Impacts of a supersonic shock front on star formation in the Bullet Cluster

Sun Mi Chung, Anthony H. Gonzalez, Douglas Clowe, Dennis Zaritsky, Maxim Markevitch, Christine Jones

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


We use the Bullet Cluster (1E0657-56) to investigate the extent to which star formation in cluster galaxies is influenced by ram pressure from supersonic gas (Mach 3) during a cluster merger. While the effects of ram pressure have been studied for individual galaxies infalling into galaxy clusters, this system provides a unique opportunity to investigate the impact of dramatic merger events on the cluster galaxy population. In this analysis, we use Spitzer IRAC data to study star formation. At the redshift of the cluster, the 6.2 μm PAH feature is redshifted into the 8 μm band, enabling use of the m 4.5-m 8 color as a proxy for specific star formation rate. We find that the color distribution on the two sides of the shock differs by less than 2σ, and conclude that ram pressure from the shock front has no dramatic, immediate impact on the star formation of cluster galaxies in the Bullet Cluster.

Original languageEnglish (US)
Pages (from-to)963-970
Number of pages8
JournalAstrophysical Journal
Issue number2
StatePublished - Feb 1 2009


  • galaxies: clusters: individual (1E0657-56, The Bullet Cluster)
  • galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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