Theoretical thermal X-ray spectra of relativistic MHD jets

Abstract

Highly relativistic jets are most probably driven by strong magnetic fields and launched from the accretion disk surrounding a central black hole. Applying the jet flow parameters (velocity, density, temperature) calculated from the magnetohydrodynamic (MHD) equations, we derive the thermal X-ray luminosity along the inner jet flow in the energy range 0.2-10.1 keV. Here, we concentrate on the case of Galactic microquasars emitting highly relativistic jets. For a 5 solar masses central object and a jet mass flow rate of 10^{-8} solar masses/year we obtain a jet X-ray luminosity L_x ~ 10^{33} erg\sec. Emission lines of Fe XXV and Fe XXVI are clearly visible. Relativistic effects such as Doppler shift and Doppler boosting were considered for different inclinations of the jet axis. Due to the chosen geometry of the MHD jet the inner X-ray emitting part is not yet collimated. Therefore, depending on the viewing angle, the Doppler boosting does not play a major role in the total spectra.