Extra-planar X-ray emission from disc-wide outflows in spiral galaxies
  We study the effects of mass and energy injection due to OB associations
spread across the rotating disc of a Milky Way-type galaxy, with the help of 3D
hydrodynamic simulations. We compare the resulting X-ray emission with that
produced from the injection of mass and energy from a central region. We find
that the predicted X-ray image shows a filamentary structure that arises even
in the absence of disc gas inhomogeneity. This structure stems from warm clumps
made of disc material being lifted by the injected gas. We show that as much as
half of the total X-ray emission comes from regions surrounding warm clumps
that are made of a mix of disk and injected gas. This scenario has the
potential to explain the origin of the observed extra-planar X-ray emission
around star forming galaxies and can be used to understand the observed
sublinear relation between the $L_X$ and SFR. We quantify the mass contained in
these `bow-shock' regions. We also show that the top-most region of the outer
shock above the central area emits harder X-rays than the rest. Further, we
find that the mass distribution in different temperature ranges is bimodal,
peaking at $10^4\hbox{-}10^5$ K (in warm clumps) and $10^6\hbox{-}10^7$ K
(X-ray emitting gas). The mass loading factor is found to decrease with
increasing SFR, consistent with previous theoretical estimates and simulations.
