Do Ultraluminous X-Ray Sources Exist in Dwarf Galaxies?
Douglas Swartz (NASA/MSFC)
A thorough search for Ultraluminous X-ray source candidates within a distance of approximately 8 Mpc is made. The search spatially matches potential ULXs detected in X-ray images or cataloged in the literature with galaxies tabulated in the Catalog of Neighboring Galaxies compiled by Karachentsev et al. (2004). The specific ULX rate (occurrence rate per unit mass) is found to be a decreasing function of host galaxy mass for host masses above
M
. There is too little mass in galaxies below Mdg to determine their ULX content in a statistically meaningful way. Possible reasons for and implications of an increase in specific ULX rate with decreasing galaxy mass are presented.