Speaker
Description
Using tracer particles propagating in an environment that simulates the accretion disk surrounding a black hole, this work aims to provide insight into the confinement of high energy particles in the galaxy NGC 1068 ( J. Bland-Hawthorn et al., 1997, Astrophysics and Space Science; K. Murase, 2022, The Astrophysical Journal Letters ), which is believed to be the source of the neutrino fluxes measured in IceCube Collaboration et al., 2022, Science. The accretion disk is evolved according to the equations of General Relativistic MagnetoHydroDynamic (GRMHD), implemented in the code AthenaK, a re-implementation of the Athena++ ( J. M. Stone et al., 2020, The Astrophysical Journal Supplement Series ) code, with the addition of purely passive particles ( B. Ripperda et al., 2018, The Astrophysical Journal Supplement Series; F. Bacchini et al., 2019, The Astrophysical Journal Supplement Series ), such that their presence doesn’t affect the
dynamics of the accretion disk. The simulations are run using parameters expected to be found in the environment of the galaxy NGC 1068, with tracer particles initialized to energies reaching $1 \; PeV$ , since these are believed to be of most interest for the generation of neutrinos. By running this setup, an estimate for the confinement times of such particles can be provided, which is otherwise usually modeled as a free parameter, but that plays a critical role in determining the properties of the injection spectrum of neutrinos, and thus in the identification of possible sources for such particles. Particular focus is dedicated to characterizing the role played by the magnetic field of the accretion disk.
