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X-ray variability in M 87: 1992 – 1998

  • D. E. Harris
  • J. A. Biretta
  • W. Junor
Conference paper
Part of the Lecture Notes in Physics book series (LNP, volume 530)

Abstract

Beginning in 1995 June, we have obtained an observation of M 87 with the ROSAT High Resolution Imager (HRI) every 6 months. We present the measurements of X-ray intensity for the core and knot A through 1998 January. We find significant changes in both components. For the core, intensities measured in June 1995, December 1996, and December 1997 are roughly 30% higher than values obtained at three intervening times. For knot A, a secular decrease of approximately 15% is interrupted only by an intensity jump (3 σ) in December 1997. Because the background used for subtraction is probably undeestimated, we suspect the actual variation is somewhat greater than these values indicate.

Keywords

High Resolution Imager Brightness Distribution Circular Aperture Lower Surface Brightness Intensity Jump 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Biretta, J.A., Stern, C.P., and Harris, D.E. (1991): The Radio to X-ray Spectrum of the M 87 Jet and Nucleus, AJ 101, 1632–1646CrossRefADSGoogle Scholar
  2. Biretta, J.A. et al. (1999) (this volume): Ringberg Workshop on M 87 (Springer, Berlin, Heidelberg)Google Scholar
  3. Harris, D.E., Biretta, J.A., and Junor, W. (1997): X-ray Variability in M 87 MNRAS 284, L21–L27Google Scholar
  4. Harris, D.E., Biretta, J.A., and Junor, W. (1999) (this volume): Ringberg Workshop on M 87 (Springer, Berlin, Heidelberg)Google Scholar
  5. Tsvetanov, Z.I., Hartig, G.F., Ford, H.C., Kriss, G.A., Dopita, M.A., Dressel, L.L., and Harms, R.J. (1999) (this volume): The Nuclear Spectrum of M 87 Ringberg Workshop on M 87 (Springer, Berlin, Heidelberg)Google Scholar

Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • D. E. Harris
    • 1
  • J. A. Biretta
    • 2
  • W. Junor
    • 3
  1. 1.Smithsonian Astrophysical ObservatoryCambridgeUSA
  2. 2.Space Telescope Science InstituteBaltimoreUSA
  3. 3.University of New MexicoAlbuquerqueUSA

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