Origins and effects of cosmic rays in large-scale structures of the Universe

• Applicant: Professor Marcus Brüggen, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 253128873

• Final Report Year: 2019

Final Report Abstract

In this project, Mr Wittor analysed simulations performed with a cosmological magnetohydrodynamics code to study the non-thermal components of the intracluster medium. In particular, he has written a code that follows fluid particles in a Lagrangian fashion in post-processing. He then employed this code to study the radio emission at shock waves that occur when galaxy clusters merge. We performed an extensive study to verify whether the obliquity of the magnetic field at the shock wave has an effect on the radio emission observed at radio relics and the abundance of cosmic ray protons in the intracluster medium. Finally, we studied the evolution of vorticity and enstrophy in the intracluster medium. This work was done in collaboration with Prof. Tom Jones at the University of Minnesota and contains very interesting results on the nature of the turbulence and the timescales involved. For example, it was shown that mainly stretching motions in the gas are responsible for the evolution of enstrophy (and thus turbulence). This work will have a great impact on attempts to derive estimates of turbulent pressures from X-ray observations. It was also shown how the dissipation of turbulence can explain the observed magnetic field strengths in galaxy clusters. Thus, this very theoretical piece of work has made very tangible connections to observable quantities.

Publications

• 2016, Galaxies, 4, 71
  Wittor, D., Vazza, F., & Brüggen, M.
  (See online at https://doi.org/10.3390/galaxies4040071)
• 2016, MNRAS , 459, 70
  Vazza, F., Brüggen, M., Wittor, D., et al.
  (See online at https://doi.org/10.1093/mnras/stw584)
• 2017, Classical and Quantum Gravity, 34, 234001
  Vazza, F., Brüggen, M., Gheller, C., et al.
  (See online at https://doi.org/10.1088/1361-6382/aa8e60)
• 2017, MNRAS , 464, 4448
  Wittor, D., Vazza, F., & Brüggen, M.
  (See online at https://doi.org/10.1093/mnras/stw2631)
• 2017, MNRAS , 471, 3212
  Wittor, D., Jones, T., Vazza, F., & Brüggen, M.
  (See online at https://doi.org/10.1093/mnras/stx1769)