1. Indication of a mass-dependent anisotropy above 10 18.7 eV in the hybrid data of the Pierre Auger Observatory
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Pierre Auger Collaboration, Mayotte, Eric, Abreu, Pedro, Aglietta, Marco, Albury, Justin M., Allekotte, Ingomar, Almela, Alejandro, Alvarez-Muniz, Jaime, Alves Batista, Rafael, Anastasi, Gioacchino Alex, Anchordoqui, Luis A., Andrada, Belén, Andringa, Sofia, Aramo, Carla, Araújo Ferreira, Paulo Ricardo, Arteaga Velazquez, Juan Carlos, Asorey, Hernán Gonzalo, Assis, Pedro, Avila, Gualberto, Badescu, Alina Mihaela, Bakalova, Alena, Balaceanu, Alexandru, Barbato, Felicia, Barreira Luz, Ricardo Jorge, Becker, Karl-Heinz, Bellido, Jose A., Berat, Corinne, Bertaina, Mario Edoardo, Bertou, Xavier, Biermann, Peter L., Binet, Virginia, Bismark, Kathrin, Bister, Teresa, Biteau, Jonathan, Blazek, Jiri, Bleve, Carla, Bohacova, Martina, boncioli, denise, Bonifazi, Carla, Bonneau Arbeletche, Luan, Borodai, Nataliia, Botti, Ana Martina, Brack, Jeffrey, Bretz, Thomas, Brichetto Orchera, P. Gabriel, Briechle, Florian Lukas, Buchholz, Peter, Bueno, Antonio, Buitink, Stijn, Buscemi, Mario, Büsken, Max, Caballero-Mora, Karen S., Caccianiga, Lorenzo, Canfora, Fabrizia, Caracas, Ioana, Carceller, Juan Miguel, Caruso, Rossella, Castellina, Antonella, Catalani, Fernando, Cataldi, Gabriella, Cazon, Lorenzo, Cerda, Marcos, Chinellato, Jose Augusto, Chudoba, Jiri, Chytka, Ladislav, Clay, Roger W., Cobos Cerutti, Agustín, Colalillo, Roberta, Coleman, Alan, Coluccia, Maria Rita, Conceição, Rúben, Condorelli, Antonio, Consolati, Giovanni, Contreras, Fernando, Convenga, Fabio, Correia dos Santos, Diego, Covault, Corbin, Dasso, Sergio, Daumiller, Kai, Dawson, Bruce R., Day, Jarryd A., Almeida, Rogerio M. de, Jesús, Joaquín de, Jong, Sijbrand J. de, De Mauro, Giuseppe, Mello Neto, João de, De Mitri, Ivan, Oliveira, Jaime de, Oliveira Franco, Danelise de, Palma, Francesco de, Souza, Vitor de, De Vito, Emanuele, Río, Mariano del, Deligny, Olivier, Deval, Luca, Matteo, Armando di, Dobrigkeit, Carola, D'Olivo, Juan Carlos, Domingues Mendes, Luis Miguel, Anjos, Rita dos, Santos, Diego dos, Dova, Maria Teresa, Ebr, Jan, Engel, Ralph, Epicoco, Italo, Erdmann, Martin, Escobar, Carlos O., Etchegoyen, Alberto, Falcke, Heino, Farmer, John, Farrar, Glennys R., Fauth, Anderson, Fazzini, Norberto, Feldbusch, Fridtjof, Fenu, Francesco, Fick, Brian, Figueira, Juan Manuel, Filipcic, Andrej, Fitoussi, Thomas, Fodran, Tomáš, Freire, Martín Miguel, Fujii, Toshihiro, Fuster, Alan, Galea, Cristina, Galelli, Claudio, García, Beatriz, García Vegas, Adrianna Luz, Gemmeke, Hartmut, Gesualdi, Flavia, Gherghel-Lascu, Alexandru, Ghia, Piera Luisa, GIACCARI, Ugo, Giammarchi, Marco, Glombitza, Jonas, Gobbi, Fabian, Gollan, Fernando, Golup, Geraldina, Gómez Berisso, Mariano, Gómez Vitale, Primo F., Gongora, Juan Pablo, González, Juan Manuel, Gonzalez, Nicolas Martin, Goos, Isabel, Gora, Dariusz, Gorgi, Alessio, Gottowik, Marvin, Grubb, Trent D., Guarino, Fausto, Guedes, Germano, Guido, Eleonora, Hahn, Steffen, Hamal, Petr, Hampel, Matías Rolf, Hansen, Patricia