ROSAT and ASCA Observations of W50 Associated with the Peculiar Source SS 433
Abstract
We report the observations of the X-ray lobes of the large Galactic source W50 associated with the two-sided jets source SS 433. The observations were made with the Position Sensitive Proportional Counter on board ROSAT. The eastern lobe has a knotty structure, with X-ray emission starting at ~15' from SS 433 and peaking at ~35'. Both thermal bremsstrahlung spectra with high temperatures (>=5 keV), as well as power-law spectra with flat photon index (Γ ~ 1-2), gave adequate fits. With ROSAT, we also detected an additional soft X-ray emission from the eastern lobe, at ~1° east of SS 433 and coincident with the radio ``ear.'' This region is associated with the terminal shock of the SS 433 jets. The western lobe has a similar morphology; however, the spectrum is softer, and no emission was found coincident with the western radio ``ear.''
We also report the observations of W50 with the Advanced Satellite for Cosmology and Astrophysics (ASCA), and combine the ROSAT and the ASCA data for a wide coverage of the spectra in the 0.1-10 keV energy range. We find that the spectrum from the brightest region (at ~35' from SS 433) requires an additional component to account for an excess of photons in the 1-3 keV band. The total X-ray luminosity from both lobes is ~1035-1036D25.5 ergs s-1. We discuss the origin of the X-rays in the model of emission from the supersonic jets of SS 433 interacting with the ambient medium, accelerating particles to very high energies, and producing a cocoon of ``hot'' shocked material. We present our interpretation in light of the correlation of X-ray emission with the map of W50 at other wavelengths.- Publication:
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The Astrophysical Journal
- Pub Date:
- July 1997
- DOI:
- 10.1086/304274
- Bibcode:
- 1997ApJ...483..868S
- Keywords:
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- Stars: Binaries: Close;
- ISM: Individual: Alphanumeric: W50;
- Radiation Mechanisms: Nonthermal;
- Stars: Individual: Alphanumeric: SS 433;
- X-Rays: Stars