A&A 503, 673-681 (2009)
DOI: 10.1051/0004-6361/200811519

High-energy emission from jet-clump interactions in microquasars

A. T. Araudo^{1, 2}, V. Bosch-Ramon³, and G. E. Romero<sup>1, 2

1</sup>  Instituto Argentino de Radioastronomía (CCT La Plata, CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires, Argentina
    e-mail: aaraudo@fcaglp.unlp.edu.ar
²  Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque, 1900 La Plata, Argentina
³  Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Received 12 December 2008 / Accepted 29 May 2009

Abstract
Context. High-mass microquasars are binary systems consisting of a massive star and an accreting compact object from which relativistic jets are launched. There is considerable observational evidence that winds of massive stars are clumpy. Individual clumps may interact with the jets in high-mass microquasars to produce outbursts of high-energy emission. Gamma-ray flares have been detected in some high-mass X-ray binaries, such as Cygnus X-1, and probably in LS 5039 and LS I+61 303.
Aims. We predict the high-energy emission produced by the interaction between a jet and a clump of the stellar wind in a high-mass microquasar.
Methods. Assuming a hydrodynamic scenario for the jet-clump interaction, we calculate the spectral energy distributions produced by the dominant non-thermal processes: relativistic bremsstrahlung, synchrotron and inverse Compton radiation, for leptons, and for hadrons, proton-proton collisions.
Results. Significant levels of emission in X-rays (synchrotron), high-energy gamma rays (inverse Compton), and very high-energy gamma rays (from the decay of neutral pions) are predicted, with luminosities in the different domains in the range ~ 10³²-10³⁵ erg s^-1. The spectral energy distributions vary strongly depending on the specific conditions.
Conclusions. Jet-clump interactions may be detectable at high and very high energies, and provide an explanation for the fast TeV variability found in some high-mass X-ray binary systems. Our model can help to infer information about the properties of jets and clumpy winds by means of high-sensitivity gamma-ray astronomy.

Key words: gamma rays: theory -- X-rays: binaries -- radiation mechanisms: non-thermal

© ESO 2009

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

• If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
• You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
• You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.