Multi-messenger particles as a probe for UHECR luminosity

Very-high energy (GeV-TeV) gamma rays in the universe suggest the presence of an accelerator in the source. Neutrinos and gamma rays are intriguing astrophysical messengers. Multi-messenger particle emission produced by interactions of cosmic rays with radiation fields and interstellar matter is a probe of luminosity of sources of cosmic rays with EeV energies, known as Ultra-High Energy Cosmic Rays (UHECRs). This work estimates the neutrino flux and suggests that gamma-ray emission is primarily caused by cosmic-ray interactions during propagation. As energy loss processes occur, secondary fluxes are generated, primarily by pion decay. We provide UHECR luminosity of galaxies from multi-messenger particles. These findings not only highlight the potential of certain galaxies as sources of UHECR, but also underscore the intricate interplay of various astrophysical processes within them. By understanding the luminosity patterns and multi-messenger particle emissions, we can gain valuable insights into the environmental conditions, acceleration mechanisms, and other intrinsic properties that position these galaxies as candidates for UHECR production.