Neutrinos from hidden ultraluminous X-ray sources in the Galaxy

TL;DR

This paper investigates the potential of hidden ultraluminous X-ray sources in our galaxy to produce detectable high-energy neutrinos through proton acceleration and photomeson interactions, despite electromagnetic obscuration.

Contribution

It presents a novel model for neutrino production in electromagnetically obscured ULXs, highlighting their potential as detectable neutrino sources within our galaxy.

Findings

Obscured ULXs can produce neutrinos detectable by KM3NeT and IceCube.

Proton acceleration occurs via magnetic reconnection above supercritical black holes.

Neutrino flux from these sources could be observed within several years.

Abstract

Ultraluminous X-ray sources (ULXs) are point-like sources that exhibit apparent X-ray luminosities exceeding the Eddington limit for stellar-mass compact objects. A widely accepted interpretation is that these systems are X-ray binaries accreting matter possibly at super-Eddington rates. In this regime, photon trapping inflates the accretion disk, making it geometrically and optically thick. Radiation-driven winds launched from the supercritical disk form funnel-shaped walls along the symmetry axis. While the apparent X-ray luminosity can exceed the Eddington limit due to geometrical beaming within this funnel, a misalignment with the observer's line of sight strongly suppresses the X-ray emission, rendering the ULX electromagnetically obscured. This work explores the potential for high-energy neutrino production in black hole-hosting ULXs. We model proton acceleration via magnetic reconnection in the region above the super-accreting black hole. Although electromagnetic emission is efficiently absorbed by the dense wind and radiation fields, neutrinos generated from photomeson interactions can escape. Our model self-consistently accounts for energy losses of pions and muons in this environment. The results indicate that misaligned, electromagnetically obscured Galactic ULXs could produce a neutrino flux detectable by instruments like KM3NeT and IceCube within several years of observation.