High-energy emission from jet-clump interactions in microquasars

TL;DR

This paper models high-energy emission resulting from interactions between jets and stellar wind clumps in microquasars, predicting observable gamma-ray signatures and variability that can inform jet and wind properties.

Contribution

It introduces a hydrodynamic model of jet-clump interactions in microquasars, predicting multi-wavelength high-energy emissions and variability.

Findings

Predicted X-ray, gamma-ray, and TeV emissions with luminosities 10^{32}-10^{35} erg/s.

Spectral energy distributions vary significantly with conditions.

Jet-clump interactions could explain observed TeV variability in high-mass X-ray binaries.

Abstract

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. 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. 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. 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 ~ 10^{32}-10^{35} erg/s. The spectral energy distributions vary strongly depending on the specific conditions. 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.