EDP Sciences
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Volume 385, Number 3, April III 2002
Page(s) 1089 - 1094
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20020196

A&A 385, 1089-1094 (2002)
DOI: 10.1051/0004-6361:20020196

Theoretical thermal X-ray spectra of relativistic MHD jets

E. Memola1, Ch. Fendt1, 2 and W. Brinkmann3

1  Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
    e-mail: ememola@aip.de, cfendt@aip.de
2  Universität Potsdam, Institut für Physik, Am Neuen Palais 10, 14469 Potsdam, Germany
3  Centre for Interdisciplinary Plasma Science, Max-Planck-Institut für extraterrestrische Physik, Giessen bach strasse, 85740 Garching, Germany
    e-mail: wpb@mpe.mpg.de

(Received 18 December 2001 / Accepted 4 February 2002 )

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 $5\,{M}_{\odot}$ central object and a jet mass flow rate of $\dot{M}_{\rm j} = 10^{-8}\,{M}_{\odot}\,{\rm yr}^{-1}$ we obtain a jet X-ray luminosity $ L_{\rm X} \approx 10^{33}\,{\rm erg\,s}^{-1}$. Emission lines of Fe XXV and Fe XXVI are clearly visible. Relativistic effects such as Doppler shift and 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.

Key words: MHD -- radiation mechanisms: thermal -- X-rays: binaries -- ISM: jets and outflows

Offprint request: E. Memola, memola@asdc.asi.it

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