Simon Steinmassl (Germany)
simon.steinmassl @ mpi-hd.mpg.de
Periastron passage of the colliding wind binary Eta Carinae as measured by HESS
Imaging atmospheric Cherenkov telescopes (IACT) are sensitive to γ-ray emission from Galactic and extragalactic sources in the energy range from ∼30 GeV to tens of TeV. The High Energy Stereoscopic System, H.E.S.S., located in Namibia, is the only IACT system integrating different telescope types into one array. With H.E.S.S. it is thus possible to observe possible sources of very high energy (VHE, E >100 GeV) γ-ray emission due to extreme particle acceleration.
Colliding wind binary systems have long been suspected to be high-energy (100 MeV < E <100 GeV) γ-ray emitters. The highly eccentric binary stellar system Eta Carinae is the most prominent member of this object class and confirmed to emit phase-locked γ rays from hundreds of MeV to ∼100 GeV energies. VHE γ-ray emission from η Car has been detected around the last periastron passage in 2014 with H.E.S.S. Due to its 5.5 years orbital period Eta Carinae will go trough its next periastron passage in February 2020, with the two extremely massive stars only a few stellar radii apart.
In autumn 2019 the camera of the largest H.E.S.S telescope is being upgraded. Hence my PhD work first focuses on developing the best observation strategy with the new camera for Eta Carinae. It lies in an optically bright region, aka the Carina Nebula, which yields a high and inhomogeneous background for the observations. With the data collected in the winter and spring of 2020, it will then be possible to do the analysis in the VHE regime. This data together with data in other wavelength regimes can then be used to interpret and model the particle acceleration and radiation in Eta Carinae.
Supervisor: Jim Hinton (MPIK)