TAROGE-M: radio antenna array on antarctic high mountain for detecting near-horizontal ultra-high energy air showers

Wang SH, Nam J, Chen P, Chen Y, Choi T, Ham YB, Hsu SY, Huang JJ, Huang MHA, Jee G, Jung J, Kim J, Kuo CY, Kwon HJ, Lee C, Leung CH, Liu TC, Shiao YSJ, Shin BK, Wang MZ, Wang YH, Anker A, Barwick SW, Besson DZ, Bouma S, Cataldo M, Gaswint G, Glaser C, Hallmann S, Hanson JC, Henrichs J, Kleinfelder SA, Lahmann R, Meyers ZS, Nelles A, Novikov A, Paul MP, Pyras LM, Persichilli C, Plaisier I, Rice-Smith R, Seikh MFH, Tatar J, Welling C, Zhao L (2022)

Publication Type: Journal article

Publication year: 2022

Journal

Journal Issue: 11

DOI: 10.1088/1475-7516/2022/11/022

Abstract

The TAROGE-M radio observatory is a self-triggered antenna array on top of the similar to 2700m high Mt. Melbourne in Antarctica, designed to detect impulsive geomagnetic emission from extensive air showers induced by ultra-high energy (UHE) particles beyond 1017 eV, including cosmic rays, Earth-skimming tau neutrinos, and particularly, the "ANITA anomalous events" (AAE) from near and below the horizon. The six AAE discovered by the ANITA experiment have signal features similar to tau neutrinos but that hypothesis is in tension either with the interaction length predicted by Standard Model or with the flux limits set by other experiments. Their origin remains uncertain, requiring 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, enhancing the relative radio signal strength. 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 TAROGEM station deployed in January 2020, corresponding to approximately one month of livetime. The station consists of six receiving antennas operating at 180-450 MHz, and can reconstruct source directions of impulsive events with an angular resolution of similar to 0.3 ffi, calibrated in situ with a drone-borne pulser system. To demonstrate TAROGE-M's ability to detect UHE air showers, a search for cosmic ray signals in 25.3-days of data together with the detection simulation were conducted, resulting in seven identified candidates. The detected events have a mean reconstructed energy of 0.95+0.46 -0.31 EeV and zenith angles ranging from 25 ffi to 82 ffi, with both distributions agreeing with the simulations, indicating an energy threshold at about 0.3 EeV. The estimated cosmic ray flux at that energy is 1.2+0.7 -0.9x10(-16) eV(-1) km(-2) yr(-1) sr(-1), also consistent with results of other experiments. The TAROGE-M sensitivity to AAEs is approximated by the tau neutrino exposure with simulations, which suggests comparable sensitivity as ANITA's at around 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.

Authors with CRIS profile

Involved external institutions

Korea Polar Research Institute (KOPRI) / 한국극지연구소 Korea, Republic of (KR) National United University Taiwan (TW) National Taiwan University (NTU) Taiwan (TW) University of California Irvine United States (USA) (US) University of Kansas (KU) United States (USA) (US) Deutsches Elektronen-Synchrotron DESY Germany (DE) Uppsala University Sweden (SE) Whittier College United States (USA) (US)

How to cite

APA:

Wang, S.-H., Nam, J., Chen, P., Chen, Y., Choi, T., Ham, Y.-B.,... Zhao, L. (2022). TAROGE-M: radio antenna array on antarctic high mountain for detecting near-horizontal ultra-high energy air showers. Journal of Cosmology and Astroparticle Physics, 11. https://dx.doi.org/10.1088/1475-7516/2022/11/022

MLA:

Wang, Shih-Hao, et al. "TAROGE-M: radio antenna array on antarctic high mountain for detecting near-horizontal ultra-high energy air showers." Journal of Cosmology and Astroparticle Physics 11 (2022).

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