X-ray binaries (XRBs) are binary systems with an accreting compact object. They have long been suggested to be possible galactic cosmic ray (CR) accelerators. In such models, the protons accelerated… Click to show full abstract
X-ray binaries (XRBs) are binary systems with an accreting compact object. They have long been suggested to be possible galactic cosmic ray (CR) accelerators. In such models, the protons accelerated by the accretion process at the compact object could carry out pp or pγ interactions in the accretion disk, in the atmosphere of the companion star, or in the stellar wind. High energy neutrinos may be produced from these interactions and will serve as a smoking-gun evidence for CR acceleration. Many models predicted their neutrino emission to be modulated by the orbital periods. In this proceeding, the result of the latest search for periodic neutrino emission from X-ray binaries performed by the IceCube Neutrino Observatory is presented. Using 7.5 years of IceCube's muon track data, this search features an unbinned maximum likelihood ratio method which has an improved statistical description of the modulation and is able to test sources with uncertain periods. This search is performed on a catalogue of 55 XRBs with declination ≥ -5°, greatly expanded over the previous periodic point-source search of 10. This study finds no evidence for neutrino emission, and has placed upper limits on the neutrino flux from each XRB. Comparisons between the results and some phenomenological models, and predictions for future observations, are also presented.
               
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