Speaker
Description
Recent detection of very-high-energy gamma-rays exceeding 10 TeV from several microquarsars suggests that microquasars are accelerating particles with the energies reaching PeV. Given that particles are indeed accelerated around microquasars, synchrotron X-rays from primary or secondary electrons are also expected. We have observed the second sub-PeV-brightest microquasar, SS433/W50 with the X-Ray Imaging Spectroscopy Mission (XRISM), whose instruments include the large field-of-view, low-background CCD imager named Xtend. Xtend images of the SS433/W50 region revealed faint diffuse emission in the X-ray dim, "inner cavity" region, within ~16 arcmin from SS433. The excess emission shows a ~0.2 keV optically-thin thermal plasma plus a power-law continuum with a slope of ~1.4. The surface brightness is ~4e-15 erg s-1 cm-2 arcmin-2 in 1–7 keV. The 4.0–5.5 keV X-ray flux varies azimuthally with maximals corresponding to the jet directions, while 1–2 keV, likely thermal X-rays, do not show clear modulations. This excess X-ray emission near SS433 may originate from some energy dissipation processes in the jet, which is possibly related to the sub-PeV emission as well.
