  Suzaku observation of the edge-on spiral galaxy NGC 4631 confirmed its X-ray
halo extending out to about 10 kpc from the galactic disk. The XIS spectra
yielded the temperature and metal abundance for the disk and the halo regions.
The observed abundance pattern for O, Ne, Mg, Si and Fe is consistent with the
metal yield from type II supernovae, with an O mass of about 1E6 Msun contained
in the halo. These features imply that metal-rich gas produced by type II
supernova is brought into the halo region very effectively, most likely through
a galactic wind. Temperature and metal abundance may be affected by charge
exchange and dust. An upper limit for the hard X-ray flux was obtained,
corresponding to a magnetic field higher than 0.5 uG.

Astrophysics