Jul 12 – 23, 2021
Europe/Berlin timezone

CR transport and feedback in galaxies

Jul 15, 2021, 12:00 PM
1h 30m


Talk CRD | Cosmic Ray Direct Discussion


Timon Thomas (Leibniz Institute for Astrophysics Potsdam)


Galactic winds can alter the evolution of a disk galaxy by launching outflows from the disk that move gas into the circumgalactic medium (CGM) so that the gas is unavailable to star formation while slowing the infall of fresh gas onto the disk. One agent that is able to drive these galactic winds are GeV cosmic rays (CR) injected by supernovae into the intersellar medium. Through a gyroresonant micro-scale plasma instability CRs drive Alfvén waves that couple their dynamics to the dynamics of their ambient medium. Galactic-scale winds are launched via the momentum transferred by the amplification of these astronomical unit-scale Alfvén waves. Once the CR passed the disk-halo interface their gyro-resonant Alfvén waves damp via various processes and heat the CGM. This heating has a significant contribution to the overall thermodynamics of the CGM and alters the kinematics of material contained in the CGM. The plethora of involved physical processes urges an investigation of the CR dynamics in galactic winds. We developed a two-moment fluid approximation for GeV-CR transport in an arbitrary magnetic field configuration and model their interaction with gyro-resonant Alfvén waves on grounds of the quasi-linear theory of this process. We present the results of high-resolution galaxy formation simulations that uses this this two-moment model. These simulation show that the majority of CRs are streaming with their self-generated Alfvén waves and that the CR diffusion-coefficient is a spatio-temporal varying quantity that cannot be approximated with the fiducial values of ~ 3e28 cm^2 / s.


Galactic Winds, Cosmic Ray Hydrodynamics, Magnetohydrodynamics, Numerics

Subcategory Theoretical Results

Primary authors

Timon Thomas (Leibniz Institute for Astrophysics Potsdam) Christoph Pfrommer (AIP) Dr Pakmor Ruediger (Max Planck Institute for Astrophysics, Garching)

Presentation materials