Exploring the implications of hadronic particle acceleration in X-ray binaries

Since their discovery, cosmic rays (CRs) remain among the most mysterious phenomena of modern physics. CRs are energetic charged particles of extraterrestrial origin, but the dominant sources, as well as the exact acceleration mechanisms, remain unknown. The CRs of energy up to PeV (10¹⁵ eV) have traditionally been considered to originate entirely in the shock waves of Galactic supernova remnants (SNRs). However, due to the lack of a “smoking-gun” TeV counterpart, in many cases, as well as the new population of non-SNR Galactic PeVatrons, this scenario has been recently questioned. In this thesis, I motivate how the small-scale analogues of active galactic nuclei, namely black-hole X-ray binaries (BHXBs), can potentially accelerate CRs. BHXBs launch two relativistic and highly collimated outflows known as jets. Such jets are CR acceleration sites and shine in the entire multiwavelength spectrum. Using a new multi-zone, lepto-hadronic jet model to take advantage of the entire multiwavelength spectra observed by BHXBs, I explore how both high- and low-mass Galactic BHXBs can contribute to the CR spectrum. Moreover, I investigate how the different assumptions about proton acceleration affect both the jet properties and the observed electromagnetic spectrum. In particular, I focus on the predictions and their implications for next-generation gamma-ray facilities, such as the Cherenkov Telescope Array (CTA), and the neutrino detectors such as KM3NeT. I further investigate the well-known problem of jet power in the hadronic scenario, and explore some more self-consistent approaches for potentially resolving this issue.