Suzaku X-Ray and Optical Spectroscopic Observations of SS 433 in the 2006 April Multiwavelength Campaign

Abstract

We report on results of the 2006 April multiwavelength campaign of SS 433, focusing on X-ray data observed with Suzaku at two orbital phases (in- and out-of-eclipse phases) and on simultaneous optical spectroscopic observations. Analyzing the FeXXV Kα lines originating from the jets, we detected a rapid variability of the Doppler shifts, dz/dt ≈ 0.019/0.33d^-1, which is larger than those expected from the precession and/or nodding motion. This phenomenon probably corresponds to ``jitter'' motions observed for the first time in X-rays, for which significant variabilities in both the jet angle and the intrinsic speed are required. From time lags between optical Doppler curves and X-ray ones, we estimated a distance between the optical jets and the base to be ∼(3--4) × 10¹⁴cm. Based on the radiatively cooling jet model, we determined that the innermost temperatures of the jets are T₀ = 13±2 keV for the out-of-eclipse phase and 16±3keV for the in-eclipse (the average of the blue and red jets) from the line intensity ratio of FeXXV Kα and FeXXVI Kα. While the broad-band-continuum spectra over the 5-40keV band in eclipse is consistent with a multitemperature-bremsstrahlung emission expected from the jets and its reflection component from cold matter, the out-of-eclipse spectrum is harder than the jet emission with the base temperature determined above, implying the presence of an additional hard component.