2007/12/31 by The Pierre Auger Collaboration, J. Abraham, P. Abreu +98 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #astro-ph #hep-ph
paper · pdf · doi:10.1016/j.astropartphys.2008.01.003
published as Astropart.Phys.29:243-256,2008 · 28 pages, 9 figures; v2: minor modifications; accepted by Astropart. Phys
arxiv created 2008/01/29 · openalex publication_date 2008/05/01 · arxiv updated 2012/08/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
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.