Detectability of southern gamma-ray sources beyond 100 TeV with ALPAQUITA, the prototype experiment of ALPACA

Kato, Shinsuke; Condori, C. A. H.; Fuente, E. dela; Gomi, A.; Hibino, K.; Hotta, N.; Toledano-Juárez, I.; Katayose, Y.; Kato, C.; Kawata, K.; Kihara, W.; Ko, Y.; Koi, T.; Kojima, Hiroshi; Kurashige, D.; Lozoya, J.; Orozco-Luna, Felipe de Jesús; Mayta, R.; Miranda, P.; Munakata, K.; Nakada, H.; Nakamura, Yuya; Nakazawa, Yu; Nina, C.; Nakamura, Masaki; Ogio, S.; Ohnishi, M.; Ohura, T.; Okukawa, S.; Oshima, A.; Raljevich, M.; Rivera, H.; Saito, T.; Sako, T. K.; Shibata, S.; Subieta, M.; Tajima, N.; Takano, W.; Takita, M.; Tameda, Y.; Tanaka, K.; Ticona, R.; Torres, H.; Tsuchiya, H.; Tsunesada, Y.; Udo, S.; Yamazaki, K.; Yokoe, Y.

doi:10.1007/s10686-021-09796-8

“…Neutrinos inevitably generated in the hadronic interaction are not currently detected and the contribution to the gamma-ray flux from hadrons is not well constrained (Huang & Li 2022). Future deep observations of neutrinos by IceCube-Gen2 (Aartsen et al 2021) and of sub-PeV gamma rays by ALPACA (Kato et al 2021), CTA (The Cherenkov Telescope Array Consortium 2019), and SWGO (Hinton & the SWGO Collaboration 2021) have great importance to find clear evidence for the acceleration of PeV CRs in this energetic source.…”

Section: Hadronic Scenariomentioning

confidence: 99%

Observation of Gamma Rays up to 320 TeV from the Middle-aged TeV Pulsar Wind Nebula HESS J1849−000

Amenomori

¹

,

Asano

²

,

Bao

³

et al. 2023

ApJ

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Gamma rays from HESS J1849−000, a middle-aged TeV pulsar wind nebula (PWN), are observed by the Tibet air shower array and the muon detector array. The detection significance of gamma rays reaches 4.0σ and 4.4σ levels above 25 TeV and 100 TeV, respectively, in units of the Gaussian standard deviation σ. The energy spectrum measured between 40 TeV < E < 320 TeV for the first time is described with a simple power-law function of dN / dE = ( 2.86 ± 1.44 ) × 10 − 16 ( E / 40 TeV ) − 2.24 ± 0.41 TeV − 1 cm − 2 s − 1 . The gamma-ray energy spectrum from the sub-TeV (E < 1 TeV) to sub-PeV (100 TeV < E < 1 PeV) ranges, including the results of previous studies, can be modeled with the leptonic scenario, i.e., inverse Compton scattering by high-energy electrons accelerated by the PWN of PSR J1849−0001. On the other hand, the gamma-ray energy spectrum can also be modeled with the hadronic scenario in which gamma rays are generated from the decay of neutral pions produced by collisions between accelerated cosmic-ray protons and the ambient molecular cloud found in the gamma-ray-emitting region. The cutoff energy of cosmic-ray protons E p,cut is estimated as log 10 ( E p , cut / TeV ) = 3.73 − 0.66 + 2.98 , suggesting that protons are accelerated up to the PeV energy range. Our study thus proposes that HESS J1849−000 should be further investigated as a new candidate as a Galactic PeV cosmic-ray accelerator, or “PeVatron.”

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“…We determined the direction of arrival of the air shower by fitting a reverse-conic-type shape to the front surface of the shower particles, which was calculated using the hit timing of each detector [26][27][28]. (v) The residual error, which represents the goodness of fit determined by this method, should be less than 1.0 m.…”

Section: Air Shower Reconstructionmentioning

confidence: 99%

Neural networks for separation of cosmic gamma rays and hadronic cosmic rays in air shower observation with a large area surface detector array

Okukawa,

Hara,

Hibino

et al. 2024

Mach. Learn.: Sci. Technol.

