IMPLICATIONS OF THE DIFFUSE GALACTIC CONTINUUM

Observations made with Ginga, OSSE and COMPTEL provide evidence that t he diffuse galactic continuum emission extends down to similar to 10 k eV, and that the spectrum steepens below about several hundred keV. If this emission is electron bremsstrahlung, then a very large power (si milar to 10(43) erg s(-1)) is required to maintain the electrons again st energy losses to the interstellar medium. This exceeds by an order of magnitude the total power provided by galactic supernovae. We sugge st that this power might be derived from the gravitational potential r eleased on the passage of the ISM through galactic spiral arm compress ions. Alternatively, the hard X-ray galactic continuum could be the su perposition of unresolved point sources such as accreting neutron star s or black holes.