An update on the arrival direction studies made with data from the Pierre Auger Observatory
G. Golup, Adila Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, Kévin Almeida Cheminant, Alejandro Almela, Roberto Aloisio, Jaime Álvarez-Muñiz, Juan Ammerman Yebra, Gioacchino Alex Anastasi, Luis A. Anchordoqui, Belén Andrada, S. Andringa, C. Aramo, Paulo Ricardo Araújo Ferreira, Enrico Arnone, Juan Carlos Arteaga Velázquez, Hernán Gonzalo Asorey, P. Assis, Gualberto Avila, Emanuele Avocone, Alina Mihaela Badescu, Alena Bakalová, Alexandru Balaceanu, Felicia Barbato, Adriel Bartz Mocellin, Jose A. Bellido, Corinne Bérat, Mario E. Bertaina, Gopal Bhatta, Marta Bianciotto, Peter L. Biermann, Virginia Binet, Kathrin Bismark, Teresa Bister, Jonathan Biteau, Jiří Blažek, C. Bleve, Johannes Blümer, Martina Boháčová, Denise Boncioli, C. Bonifazi, Luan Bonneau Arbeletche, Nataliia Borodai, J. Brack, P. Gabriel Brichetto Orchera, Florian Lukas Briechle, A. Bueno, S. Buitink, Mario Buscemi, Max Büsken, Anthony Bwembya, K. S. Caballero‐Mora, Sergio Cabana-Freire, Lorenzo Caccianiga, Ioana Caracas, R. Caruso, A. Castellina, Fernando Catalani, G. Cataldi, Lorenzo Cazon, Marcos Cerda, Alessandro Cermenati, J. A. Chinellato, J. Chudoba, L. Chytka, R. W. Clay, Agustín Cobos Cerutti, Roberta Colalillo, Alan Coleman, Maria Rita Coluccia, R. Conceição, Antonio Condorelli, Giovanni Consolati, Matteo Conte, Fabio Convenga, Diego Correia dos Santos, Pedro J. Costa, C. E. Covault, M. Cristinziani, Carlo Salvattore Cruz Sanchez, S. Dasso, K. Daumiller, B. R. Dawson, Rogerio M. de Almeida, Joaquin de Jesus, S. J. de Jong, João de Mello Neto, I. De Mitri, Jaime de Oliveira, Danelise de Oliveira Franco, Francesco de Palma, Vitor de Souza, Emanuele De Vito, Antonino Del Popolo, Olivier Deligny, Nikolas Denner, Luca Deval, Armando di Matteo
Abstract
The search for anisotropies in the arrival directions of ultra-high-energy cosmic rays plays a key role in the efforts to understand their origin. The observed first-harmonic modulation in right ascension (R.A.) above $8\,$EeV, detected by the Pierre Auger Observatory with a current significance of $6.9\sigma$, suggests an extragalactic origin above this energy. Furthermore, there are indications, at the $\sim$$4\sigma$ significance level, of anisotropies at intermediate angular scales, which are obtained when comparing the arrival directions against the distribution of potential sources from astrophysical catalogs, in particular that of nearby starburst galaxies, and around the Centaurus region. In this contribution, we present the status of the different searches for anisotropies at small, intermediate and large angular scales. We use the latest available data set, with 19 years of operation that has yielded $135,000\,$km$^2\,$yr$\,$sr of accumulated exposure, covering the sky at declinations from $-90^\circ$ to $45^\circ$. At small and intermediate scales, we report updates of the all-sky blind search for localized excesses, the study around the Centaurus region, and the likelihood analysis with catalogs of candidate sources. We have also studied the regions of the sky from which the Telescope Array Collaboration has reported hints of excesses in their data and we find no significant effects in the same directions with a data set of comparable size. At large angular scales, the dipolar and quadrupolar amplitudes in energy bins are updated. We discuss the prospects of these searches, both in regards to increases in statistics and in relation to the future inclusion of event-by-event mass estimators in these analyses through the upgrade of the Observatory, AugerPrime.