Astroparticles from X-Ray Binary Coronae

• Published in: Astrophysical journal. Letters 2024-11, Vol.975 (2), p.L35
• Main Authors: Fang, K., Halzen, Francis, Heinz, Sebastian, Gallagher, John S.
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Binary stars; Black holes; Emissions; Emitters; Galactic cosmic rays; Gamma emission; Gamma rays; High energy astronomy; Milky Way; Neutrinos; Observatories; Particle acceleration; Particle astrophysics; Stellar coronas; X ray binaries; X ray sources; X ray stars; X-ray astronomy; X-ray binary stars; X-rays
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/ad887b

The recent observation of high-energy neutrinos from the Galactic plane implies an abundant population of hadronic cosmic-ray sources in the Milky Way. We explore the role of the coronae of accreting stellar-mass black holes as such astroparticle emitters. We show that the particle acceleration and interaction timescales in the coronal region are tied to the compactness of the X-ray source. Thus, neutrino emission processes may similarly happen in the cores of active galactic nuclei and black hole X-ray binaries (XRBs), despite their drastically different masses and physical sizes. We apply the model to the well-measured XRB Cygnus X-1 and find that the cascaded gamma rays accompanying the neutrino emission naturally explain the GeV emission that only presents during the source’s hard state, while the state-averaged gamma-ray emission explains the LHAASO observation above 20 TeV. We show that XRB coronae could contribute significantly to the Galactic cosmic-ray and Galactic plane neutrino fluxes. Our model predicts variable high-energy neutrino emission from bright Galactic XRBs that may be observed by IceCube and future neutrino observatories.