Full text
| |
| Author(s): |
Cainã de Oliveira
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2021-02-10 |
| Examining board members: |
Luiz Vitor de Souza Filho;
Ivone Freire da Mota e Albuquerque;
João Ramos Torres de Mello Neto
|
| Advisor: | Luiz Vitor de Souza Filho |
| Abstract | |
The production of the most energetic particles in the Universe keeps one of the most greater mysteries of contemporary science. The mechanisms of particle acceleration in astrophysical sources are yet unknown, and recent results point to the need for a multi- messenger approach to solving this problem. In the last years, precise measurements of anisotropy and spectrum of charged cosmic rays indicate the need for local extragalactic sources, however, the neutral parcel (neutrinos and gamma rays) that could point to the source, have not been measured. Recent studies indicate that the backflows of jets emitted by Active Galactic Nuclei are regions especially favorable to the acceleration of particles, making radiogalaxies possible sources especially interesting. In this work, Centaurus A is explored as a local source of ultra high energy cosmic rays (UHECR). We analyze in detail the UHECR propagation, assuming that only this source is enough to produce the spectrum measured by the Pierre Auger Observatory. We suppose that the source produces a power-law spectrum with an exponential cutoff and, both the flux normalization and the cutoff energy are obtained by the radio luminosity of the source, remaining three free parameters (spectral index and two intrinsic to source factor) that are obtained by a fit of the Pierre Auger Observatory data. The particle´s propagation was realized in the CRPropa3 framework, with all the relevant energy loss processes with the cosmic background microwave and the extragalactic background light. Due to uncertainties in injected composition and extragalactic magnetic fields, we use five compositions and three structured extragalactic magnetic fields models, recently developed. These fifteen astrophysical scenarios allowed us to analyze the arrival directions of UHECR, secondaries neutrinos and photons, in addition to predict the secondaries flux. We find that the arrival direction of the UHECR, and consequently of the secondaries produced, are highly dependent on the extragalactic magnetic field model. The secondaries neutrino and photons flux are not capable of detection due to the low sensitivity of the observatories. We show that the flux of secondaries neutrinos are sufficiently anisotropic to be detected in front of a cosmogenic isotropic neutrinos flux. (AU) | |
| FAPESP's process: | 18/24256-8 - Local sources of ultra-high-energy cosmic rays |
| Grantee: | Cainã de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Master |