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Diffusion, acceleration and propagation of cosmic rays in turbulent astrophysical environments

Grant number: 17/12828-4
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): December 01, 2017
Effective date (End): July 31, 2019
Field of knowledge:Physical Sciences and Mathematics - Astronomy
Principal Investigator:Elisabete Maria de Gouveia Dal Pino
Grantee:Rafael Alves Batista
Home Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo, SP, Brazil
Associated research grant:13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA), AP.TEM


Astrophysical environments are strongly affected by the presence of relativistic parti- cles. Although the interstellar medium in the Milky Way and other galaxies seems to contain large amounts of cosmic rays (CRs) in equilibrium with the moving turbulent gas and the pervading magnetic fields, the relationship between these components is currently poorly understood. Furthermore, the evolution of galaxies, the formation of stars, and the pervasive extragalactic background light are presumably related to CRs. The interaction of CRs with ambient gas and photons stem associated fluxes of secondary particles such as photons and neutrinos, via photohadronic or hadronu- clear processes. CRs can, therefore, be valuable probes of extreme astrophysical environments; combined with other messengers such as gamma rays and neutrinos, one can aim for a better understanding of how particles are produced by cosmic accelerators, how they propagate through the interstellar and intergalactic media, and the properties of the regions they traverse. In this project new studies of the propagation of CRs in turbulent media are proposed, focusing also in the secondary gamma-ray and neutrinos associated with the CRs. An open problem in cosmology is the origin of cosmic magnetic fields a fundamental question which connects to other open issues including the distribution of matter in large scales, the existence of intergalactic magnetic fields (IGMFs) in cosmic voids, and the universal matter-antimatter asymmetry. Magnetic fields also affect the trajectories of particles commonly used as cosmic messengers to probe the universe up to large distances. During their propagation, high-energy gamma rays may induce electromagnetic cascades, generating electron-positron pairs, whose opening angle is sensitive to the strength of intervening magnetic fields. While this method has been widely used to infer the strength and coherence length of IGMFs, plasma instabilities arising due to interactions of the ionised component of the intergalactic medium with the electron-positron pairs may affect the development of the cascade, potentially rendering this method ineffective. This project also aims to understand the role played by plasma effects on the development of electromagnetic cascades induced by high-energy gamma rays.

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BATISTA, RAFAEL ALVES; SAVELIEV, ANDREY. On the measurement of the helicity of intergalactic magnetic fields using ultra-high-energy cosmic rays. Journal of Cosmology and Astroparticle Physics, n. 3 MAR 2019. Web of Science Citations: 0.
BATISTA, RAFAEL ALVES; DE ALMEIDA, ROGERIO M.; LAGO, BRUNO; KOTERA, KUMIKO. Cosmogenic photon and neutrino fluxes in the Auger era. Journal of Cosmology and Astroparticle Physics, n. 1 JAN 2019. Web of Science Citations: 3.

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