Colliding Winds in and around the Stellar Group IRS 13E at the Galactic
  Center
  IRS~13E is an enigmatic compact group of massive stars located in projection
only 3.6 arcseconds away from Sgr A*. This group has been suggested to be
bounded by an intermediate-mass black hole (IMBH). We present a
multi-wavelength study of the group and its interplay with the environment.
Based on Chandra observations, we find the X-ray spectrum of IRS~13E can be
well characterized by an optically thin thermal plasma. The emission peaks
between two strongly mass-losing Wolf-Rayet stars of the group. These
properties can be reasonably well reproduced by simulated colliding winds of
these two stars. However, this scenario under-predicts the X-ray intensity in
outer regions. The residual emission likely results from the ram-pressure
confinement of the IRS~13E group wind by the ambient medium and is apparently
associated with a shell-like warm gas structure seen in Pa-alpha and in ALMA
observations. These latter observations also show strongly peaked thermal
emission with unusually large velocity spread between the two stars. These
results indicate that the group is colliding with the bar of the dense cool gas
mini-spiral around Sgr A*. The extended X-ray morphology of IRS~13E and its
association with the bar further suggest that the group is physically much
farther away than the projected distance from Sgr A*. The presence of an IMBH,
while favorable to keep the stars bound together, is not necessary to explain
the observed stellar and gas properties of IRS~13E.
