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 / Tavani M; Bulgarelli A; Piano G; Sabatini S; Striani E; Evangelista Y; Trois A; Pooley G; Trushkin S; Nizhelskij NA; McCollough M; Koljonen KII; Pucella G; Giuliani A; Chen AW; Costa E; Vittorini V; Trifoglio M; Gianotti F; Argan A; Barbiellini G; Caraveo P; Cattaneo PW; Cocco V; Contessi T; DAmmando F; Del Monte E; De Paris G; Di Cocco G; Di Persio G; Donnarumma I; Feroci M; Ferrari A; Fuschino F; Galli M; Labanti C; Lapshov I; Lazzarotto F; Lipari P; Longo F; Mattaini E; Marisaldi M; Mastropietro M; Mauri A; Mereghetti S; Morelli E; Morselli A; Pacciani L; Pellizzoni A; Perotti F; Picozza P; Pilia M; Prest M; Rapisarda M; Rappoldi A; Rossi E; Rubini A; Scalise E; Soffitta P; Vallazza E; Vercellone S; Zambra A; Zanello D; Pittori C; Verrecchia F; Giommi P; Colafrancesco S; Santolamazza P; Antonelli A; Salotti L. - In: NATURE. - ISSN 0028-0836. - STAMPA. - 462:7273(2009), pp. 620-623. [10.1038/nature08578]
Extreme particle acceleration in the microquasar Cygnus X-3
D'AMMANDO, FILIPPO;
2009
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
