Tentative Detection of the Circumgalactic Medium of the Isolated
  Low-Mass Dwarf Galaxy WLM
  We report a tentative detection of the circumgalactic medium (CGM) of WLM, an
isolated, low-mass (log$M_*/M_\odot\approx7.6$), dwarf irregular galaxy in the
Local Group (LG). We analyze an HST/COS archival spectrum of a quasar sightline
(PHL2525), which is 45 kpc (0.5 virial radius) from WLM and close to the
Magellanic Stream (MS). Along this sightline, two ion absorbers are detected in
Si II, Si III, Si IV, C II, and C IV at velocities of $\sim$-220 km s$^{-1}$
(Component v-220) and $\sim$-150 km s$^{-1}$ (Component v-150). To identify
their origins, we study the position-velocity alignment of the components with
WLM and the nearby MS. Near the Magellanic longitude of PHL2525, the MS-related
neutral and ionized gas moves at $\lesssim-190$ km s$^{-1}$, suggesting an MS
origin for Component v-220, but not for Component v-150. Because PHL2525 passes
near WLM and Component v-150 is close to WLM's systemic velocity ($\sim$-132 km
s$^{-1}$), it is likely that Component v-150 arises from the galaxy's CGM. This
results in a total Si mass in WLM's CGM of $M_{\rm Si}^{\rm
CGM}\sim(0.2-1.0)\times10^5~M_\odot$ using assumption from other COS dwarf
studies. Comparing $M_{\rm Si}^{\rm CGM}$ to the total Si mass synthesized in
WLM over its lifetime ($\sim$1.3$\times10^5~M_\odot$), we find $\sim$3% is
locked in stars, $\sim$6% in the ISM, $\sim$15%-77% in the CGM, and the rest
($\sim$14%-76%) is likely lost beyond the virial radius. Our finding resonates
with other COS dwarf galaxy studies and theoretical predictions that low-mass
galaxies can easily lose metals into their CGM due to stellar feedback and
shallow gravitational potential.
