Updated Limits on Anisotropy in Electron+Positron Cosmic Rays from CALET Data

Motz, Holger; Akaike, Yosui; Adriani, O.; Asano, K.; Asaoka, Y.; Berti, E.; Betti, P.; Bigongiari, G.; Binns, W.R.; Bongi, M.; Brogi, P.; Bruno, A.; Cannady, N.; Castellini, G.; Checchia, C.; Cherry, M.L.; Collazuol, G.; Ebisawa, K.; Ficklin, A.W.; Fuke, H.; Gonzi, S.; Guzik, T.G.; Hams, T.; Hibino, K.; Ichimura, M.; Israel, M.H.; Kasahara, K.; Kataoka, J.; Kataoka, R.; Katayose, Y.; Kato, C.; Kawanaka, N.; Kawakubo, Y.; Kobayashi, K.; Kohri, K.; Krawczynski, H.S.; Krizmanic, J.F.; Maestro, P.; Marrocchesi, P.S.; Mattiazzi, M.; Messineo, A.M.; Mitchell, J.W.; Miyake, S.; Moiseev, A.A.; Mori, M.; Mori, N.; Munakata, K.; Nakahira, S.; Negro, M.; de Nolfo, G.A.; Nishimura, J.; Okuno, S.; Ormes, J.F.; Ozawa, S.; Pacini, L.; Papini, P.; Rauch, B.F.; Ricciarini, S.B.; Sakai, K.; Sakamoto, T.; Sasaki, M.; Shimizu, Y.; Shiomi, A.; Spillantini, P.; Stolzi, F.; Sugita, S.; Sulaj, A.; Takita, M.; Tamura, T.; Terasawa, T.; Torii, S.; Tsunesada, Y.; Uchihori, Y.; Vannuccini, E.; Wefel, J.P.; Yamaoka, K.; Yanagita, S.; Yoshida, A.; Yoshida, K.; Zober, W.V.; on behalf of the CALET Collaboration,

doi:10.22323/1.501.0100

Volume 501 - 39th International Cosmic Ray Conference (ICRC2025) - Cosmic-Ray Direct & Acceleration

Updated Limits on Anisotropy in Electron+Positron Cosmic Rays from CALET Data

H. Motz*, Y. Akaike, O. Adriani, K. Asano, Y. Asaoka, E. Berti, P. Betti, G. Bigongiari, W.R. Binns, M. Bongi, P. Brogi, A. Bruno, N. Cannady, G. Castellini, C. Checchia, M.L. Cherry, G. Collazuol, K. Ebisawa, A.W. Ficklin, H. Fuke, S. Gonzi, T.G. Guzik, T. Hams, K. Hibino, M. Ichimura, M.H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H.S. Krawczynski, J.F. Krizmanic, P. Maestro, P.S. Marrocchesi, M. Mattiazzi, A.M. Messineo, J.W. Mitchell, S. Miyake, A.A. Moiseev, M. Mori, N. Mori, K. Munakata, S. Nakahira, M. Negro, G.A. de Nolfo, J. Nishimura, S. Okuno, J.F. Ormes, S. Ozawa, L. Pacini, P. Papini, B.F. Rauch, S.B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J.P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, W.V. Zober on behalf of the CALET Collaborationet al. (click to show)

*: corresponding author

Full text: pdf

Pre-published on: September 23, 2025

Published on: December 30, 2025

Abstract

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum and direction distribution of electron+positron cosmic-rays up to 20 TeV. The electron+positron events measured by CALET have been analyzed for a possible dipole anisotropy, which could be a signature of nearby SNR such as Vela.
The methods used to derive limits on the anisotropy from the reconstructed events are explained, including the procedures to compensate for non-uniform sky exposure and inhomogeneous detector acceptance.
Upper limits on the dipole moment as a function of lower threshold energy, with doubled statistics compared to of previously shown results, are presented.

DOI: https://doi.org/10.22323/1.501.0100

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