The blazar content in the Swift -BAT hard X-ray sky

A. Maselli, G. Cusumano, E. Massaro, V. La Parola, A. Segreto, B. Sbarufatti

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Aims. We present the results from a study of the blazar content in the 15-150 keV map of the entire sky obtained analysing 39 months of data collected by the BAT telescope aboard the Swift satellite. Methods. We performed a cross-correlation of the significance map, obtained with a dedicated highly efficient algorithm for data processing and image reconstruction of the BAT survey data, with the blazar population of the Roma-BZCAT. After corrections for source confusion and spurious detections, we found significance excesses higher than two standard deviations for 304 sources, and the corresponding fraction of expected spurious associations is ∼20%. We selected hard X-ray blazars according to their significance level and carried out a statistical analysis to characterise their emission properties. Results. A sample of 121 blazars detected at a significance level σ > 3 is discussed in greater detail. The fraction of blazars with uncertain classification in this sample is considerable (∼23%), more than twice the percentage obtained considering all the blazars classified in the Roma-BZCAT (∼9%). We attribute the X-ray flux of the majority of selected BL Lac objects to the synchrotron emission.

Original languageEnglish (US)
Article numberA47
JournalAstronomy and Astrophysics
Issue number6
StatePublished - Sep 30 2010

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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