Speaker: Gonzalo Herrera (TUM)
Neutrino and gamma-ray attenuation by dark matter spikes
In this talk, I will discuss the attenuation of high energy neutrinos and photons produced in a blazar when they propagate through the dark matter spike around the central black hole and the halo of the host galaxy. In particular, I will discuss new constraints on the dark matter-neutrino and dark matter-photon scattering cross sections obtained from the observation by IceCube of a few high-energy neutrino events from TXS 0506+056, and their coincident gamma-ray events. I will emphasize the dependence of the constraints with the location where the neutrinos and gamma-rays are produced, and the dependence with the dark matter self-annihilation cross section. The constraints are orders of magnitude more stringent than those derived from considering the attenuation through the intergalactic medium and the Milky Way dark matter halo. When the cross-section increases with energy, the constraints are also stronger than those derived from the CMB and large-scale structure.
Speaker: Rostom Mbarek (U Chicago)
High-Energy Neutrino Emission from Espresso-Accelerated Ions in Jets of Active Galactic Nuclei
We present a bottom-up calculation of the flux of ultra-high energy cosmic rays (UHECRs) and high-energy neutrinos produced by powerful jets of active galactic nuclei (AGNs). By propagating test particles in 3D relativistic magnetohydrodynamic jet simulations, including a Monte Carlo treatment of sub-grid pitch-angle scattering and attenuation losses due to realistic photon fields, we study the spectrum and composition of the accelerated UHECRs and estimate the amount of neutrinos produced in such sources. We find that UHECRs may not be significantly affected by photodisintegration in AGN jets where the espresso mechanism efficiently accelerates particles, consistent with Auger's results that favor a heavy composition at the highest energies. Moreover, we present estimates and upper bounds for the flux of high-energy neutrinos expected from AGN jets. In particular, we find that: i) source neutrinos may account for a sizable fraction, or even dominate, the expected flux of cosmogenic neutrinos; ii) neutrinos from the beta-decay of secondary neutrons produced in nucleus photodisintegration could in principle contribute to the PeV neutrino flux observed by IceCube, but can hardly account for all of it; iii) UHECRs accelerated via the espresso mechanism lead to nearly isotropic neutrino emission, which suggests that nearby radio galaxies may be more promising as potential sources. We discuss our results in the light of multi messenger astronomy and current/future neutrino experiments.
