Magnetic fields in the outskirts of galaxy clusters: Insights from radio relics

• Applicants: Professor Marcus Brüggen, Ph.D.; Dr. Matthias Hoeft
• Subject Area: Astrophysics and Astronomy
• Term: from 2010 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 108727618

• Final Report Year: 2017

Final Report Abstract

The aim of project A6 was to use radio relics as a probe for magnetic fields in the outskirts of galaxy clusters. Several approaches have been used to get insight into the strength and the structure of magnetic fields at the location of the relics, in particular, RM studies at the location of the radio relic in the Coma cluster, upper limits of the gamma-ray emission of merger shocks, a comparison of the sample of all relics found in the NVSS with a mock sample and high resolution image of the Toothbrush radio relic. Interestingly, the different methods result provide estimates or limits of the magnetic field strength in the cluster outskirts but partly contradicting each other. For the Coma relic a field strength of ∼ 2µG has been found. The analysis of the downstream profiles of the Toothbrush result in a field strength ≲ 5µG. In contrast, limits of the gamma-ray flux of merging clusters indicate a higher magnetic field, if the standard assumptions for electron acceleration via diffusive shock acceleration apply. The project A6 has provided interesting new evidence on magnetic fields in the cluster outskirts. It has also shown that the phenomena of radio relics is more complex than previously thought.

Publications

• 2013, MNRAS 428, 2366
  Vazza, F., Brüggen, M., & Gheller, C.
  (See online at https://doi.org/10.1093/mnras/sts213)
• 2013, MNRAS 429, 799
  Vazza, F., Eckert, D., Simionescu, A., Brüggen, M., & Ettori, S.
  (See online at https://doi.org/10.1093/mnras/sts375)
• 2013, MNRAS 433, 3208
  Bonafede, A., Vazza, F., Brüggen, M., Murgia, M., Govoni, F., Feretti, L., Giovannini, G., & Ogrean, G.
  (See online at https://doi.org/10.1093/mnras/stt960)
• 2014, MNRAS 437, 2291
  Vazza, F., & Brüggen, M.
  (See online at https://doi.org/10.1093/mnras/stt2042)
• 2014, MNRAS 439, 2662
  Vazza, F., Gheller, C., & Brüggen, M.
  (See online at https://doi.org/10.1093/mnras/stu126)
• 2014, MNRAS 445, 3706
  Vazza, F., Brüggen, M., Gheller, C., & Wang, P.
  (See online at https://doi.org/10.1093/mnras/stu1896)
• 2014, MNRAS, 440, 1542
  de Gasperin, F., Brüggen, M., Beck, R., Bonafede, A. et al.
  (See online at https://doi.org/10.1093/mnras/stu360)
• 2014, MNRAS, 444, 3130
  de Gasperin, F., van Weeren, R. J., Brüggen, M., Vazza, F., Bonafede, A. Intema, H.T.
  (See online at https://doi.org/10.1093/mnras/stu1658)
• 2015, MNRAS, 453, 3483
  de Gasperin, F., Intema, H.T., van Weeren, R.J., Dawson, W.A., Golovich, N., Wittman, D., Bonafede, A., Brüggen
  (See online at https://doi.org/10.1093/mnras/stv1873)
• 2017, A&A, 597, 15
  de Gasperin, F., Intema, H.T., Ridl, J., Salvato, M., van Weeren, R., Bonafede, A., Greiner, J., Cassano, R., Brüggen, M.
  (See online at https://doi.org/10.1051/0004-6361/201628945)