Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory

J Abraham,M Gómez Berisso,C Newman-Holmes,R Tcaciuc,F Arqueros,M Mostafá,L Nožka,V Verzi,M Prouza,G Hebrero,T Huege,F Sarazin,P Abreu,P Homola,V Rizi,H Falcke,O Deligny,P Allison,T Bäcker,S Benzvi,S Grebe,D Ravignani,A Tamburro,W Fulgione,H Schieler,A Tonachini,H Glass,J Pallotta,M Iarlori,N Smetniansky De Grande,H Blümer,C Rivière,M Kaducak,R Cester,J Chye,S Coutu,A Horneffer,M Pimenta,L Wiencke,P Wahrlich,M Monasor,R Sato,X Garrido,A Gorgi,P Petrinca,A Cordier,S Schulte,J Knapp,O Pisanti,M Melissas,C Bleve,T Hebbeker,T Paul,N Fazzini,M Ave,G Matthiae,S Navas,R Squartini,R Šmída,A Schmidt,I Valiño,J Rautenberg,B Wundheiler,D Góra,X Bertou,L Villaseñor,K Payet,M Kleifges,M Zavrtanik,C Timmermans,N Scharf,R Engel,D D’Urso,A Creusot,F Schroeder,T Asch,H Spinka,R Meyhandan,D Monnier Ragaigne,I Fleck,M Mcewen,U Cotti,D García Gámez,J Chudoba,M Erdmann,M Platino,D Thomas,V Pirronello,D Mandat,M Tueros,E Trovato,H Wilczyński,I Sidelnik,P Billoir,D Semikoz,F Ionita,L Del Peral,Y Guardincerri,R López,M Santander,I Lhenry-Yvon,A Castellina,M Roth,A Chou,R Ticona,F Contreras,J Kleinfeller,D Maurizio,C Di Giulio,M Risse,R Conceição,F Sánchez,G Parente,F Montanet,B Keilhauer,A Lucero,P Assis,O Krömer,B Connolly,G Ros,G Golup,A Bellétoile,D Nitz,A Segreto,M Settimo,C Morris,R Pesce,A Anzalone,O Wainberg,N Pacheco,C Aguirre,M Giller,K Arisaka,I Zaw,Z Szadkowski,D Newton,R Mussa,P Privitera,F Arneodo,M Patel,P Brogueira,M Hrabovský,S Riggi,D Heck,W Tkaczyk,G Salina,B Morales,S Petrera,S Mueller,D Tcherniakhovski,A Zepeda,C Morello,A Pichel,A Bueno,E Strazzeri,A Curutiu,S Jiraskova,J Coppens,J Allen,L Miramonti,G Yuan,T Tarutina,C Lachaud,T Beau,E Zas,H Salazar,N Nierstenhoefer,U Giaccari,J Rosado,S Vorobiov,M Urban,J Brack,J Sorokin,P Facal San Luis,E Kemp,J Aublin,O Catalano,P Younk,C Aramo,A Della Selva,D Melo,R Knapik,Y Petrov,C Robledo,M Aglietta,S Pastor,K Daumiller,F Salamida,A Dorofeev,D Nosek,I De Mitri,H Schoorlemmer,D Dornic,G La Rosa,M Scuderi,P Gonçalves,J Tiffenberg,V Scherini,B Wilczyńska,T Pierog,A Etchegoyen,L Caramete,B Tomé,P Hansen,S Reucroft,P Lebrun,A Insolia,V De Souza,C Dobrigkeit,S Harmsma,V Halenka,T Schmidt,S Westerhoff,R Ulrich,P Mantsch,C Pfendner,B Fick,D Zavrtanik,J Swain,R Pelayo,M Pontz,D Veberič,I Torres,T Karova,D Badagnani,A Tamashiro,S Gambetta,R Bruijn,A Stutz,A Filevich,M Pech,G Decerprit,A Petrolini,P Gouffon,C Macolino,L Nellen,A Italiano,J Lee,P Sommers,E Parizot,A Velarde,S Andringa,S Sarkar,M Grigat,R Piegaia,F Blanco,G Tristram,H Gemmeke,J Pochon,M Unger,R Caruso,L Perrone,J Gutiérrez,D Pakk Selmi-Dei,E Petermann,S Maldera,A Criss,T Suomijärvi,R Bonino,N Kunka,M Palatka,F Guarino,S Parlati,D Warner,E Colombo,P Buchholz,D Lebrun,P Schiffer,C De Donato,V Pavlidou,B Rouillé-D’Orfeuil,L Valore,A Ferrero,D Harari,M Leuthold,A Menshikov,C Delle Fratte,H Asorey,D Garcia-Pinto,M Videla,A Haungs,I Allekotte,G Navarra,S Fliescher,V Tuci,C Hojvat,P Bauleo,D Martello,E Menichetti,D Gonzalez,M Hussain,C Bonifazi,G De 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Rodrı́guez Martino ,D H Koang ,J C Diaz ,J L Harton ,Marcelo Amaral ,J L La Rosa Navarro ,B B Siffert ,P L Ghia ,C J Todero Peixoto ,S L C Barroso ,J Petrović ,Juan Rojo ,J Schovancová ,Daniel Kruppke ,P Nečesal ,Olaf Scholten ,H O Klages ,William H Miller ,M A Duvernois ,P A Kasper ,M S A B Leão ,W J M De Mello ,A F Barbosa ,I Duţan ,D B Tridapalli ,C O Escobar ,María Teresa Dova ,P N Diep ,B E Smith ,S Dagoret ,A D Supanitsky ,J C Dos Anjos ,M Bohã̌cov́a ,W Rodrigues De Carvalho ,J N Matthews ,Alexander Kusenko ,A S Krieger ,Jan Pękala ,J Álvarez-Muñiz ,M C Maccarone ,S Argirò ,John Matthews ,Ioana Codrina Maris ,David M Schuster ,P Trávníc̆ek ,J R T De Mello Neto ,G Rodríguez ,G R Snow ,G Ávila ,J D Hague ,M D Rodríguez‐Frías ,J F Valdés Galicia ,J J Beatty ,I M Pepe ,J C D’olivo ,C Bérat ,H.-P Dembinski ,S J Sciutto ,A A Watson ,I Rodríguez-Cabo ,A M Van Den Berg ,Nguyễn Thị Phương Thảo ,María J Ortiz ,Fabrizio Ortolani ,Luis A Anchordoqui ,Silvia Mollerach ,Glennys R Farrar ,M Gold ,P T Nhung ,B J Whelan ,H J Mathes ,M Sutherland ,M A Leigui De Oliveira ,Petr Schovánek ,A F Grillo ,R M De Almeida ,J J Lozano Bahilo ,L Cazón ,G Medina‐Tanco ,C E Santo ,R F Gamarra ,Balázs Kégl ,E D Fraenkel ,Antonio Fernández-Aliseda Redondo ,W C Brown ,A Smia Lkowski ,A G Mariazzi ,O Martinez ,Péter Mazur ,Graciela B Gelmini ,Flávio Rezende ,K B Barber ,J W Cronin

doi:10.1016/j.astropartphys.2009.04.003

Abstract

From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV ( 1 EeV ≡ 10 18 eV ) , respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top–down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton-air cross-section.

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