0

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The Tibet ASγ experiment has been observing cosmic gamma rays and cosmic rays in the energy range from teraelectron volts to several tens of petaelectron volts with a surface detector array since 1990.The derivation of cosmic gamma-ray flux is made by finding the excess distribution of the arrival direction of air showers above background cosmic rays. In 2014, the underground water Cherenkov muon detector (MD) was added to separate cosmic gamma rays from the background on the basis of the muon-less feature of the air showers of gamma-ray origin; hybrid observations using these two detectors were started at this time.In the present study, we developed methods to separate gamma-ray-induced air showers and hadronic cosmic-ray-induced ones using the measured particle number density distribution to improve the sensitivity of cosmic gamma-ray measurements using the Tibet air shower array data alone before the installation of the MD.We tested two approaches based on neural networks. The first method used feature values representing the lateral spread of the secondary particles, and the second method used the shower image data.To compare the separation performance of each method, we analyzed Monte Carlo air shower events in the vertically incident direction with mono-initial-energy gamma rays and protons.When discriminated by a single feature, the feature with the highest separation performance has an area under the curve (AUC) value of 0.701 for a gamma-ray energy of 10 TeV and 0.808 for 100 TeV. A separation method with a multilayer perceptron (MLP) based on multiple features has AUC values of 0.761 for a gamma-ray energy of 10 TeV and 0.854 for 100 TeV, which represents an improvement of approximately 5 % in the AUC value compared with the single-feature case. We also found that the feature values that effectively contribute to the separation vary depending on the energy.A separation method with a convolutional neural network (CNN) using the shower image data has AUC values of 0.781 for a gamma-ray energy of 10 TeV and 0.901 for 100 TeV, which are approximately 5 % higher than those of the MLP method. We applied the CNN separation method to Monte Carlo gamma-ray and cosmic-ray events from the Crab Nebula in the energy range 10−100 TeV.The AUC values range from 0.753 to 0.879, and the significance of the observed gamma-ray excess is improved by 1.3 to 1.8 times compared with the case without the separation procedure.

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“…Another planned project that will exploit a surface array of detectors for gamma-ray observations in the Southern hemisphere is ALPACA and its prototype array ALPAQUITA [39]. ALPACA will have a similar design to the Tibet ASγ experiment, with a sparse array of scintillation detectors and underground muon detectors.…”

Section: Future Instrumentsmentioning

confidence: 99%

TeV Instrumentation: Current and Future

Sitarek

¹

2022

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During the last 20 years, TeV astronomy has turned from a fledgling field, with only a handful of sources, into a fully-developed astronomy discipline, broadening our knowledge on a variety of types of TeV gamma-ray sources. This progress has been mainly achieved due to the currently operating instruments: imaging atmospheric Cherenkov telescopes, surface arrays and water Cherenkov detectors. Moreover, we are at the brink of a next generation of instruments, with a considerable leap in performance parameters. This review summarizes the current status of the TeV astronomy instrumentation, mainly focusing on the comparison of the different types of instruments and analysis challenges, as well as providing an outlook into the future installations. The capabilities and limitations of different techniques of observations of TeV gamma rays are discussed, as well as synergies to other bands and messengers.

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Detectability of southern gamma-ray sources beyond 100 TeV with ALPAQUITA, the prototype experiment of ALPACA

Cited by 17 publications

References 40 publications

Observation of Gamma Rays up to 320 TeV from the Middle-aged TeV Pulsar Wind Nebula HESS J1849−000

Observation of Gamma Rays up to 320 TeV from the Middle-aged TeV Pulsar Wind Nebula HESS J1849−000

Neural networks for separation of cosmic gamma rays and hadronic cosmic rays in air shower observation with a large area surface detector array

TeV Instrumentation: Current and Future

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