Dynamics and magnetization in galaxy cluster cores traced by x-ray cold fronts

Uri Keshet, Maxim Markevitch, Yuval Birnboim, Abraham Loeb

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Cold fronts (CFs) - density and temperature plasma discontinuities - are ubiquitous in cool cores of galaxy clusters, where they appear as X-ray brightness edges in the intracluster medium, nearly concentric with the cluster center. We analyze the thermodynamic profiles deprojected across core CFs found in the literature. While the pressure appears continuous across these CFs, we find that all of them require significant centripetal acceleration beneath the front. This is naturally explained by a tangential, nearly sonic bulk flow just below the CF, and a tangential shear flow involving a fair fraction of the plasma beneath the front. Such shear should generate near-equipartition magnetic fields on scales ≲50 pc from the front and could magnetize the entire core. Such fields would explain the apparent stability of cool core CFs and the recently reported CF-radio minihalo association.

Original languageEnglish
Pages (from-to)L74-L78
JournalAstrophysical Journal Letters
Volume719
Issue number1 PART 2
DOIs
StatePublished - 10 Aug 2010
Externally publishedYes

Keywords

  • Galaxies: clusters: general
  • Galaxies: clusters: intracluster medium
  • Hydrodynamics
  • Intergalactic medium
  • Magnetic fields
  • X-rays: galaxies: clusters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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