Speaker
Description
The Orion-Eridanus superbubble, formed from the winds and the explosions of Orion’s massive stars, could be a cosmic-ray acceleration site. Inside the superbubble, the large level of MHD turbulence and the core-collapse supernovae have created a turbulent medium which effect on cosmic rays can be probed comparing their flux and spectrum in the superbubble to the average in nearby interstellar clouds.
To study cosmic rays in the superbubble, we first rely on Fermi LAT data. Eight years of data and gamma rays above 100 MeV have been used. We are particularly interested in gamma rays resulting from the decay of neutral pions produced by the interaction of cosmic rays with interstellar gas. Hence, knowing both gas distribution and gamma-ray emission allows to obtain the cosmic-ray flux. This requires to model the interstellar emission using multiwavelength tracers for the gas column densities in the different phases (atomic, molecular, ionized) of the superbubble.
First results show that the emissivity spectrum differs from the local measurement by less than 30%. We will discuss systematic uncertainties on this measurement and on the previous local estimates to compare the diffusion properties of CRs in and out of the superbubble.