María, Harari, Diego, Harvey, Violet M., Haungs, Andreas, Hebbeker, Thomas, Heck, Dieter, Hill, Gary C., Hojvat, Carlos, Hörandel, Jörg, Horvath, Pavel, Hrabovsky, Miroslav, Huege, Tim, Insolia, Antonio, Isar, Paula Gina, Janecek, Petr, Johnsen, Jeffrey A., Juryšek, Jakub, Kääpä, Alex, Kampert, Karl-Heinz, Karastathis, Nikolaos, Keilhauer, Bianca, Kemp, Julian, Khakurdikar, Abha, Kizakke Covilakam, Varada Varma, Klages, Hans, Kleifges, Matthias, Kleinfeller, Jonny, Köpke, Marcel, Kunka, Norbert, Lago, Bruno L., Lang, Rodrigo Guedes, Langner, Niklas, Leigui de Oliveira, Marcelo Augusto, Lenok, Vladimir, Letessier-Selvon, Antoine, Lhenry-Yvon, Isabelle, Lo Presti, Domenico, LOPES, Luis, López, Rebeca, Lu, Lu, Luce, Quentin, Lundquist, Jon Paul, Machado Payeras, Allan, Mancarella, Giovanni, Mandat, Dusan, Manning, Bradley C., Manshanden, Julien, Mantsch, Paul, Marafico, Sullivan, Mariazzi, Analisa, Maris, Ioana Codrina, Marsella, Giovanni, Martello, Daniele, Martinelli, Sara, Martínez Bravo, Oscar, Mastrodicasa, Massimo, Mathes, Hermann-Josef, Matthews, James, Matthiae, Giorgio, Mazur, Peter, Medina-Tanco, Gustavo, Melo, Diego, Menshikov, Alexander, Merenda, Kevin-Druis, Michal, Stanislav, Micheletti, Maria Isabel, Miramonti, Lino, Mollerach, Silvia, Montanet, François, Morello, Carlo, Mostafa, Miguel, Müller, Ana L., Muller, Marcio Aparecido, Mulrey, Katharine, Mussa, Roberto, Muzio, Marco Stein, Namasaka, Wilson M., Nasr-Esfahani, Alina, Nellen, Lukas, Niculescu-Oglinzanu, Mihai, Niechciol, Marcus, Nitz, Dave, Nosek, Dalibor, Novotný, Vladimír, Nozka, Libor, Nucita, Achille, Nunez, Luis A., Palatka, Miroslav, Pallotta, Juan, Papenbreer, Philipp, Parente, Gonzalo, Parra, Alejandra, Pawlowsky, Jannis, Pech, Miroslav, Pedreira, Francisco, Pękala, Jan, Pelayo, Rodrigo, Peña-Rodríguez, Jesús, Pereira Martins, Edyvania Emily, Perez Armand, Johnnier, Pérez Bertolli, Carmina, Perlin, Matías, Perrone, Lorenzo, Petrera, Sergio, Pierog, Tanguy, Pimenta, Mário, Pirronello, Valerio, Platino, Manuel, Pont, Bjarni, Pothast, Mart, Privitera, Paolo, Prouza, Michael, Puyleart, Andrew, Querchfeld, Sven, Rautenberg, Julian, Ravignani, Diego, Reininghaus, Maximilian, Ridky, Jan, Riehn, Felix, Risse, Markus, Rizi, Vincenzo, Rodrigues de Carvalho, Washington, Rodriguez Rojo, Jorge Rubén, Roncoroni, Matías J., Rossoni, Simone, Roth, Markus, Roulet, Esteban, Rovero, Adrian, Ruehl, Philip, Saftoiu, Alexandra, Salamida, Francesco, Salazar, Humberto Ibarguen, Salina, Gaetano, Sanabria Gomez, Jose, Sánchez, Federico Andrés, Santos, Edivaldo Moura, Santos, Eva, Sarazin, Fred, Sarmento, Raul, Sarmiento-Cano, Christian, Sato, Ricardo, Savina, Pierpaolo, Schäfer, Christoph M., Scherini, Viviana, Schieler, Harald, Schimassek, Martin, Schimp, Michael, Schlüter, Felix, Schmidt, David, Scholten, Olaf, Schovanek, Petr, Schröder, Frank G., Schröder, Sonja, Schulte, Josina, Sciutto, Sergio, Scornavacche, Marina, Segreto, Alberto, Sehgal, Srijan, Shellard, Ronald C., Sigl, Guenter, Silli, Gaia, Sima, Octavian, Smida, Radomir, Sommers, Paul, Soriano, Jorge