Resolving the Crab pulsar wind nebula at teraelectronvolt energies

• Main Authors: Abdalla, H, Benkhali, F. Ait, Angüner, E. O, Arakawa, M, Arcaro, C, Arm, C, Becherini, Y, Bernlöhr, K, Bonnefoy, S, Bregeon, J, Brun, F, Bulik, T, Casanova, S, Cerruti, M, Chakraborty, N, Ch, T, Chen, A, Colafrancesco, S, Deil, C, Djannati-Ataï, A, Dmytriiev, A, Doroshenko, V, Dyks, J, Egberts, K, Emery, G, Ernenwein, J. -P, Eschbach, S, Fegan, S, Fiasson, A, Gabici, S, Gallant, Y. A, Gaté, F, Giavitto, G, Gottschall, D, Grondin, M. -H, Henri, G, Hofmann, W, Hoischen, C, Holch, T. L, Huber, D, Iwasaki, H, Jamrozy, M, Jouvin, L, Kastendieck, M. A, Katarzyński, K, Katz, U, King, J, Kluźniak, W, Komin, Nu, Kosack, K, Kraus, M, Lamanna, G, Lau, J, Lemoine-Goumard, M, Malyshev, D, Marx, R, Moderski, R, Mohrmann, L, Moulin, E, Murach, T, Niemiec, J, Oakes, L, O'Brien, P, Ohm, S, Oya, I, Parsons, R. D, Petrucci, P. -O, Peyaud, B, Piel, Q, Noel, A. Priyana, Prokoph, H, Pühlhofer, G, Punch, M, Raab, S, Rauth, R, Reimer, A, Reimer, O, Sahakian, V, Saito, S, Sanchez, D. A, Schüssler, F, Schutte, H, Senniappan, M, Simoni, R, Sinha, A, Sol, H, Specovius, A, Stegmann, C, Tavernet, J. -P, Terrier, R, Tuffs, R, Uchiyama, Y, van Rensburg, C, van Soelen, B, Vasileiadis, G, Vink, J, Wadiasingh, Z, Wagner, S. J, White, R, Żywucka, N
• Format: Journal Article
• Language: English
• Published: 20-09-2019
• Subjects: Physics - High Energy Astrophysical Phenomena
• DOI: 10.48550/arxiv.1909.09494

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. It is known from radio to gamma-ray observations 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 (PWN), a region of up to 10~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. While the synchrotron morphology
of the nebula is well established, it was up to now not known in which region
the very high-energy gamma rays are emitted. Here we report that the Crab
nebula has an angular extension at gamma-ray energies of 52 arcseconds
(assuming a Gaussian source width), significantly 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 are a new probe of a previously inaccessible electron and positron
energy range. We find that simulations of the electromagnetic emission
reproduce our new measurement, providing a non-trivial test of our
understanding of particle acceleration in the Crab nebula.