Search for photons with energies above 10 < sup> 18 eV using the hybrid detector of the Pierre Auger Observatory


A. Aab, Radboud University Nijmegen
P. Abreu, Universidade de Lisboa
M. Aglietta, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
I. Al Samarai, Laboratoire de Physique Nucléaire et de Hautes Energies
I. F.M. Albuquerque, Universidade de Sao Paulo - USP
I. Allekotte, Centro Atomico Bariloche
A. Almela, Consejo Nacional de Investigaciones Científicas y Técnicas
J. Alvarez Castillo, Universidad Nacional Autónoma de México
J. Alvarez-Muñiz, Universidad de Santiago de Compostela
G. A. Anastasi, Gran Sasso Science Institute
L. Anchordoqui, Lehman College
B. Andrada, Consejo Nacional de Investigaciones Científicas y Técnicas
S. Andringa, Universidade de Lisboa
C. Aramo, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
F. Arqueros, Universidad Complutense de Madrid
N. Arsene, Universitatea din Bucuresti
H. Asorey, Centro Atomico Bariloche
P. Assis, Universidade de Lisboa
J. Aublin, Laboratoire de Physique Nucléaire et de Hautes Energies
G. Avila, Pierre Auger Observatory
A. M. Badescu, University Politehnica of Bucharest
A. Balaceanu, Horia Hulubei National Institute of Physics and Nuclear Engineering
R. J. Barreira Luz, Universidade de Lisboa
J. J. Beatty, The Ohio State University
K. H. Becker, Bergische Universitat Wuppertal
J. A. Bellido, The University of Adelaide
C. Berat, Universite Grenoble Alpes
M. E. Bertaina, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
X. Bertou, Centro Atomico Bariloche
P. L. Biermann, Max Planck Institute for Radio Astronomy
P. Billoir, Laboratoire de Physique Nucléaire et de Hautes Energies
J. Biteau, Institut de Physique Nucléaire Orsay
B. Fick, Michigan Technological UniversityFollow
R. Kieckhafer, Michigan Technological UniversityFollow
D. F. Nitz, Michigan Technological UniversityFollow
et. al.

Document Type


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Department of Physics; Department of Electrical and Computer Engineering


A search for ultra-high energy photons with energies above 1 EeV is performed using nine years of data collected by the Pierre Auger Observatory in hybrid operation mode. An unprecedented separation power between photon and hadron primaries is achieved by combining measurements of the longitudinal air-shower development with the particle content at ground measured by the fluorescence and surface detectors, respectively. Only three photon candidates at energies 1 - 2 EeV are found, which is compatible with the expected hadroninduced background. Upper limits on the integral flux of ultra-high energy photons of 0.027, 0.009, 0.008, 0.008 and 0.007 km-2 sr-1 yr-1 are derived at 95% C.L. for energy thresholds of 1, 2, 3, 5 and 10 EeV. These limits bound the fractions of photons in the all-particle integral flux below 0.1%, 0.15%, 0.33%, 0.85% and 2.7%. For the first time the photon fraction at EeV energies is constrained at the sub-percent level. The improved limits are below the flux of diffuse photons predicted by some astrophysical scenarios for cosmogenic photon production. The new results rule-out the early top-down models - in which ultra-high energy cosmic rays are produced by, e.g., the decay of super-massive particles - and challenge the most recent super-heavy dark matter models.

Publisher's Statement

© 2017 IOP Publishing Ltd and Sissa Medialab. Publisher’s version of record: https://doi.org/10.1088/1475-7516/2017/04/009

Erratum: https://doi.org/10.1088/1475-7516/2020/09/E02

Publication Title

Journal of Cosmology and Astroparticle Physics