Emma de Ona Wilhelmi, "The first VHE detection of a nova with the H.E.S.S. telescopes," **hybrid format**

Friday 22 Apr 2022, 10:30 → 11:30 Europe/Berlin

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of material from a binary companion. In the last years a dozen of these novae have been detected with the LAT telescope up to a few GeV, probing ultrasonic shocks energetically relevant for the nova dynamics. In such shocks, particles are believed to be accelerated to high energies; however, basic questions like the type of particles (protons or electrons) or the location of the shock are still under debate. We will present the detection of TeV gamma-rays from the nova RS Ophiuchi, using the HESS telescopes, reaching the theoretical limit for the maximum achievable particle energy via diffusive shock acceleration. The large signal detected allows us to follow the evolution in time of the shock up to one month. Combining LAT and HESS data we constrain different models, favouring a hadronic emission scenario over the leptonic alternative. The detection of the first nova in the TeV regime, which resembles a small-scale supernova, provides also information about cosmic-ray acceleration in supernova remnants from massive stars.

This will be a hybrid seminar. If you would like to attend in person, in SR3, please add your name to https://confluence.desy.de/pages/viewpage.action?pageId=252825573. We highly recommend a self test in the morning for all attendees. Please contact the seminar organizers if you have any questions.