X-ray Binaries: a potential dominant contributor to the cosmic ray spectral knee structure

TL;DR

This paper investigates the role of X-ray binaries as potential dominant sources of cosmic rays around the spectral knee, using modeling and recent observations to support their significant contribution.

Contribution

It introduces a detailed model of X-ray binary distribution and their cosmic ray output, highlighting their potential dominance in the knee region of the spectrum.

Findings

X-ray binaries could be major contributors to cosmic rays at PeV energies.

Model predicts observable signatures in gamma rays and anisotropy.

Future observations by LHAASO and HAWC can confirm these contributions.

Abstract

``PeVatrons" refer to astrophysical sources capable of accelerating particles to energies $\sim$PeV and higher, potentially contributing to the cosmic ray spectrum in the knee region. Recently, HAWC and LHAASO have discovered a new type PeVatrons -- X-ray binaries, allowing us to investigate in greater depth of the contributions of these sources to cosmic rays around the knee region. There are hundreds of X-ray binaries in our galaxy observed, which are potential PeVatrons.In this work, we derive the radial distribution of X-ray binaries in the Galaxy. Then we use the DRAGON package to calculate energy spectrum, anisotropy of cosmic rays as well as the resulting diffuse gamma ray emissions, after considering them as factories of cosmic rays in the knee energy bands. Our findings show that the contributions from X-ray binary PeVatrons may be dominant. More X-ray binary PeVatrons can be observed by LHAASO and HAWC in the future, and will confirm the contribution of X-ray binaries to high energy cosmic rays.