ROSAT AND ASCA OBSERVATIONS OF W50 ASSOCIATED WITH THE PECULIAR SOURCE SS-433

We report the observations of the X-ray lobes of the large Galactic so urce W50 associated with the two-sided jets source SS 433. The observa tions were made with the Position Sensitive Proportional Counter on bo ard ROSAT. The eastern lobe has a knotty structure, with X-ray emissio n starting at similar to 15' from SS 433 and peaking at similar to 35' . Both thermal bremsstrahlung spectra with high temperatures (greater than or equal to 5 keV), as well as power-law spectra with flat photon index (Gamma similar to 1-2), gave adequate fits. With ROSAT, we also detected an additional soft X-ray emission from the eastern lobe, at similar to 1 degrees east of SS 433 and coincident with the radio ''ea r.'' This region is associated with the terminal shock of the SS 433 j ets. 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 Sat ellite for Cosmology and Astrophysics (ASCA), and combine the ROSAT an d the ASCA data for a wide coverage of the spectra in the 0.1-10 keV e nergy range. We find that the spectrum from the brightest region (at s imilar to 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 luminos ity from both lobes is similar to 10(35)-10(36)D(5.5)(2) ergs s(-1). W e discuss the origin of the X-rays in the model of emission from the s upersonic jets of SS 433 interacting with the ambient medium, accelera ting particles to very high energies, and producing a cocoon of ''hot' ' shocked material. We present our interpretation in light of the corr elation of X-ray emission with the map of W50 at other wavelengths.