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BL Lac Objects pp 290-295 | Cite as

The exosat spectral survey of BL Lacertae objects

  • P. Barre
  • P. Giommi
  • A. Pollock
  • G. Tagliaferri
  • D. Maccagni
  • B. Garilli
VI. X-ray Spectra and Variability
Part of the Lecture Notes in Physics book series (LNP, volume 334)

Abstract

The results of an analysis of the X-ray spectra of seventeen BL Lacertae objects measured in 66 observations are presented. The 0.1 - 10 keV spectra of these objects exhibit convex curvature in the log Fν - log ν plane. This curvature is intrinsic to the continuum . No evidence for high energy tails is found, at least below energies of ≈8 − 10 keV, nor for very steep (energy spectral index α ≥2)soft X-ray spectra . A broken power law model gives an excellent fit to the spectra at each epoch but is unattractive from physical considerations and also when attempting to model the X-ray variability; other curved, convex continuum models should be considered.

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References

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Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • P. Barre
    • 1
  • P. Giommi
    • 1
    • 2
  • A. Pollock
    • 1
  • G. Tagliaferri
    • 1
  • D. Maccagni
    • 3
  • B. Garilli
    • 3
  1. 1.Space Science Department of ESAEXOSAT ObservatoryItaly
  2. 2.On leave from Istituto dfi Fisica Cosmica del CNRMilanItaly
  3. 3.Istituto di Fisica Cosmica del CNRMilanItaly

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