TAROGE-M: Radio Antenna Array on Antarctic High Mountain for Detecting Near-Horizontal Ultra-High Energy Air Showers
Creators: name: TAROGE Collaboration
name: Wang, Shih-Hao
name: Nam, Jiwoo
name: Chen, Pisin
name: Chen, Yaocheng
name: Choi, Taejin
name: Ham, Young-bae
name: Hsu, Shih-Ying
name: Huang, Jian-Jung
name: Huang, Ming-Huey A.
name: Jee, Geonhwa
name: Jung, Jongil
name: Kim, Jieun
name: Kuo, Chung-Yun
name: Kwon, Hyuck-Jin
name: Lee, Changsup
name: Leung, Chung-Hei
name: Liu, Tsung-Che
name: Shiao, Yu-Shao J.
name: Shin, Bok-Kyun
name: Wang, Min-Zu
name: Wang, Yu-Hsin
name: Collaboration, ARIANNA
name: :
name: Anker, Astrid
name: Barwick, Steven W.
name: Besson, Dave Z.
name: Bouma, Sjoerd
name: Cataldo, Maddalena
name: Gaswint, Geoffrey
name: Glaser, Christian
name: Hallmann, Steffen
name: Hanson, Jordan C.
name: Henrichs, Jakob
name: Kleinfelder, Stuart A.
name: Lahmann, Robert
name: Meyers, Zachary S.
name: Nelles, Anna
name: Novikov, Alexander
name: Paul, Manuel P.
name: Pyras, Lilly
name: Persichilli, Christopher
name: Plaisier, Ilse
name: Rice-Smith, Ryan
name: Seikh, Mohammad F. H.
name: Tatar, Joulien
name: Welling, Christoph
name: Zhao, Leshan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: TAROGE-M is a self-triggered radio antenna array atop the 2700 m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 0.1 EeV, including cosmic rays (CRs), Earth-skimming tau neutrinos, and particularly, the "ANITA anomalous events" (AAEs) from near and below the horizon, which origin remains uncertain and requires more experimental inputs for clarification. The detection concept of TAROGE-M takes advantage of a high altitude with synoptic view toward the horizon as an efficient signal collector, and the radio quietness as well as strong and near vertical geomagnetic field in Antarctica. This approach has a low energy threshold, high duty cycle, and is easy to extend for quickly enlarging statistics. Here we report experimental results from the first TAROGE-M station deployed in 2020, corresponding to $25.3$-days of livetime. The station consists of six receiving antennas operating at 180-450 MHz, and can reconstruct source directions with $\sim0.3^\circ$ angular resolution. To demonstrate its ability to detect UHE air showers, a search for CR signals in the data was conducted, resulting in seven identified events. These events have a mean reconstructed energy of $0.95_{-0.31}^{+0.46}$ EeV and zenith angles between $25^\circ-82^\circ$, with both distributions agreeing with simulations. The estimated CR flux is also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, suggesting comparable sensitivity as ANITA's at $~1$ EeV energy with a few station-years of operation. These first results verified the station design and performance in a polar and high-altitude environment, and are promising for further discovery of tau neutrinos and AAEs after an extension in the near future.
description: 41 pages, 23 figures, submitted to JCAP; minor corrections in references; minor modifications in simulation description in section 5 &amp; 6 for clarity