Resolving the Crab pulsar wind nebula at teraelectronvolt energies
Date
2019
Authors
Abdalla, H.
Aharonian, F.
Ait Benkhali, F.
Angüner, E.O.
Arakawa, M.
Arcaro, C.
Armand, C.
Backes, M.
Barnard, M.
Becherini, Y.
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Journal article
Citation
Nature Astronomy, 2019; 4(2):167-173
Statement of Responsibility
H. Abdalla, F. Aharonian, Benkhali F. Ait, E. O. Angüner ... Gavin Rowell ... Fabien Voisin ... et al.
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Abstract
The Crab nebula is one of the most-studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very-high-energy gamma rays 1,2. It is known from observations in the radio to gamma-ray part of the spectrum that the nebula is powered by a pulsar, which converts most of its rotational energy losses into a highly relativistic outflow. This outflow powers a pulsar wind nebula, a region of up to ten light-years across, filled with relativistic electrons and positrons. These particles emit synchrotron photons in the ambient magnetic field and produce very-high-energy gamma rays by Compton up-scattering of ambient low-energy photons. Although the synchrotron morphology of the nebula is well established, it has not been known from which region the very-high-energy gamma rays are emitted 3,4,5,6,7,8. Here we report that the Crab nebula has an angular extension at gamma-ray energies of 52 arcseconds (assuming a Gaussian source width), much larger than at X-ray energies. This result closes a gap in the multi-wavelength coverage of the nebula, revealing the emission region of the highest-energy gamma rays. These gamma rays enable us to probe a previously inaccessible electron and positron energy range. We find that simulations of the electromagnetic emission reproduce our measurement, providing a non-trivial test of our understanding of particle acceleration in the Crab nebula.
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2019 © The Author(s), under exclusive licence to Springer Nature Limited 2019