HADRONIC GAMMA-RAY AND NEUTRINO EMISSION FROM CYGNUS X-3

作者：Sahakyan N^*; Piano G; Tavani M

来源：Astrophysical Journal, 2014, 780(1): 29.

DOI：10.1088/0004-637X/780/1/29

• gamma rays: general
• neutrinos
• stars: individual (Cygnus X-3)
• X-rays: binaries

Cygnus X-3 (Cyg X-3) is a remarkable Galactic microquasar (X-ray binary) emitting from radio to gamma-ray energies. In this paper, we consider the hadronic model of emission of gamma-rays above 100 MeV and their implications. We focus on the joint gamma-ray and neutrino production resulting from proton-proton interactions within the binary system. We find that the required proton injection kinetic power, necessary to explain the gamma-ray flux observed by AGILE and Fermi-LAT, is L-p similar to 10(38) erg s(-1), a value in agreement with the average bolometric luminosity of the hypersoft state (when Cyg X-3 was repeatedly observed to produce transient gamma-ray activity). If we assume an increase of the wind density at the superior conjunction, the asymmetric production of gamma-rays along the orbit can reproduce the observed modulation. According to observational constraints and our modeling, a maximal flux of high-energy neutrinos would be produced for an initial proton distribution with a power-law index alpha = 2.4. The predicted neutrino flux is almost two orders of magnitude less than the two-month IceCube sensitivity at similar to 1 TeV. If the protons are accelerated up to PeV energies, the predicted neutrino flux for a prolonged "soft X-ray state" would be a factor of about three lower than the one-year IceCube sensitivity at similar to 10 TeV. This study shows that, for a prolonged soft state (as observed in 2006) possibly related to gamma-ray activity and a hard distribution of injected protons, Cyg X-3 might be close to being detectable by cubic-kilometer neutrino telescopes such as IceCube.

• 出版日期2014-1-1