42 research outputs found

    An indication of anisotropy in arrival directions of utra-high-energy cosmic rays through comparison to the flux pattern of extragalactic gamma-ray sources

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    CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICOFINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE RIO DE JANEIROFAPESP - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULOMCTIC - MINIST√ČRIO DA CI√äNCIA, TECNOLOGIA, INOVA√á√ēES E COMUNICA√á√ēESA new analysis of the data set from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 degrees. recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS surveys, have been investigated for comparison. The sky model of cosmic-ray density constructed using each catalog has two free parameters, the fraction of events correlating with astrophysical objects, and an angular scale characterizing the clustering of cosmic rays around extragalactic sources. A maximum-likelihood ratio test is used to evaluate the best values of these parameters and to quantify the strength of each model by contrast with isotropy. It is found that the starburst model fits the data better than the hypothesis of isotropy with a statistical significance of 4.0 sigma, the highest value of the test statistic being for energies above 39 EeV. The three alternative models are favored against isotropy with 2.7 sigma-3.2 sigma significance. The origin of the indicated deviation from isotropy is examined and prospects for more sensitive future studies are discussed.8532110CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICOFINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE RIO DE JANEIROFAPESP - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULOMCTIC - MINIST√ČRIO DA CI√äNCIA, TECNOLOGIA, INOVA√á√ēES E COMUNICA√á√ēESCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICOFINEP - FINANCIADORA DE ESTUDOS E PROJETOSFAPERJ - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE RIO DE JANEIROFAPESP - FUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULOMCTIC - MINIST√ČRIO DA CI√äNCIA, TECNOLOGIA, INOVA√á√ēES E COMUNICA√á√ēESSem informa√ß√£oSem informa√ß√£oSem informa√ß√£oSem informa√ß√£oSem informa√ß√£oAg√™ncias de fomento estrangeiras apoiaram essa pesquisa, mais informa√ß√Ķes acesse artig

    Inferences on mass composition and tests of hadronic interactions from 0.3 to 100 EeV using the water-Cherenkov detectors of the Pierre Auger Observatory

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    CONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICO - CNPQFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDA√á√ÉO CARLOS CHAGAS FILHO DE AMPARO √Ä PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULO - FAPESPWe present a new method for probing the hadronic interaction models at ultrahigh energy and extracting details about mass composition. This is done using the time profiles of the signals recorded with the water-Cherenkov detectors of the Pierre Auger Observatory. The profiles arise from a mix of the muon and electromagnetic components of air showers. Using the risetimes of the recorded signals, we define a new parameter, which we use to compare our observations with predictions from simulations. We find, first, inconsistencies between our data and predictions over a greater energy range and with substantially more events than in previous studies. Second, by calibrating the new parameter with fluorescence measurements from observations made at the Auger Observatory, we can infer the depth of shower maximum X-max for a sample of over 81,000 events extending from 0.3 to over 100 EeV. Above 30 EeV, the sample is nearly 14 times larger than what is currently available from fluorescence measurements and extending the covered energy range by half a decade. The energy dependence of < X-max gt; is compared to simulations and interpreted in terms of the mean of the logarithmic mass. We find good agreement with previous work and extend the measurement of the mean depth of shower maximum to greater energies than before, reducing significantly the statistical uncertainty associated with the inferences about mass composition.9612122CONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICO - CNPQFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDA√á√ÉO CARLOS CHAGAS FILHO DE AMPARO √Ä PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENT√ćFICO E TECNOL√ďGICO - CNPQFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDA√á√ÉO CARLOS CHAGAS FILHO DE AMPARO √Ä PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDA√á√ÉO DE AMPARO √Ä PESQUISA DO ESTADO DE S√ÉO PAULO - FAPESPSem informa√ß√£oSem informa√ß√£oSem informa√ß√£o1999/05404-32010/07359-6The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malargue. We are very grateful to the following agencies and organizations for financial support: (Argentina) Comision Nacional de Energia Atomica; Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Gobierno de la Provincia de Mendoza; Municipalidad de Malargue; and NDM Holdings and Valle Las Lenas in gratitude for their continuing cooperation over land access; (Australia) the Australian Research Council; (Brazil) Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Financiadora de Estudos e Projetos (FINEP); Fundacao de Amparo a Pesquisa do Estado de Rio de Janeiro (FAPERJ); Sao Paulo Research Foundation (FAPESP) Grants No. 2010/07359-6 and No. 1999/05404-3; Ministerio de Ciencia e Tecnologia (MCT); (Czech Republic) Grants No. MSMT CR LG15014, LO1305, LM2015038, and CZ.02.1.01/0.0/0.0/16\_013/0001402; (France) Centre de Calcul IN2P3/CNRS; Centre National de la Recherche Scientifique (CNRS); Conseil Regional Ile-de-France; Departement Physique Nucleaire et Corpusculaire (PNC-IN2P3/CNRS); Departement Sciences de l'Univers (SDU-INSU/CNRS); Institut Lagrange de Paris (ILP) Grant No. LABEX ANR-10-LABX-63 within the Investissements d'Avenir Programme Grant No. ANR-11-IDEX-0004-02; (Germany) Bundesministerium fur Bildung und Forschung (BMBF); Deutsche Forschungsgemeinschaft (DFG); Finanzministerium Baden-Wurttemberg; Helmholtz Alliance for Astroparticle Physics (HAP); Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF); Ministerium fur Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen; Ministerium fur Wissenschaft, Forschung und Kunst des Landes Baden-Wurttemberg; (Italy) Istituto Nazionale di Fisica Nucleare (INFN); Istituto Nazionale di Astrofisica (INAF); Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR); CETEMPS Center of Excellence; Ministero degli Affari Esteri (MAE); (Mexico) Consejo Nacional de Ciencia y Tecnologia (CONACYT) Grant No. 167733; Universidad Nacional Autonoma de Mexico (UNAM); PAPIIT DGAPA-UNAM; (Netherlands) Ministerie van Onderwijs, Cultuur en Wetenschap; Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO); Stichting voor Fundamenteel Onderzoek der Materie (FOM); (Poland) National Centre for Research and Development, Grants No. ERA-NET-ASPERA/01/11 and No. ERA-NET-ASPERA/02/11; National Science Centre, Grants No. 2013/08/M/ST9/00322, No. 2013/08/M/ST9/00728, No. HARMONIA 5-2013/10/M/ST9/00062, and No. UMO-2016/22/M/ST9/00198; (Portugal) Portuguese national funds and FEDER funds within Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia (COMPETE); (Romania) Romanian Authority for Scientific Research ANCS; CNDI-UEFISCDI partnership projects Grants No. 20/2012, No. 194/2012, and No. PN 16 42 01 02; (Slovenia) Slovenian Research Agency; (Spain) Comunidad de Madrid; Fondo Europeo de Desarrollo Regional (FEDER) funds; Ministerio de Economia y Competitividad; Xunta de Galicia; European Community 7th Framework Program Grant No. FP7-PEOPLE-2012-IEF-328826; (USA) Department of Energy, Contracts No. DE-AC02-07CH11359, No. DE-FR02-04ER41300, No. DE-FG02-99ER41107, and No. DE-SC0011689; National Science Foundation, Grant No. 0450696; The Grainger Foundation; Marie Curie-IRSES/EPLANET (European Union); European Particle Physics Latin American Network; European Union 7th Framework Program, Grant No. PIRSES-2009-GA-246806; European Union's Horizon 2020 Research and Innovation Programme (Grant No. 646623); and UNESCO

    Multi-messenger observations of a binary neutron star merger