Organized by: Prof. Lu Lu
Events on Thursday, April 4th, 2024
- Tuning into Cosmic Neutrinos at the Highest Energies
- Time: 9:00 am - 10:00 am
- Place: 5280 Chamberlin Hall
- Speaker: Stephanie Wissel, Penn State
- Abstract: Neutrinos are powerful probes of both astrophysics and fundamental particle physics at the highest energies. Weakly interacting and uncharged, they propagate undeterred and unabsorbed through the universe. In the last decade, we have observed a flux of high-energy (TeV-scale) neutrinos and through a multi-messenger lens — the combined observations of neutrinos and other messengers like photons — we are starting to see hints of energetic neutrino sources for the first time. At higher energies still, beyond the PeV scale, we can probe the most energetic sources of both neutrinos and cosmic rays, but current neutrino experiments become too small to observe a sizable flux. With long propagation lengths in both ice and air, radio detection offers an attractive solution to building the gigaton-scale detectors needed by allowing us to build sparse detectors sensitive to neutrinos over hundreds of kilometers. In this talk, I will review the landscape of current radio neutrino experiments and how next generation detectors can lead to new discoveries. I will also present my vision for the future of the Wisconsin IceCube Particle Astrophysics Center.
- Host: Francis Halzen
- Multi-wavelength emission from Jets of nearby radio galaxies
- Time: 2:30 pm - 3:30 pm
- Place: CH 5280
- Speaker: Riku Kuze, Tohoku University
- Abstract: Relativistic jets in radio galaxies emit multi-wavelength photons, indicating the existence of nonthermal particles. However, the origin of these nonthermal particles is unknown. One plausible scenario is the electron-positron pair production via the two-photon interaction using the gamma rays produced by magnetic reconnection in the black-hole magnetosphere. This scenario is possible if the accretion flow is in a highly magnetized state, i.e., magnetically arrested disk (MAD) state. We construct the multi-wavelength photon emission model based on this scenario. In this talk, we will show the results of applying our model to M87. We calculate emissions from jets and MADs and compare the model prediction to the simultaneous multi-wavelength observational data for M87. We find that the emission from jets explains the optical to the X-ray data, and that from MADs explains the gamma-ray data. We also estimate the neutrino emission from jets and MADs, and we find that the neutrino luminosity is too low to observe by the IceCube Gen-2.
- Host: Ke Fang