Measurement of the cosmic-ray energy spectrum above 2.5 × 10(18) eV using the Pierre Auger Observatory
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Amer Physical Soc
Date
2020-09-16Referencia bibliográfica
Aab, A., Abreu, P., Aglietta, M., Albury, J. M., Allekotte, I., Almela, A., ... & Anchordoqui, L. (2020). Measurement of the cosmic-ray energy spectrum above 2.5× 10 18 eV using the Pierre Auger Observatory. Physical Review D, 102(6), 062005. [DOI:10.1103/PhysRevD.102.062005]
Sponsorship
Argentina-Comision Nacional de Energia Atomica; ANPCyT; Argentina-Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Argentina-Gobierno de la Provincia de Mendoza; Argentina-Municipalidad de Malargue; Argentina-NDM Holdings; Argentina-Valle Las Lenas; National Council for Scientific and Technological Development (CNPq); Brazil-Financiadora de Estudos e Projetos (FINEP); Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ); Brazil-Sao Paulo Research Foundation (FAPESP) 2019/10151-2 2010/07359-6 1999/05404-3; Brazil-Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes (MCTIC); France-Centre de Calcul IN2P3/CNRS; Centre National de la Recherche Scientifique (CNRS); France-Conseil Regional Ile-deFrance; France-Departement Physique Nucleaire et Corpusculaire (PNC-IN2P3/CNRS); France-Departement Sciences de l'Univers (SDU-INSU/CNRS; French National Research Agency (ANR) LABEX ANR-10-LABX-63 ANR-11-IDEX-0004-02; Federal Ministry of Education & Research (BMBF); German Research Foundation (DFG); Germany-Finanzministerium Baden-Wurttemberg; Germany-Helmholtz Alliance for Astroparticle Physics (HAP); Germany-Helmholtz Gemeinschaft Deutscher Forschungszentren (HGF); Germany-Ministerium fur Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen; Germany-Ministerium fur Wissenschaft, Forschung und Kunst des Landes Baden Wurttemberg; Italy-Istituto Nazionale di Fisica Nucleare (INFN); Italy-Istituto Nazionale di Astrofisica (INAF); Italy-Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR); Italy-CETEMPS Center of Excellence; Italy-Ministero degli Affari Esteri (MAE); Consejo Nacional de Ciencia y Tecnologia (CONACyT) 167733; Mexico-Universidad Nacional Autonoma de Mexico (UNAM); Mexico-PAPIIT DGAPA-UNAM; The Netherlands-Ministry of Education, Culture and Science; The Netherlands-Netherlands Organisation for Scientific Research (NWO); SURF Cooperative; Poland -Ministry of Science and Higher Education DIR/WK/2018/11; Poland -National Science Centre 2013/08/M/ST9/00322 2016/23/B/ST9/01635 HARMONIA 52013/10/M/ST9/00062 UMO-2016/22/M/ST9/00198; Portugal-Portuguese national funds; Portugal-FEDER funds within Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia (COMPETE); Romania-Program Nucleu within MCI PN19150201/16N/2019 PN19060102; Romania-PNCDI III PN-III-P1-1.2-PCCDI-2017-0839/19PCCDI/2018; Slovenia-Slovenian Research Agency P1-0031 P1-0385 I0-0033 N1-0111; Spain Ministerio de Economia, Industria y Competitividad FPA2017-85114-P FPA2017-85197-P; Spain Xunta de Galicia ED431C 2017/07; Junta de Andalucía SOMM17/6104/UGR; Spain Feder Funds; Spain RENATA Red Nacional Tematica de Astroparticulas FPA2015-68783-REDT; Spain Maria de Maeztu Unit of Excellence MDM-2016-0692; United States Department of Energy (DOE) DE-AC02-07CH11359 DE-FR02-04ER41300 DE-FG02-99ER41107 DE-SC0011689; National Science Foundation (NSF) 0450696; USA-Grainger Foundation; USA-Marie Curie-IRSES/EPLANET; USA-European Particle Physics Latin American Network; USA-UNESCO; Dutch national e-infrastructure; Australian Research Council; Romania-Romanian Ministry of Education and Research; MSMT CR LTT18004 LM2015038 LM2018102 CZ.02.1.01/0.0/0.0/16_013/0001402 CZ.02.1.01/0.0/0.0/18_046/0016010 CZ.02.1.01/0.0/0.0/17_049/0008422Abstract
We report a measurement of the energy spectrum of cosmic rays for energies above 2.5 × 1018 eV based
on 215,030 events recorded with zenith angles below 60°. A key feature of the work is that the estimates of
the energies are independent of assumptions about the unknown hadronic physics or of the primary mass
composition. The measurement is the most precise made hitherto with the accumulated exposure being so
large that the measurements of the flux are dominated by systematic uncertainties except at energies above
5 × 1019 eV. The principal conclusions are
(1) The flattening of the spectrum near 5 × 1018 eV, the so-called “ankle,” is confirmed.
(2) The steepening of the spectrum at around 5 × 1019 eV is confirmed.
(3) Anewfeature has been identified in the spectrum: in the region above the ankle the spectral index γ of the
particle flux (∝ E−γ) changes from 2.51 0.03 ðstatÞ 0.05 ðsystÞ to 3.05 0.05 ðstatÞ 0.10 ðsystÞ
before changing sharply to 5.1 0.3 ðstatÞ 0.1 ðsystÞ above 5 × 1019 eV.
(4) No evidence for any dependence of the spectrum on declination has been found other than a mild
excess from the Southern Hemisphere that is consistent with the anisotropy observed above
8 × 1018 eV.