The Crab pulsar was discovered1 by the occasional exceptionally bright radio pulses it emits, subsequently dubbed ‘giant’ pulses. Only two other pulsars are known to emit giant pulses2,3. There is no satisfactory explanation for the occurrence of giant pulses, nor is there a complete theory of the pulsar emission mechanism in general. Competing models for the radio emission mechanism can be distinguished by the temporal structure of their coherent emission. Here we report the discovery of isolated, highly polarized, two-nanosecond subpulses within the giant radio pulses from the Crab pulsar. The plasma structures responsible for these emissions must be smaller than one metre in size, making them by far the smallest objects ever detected and resolved outside the Solar System, and the brightest transient radio sources in the sky. Only one of the current models—the collapse of plasma-turbulent wave packets in the pulsar magnetosphere—can account for the nanopulses we observe.
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T.H.H. thanks NRAO and NAIC for partial sabbatical leave support at the Green Bank and Arecibo Observatories. J.S.K. thanks NRAO for pre-doctoral support. We thank B. Driggers of TMS and LeCroy for the loan of a LeCroy LT584L oscilloscope, J. Ford at NRAO Green Bank for square-law detectors, NRAO Socorro for computer support and technical assistance, and the NSF for a research grant. The Arecibo Observatory is operated by Cornell University under a cooperative agreement with the National Science Foundation.
The authors declare that they have no competing financial interests.
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Hankins, T., Kern, J., Weatherall, J. et al. Nanosecond radio bursts from strong plasma turbulence in the Crab pulsar. Nature 422, 141–143 (2003). https://doi.org/10.1038/nature01477
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