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|Title:||Gamma rays from microquasars Cygnus X-1 and Cygnus X-3||Authors:||Fernandez-Barral, A.
de Oña Wilhemi, E.
|Issue Date:||2017||Journal:||POS PROCEEDINGS OF SCIENCE||Volume:||35th International Cosmic Ray Conference (ICRC2017)||Number:||301||First Page:||734||Abstract:||Gamma-ray observations of microquasars at high and very-high energies can provide valuable information of the acceleration processes inside the jets, the jet-environment interaction and the disk-jet coupling. Two high-mass microquasars have been deeply studied to shed light on these aspects: Cygnus X-1 and Cygnus X-3. Both systems display the canonical hard and soft X-ray spectral states of black hole transients, where the radiation is dominated by non-thermal emission from the corona and jets and by thermal emission from the disk, respectively. Here, we report on the detection of Cygnus X-1 above 60 MeV using 7.5 yr of Pass8 Fermi-LAT data, correlated with the hard X-ray state. A hint of orbital flux modulation was also found, as the source is only detected in phases around the compact object superior conjunction. We conclude that the high-energy gamma-ray emission from Cygnus X-1 is most likely associated with jets and its detection allow us to constrain the production site. Moreover, we include in the discussion the final results of a MAGIC long-term campaign on Cygnus X-1 that reaches almost 100 hr of observations at different X-ray states. On the other hand, during summer 2016, Cygnus X-3 underwent a flaring activity period in radio and high-energy gamma rays, similar to the one that led to its detection in the high-energy regime in 2009. MAGIC performed comprehensive follow-up observations for a total of about 70 hr. We discuss our results in a multi-wavelength context.||Conference Name:||35th International Cosmic Ray Conference (ICRC2017)||Conference Place:||Bexco, Busan, Korea||Conference Date:||10-20 July, 2017||URI:||http://hdl.handle.net/20.500.12386/27222||URL:||https://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=301
|Appears in Collections:||3.01 Contributi in Atti di convegno|
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