A large light-mass component of cosmic rays at 10(17)-10(17.5) electronvolts from radio observations

Buitink S, Corstanje A, Falcke H, Hoerandel JR, Huege T, Nelles A, Rachen JP, Rossetto L, Schellart P, Scholten O, Ter Veen S, Thoudam S, Trinh TNG, Anderson J, Asgekar A, Avruch IM, Bell ME, Bentum MJ, Bernardi G, Best P, Bonafede A, Breitling F, Broderick JW, Brouw WN, Brueggen M, Buteher HR, Carbone D, Ciardi B, Conway JE, De Gasperin E, De Geus E, Deller A, Dettmar RJ, Van Diepen G, Duscha S, Eisloeffel J, Engels D, Enriquez JE, Fallows RA, Fender R, Ferrari C, Frieswijk W, Garrett MA, Griessmeier JM, Gunst AW, Van Haarlem MP, Hassall TE, Heald G, Hessels JWT, Hoeft M, Horneffer A, Iaeobelli M, Intema H, Juette E, Karastergiou A, Kondratiev VI, Kramer M, Kuniyoshi M, Kuper G, Van Lecuwen J, Loose GM, Maat P, Nann G, Markoff S, Mcfadden R, Mckay-Bukowski D, Mckean JP, Mevius M, Mulcahy DD, Munk H, Norden MJ, Orru E, Paas H, Pandey-Pommier M, Pandey VN, Pietka M, Pizzo R, Polatidis AG, Reich W, Roetgering HJA, Scaife AMM, Schwarz DJ, Serylak M, Sluman J, Smirnov O, Stappers BW, Steinmetz M, Stewart A, Swinbank J, Tagger M, Tang Y, Tasse C, Toribio MC, Vermeulen R, Vocks C, Vogt C, Van Weeren RJ, Wijers RAMJ, Wijnholds SJ, Wise MW, Wucknitz O, Yatawatta S, Zarka P, Zensuss JA (2016)

Publication Status: Published

Publication Type: Journal article

Publication year: 2016

Journal

Publisher: NATURE PUBLISHING GROUP

Book Volume: 531

Pages Range: 70-+

Journal Issue: 7592

DOI: 10.1038/nature16976

Abstract

Cosmic rays are the highest-energy particles found in nature. Measurements of the mass composition of cosmic rays with energies of 10(17)-10(18) electronvolts are essential to understanding whether they have galactic or extragalactic sources. It has also been proposed that the astrophysical neutrino signal1 comes from accelerators capable of producing cosmic rays of these energies(2). Cosmic rays initiate air showers-cascades of secondary particles in the atmosphere-and their masses can be inferred from measurements of the atmospheric depth of the shower maximum3 (Xmax; the depth of the air shower when it contains the most particles) or of the composition of shower particles reaching the ground(4). Current measurements(5) have either high uncertainty, or a low duty cycle and a high energy threshold. Radio detection of cosmic rays(6-8) is a rapidly developing technique(9) for determining Xmax (refs 10, 11) with a duty cycle of, in principle, nearly 100 per cent. The radiation is generated by the separation of relativistic electrons and positrons in the geomagnetic field and a negative charge excess in the shower front(6,12). Here we report radio measurements of X-max with a mean uncertainty of 16 grams per square centimetre for air showers initiated by cosmic rays with energies of 1017-1017.5 electronvolts. This high resolution in Xmax enables us to determine the mass spectrum of the cosmic rays: we find a mixed composition, with a light-mass fraction (protons and helium nuclei) of about 80 per cent. Unless, contrary to current expectations, the extragalactic component of cosmic rays contributes substantially to the total flux below 10(17.5) electronvolts, our measurements indicate the existence of an additional galactic component, to account for the light composition that we measured in the 10(17)-10(17.5) electronvolt range.

Authors with CRIS profile

Involved external institutions

Netherlands Institute for Radio Astronomy Netherlands (NL) University of Southampton United Kingdom (GB) University of Edinburgh United Kingdom (GB) Ruhr-Universität Bochum (RUB) Germany (DE) Chalmers University of Technology / Chalmers tekniska högskola Sweden (SE) University of Groningen / Rijksuniversiteit Groningen Netherlands (NL) Radboud University Nijmegen Netherlands (NL) Leibniz Institute for Astrophysics Potsdam / Leibniz-Institut für Astrophysik Potsdam Germany (DE) Karlsruhe Institute of Technology (KIT) Germany (DE) Universität Hamburg (UHH) Germany (DE) Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. (MPG) / Max Planck Society for the Advancement of Science Germany (DE) Netherlands Institute for Space Research / Stichting Ruimteonderzoek Nederland (SRON) Netherlands (NL) Leiden University Netherlands (NL) University of Oxford United Kingdom (GB) Oulun Yliopisto / University of Oulo Finland (FI) Thüringer Landessternwarte Tautenburg (TLS) - Karl-Schwarzschild-Observatorium Germany (DE) Max-Planck-Institut für Radioastronomie / Max Planck Institute for Radio Astronomy Germany (DE) University of Amsterdam Netherlands (NL) University of Manchester United Kingdom (GB) Universität Bielefeld Germany (DE) SKA South Africa South Africa (ZA) Observatoire de Lyon France (FR) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR) Hamburger Sternwarte Germany (DE) Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ Germany (DE) Australia Telescope National Facility (ATNF) Australia (AU) University of Orléans / Université d'Orléans France (FR) Harvard University United States (USA) (US) University of Côte d'Azur / Université Côte d'Azur France (FR) Australian National University (ANU) Australia (AU) National Astronomical Observatory of Japan / 国立天文台(NAOJ) Japan (JP) Vrije Universiteit Brussel (VUB) Belgium (BE) Rhodes University South Africa (ZA)

How to cite

APA:

Buitink, S., Corstanje, A., Falcke, H., Hoerandel, J.R., Huege, T., Nelles, A.,... Zensuss, J.A. (2016). A large light-mass component of cosmic rays at 10(17)-10(17.5) electronvolts from radio observations. Nature, 531(7592), 70-+. https://dx.doi.org/10.1038/nature16976

MLA:

Buitink, S., et al. "A large light-mass component of cosmic rays at 10(17)-10(17.5) electronvolts from radio observations." Nature 531.7592 (2016): 70-+.

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