radius. The virial temperature for galaxies with M_h ∼ 10⁹-10¹⁰M_☉ is similar to the collisional ionization equilibrium temperature for the C IV ion. We search for UV absorption from C IV in six sightlines toward three dwarf galaxies in the anti-M31 direction and at the periphery of the Local Group (D ≃ 1.3 Mpc; Sextans A, Sextans B, and NGC 3109). The C IV doublet is detected in only one of six sightlines, toward Sextans A, with logN(C IV)=13.06±0.08. This is consistent with our gaseous halo models, where the halo gas mass is determined by the cooling rate, feedback, and the star formation rate; the inclusion of photoionization is an essential ingredient. This model can also reproduce the higher detection rate of O VI absorption in other dwarf samples (beyond the Local Group), with C IV only detectable within ∼0.5R_vir.