2023 Fiscal Year Annual Research Report
Combined Spectrum and Anisotropy Study of Cosmic Rays from the Vela SNR with CALET
| Project/Area Number |
21K03604
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| Research Institution | Waseda University |
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Principal Investigator |
Motz Holger 早稲田大学, 理工学術院, 教授(任期付) (30647904)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | cosmic rays / CALET / anisotropy / Vela SNR |
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| Outline of Annual Research Achievements |
The potential spectral shape in the TEV region based on the contribution from nearby SNR, foremost Vela, was studied. This prediction is compared to latest results by CALET revealing a hint for the existence of a signature from nearby SNR, as was published in Phys. Rev. Lett. 131, 191001 (2023).
An unbinned analysis based on the PDF of the event distribution in energy was developed and its performance tested with Monte Carlo simulations, confirming that with CALET data taken by 2030, it could yield above 5 sigma significance on the spectral hardening associated with the signature of a nearby SNR (if present).
Based on the same Monte Carlo samples of predicted CALET events, the possible significance of an anisotropy signature was studied, finding that a 2 sigma significance may be achieved by 2030, but with strong dependence on the cosmic ray propagation condition.
While both unbinned and anisotropy analysis methods were refined and extensively tested in simulations, their application on CALET flight data and their envisioned combination for a higher significance combined signature are still being worked on.
Further, the variability and expected inherent structures of the electron and positron spectrum was studied by random sampling of individual sources (SNR, pulsars) throughout the Galaxy, and fitting the resulting spectra to CALET and AMS-02. It was shown that the overlapping individual source spectra can agree to the experimental data, and favored parameters for the sources derived. These results were used also as background for calculation of Dark Matter limits.
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