It’s a Breeze: The Circumgalactic Medium of a Dwarf Galaxy Is Easy to Strip

Abstract

The circumgalactic medium (CGM) of star-forming dwarf galaxies plays a key role in regulating the galactic baryonic cycle. We investigate how susceptible the CGM of dwarf satellite galaxies is to ram pressure stripping in Milky Way–like environments. In a suite of hydrodynamical wind tunnel simulations, we model an intermediate-mass dwarf satellite galaxy ( M _* = 10 ^7.2 M _⊙ ) with a multiphase interstellar medium (ISM; M _ISM = 10 ^7.9 M _⊙ ) and CGM ( M _CGM,vir = 10 ^8.5 M _⊙ ) along two first-infall orbits to more than 500 Myr past pericenter of a Milky Way–like host. The spatial resolution is ∼79 pc in the star-forming ISM and 316−632 pc in the CGM. Our simulations show that the dwarf satellite CGM removal is fast and effective: more than 95% of the CGM mass is ram pressure stripped within a few hundred megayears, even under a weak ram pressure orbit where the ISM stripping is negligible. The conditions for CGM survival are consistent with the analytical halo gas stripping predictions in McCarthy et al. We also find that including the satellite CGM does not effectively shield its galaxy, and therefore the ISM stripping rate is unaffected. Our results imply that a dwarf galaxy CGM is unlikely to be detected in satellite galaxies; and that the star formation of gaseous dwarf satellites is likely devoid of replenishment from a CGM.

Keywords

• Interstellar medium
• Circumgalactic medium
• Dwarf galaxies
• Galaxy interactions
• Hydrodynamical simulations
• Ram pressure stripped tails