Speaker
Description
SS 433 is a unique Galactic microquasar that exhibits persistent supercritical accretion and relativistic baryonic jets. It is also one of the brightest microquasars in the TeV gamma-ray band and is considered a promising PeVatron candidate. We conducted SS 433 observations with the X-Ray Imaging Spectroscopy Mission XRISM, complemented by simultaneous optical spectroscopic monitoring. The X-ray microcalorimeter Resolve onboard XRISM, which achieves an unprecedented energy resolution of ~5 eV at 6 keV with high sensitivity, enabled high-resolution time-resolved spectroscopy of SS 433. These data revealed the complex motions and spatial structures of the jets in unprecedented detail. In addition, comparison of the X-ray spectra with contemporaneous optical Halpha spectroscopy provided insight into the evolution of the jet plasma from the vicinity of the compact object to the optical emitting regions. The results suggest that the plasma is relatively uniform near the compact object, while it separates into discrete blobs as it propagates outward to the optical emitting region. The other XRISM instrument, Xtend, a wide-field CCD imager, also revealed diffuse X-ray emission between the central source and the eastern/western X-ray jets, suggesting that particle acceleration may be taking place in this region. In this presentation, we will report on the jet structure and dynamics revealed by the XRISM observations, together with the optical spectroscopy. If time permits, we will also briefly discuss whether there are systematic differences in the X-ray observational properties between microquasars with and without detected TeV gamma-ray emission, including SS 433.
