  Chandra has resolved the starburst nuclear region of the face-on grand-design
spiral M83. Eighty-one point sources are detected above 3.5 sigma in the ACIS
S3 image, and 15 of them are within the inner 16-arcsec region of the galaxy. A
point source with L_x ~ 3 x 10^(38) erg/s in the 0.3--8.0 keV band is found to
coincide with the infra-red nuclear photometric peak, one of the two dynamical
nuclei of the galaxy. No point-like sources are resolved (at a 2.5-sigma level)
at the centre of symmetry of the outer optical isophote ellipses, suspected to
be another dynamical nucleus. About 50% of the total emission in the nuclear
region is unresolved; of this, about 70% can be attributed to hot thermal
plasma, and the rest is probably due to unresolved point sources (eg, faint
X-ray binaries). The azimuthally-averaged radial distribution of the unresolved
emission has a King-like profile, with no central cusp. Strong emission lines
are seen in the spectrum of the optically thin plasma component. The high
abundances of C, Ne, Mg, Si and S with respect to Fe suggest that the
interstellar medium in the nucleus is enriched and heated by type-II supernova
explosions and winds from massive stars. The cumulative luminosity distribution
of the discrete X-ray sources is neither a single nor a broken power law.
Separating the sources in the nuclear region (within a distance of 60 arcsec
from the X-ray centre) from the rest reveals that the two groups have different
luminosity distributions. The log[N(>S)]--log S curve of the sources in the
inner region (nucleus and stellar bar) is a single power law, which we
interpret as due to continuous, ongoing star formation. Outside the central
region, there is a smaller fraction of sources brighter than the Eddington
limit for an accreting neutron star.
