Upper limit on the cosmic-ray photon flux above 1019 eV using the surface detector of the Pierre Auger Observatory
Date
2008
Authors
Abraham, J.
Abreu, P.
Aglietta, M.
Aguirre, I.
Allard, D.
Allekotte, I.
Allen, J.
Allison, P.
Alvarez-Muniz, J.
Ambrosio, M.
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Advisors
Journal Title
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Volume Title
Type:
Journal article
Citation
Astroparticle Physics, 2008; 29(4):243-256
Statement of Responsibility
J. Abraham...B.R. Dawson...M. Ziolkowski et al.
Conference Name
Abstract
A method is developed to search for air showers initiated by photons using data recorded by the surface detector of the Auger Observatory. The approach is based on observables sensitive to the longitudinal shower development, the signal risetime and the curvature of the shower front. Applying this method to the data, upper limits on the flux of photons of 3.8 × 10- 3, 2.5 × 10- 3, and 2.2 × 10- 3 km- 2 sr- 1 yr- 1 above 1019 eV, 2 × 1019 eV, and 4 × 1019 eV are derived, with corresponding limits on the fraction of photons being 2.0%, 5.1%, and 31% (all limits at 95% c.l.). These photon limits disfavor certain exotic models of sources of cosmic rays. The results also show that the approach adopted by the Auger Observatory to calibrate the shower energy is not strongly biased by a contamination from photons. © 2008 Elsevier B.V. All rights reserved.
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Copyright © 2008 Elsevier B.V. All rights reserved.