Cold fronts by merging of shocks

Yuval Birnboim*, Uri Keshet, Lars Hernquist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Cold fronts (CFs) are found in most galaxy clusters, as well as in some galaxies and groups of galaxies. We propose that some CFs are relics of merging between two shocks propagating in the same direction. Such shock mergers typically result in a quasi-spherical, a factor of ≈1.4-2.7 discontinuity in density and in temperature. These CFs may be found as far out as the virial shock, unlike what is expected in other CF formation models.As a demonstration of this effect, we use 1D simulations of clusters and show that shock-induced CFs form when perturbations such as explosions or mergers occur near the cluster's centre. Perturbations at a cluster's core induce periodic merging between the virial shock and outgoing secondary shocks. These collisions yield a distinctive, concentric, geometric sequence of CFs which trace the expansion of the virial shock.

Original languageAmerican English
Pages (from-to)199-212
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Oct 2010
Externally publishedYes


  • Galaxies: clusters: general
  • Galaxies: haloes
  • Shock waves
  • X-rays: galaxies: clusters


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