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http://hdl.handle.net/20.500.12386/29835
Title: | ARGO-YBJ Observation of the Large-scale Cosmic Ray Anisotropy During the Solar Minimum between Cycles 23 and 24 | Authors: | Bartoli, B. Bernardini, P. Bi, X. J. Cao, Z. Catalanotti, S. Chen, S. Z. Chen, T. L. Cui, S. W. Dai, B. Z. D'Amone, A. Danzengluobu De Mitri, I. D'Ettorre Piazzoli, B. Di Girolamo, T. Di Sciascio, G. Feng, C. F. Feng, Zhaoyang Feng, Zhenyong Gao, W. Gou, Q. B. Guo, Y. Q. He, H. H. Hu, Haibing Hu, Hongbo Iacovacci, M. Iuppa, R. Jia, H. Y. Labaciren Li, H. J. Liu, C. Liu, J. Liu, M. Y. Lu, H. Ma, L. L. Ma, X. H. Mancarella, G. Mari, S. M. Marsella, G. Mastroianni, S. Montini, P. Ning, C. C. Perrone, L. Pistilli, P. Salvini, P. Santonico, R. Shen, P. R. Sheng, X. D. Shi, F. Surdo, A. Tan, Y. H. VALLANIA, PIERO VERNETTO, Silvia Teresa Vigorito, C. Wang, H. Wu, C. Y. Wu, H. R. Xue, L. Yang, Q. Y. Yang, X. C. Yao, Z. G. Yuan, A. F. Zha, M. Zhang, H. M. Zhang, L. Zhang, X. Y. Zhang, Y. Zhao, J. Zhaxiciren Zhaxisangzhu Zhou, X. X. Zhu, F. R. Zhu, Q. Q. ARGO-YBJ Collaboration |
Issue Date: | 2015 | Journal: | THE ASTROPHYSICAL JOURNAL | Number: | 809 | Issue: | 1 | First Page: | 90 | Abstract: | This paper reports on the measurement of the large-scale anisotropy in the distribution of cosmic-ray arrival directions using the data collected by the air shower detector ARGO-YBJ from 2008 January to 2009 December, during the minimum of solar activity between cycles 23 and 24. In this period, more than 2 × 10<SUP>11</SUP> showers were recorded with energies between ̃1 and 30 TeV. The observed two-dimensional distribution of cosmic rays is characterized by two wide regions of excess and deficit, respectively, both of relative intensity ̃10<SUP>-3</SUP> with respect to a uniform flux, superimposed on smaller size structures. The harmonic analysis shows that the large-scale cosmic-ray relative intensity as a function of R.A. can be described by the first and second terms of a Fouries series. The high event statistics allow the study of the energy dependence of the anistropy, showing that the amplitude increases with energy, with a maximum intensity at ̃10 TeV, and then decreases while the phase slowly shifts toward lower values of R.A. with increasing energy. The ARGO-YBJ data provide accurate observations over more than a decade of energy around this feature of the anisotropy spectrum. | Acknowledgments: | This work is supported in China by NSFC (No. 11375052, No. 10975046, No. 10120130794, No. 11165013), the Chinese Ministry of Science and Technology, the Chinese Academy of Sciences, and the Key Laboratory of Particle Astrophysics, CAS, and in Italy by the Istituto Nazionale di Fisica Nucleare (INFN). We also acknowledge essential support from W.Y. Chen, G. Yang, X. F. Yuan, C. Y. Zhao, R. Assiro, B. Biondo, S. Bricola, F. Budano, A. Corvaglia, B. D’Aquino, R. Esposito, A. Innocente, A. Mangano, E. Pastori, C. Pinto, E. Reali, F. Taurino, and A. Zerbini in the installation, debugging, and maintenance of the detector. | URI: | http://hdl.handle.net/20.500.12386/29835 | URL: | https://iopscience.iop.org/article/10.1088/0004-637X/809/1/90 | ISSN: | 0004-637X | DOI: | 10.1088/0004-637X/809/1/90 | Bibcode ADS: | 2015ApJ...809...90B | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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2015_ApJ_809_90_Anisotropy_ARGO.pdf | Pdf editoriale | 1.53 MB | Adobe PDF | View/Open |
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