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Cluster magnetic fields from large scale structure shocks

Medvedev, Mikhail V. and Silva, Luis O. and Kamionkowski, Marc (2007) Cluster magnetic fields from large scale structure shocks. In: Turbulence and Nonlinear Processes in Astrophysical Plasmas: 6th Annual International Astrophysics Conference, Oahu, Hawaii, 16-22 March 2007. AIP Conference Proceedings. No.932. American Institute of Physics , Melville, NY, pp. 117-122. ISBN 978-0-7354-0443-4.

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The origin of the micro-Gauss magnetic fields in galaxy clusters is one of the outstanding problem of modern cosmology. We suggest that these fields could have been produced via the Weibel instability operating at shocks during the Large-Scale Structure formation and at accretion shocks in Galaxy Clusters. We have performed three-dimensional particle-in-cell simulations of the nonrelativistic Weibel instability in an electron-proton plasma (with the ion-to-electron mass ratio of 100), in conditions typical of cosmological shocks. These simulations indicate that cluster fields could have been produced by shocks propagating through the intergalactic medium during the formation of large-scale structure or by shocks within the cluster. The strengths of the shock-generated fields range from tens of nano-Gauss in the intercluster medium to a few micro-Gauss inside galaxy clusters. We discuss whether and how our results may change with the change the mass ratio to the realistic value of 1836. We stress that even if the Weibel-generated small-scale magnetic fields decay with time, they can serve as seed fields that can be further amplified and inverse-cascade to larger scales by turbulent motions of post-shock MHD turbulence.

Item Type:Book Section
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Kamionkowski, Marc0000-0001-7018-2055
Additional Information:© 2007 American Institute of Physics The simulations were performed in the eXpp cluster at IST, Lisbon. The work of MVM has been supported by DoE grant DE-FG02-04ER54790, NASA grant NNG-04GM41G. The work of LOS was partially supported by FCT (Portugal) through grants PDCT/FP/FAT/50190/2003 and POCI/FIS/55905/2004. MK was supported by DoE DE-FG03-92-ER40701 and NASA NNG05GF69G.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-04ER54790
Fundação para a Ciência e a Tecnologia (FCT)PDCT/FP/FAT/50190/2003
Fundação para a Ciência e a Tecnologia (FCT)POCI/FIS/55905/2004
Department of Energy (DOE)DE-FG03-92-ER40701
Subject Keywords:intergalactic magnetic fields; clusters of galaxies; shock wave effects; cosmology; astrophysical plasma; plasma simulation; plasma instability
Series Name:AIP Conference Proceedings
Issue or Number:932
Record Number:CaltechAUTHORS:MEDaipcp07
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8658
Deposited By: Archive Administrator
Deposited On:03 Sep 2007
Last Modified:02 Oct 2019 23:53

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