Quasars Associated with M82

The starburst / AGN galaxy M82 was studied by M. Dahlem, K. Weaver and T. Heckman using X-ray data from ROSAT and ASCA. This was part of their survey of edge-on starburst galaxies, to study the hot plasma around the strongly X-ray-emitting nuclei. Serendipitously they found seventeen unresolved hard-X-ray sources around M82, in addition to its strong nuclear source and other X-rays within the main body of M82. We measured optical point sources at these unresolved source positions, and obtained spectra of six at the Keck I 10-m telescope, using the low-resolution imaging spectrograph (LRIS). All six turned out to be quasars with redshifts ranging from 0.111 to 1.086. In addition to these six there are nine more QSOs lying very close to M82 which were discovered many years ago. There is no difference between optical spectra of these latter QSOs none of which is known to be an X-ray source and the X-ray emitters. The redshifts of the fifteen range between 0.111 and 2.05. The large number of QSOs and their peculiar configuration about M82 both suggest that they are physically associated with the galaxy, and have large intrinsic redshift components. If this is correct, the absolute magnitudes lie in the range -8 < {M_v} < -10.