Very High-energy Gamma-Ray and Neutrino Emission from Hadronic Interaction in Compact Binary Millisecond Pulsars

Abstract Black widow and redback systems are millisecond pulsars in compact orbits with ultra-light and low-mass companions, respectively, collectively known as “spider pulsars.” In such systems, an intrabinary shock can form between the pulsar and the companion winds, serving as a site for particle acceleration and associated nonthermal emission. Assuming that protons can be extracted from the neutron star surface and accelerated at the intrabinary shock and/or within the pulsar wind, we model the very high-energy gamma-ray and neutrino emissions (0.1–10 3 TeV) produced through interactions with the companion wind and the companion star. We first calculate the high-energy emissions using an optimistic combination of parameters to maximize the gamma-ray and neutrino fluxes. We find that, for energetic spider pulsars with a spin-down power ≳10 35 erg s −1 and a magnetic field of ∼10 3 G in the companion region, the gamma-ray emission could be detectable as point sources by the Cherenkov Telescope Array and the Large High Altitude Air Shower Observatory, while the neutrino emission could be detectable by the future TRIDENT detector. Finally, we build a synthetic population of these systems, compute the cumulative neutrino flux expected from spider pulsars, and compare it with the Galactic neutrino diffuse emission measured by IceCube. We find that, under realistic assumptions on the fraction of the spin-down power converted into protons, the contribution of spiders to the diffuse Galactic neutrino flux is negligible.