2025-06-13 ペンシルベニア州立大学
The unusual radio pulses were detected by the Antarctic Impulsive Transient Antenna (ANITA) experiment, a range of instruments flown on balloons high above Antarctica that are designed to detect radio waves from cosmic rays hitting the atmosphere. Credit: Stephanie Wissel / Penn State. Creative Commons
◆Pierre Auger観測所は、ANITAが南極で検出した上向きラジオパルスの正体を検証するため、2004〜2018年のデータから上向きエアシャワー候補を探索しました。解析対象は天頂角110度以上のイベントで、エネルギー範囲は0.1〜33 EeV。結果、1件の候補が見つかったものの、これは誤再構成による通常の宇宙線と一致し、ANITAの観測を裏付ける証拠は得られませんでした。このことから、標準モデル内の現象ではANITAの異常信号を説明できず、新たな物理の可能性が示唆されます。
- https://www.psu.edu/news/research/story/strange-radio-pulses-detected-coming-ice-antarctica
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.121003
ピエール・オージェ観測所を用いたANITAで検出された異常事象の探索 Search for the Anomalous Events Detected by ANITA Using the Pierre Auger Observatory
A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, A. Almela,, R. Aloisio, J. Alvarez-Muñiz, J. Ammerman Yebra et al. (Pierre Auger Collaboration)
Physical Review Letters Published: 27 March, 2025
DOI: https://doi.org/10.1103/PhysRevLett.134.121003
Abstract
A dedicated search for upward-going air showers at zenith angles exceeding 110° and energies >0.1 EeV has been performed using the Fluorescence Detector of the Pierre Auger Observatory. The search is motivated by two “anomalous” radio pulses observed by the ANITA flights I and III that appear inconsistent with the standard model of particle physics. Using simulations of both regular cosmic-ray showers and upward-going events, a selection procedure has been defined to separate potential upward-going candidate events and the corresponding exposure has been calculated in the energy range [0.1–33] EeV. One event has been found in the search period between January 1, 2004, and December 31, 2018, consistent with an expected background of 0.27 ±0.12 events from misreconstructed cosmic-ray showers. This translates to an upper bound on the integral flux of (7.2±0.2)×10−21 cm−2 sr−1 y−1 and (3.6±0.2)×10−20 cm−2 sr−1 y−1 for an −1 and −2 spectrum, respectively. An upward-going flux of showers normalized to the ANITA observations is shown to predict over 34 events for an −3 spectrum and over 8.1 events for a conservative −5 spectrum, in strong disagreement with the interpretation of the anomalous events as upward-going showers.
