Electron injection mechanisms in protostellar jet termination shocks - LATE PROJECT

Fermi I acceleration is the most efficient mechanism for cosmic ray acceleration. The injection problem is to find the initial process that heats the plasma electrons to the minimum energy needed to initiate Fermi I acceleration. This is currently the most pressing problem in cosmic ray physics. Although several injection mechanisms have been proposed, it remains an unsolved problem, mainly due to the lack of reliable tests.

We propose a PhD project on the study of protostellar jets in our Galaxy as a promising setting for advanced testing of injection mechanisms. The main advantage of these systems lies in the existence of two competing electron injection mechanisms in the jet termination shocks: stochastic acceleration in Weibel turbulence, and acceleration in the electrostatic field within the cavities created by Buneman instabilities. Electrons accelerated by these mechanisms produce a very distinctive electromagnetic spectra at radio wavelengths.

The objectives of the proposed PhD thesis are i) to quantify for the very first time the relevance of the two competing mechanisms mentioned above for the heating of electrons under different plasma conditions and shock velocities and ii) to study the radio signatures produced in jets from massive protostars by the processes of electron injection, making predictions testable with the current and forthcoming radio telescopes and with scaled laser-plasma experiments.

The proposed PhD position is theoretically oriented. The candidate will perform phenomenological modelling together with semi-analytical and numerical calculations. The position is fully funded.

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