http://arxiv.org/abs/2207.00573
We present a broadband X-ray study of W50 (
the Manatee nebula'), the complex region powered by the microquasar SS 433, that provides a test-bed for several important astrophysical processes. The W50 nebula, a Galactic PeVatron candidate, is classified as a supernova remnant but has an unusual double-lobed morphology likely associated with the jets from SS 433. Using NuSTAR, XMM-Newton, and Chandra observations of the inner eastern lobe of W50, we have detected hard non-thermal X-ray emission up to $\sim$30 keV, originating from a few-arcminute size knotty region (Head’) located $\lesssim$ 18$^{\prime}$ (29 pc for a distance of 5.5 kpc) east of SS 433, and constrain its photon index to 1.58$\pm$0.05 (0.5-30 keV band). The index gradually steepens eastward out to the radio ear' where thermal soft X-ray emission with a temperature $kT$$\sim$0.2 keV dominates. The hard X-ray knots mark the location of acceleration sites within the jet and require an equipartition magnetic field of the order of $\gtrsim$12$\mu$G. The unusually hard spectral index from theHead’ region challenges classical particle acceleration processes and points to particle injection and re-acceleration in the sub-relativistic SS 433 jet, as seen in blazars and pulsar wind nebulae.
S. Safi-Harb, B. Intyre, S. Zhang, et. al.
Mon, 4 Jul 22
27/62
Comments: 19 pages, 9 figures, 2 tables, accepted for publication in the Astrophysical Journal
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