F., Souchard, Julien, Squartini, Ruben, Stadelmaier, Maximilian, Stanca, Denis, Stanič, Samo, Stasielak, Jaroslaw, Stassi, Patrick, Streich, Alexander, Suárez-Durán, Mauricio, Sudholz, Tristan, Suomijarvi, Tiina, Supanitsky, A. Daniel, Szadkowski, Zbigniew, Tapia, Alex, Taricco, Carla, Timmermans, Charles, Tkachenko, Olena, Tobiska, Petr, Todero Peixoto, Carlos J., Tomé, Bernardo, Torrès, Zoé, Travaini, Andres, Travnicek, Petr, Trimarelli, Caterina, Tueros, Matias, Ulrich, Ralf, Unger, Michael, Vaclavek, Lukáš, Vacula, Martin, Valdés Galicia, Jose F., Valore, Laura, Varela, Enrique, Vásquez-Ramírez, Adriana, Veberic, Darko, Ventura, Cynthia, Vergara Quispe, Indira D., Verzi, Valerio, Vicha, Jakub, Vink, Jacco, Vorobiov, Serguei, Wahlberg, Hernan, Watanabe, Clara Keiko Oliveira, Watson, Alan, Weber, Marc, Weindl, Andreas, Wiencke, Lawrence, Wilczyński, Henryk, Wirtz, Marcus, Wittkowski, David, Wundheiler, Brian, Yushkov, Alexey, Zapparrata, Orazio, Zas, Enrique, Zavrtanik, Danilo, Zavrtanik, Marko, and Zehrer, Lukas
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Physics ,Pierre Auger Observatory ,Astronomy ,Astrophysics ,Galactic plane ,Mass composition ,Threshold energy ,Distribution (mathematics) ,Experimental High Energy Physics ,Sensitivity (control systems) ,High Energy Physics ,ddc:620 ,Anisotropy ,Hybrid data ,Engineering & allied operations - Abstract
We test the hypothesis of an anisotropy laying along the galactic plane which depends on the mass of primary cosmic-rays. The sensitivity to primary mass is provided by the depth of shower maximum, $X_\text{max}$, from hybrid events measured at the Pierre Auger Observatory. The 14 years of available data are split into on- and off-plane regions using the galactic latitude of each event to form two distributions in $X_\text{max}$, which are compared using the Anderson-Darling 2-samples test. A scan over a subset of the data is used to select an optimal threshold energy of $10^{18.7}$ eV and a galactic latitude splitting at $|b| = 30^\circ$, which are then set as a prescription for the remaining data. With these thresholds, the distribution of $X_\text{max}$ from the on-plane region is found to have a $9.1 \pm 1.6^{+2.1}_{-2.2}$ g/cm$^{2}$ shallower mean and a $5.9\pm2.1^{+3.5}_{-2.5}$ g/cm$^{2}$ narrower width than that of the off-plane region. These differences are as such to indicate that the mean mass of primary particles arriving from the on-plane region is greater than that of those coming from the off-plane region. Monte-Carlo studies yield a $4.4\,\sigma$ post-penalization statistical significance for the independent data. Including the scanned data results in a $4.9^{+1.4}_{-1.5}\,\sigma$ post-penalization statistical significance, where the uncertainties are of systematic origin. Accounting for systematic uncertainties leads to an indication for anisotropy in mass composition above $10^{18.7}$ eV at a confidence level of $3.3\,\sigma$. The anisotropy is observed independently at each of the four fluorescence telescope sites. Interpretations of possible causes of the observed effect are discussed.
- Published
- 2022