SEARCH FOR ANISOTROPY OF ULTRAHIGH ENERGY COSMIC RAYS WITH THE TELESCOPE ARRAY EXPERIMENT
- High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, UT (United States)
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu, Yamanashi (Japan)
- Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo (Japan)
- Department of Physics and The Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul (Korea, Republic of)
- Department of Physics, Tokyo University of Science, Noda, Chiba (Japan)
- Department of Physics, Kinki University, Higashi Osaka, Osaka (Japan)
- Department of Physics, Yonsei University, Seodaemun-gu, Seoul (Korea, Republic of)
- Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki (Japan)
- Graduate School of Science, Osaka City University, Osaka, Osaka (Japan)
- Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba (Japan)
We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E > 57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure (LSS) of the universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the universe (the LSS hypothesis), while the event set with E > 10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis.
- OSTI ID:
- 22092299
- Journal Information:
- Astrophysical Journal, Vol. 757, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory
Searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory