Am Montag, den 1. Dezember 2025, um 12:00 Uhr c.t. findet unser nächstes Physikalisches Kolloquium statt. Associate Professor Tim Linden ist Dozent an der Universität Stockholm und arbeitet derzeit am Erlanger Zentrum für Astroteilchenphysik. Das Thema seines Vortrags lautet „Unexpected Features of Solar Gamma-Ray and Neutrino Emission”.
The Sun is a bright gamma-ray source – but not in the ways that many imagine. While the Sun cannot accelerate particles to high energies to produce gamma-ray emission above ~1 GeV, the Sun is a powerful passive source that can convert galactic cosmic rays into gamma rays that can be detected from Earth. There are two mechanisms. First, ambient cosmic-ray protons can undergo hadronic interactions with the solar atmosphere, producing a bright flux across the solar disk. Second, cosmic-ray electrons can inverse-Compton scatter ambient sunlight to gamma-ray energies. Observations by the Fermi-LAT and HAWC telescope have detected both components, and tracked their evolution across the solar cycle. The inverse-Compton scattering halo tracks theoretical expectations. However, the disk emission is peculiar in every way. First, the gamma-ray emission extends to energies above 3 TeV, implying that Solar magnetic fields can redirect multi-TeV protons. Second, the morphology and spectrum of gamma-ray emission vary significantly over the solar cycle. Third, a significant “spectral-dip” appears between energies of 30-50 GeV. These observations are in significant tension with all current models of solar gamma-ray production. In this talk, I will discuss possible models for solar gamma-ray and neutrino emission, and discuss the potential for Solar observations to better constrain solar processes, and perhaps discover physics beyond the standard model.
Abstract des Vortrags von Prof. Linden
Prof. Dr. Anna Franckowiak gibt eine Einführung in den Vortrag.
Die Fakultät lädt alle Interessierten herzlich ein. Die Veranstaltung findet im Hörsaal HZO 20 statt.
Foto: NASA Hubble Space Telescope auf Unsplash