Reaching for PeVatrons with the future Southern Wide-field Gamma-ray Observatory
PT-CERN Call 2022/1
Instituto Superior Técnico (Universidade de Lisboa)
Laboratório de Instrumentação e Física Experimental de Partículas
This thesis focuses on measuring PeVatrons with the future Southern Wide-field Gamma-ray Observatory (SWGO), which will have the ability to survey the Galactic center. The recent observation of Galatic PeVatrons by LHAASO shows that it is possible to detect them provided that the experiment covers sufficiently large areas and has excellent capabilities of identifying the gamma-induced shower events amongst the hadronic background, as done in LHAASO at the cost of buried muon detectors. To find a cost-effective solution for SWGO that allows reaching for larger array areas with an excellent gamma/hadron discrimination, the following strategy will be employed: - Investigation of the characteristics of PeV electromagnetic and hadronically induced showers to identify quantities that might ensure a very high level of hadronic background rejection. For instance, the quantification of the azimuthal non-uniformities of the particle distributions on ground, that we introduced recently, will be fully explored with simulated and real data from LHAASO and Auger. - Development of dedicated analyses to estimate the muon content in air showers on an event-by-event basis, without shielding the detectors to absorb the electromagnetic component of the shower. - Optimization of the detector unit, making it as simple/cheap as possible. Namely, the use of only one PMT per station in the outer regions of the array will be studied. - Optimization of the array layout configuration. Such shall be done recurring to genetic algorithms to probe a more extensive phase space with a limited number of simulations. All these tasks are intertwined and should be iterated upon each other. Ultimately, the sensitivity of SWGO to PeVatrons and its physics reach should be investigated. The study on the shower characteristics will also be used to improve the determination of the cosmic ray mass composition and hadronic interaction properties, which might shed some light on the EAS muon puzzle.
October 01, 2022