Astrophysique à Haute Energie

High-energy neutrinos, cosmic rays, and gamma rays from gamma-ray bursts

Ultra-high-energy cosmic rays and high-energy astrophysical neutrinos are
routinely detected, but their sources remain unknown.  Gamma-ray bursts
(GRBs) have long been considered attractive candidate sources.  Recently, the
lack of neutrinos detected in coincidence with known GRBs has motivated
revisions of the multi-messenger emission mechanism --- gamma rays, cosmic rays,
neutrinos --- from within the GRB jet.  By embedding this revised mechanism in a
simulation of multiple emission regions within the jet, we obtain a robust

Analyzing diffuse gamma rays to understand the physics of cosmic-ray propagation

I present a broad overview of the current cosmic-ray (CR) transport modeling, and discuss several recent results obtained with the DRAGON code. Several anomalies in the measured CR spectra and gamma-ray data are discussed with particular focus on: the positron excess, the hint of an antiproton excess, the proton and helium spectral breaks, the gamma-ray GeV excess, which may point to either new classes of sources, non-standard propagation models, or new physics.

X-raying Supernova Remnants in the Magellanic Clouds

Supernova remnants (SNRs) mark the end point of stellar evolution. As they release tremendous amounts of kinetic energy and freshly-produced heavy elements into the interstellar medium (ISM), and accelerate cosmic-rays, SNRs are a key component of the chemical and thermodynamical evolution of the ISM in galaxies. X-ray emission is ubiquitous in SNRs, as their shocks heat the SN ejecta and ambient medium to multi-million degree temperatures. X-ray observations are thus an excellent tool to measure properties of SNRs (e.g.

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