| Grant number: | 13/15115-8 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | October 01, 2013 |
| End date: | September 30, 2015 |
| Field of knowledge: | Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics |
| Principal Investigator: | Elisabete Maria de Gouveia Dal Pino |
| Grantee: | Reinaldo Santos de Lima |
| Host Institution: | Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract Astrophysical plasmas can be distinguished into collisional or collisionless ones, depending on the scales of interest. In the collisional regime, the fast binary collisions rate keeps the particles thermal velocity isotropic. In this regime, the magnetohydrodynamic (MHD) theory describes the large scale dynamics of the plasma. Many important predictions of astrophysical phenomena rely on the collisional-MHD theory. These include, for example, processes related to star-formation, accretion disk formation and dynamics, turbulence in the interstellar medium, magnetic field dynamo amplification in stars and galaxies, etc. The collisional-MHD description has been applied even to collisionless astrophysical media, like the intracluster media (ICM). However, collisionless plasmas can behave very differently. For example, in the ICM the temperature anisotropy triggers electromagnetic instabilities. These instabilities in turn, interact with the particles, decreasing the anisotropy. The microphysics involved in this process is not completly understood yet. It has been demonstrated that the rate of reduction of this anisotropy alters drastically the turbulence statistics and the behavior of the dynamo amplification of the magnetic fields. All collisionless effects, the transport properties, and also the heating of particles via collisionless damping, should be taken into account in the investigation of acceleration and propagation of particles in the ICM and for a correct description of the large scale dynamics and structure of the turbulent ICM. This project aims to explore: (i) MHD models which take into account collisionless plasma effects for investigating the structure and evolution of the ICM, (ii) the interaction between the plasma instabilities and the temperature anisotropy evolution, and (iii) the acceleration and propagation of cosmic rays (CRs) in the collisionless ICM. In particular, the studies on CR propagation effects through the ICM will allow to establish new constraints and allow to make predictions for high energy detectors, in particular, for the coming Cherenkov Telescope Array (CTA). This array of about 100 telescopes will have sensitivity 10 times larger than the current gamma-ray observatories to detect the emission originated in astrophysical cosmic ray accelerators, such as active galactic nuclei, gamma-ray bursts, and galaxy cluster mergers. (AU) | |
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