Speaker
Victor Zabalza
(University of Leicester)
Description
Eta Carina is the only colliding-wind binary for which
non-thermal emission is detected from hard X-rays to high-energy gamma
rays. Although the physical conditions in the shock region change on
timescales of hours to days, the variability seen at GeV energies is
quite weak and on significantly longer timescales. The gamma-ray
spectrum exhibits two spectral features that can be interpreted as
emission originating from the shock and post-shock regions of the two
distinct stellar winds. Here we report on the first time-dependent
modelling of the non-thermal emission in Eta Carina in this scenario,
which aims to explain the level of gamma-ray emission as well as the
variability with orbital phase. We used a time-dependent acceleration
scheme to derive the spectrum of relativistic particles in the adiabatic
shock of the companion star, including the effects of cosmic ray
pressure modification. We find that emission from primary electrons is
unlikely to be responsible for the gamma-ray emission, and that
gamma-ray emission from accelerated protons interacting with the dense
shocked wind material can explain the observations. The significant pair
production absorption in the stellar radiation fields leads to a drop in
the predicted gamma-ray emission above several hundred GeV - consistent
with the upper limits as reported by H.E.S.S.
| Registration number following "ICRC2015-I/" | 571 |
|---|---|
| Collaboration | -- not specified -- |
Authors
Dr
Elliot Ross Parkin
(University of Leeds)
Jim Hinton
(University of Leicester)
Stefan Ohm
(DESY)
Victor Zabalza
(University of Leicester)
