Deep Chandra observations of diffuse hot plasma in M83
  It is widely believed that galaxy formation and evolution is regulated by
stellar mechanical feedback in forms of fast stellar winds and supernova
explosions. However, the coupling of this feedback with the interstellar medium
remains poorly understood. We examine how the coupling may be traced by diffuse
soft X-ray emission in M83 -- a nearby face-on spiral galaxy undergoing active
star formation, based chiefly on 729~ks Chandra observations. Our main findings
are 1) the X-ray emission is enhanced not only along the galaxy's grand spiral
arms, but also clearly in their downstreams; 2) the spectrum of the emission
can be well characterized by a super-solar metallicity plasma with a lognormal
temperature distribution, plus an X-ray absorption of a lognormal column
density distribution; 3) the intensity of the emission is strongly
anti-correlated with the dust obscuration seen in optical images of the galaxy.
These findings suggest A) the morphology of the X-ray emission is likely due to
the convolution of the feedback heating of the plasma with its thermal and
dynamical evolution; B) the X-ray emission, accounting for ~10% of the feedback
energy input rate, probably traces only the high-energy tail of the radiation
from the plasma; C) a good fraction of the recent star forming regions seems
sufficiently energetic to produce multi-phased outflows, likely responsible for
much of the dust obscuration and X-ray absorption. Direct confrontation of the
findings with theories/simulations could help to understand the underlying
astrophysics of the coupling and how the hot plasma shapes the interstellar
medium.
