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

TL;DR

This study presents multi-wavelength observations of SS 433, revealing rapid jet variability, estimating jet distances, and analyzing jet temperatures and spectra, highlighting complex jet dynamics and additional hard X-ray components.

Contribution

First detection of X-ray jitter motions in SS 433's jets, providing new insights into jet variability and structure through combined Suzaku and optical spectroscopy data.

Findings

Detected rapid Doppler shift variability in X-ray jets.

Estimated optical jet distance from the jet base as ~(3-4) × 10^14 cm.

Identified additional hard X-ray component beyond jet emission.

Abstract

We report results of the 2006 April multi-wavelengths campaign of SS 433, focusing on X-ray data observed with Suzaku at two orbital phases (in- and out-of- eclipse) and simultaneous optical spectroscopic observations. By analyzing the Fe25 K_alpha lines originating from the jets, we detect rapid variability of the Doppler shifts, dz/dt ~ 0.019/0.33 day^-1, which is larger than those expected from the precession and/or nodding motion. This phenomenon probably corresponding to "jitter" motions observed for the first time in X-rays, for which significant variability both in the jet angle and intrinsic speed is required. From the time lag of optical Doppler curves from those of X-rays, we estimate the distance of the optical jets from the base to be ~(3-4) \times 10^14 cm. Based on the radiatively cooling jet model, we determine the innermost temperature of the jets to be T_0 = 13 +/- 2 keV and 16 +/- 3 keV (the average of the blue and red jets) for the out-of-eclipse and in-eclipse phase, respectively, from the line intensity ratio of Fe25 K_alpha and Fe26 K_alpha. While the broad band continuum spectra over the 5--40 keV band in eclipse is consistent with a multi-temperature 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.