The synchrotron emission from the M87 jet

  • Sebastian Heinz
  • Mitchell C. Begelman
Conference paper
Part of the Lecture Notes in Physics book series (LNP, volume 530)


We show that the intensity changes and the spectral evolution along the M 87 jet are consistent with adiabatic changes to the particle momentum distribution function and the magnetic field. We use the deprojection of a 2 cm VLA intensity map by Sparks, Biretta, & Macchetto and spectral data by Neumann, Meisenheimer, & Röser to derive limits on the magnetic field and the total pressure. To explain the weakness of synchrotron cooling along the jet, the magnetic field strength must lie in the range 20 − 40 µG, departing from equipartition by a factor ≈1.5–5. Bulk Lorentz factors Γ jet in the range 2–5 and inclination angles ϑ LOS≲25° lead to pressure estimates close to the ISM pressure. Extrapolation of our model back towards the core shows that particle acceleration to the observed spectral shape likely occurs at distances as far as 10 pc away from the core.


Cutoff Frequency Spectral Index Adiabatic Compression Oblique Shock Synchrotron Emission 
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Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • Sebastian Heinz
    • 1
    • 2
  • Mitchell C. Begelman
    • 1
    • 2
  1. 1.JILA University of Colorado and National Institute of Standards and TechnologyBoulder
  2. 2.Department of Astrophysical and Planetary SciencesUniversity of ColoradoBoulderUSA

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