Galaxy clusters in the Swift/BAT era. II. 10 more clusters detected above 15 keV

M. Ajello, P. Rebusco, N. Cappelluti, O. Reimer, H. Böhringer, V. La Parola, G. Cusumano

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/Burst Alert Telescope (BAT) all-sky survey. Among the newly BAT-discovered clusters there are Bullet, A85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters, we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess.We find that in most cases the clusters' emission in the 0.3-200 keV band can be explained by a multitemperature thermal model confirming our previous results. For two clusters (Bullet and A3667), we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law-like, component with a 20-100 keV flux of 3.4×10-12 erg cm-2 s-1 as detected in previous studies. For A3667, the excess emission can be successfully modeled as a hot component (kT ∼ 13 keV). We thus conclude that the hard X-ray emission from galaxy clusters (except the Bullet) has most likely a thermal origin.

Original languageEnglish (US)
Pages (from-to)1688-1706
Number of pages19
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 20 2010
Externally publishedYes


  • Acceleration of particles
  • Galaxies: clusters: general
  • Magnetic fields
  • Radiation mechanisms: non-thermal
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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