Speaker
Anna Franckowiak
(SLAC)
Description
Supernovae (SNe) exploding in a dense circumstellar medium (CSM) are hypothesized to accelerate cosmic rays in collisionless shocks and emit GeV gamma rays and TeV neutrinos on a time scale of several months. We perform the first systematic search for gamma-ray emission in Fermi LAT data in the energy range from 100 MeV to 300 GeV from the ensemble of SNe exploding in dense CSM. We study a sample of 147 SNe Type IIn and search for a gamma-ray excess at each SNe location using the maximum likelihood method for each source in a one year time window. In order to enhance a possible weak signal, we simultaneously study the closest and optically brightest sources of our sample in a joint likelihood analysis in three different time windows (1 year, 6 months and 3 months). We do not find a significant excess in gamma rays for any individual source nor for the combined sources and provide flux upper limits at 95% confidence level (CL) for both cases. We calculate model independent limits on the gamma-ray flux for individual sources as well as the combined source sample. In addition, we derive limits on the gamma-ray luminosity and the ratio of gamma-ray to optical luminosity as a function of the index of the proton injection spectrum assuming a generic gamma-ray production model.
| Registration number following "ICRC2015-I/" | 100 |
|---|---|
| Collaboration | FERMI |
Primary author
Anna Franckowiak
(SLAC)
