MSc Thesis Defense by Kathrine Mørch Groth

Probing Ultra-High Energy Cosmic Ray Models with Cosmogenic Neutrinos and Photons

Cosmic ray (CR) interactions with cosmic radiation backgrounds are a guaranteed source of high- energy neutrinos and photons. The most optimistic scenario assumes the dominance of CR protons at ultra-high energies (UHE) that rapidly interact with the cosmic microwave background above the Greisen-Zatsepin-Kuzmin (GZK) cutoff. The corresponding cosmogenic fluxes are testable with present neutrino and CR observatories. On the other hand, if heavy nuclei dominate the UHECR spectrum, the fluxes of GZK neutrinos and photons can become orders of magnitude smaller. In this project we implement a new numerical cascade module designed for state-of-the-art Monte Carlo propagation codes like CRPropa to allow for efficient development of the electromagnetic cascades responsible for cosmogenic gamma ray fluxes. Combining this with CRPropa, we revise predictions of cosmogenic fluxes based on recent observations of the spectrum and chemical composition of UHECRs. In particular, we focus on deriving lower limits on the cosmogenic neutrino and photon flux depending on astrophysical uncertainties. We investigate the prospects and requirements of future large-scale neutrino and CR observatories to observe these fluxes.

Link to Zoom session

Zoom meeting ID: 674 8007 5098