Choose timezone
Your profile timezone:
IAP-Intern
IAP - High-Energy Universe Group Seminar (Igor Vaiman, UHECR and IFT) (4/17)
→
Europe/Berlin
206 (KIT CN Bld 425)
206
KIT CN Bld 425
Description
WS 2025/26
Igor Vaiman
GSSI, Italy
" Reconstruction of UHECR source spectra with Information Field Theory"
abstract: The Pierre Auger Observatory measures key characteristics of ultra-high-energy cosmic rays (UHECRs): energy, depth of the shower maximum (sensitive to mass), and arrival direction. The former two are known to constrain the properties of cosmic-ray sources in a simplified case of diffuse, spherically symmetric, identical sources. However, the results are often challenging for theoretical interpretation (e.g., the very hard spectral index down to -1.5) and sensitive to assumptions of the model (e.g., cutoff shape and source evolution with distance). We show that the parameter space of standard spectral models is highly degenerate and doesn’t offer a clear insight into the underlying physics. This motivates a nonparametric approach, for which we use methods and ideas from Information Field Theory. We model the injection energy spectrum as a Gaussian random field, assuming a certain apriori correlation structure to ensure physical interpretability of the reconstruction. We benchmark the method using both synthetic and real data in well-established scenarios: the dip model for the proton-only scenario, and the full combined fit of UHECR spectrum and composition. The reconstruction performs well on synthetic data, reproduces main results from the literature, and manages to find better-fitting source spectra for most cases. We also discuss further extension of the analysis to allow the source spectrum to vary with distance.
chair: Michael Unger