Abstract
THE compact low-frequency radio source1 in the Crab nebula is exceptional in most of its properties. Its spectral index2 of ∼ 1.75 between 26.5 and 1,407 MHz is the highest known for a galactic continuum source, and its brightness temperature of ∼ 1014 K at 38 MHz implies an unusual emission mechanism with a high volume emissivity. The high spectral index suggests that only a small fraction of the total radio luminosity of the source may have been observed in the frequency range studied so far. The error field of its radio position3 contains the pulsar NP 0532, and these objects may therefore be related; if the relationship were substantiated, it would be the only continuum source of small angular size known to coincide with a pulsar. This report presents evidence that the high spectral index is maintained to 10 MHz.
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BRIDLE, A. Low-frequency Spectrum of the Crab Nebula. Nature 225, 1035–1037 (1970). https://doi.org/10.1038/2251035a0
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DOI: https://doi.org/10.1038/2251035a0
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