Revisiting the ultraluminous supersoft source in M 101: an optically thick outflow model

摘要: The M101 galaxy contains the best-known example of an ultraluminous supersoft source (ULS), dominated by a thermal component at kT ~ 0.1 keV. origin and relation between ULSs standard (broad-band spectrum) X-ray sources (ULXs) are still controversial. We re-examined spectral timing properties ULS using archival Chandra XMM-Newton observations. show that time-variability inconsistent with disk emission. characteristic radius R_{bb} emitter varies from epoch to ~10,000 km ~100,000 km; colour temperature kT_{bb} ~50 eV ~140 eV; two quantities scale approximately as T_{bb}^{-2}. In addition smooth continuum, we also find (at some epochs) residuals well fitted plasma models absorption edges: interpret this evidence looking clumpy, multi-temperature outflow. suggest sufficiently high accretion rates inclination angles, super-critical, radiatively driven outflow becomes effectively optically thick completely thermalizes harder photons inner part inflow, removing hard tail. develop simple, spherically symmetric model it is consistent observed temperatures, radii luminosities. A larger, cooler photosphere shifts emission peak into far-UV makes dimmer in X-rays but possibly UV. compare our results interpretation those Liu et al. (2013).