ChandraX‐Ray Point Sources, Including Supernova 1979C, in the Spiral Galaxy M100

Six x-ray point sources, with luminosities of $4 \times 10^{38} - 2 \times10^{39} \rm ergs s^{-1}$ in the 0.4--7 keV band, were detected in Chandraobservations of the spiral galaxy M100. One source is identified with supernovaSN 1979C and appears to have roughly constant x-ray flux for the period 16--20years after the outburst. The x-ray spectrum is soft, as would be expected ifthe x-ray emission is due to the interaction of supernova ejecta withcircumstellar matter. Most of the other sources are variable either within theChandra observation or when compared to archival data. None are coincident withthe peak of the radio emission at the nucleus. These sources have harderspectra than the supernova and are likely x-ray binaries. M100 has more brightx-ray sources than typical for spiral galaxies of its size. This is likelyrelated to active star formation occurring in the galaxy.Comment: accepted by the Astrophysical Journal, 7 page