Banca de QUALIFICAÇÃO: RAFAELA WIKLICH SOBRINHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : RAFAELA WIKLICH SOBRINHO
Data: 23/10/2026
HORA: 13:00
LOCAL: PRESENCIAL - S.A.
TÍTULO:

Searching for Galactic PeVatrons in the Very-High-Energy Gamma-Ray Sky: Spectral and Energetic Constraints on Particle Acceleration

PÁGINAS: 50
RESUMO:

The origin of galactic cosmic rays up to the knee, around a few PeV, remains an open problem whose solution depends on identifying the sources able to accelerate protons to PeV energies, the so-called PeVatrons. Since cosmic rays are charged particles whose trajectories are deflected by galactic magnetic fields, identifying their possible accelerators requires neutral messengers, in particular gamma rays. The detection of gamma-ray emission in the ultra-high-energy (UHE) domain provides evidence of acceleration to extreme energies, but does not by itself distinguish between hadronic and leptonic scenarios, making a spectral and energetic analysis of the emission necessary.

This project develops and applies a spectral and energetic methodology to test the hadronic-PeVatron hypothesis in individual galactic sources. The completed component consisted of a study of the evolved pulsar wind nebula HESS J1857+026, which served as a case study to develop and test this methodology. The UHE upper limit provided by LHAASO-KM2A is incorporated as an active constraint on the spectral model, while the proton cutoff energy (Ep,cut) is left as a free parameter. From this model, we simulate CTAO observations and assess, through an approach combining Bayesian inference and frequentist analysis, the capability of the instrument to constrain the maximum proton energy and to discriminate between different acceleration scenarios.

The analysis shows that, for a cutoff near 100 TeV, CTAO can recover the cutoff energy with a precision of 7 to 15%, whereas its ability to constrain Ep,cut becomes limited for cutoffs above approximately 1 PeV. The source energetics provide a complementary constraint, allowing the energetic plausibility of the different acceleration scenarios to be assessed. The next stage of the thesis is to generalize this methodology to a selected sample of accelerator classes, considering both CTAO sites. This stage will also quantify the complementarity between CTAO, air-shower arrays such as LHAASO and SWGO, and neutrino observatories. The expected outcome is a reproducible, class-resolved assessment of the scenarios able to explain the acceleration of galactic cosmic rays up to PeV energies, connecting the spectral inference of the sources to the questions surrounding the origin of galactic cosmic rays.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 2616823 - ALYSSON FABIO FERRARI
Membro Titular - Examinador(a) Interno ao Programa - 1574260 - ROLDAO DA ROCHA JUNIOR
Membro Titular - Examinador(a) Externo ao Programa - 1309403 - LUIZ AUGUSTO STUANI PEREIRA
Membro Suplente - Examinador(a) Interno ao Programa - 1549709 - GERMAN LUGONES