Gwenael Giacinti

Cosmic rays in a galactic breeze

Motivated by the discovery of the non-thermal Fermi bubble features both below and above the Galactic plane, we investigate a scenario in which these bubbles are formed through Galacto-centric outflow. Cosmic rays (CR) both diffusing and advecting within a Galactic breeze outflow, interacting with the ambient gas present, give rise to gamma-ray emission, providing an approximately flat surface brightness profile of this emission, as observed. Applying the same outflow profile further out within the disk, the resultant effects on the observable CR spectral properties are determined. A hardening in the spectra due to the competition of advective and diffusive propagation within a particular energy range is noted, even in the limiting case of equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of

Constraining the properties of the magnetic turbulence in the Geminga region using HAWC

\approx 200

\gamma

GV.

-ray data

Observations of extended gamma-ray emission around Galactic cosmic-ray (CR) sources can be used as novel probes of interstellar magnetic fields. Using very-high-energy gamma-ray data from the HAWC Observatory, we place constraints on the properties of the magnetic turbulence within

Large-scale Cosmic-Ray Anisotropy as a Probe of Interstellar Turbulence

\approx 25

Galactic Cosmic-Rays in a Breeze

pc from Geminga. We inject and propagate individual CR electrons in 3D realizations of turbulent magnetic fields, calculate the resulting gamma-ray emission, and compare with HAWC measurements of this region. We find that HAWC data is compatible with expectations for Kolmogorov or Kraichnan turbulence, and can be well fitted for reasonable coherence lengths and strengths of the turbulence, despite implying a CR diffusion coefficient significantly smaller than those suggested by Galactic CR propagation codes. The best fit is found for a coherence length

Core-collapse supernovae as cosmic ray sources

L_{\rm c} \approx 1

Inductive spikes and gamma-ray flares from the Crab Nebula

pc and a magnetic field strength

A Hadronic Model of the Fermi Bubbles: Cosmic-Rays in a Galactic Breeze

B_{\rm rms} \approx 3 \mu

TeV-PeV Cosmic-Ray Anisotropy as a Probe of the Local Interstellar Turbulence

G, and the preferred value for