Decisive advances in the understanding of explosive transients have been made possible by the development of multi-messenger astronomy and time-domain astronomy. However, the origin of high-energy (HE) to ultra-high-energy (UHE) cosmic rays and neutrinos remain unclear. Deciding between the various source candidates requires a precise modeling of the propagation, acceleration and interactions...
Three observables of ultra-high-energy cosmic rays can be measured with present-day observatories: the energy spectrum, the distribution of maximum shower depths and the arrival directions. We use all three observables for a combined fit, in which the parameters of possible UHECR sources are constrained. The astrophysical model used in this fit is based on 1-dimensional CRPropa3 simulations,...
As shown by the Pierre Auger Collaboration, the combined fit of energy spectrum and depth of shower maximum distributions of ultra-high-energy cosmic rays can provide constraints on the parameters their sources. To this end, a database describing the connection between the shape of the injected energy spectrum and composition at the sources and the observables measured on Earth is built using...
In this talk I will introduce PriNCe (Heinze et al 2019) as a novel open-source Python software for UHECR propagation. The computational efficiency of PriNCe allows the user to perform vast scans of the source parameters, the emitted spectral shape, and the mass composition. I then discuss recent applications of the code, such as the first joint fit to Auger and Telescope Array (TA) spectral...
Despite the great progress made by modern cosmic ray observatories, the origin and acceleration mechanism of ultra-high-energy cosmic rays (UHECRs) remains an unsolved problem to this day. However, there is experimental evidence for an anisotropic component in the UHECR arrival direction greater then few EeV. The search for UHECR sources is further complicated by two main factors: during...
Cosmic rays can be accelerated to high energies by astrophysical objects embedded in clusters of galaxies or by shocks taking place in the intracluster medium. These cosmic rays are trapped within clusters, interacting with the gas and radiation permeating this environment, producing high-energy non-thermal messengers including neutrinos and gamma rays. These messengers can be observed either...
Recent measurements of the synchrortron emission of the external galaxy M51 give indirect implication for the cosmic-ray electron (CRE) transport in the interstellar medium.
By modelling the CRE transport considering all relevant energy loss processes we aim to distinguish the contribution of diffusive and advective transport. The current measurements give insights in the diffusion...
The energy range pertaining to the shin region of the cosmic ray (CR) energy spectrum is noteworthy in that propagation shifts from diffusive to ballistic with increasing energy. At the same time, the transition from Galactic cosmic rays (GCRs) to extragalactic cosmic rays (EGCRs) in this energy range, the details of which hitherto not certain.
This talk details the approach I employed in the...
The diffuse extragalactic background light (EBL) is formed by ultraviolet (UV), optical, and infrared (IR) photons mainly produced by star formation processes over the history of the Universe and contains essential information about galaxy evolution and cosmology. The EBL also attenuates gamma-ray fluxes that travel cosmological distances through pair-production interactions, leaving a...
Cosmic ray particles reach energies as high as $10^{21}\,$eV, and most likely they are accelerated in varying electromagnetic fields present in astrophysical sources and the interstellar medium. Most promising acceleration mechanisms are the First and Second Order Fermi acceleration: Cosmic ray particles repeatedly scatter on moving magnetic field turbulences and on average they gain energy...
