Super-massive black holes in active galaxies can accelerate particles to relativistic energies(1), producing jets with associated c-ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares(2). Apart from an isolated event detected(3) in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four gamma-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary(4-6) that sporadically produces radio jets(7-9)). There is a clear pattern of temporal correlations between the c-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

Extreme particle acceleration in the microquasar Cygnus X-3

PREST, MICHELA;
2009-01-01

Abstract

Super-massive black holes in active galaxies can accelerate particles to relativistic energies(1), producing jets with associated c-ray emission. Galactic 'microquasars', which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares(2). Apart from an isolated event detected(3) in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four gamma-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary(4-6) that sporadically produces radio jets(7-9)). There is a clear pattern of temporal correlations between the c-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.
2009
AGILE; super massive black holes; Cygnus; X-ray emission
Tavani, Marco; Bulgarelli, A; Piano, Giovanni; Sabatini, Sabina; Striani, Edoardo; Evangelista, Yuri; Trois, A; Pooley, G; Trushkin, S; Nizhelskij, Na...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/1737394
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