A magnetic reconnection model for explaining the multi-wavelength emission of the microquasars Cyg X-1 and Cyg X-3

摘要

Recent studies have indicated that cosmic ray acceleration by a first-orderFermi process in magnetic reconnection current sheets can be efficient enoughin the surrounds of compact sources. In this work, we discuss this accelerationmechanism operating in the core region of galactic black hole binaries (ormicroquasars) and show the conditions under which this can be more efficientthan shock acceleration. In addition, we compare the corresponding accelerationrate with the relevant radiative loss rates obtaining the possible energycut-off of the accelerated particles and also compute the expected spectralenergy distribution (SED) for two sources of this class, namely Cygnus X-1 andCygnus X-3, considering both leptonic and hadronic processes. The derived SEDsare comparable to the observed ones in the low and high energy ranges. Ourresults suggest that hadronic non-thermal emission due to photo-mesonproduction may produce the very high energy gamma-rays in these microquasars.