Speaker
Description
Novae are thermonuclear explosions occurring on the surface of a white dwarf in a binary system. These explosive events are detected across multiple wavelengths, from radio to X-rays, mostly due to thermal emission. However, in 2010, Fermi-LAT unexpectedly detected gamma-ray emission from the nova V407 Cyg, challenging prior expectations, as novae were not considered capable of accelerating particles to energies yielding GeV emission. In response to this discovery, the H.E.S.S. collaboration initiated a nova observation program, which led to the detection of TeV emission from the exceptionally bright recurrent nova RS Ophiuchi. This success has reinvigorated our ongoing nova observation campaign, including other recurrent novae, such as the imminent T Coronae Borealis one. In this presentation we will present the H.E.S.S. nova ToO programme, and in particular observations of the bright nova YZ Reticuli (2020) and the GeV characteristics revealed during its two-week detection by the Fermi-LAT. This analysis of the GeV-TeV range provides crucial insights into the particle acceleration mechanisms at work in novae, shedding light on the role of shocks in producing high-energy emission.
