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The seminar of the Astro & Theory Section takes place Wednesdays  in E??   and on zoom, starting normally at 14.15. If you would like to suggest a seminar speaker or want to be added to the email list, please contact the organizer (

The (planned) seminars in 2023 are

  • 22.02., Alexander van der Horst (George Washington U.): Radio View on Gamma-Ray Burst Extremes
    Abstract: Many high-energy astrophysical sources accelerate electrons to extreme velocities, resulting in multi-wavelength emission from synchrotron and other radiation processes. Gamma-ray bursts represent some of the most extreme electron accelerators, in the collimated outflows, or jets, of massive stellar explosions and the mergers of compact objects. Observations of gamma-ray bursts across the electromagnetic spectrum, from GHz radio frequencies to TeV gamma-ray energies, provide a unique probe of electron acceleration due to the relativistic nature of their jets. I will discuss recent developments in this area, both observationally and in modeling the observations, focusing on gamma-ray burst extremes from a radio perspective.

  • 15.03., Egor Podlesnyi (IFY, NTNU):  Modelling the persistent low-state γ-ray emission of the PKS 1510-089 blazar
    Abstract: Blazars may accelerate protons and/or nuclei as well as electrons. The hadronic component of accelerated particles in blazars may constitute the bulk of their high-energy budget; nevertheless, this component is elusive due to a high value of the energy threshold of proton interaction with photon fields inside the source. However, broad line regions (BLRs) of some flat spectrum radio quasars (FSRQs) may contain a sufficient amount of matter to render primary protons "visible" in γ rays via hadronuclear interactions. In the present work, we study the persistent γ-ray emission of the FSRQ PKS 1510-089 in its low state utilizing the publicly-available Fermi-LAT data and the spectrum measured with the MAGIC imaging atmospheric Cherenkov telescopes. We find an indication for an excess of γ rays at the energy range ≳20 GeV with respect to a simple baseline log-parabolic intrinsic spectral model. This excess could be explained in a scenario invoking hadronuclear interactions of primary protons on the BLR material with the subsequent development of electromagnetic cascades in photon fields. We present a Monte Carlo calculation of the spectrum of this cascade component, taking as input the BLR photon field spectrum calculated with the Cloudy code.

  • 27.03., Tor Nordam (IFY NTNU): ??
    Abstract: D

  • 29.03. Jordan Simpson (IFY, NTNU): ??
    Abstract:  On

  • 19.04. Enrico Peretti  (NBI): ??
    Abstract:  I

  • 26.04.,  Mark Kennedy (U Cork):  ??
    Abstract: Co

  • xx.yy. Michael Unger (KIT and IFY, NTNU): ??
    Abstract:  On

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