M 101 Chandra X-Ray Point Source Catalog

From this rich data set, the authors have created a catalog of the 110 sources from the S3 chip which were detected with a significance of greater than 3-sigma. This detection threshold corresponds to a flux of ~ 10^-16 ergs/cm²/s and a luminosity of ~ 10³⁶ ergs/s for a distance to M 101 of 7.2 Mpc.

The sources display a distinct correlation with the spiral arms of M101 and include a variety of X-ray binaries, supersoft sources, supernova remnants, and other objects of which only ~27 are likely to be background sources. The 29 brightest sources have enough flux (greater than 100 counts) to perform at least crude spectral modeling using the HEASARC XSPEC model fitting program. Most of the sources could be satisfactorily fitted with a simple absorbed power-law spectrum model; however, eight of the softest sources were better fitted by an absorbed blackbody model.