Extrapolating electron spectra to low energies

  • D. E. Harris
VIII. Extragalactic Low Frequency Astrophysics
Part of the Lecture Notes in Physics book series (LNP, volume 362)


There are both theoretical and observational indications that the electron spectra inferred from radio observations can not be extrapolated to γ values much below 1000 without a break or cutoff in the power laws found at higher energies. The capability of making reliable observations in the decade below 30 MHz would allow us to evaluate loss mechanisms other than the standard E2 losses, and would also permit tests of acceleration models.

Although the main theme of this meeting was the science which could be done by space observations, it seems reasonable to conclude with a few remarks on instrumentation. As always, we require high resolution and high sensitivity. Because of the horrendous interference environment in near Earth orbit (and it can only get worse, it seems to us that the backside of the moon is the place to be. Because of the difficulty of delivery and operation at that site, we, believe that a simple “W” type of interferometer is the most promising concept: one element in orbit around the moon, observing so long as the Earth is below the horizon, with one or more elements on “luna firma”. In the meantime, while we plan for the eventual lunar observatory, we should build the best possible Earth-based observatory in the best possible location to cover the 5 to 50 MHz band. Together, these two installations would allow us to obtain the scientific results discussed at this meeting.


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • D. E. Harris
    • 1
  1. 1.Harvard-Smithsonian Center for AstrophysicsCambridge

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