Discovery of the Ultrahigh-energy Gamma-Ray Source LHAASO J2108+5157

Cao, Z.; Aharonian, F.; An, Q.; Axikegu,; Bai, Lixin; Bai, Y.; Bao, Yiwei; Bastieri, D.; Bi, X. J.; Bi, Y. J.; Cai, H.; Cai, J. T.; Cao, Zhe; Chang, J. F.; Chen, B. M.; Chen, E. S.; Chen, J.; Chen, Liang; Chen, Long; Chen, M. J.; Chen, M. L.; Chen, Q. H.; Chen, S. H.; Chen, S. Z.; Chen, T. L.; Chen, X. L.; Chen, Y.; Cheng, Ning; Cheng, Yaodong; Cui, S. W.; Cui, Xiaohong; Cui, Yudong; Piazzoli, B. D’Ettorre; Dai, B. Z.; Dai, H. L.; Dai, Z. G.; Danzengluobu, D.; Volpe, D. della; Dong, X.; Duan, Kai-Kai; Fan, J. H.; Fan, Yi‐Zhong; Zhou, Fan; Fang, Jun; Fang, Kun; Feng, C.; Feng, Li; Feng, S. H.; Feng, Y. L.; Gao, Bo; Gao, Chengyong; Gao, Liang; Gao, Qi; Gao, Wei; Ge, M. M.; Geng, L. S.; Gong, Guanghua; Gou, Q. B.; Gu, M. H.; Guo, Fulai; Guo, J. G.; Guo, Xiaolei; Guo, Y. Q.; Guo, Y. Y.; Han, Y. A.; He, H. H.; He, Hao-Ning; He, J.; He, S. L.; He, Xinbo; He, Y.; Heller, M.; Hor, Y. K.; Hou, Chao; Hu, Hongbo; Hu, S. C.; Hu, X.; Huang, D.; Huang, Q.; Huang, Wenhao; Huang, X. T.; Huang, Xiaoyuan; Huang, Z. C.; Ji, Fei; Ji, X. L.; Jia, H. Y.; Jiang, Z. J.; Jin, Chao; Tang, Ke; Kuleshov, D.; Levochkin, K.; Li, B. B.; Li, Cheng; Li, Cong; Li, F.; Li, H. B.; Li, H. C.; Li, H. Y.; Li, Jian; Li, K.; Li, W. L.; Li, X. R.; Li, Xin; Li, Y.; Li, Y.Z.; Li, Zhe; Li, Zhuo; Liang, En‐Wei; Liang, Yun-Feng; Lin, S. J.; Liu, B.; Liu, C.; Liu, D.; Liu, H.; Liu, H. D.; Liu, J.; Liu, J. L.; Liu, J. S.; Liu, J. Y.; Liu, M. Y.; Liu, Ruo-Yu; Liu, Siming; Liu, Wei; Liu, Y.; Liu, Y. N.; Liu, Z. X.; Long, W. J.; Lü, Rui; Lv, Hongkui; Q., B.; L., L.; H., X.; Mao, J.; Masood, A.; Mitthumsiri, W.; Montaruli, T.; Nan, Y. C.; Pang, B. Y.; Pattarakijwanich, P.; Pei, Z. Y.; Qi, M. Y.; Qi, Y. Q.; Qiao, Bing-Qiang; Qin, Jiajun; Ruffolo, D.; Rulev, V.; Sáiz, A.; Shao, L.; Shchegolev, O. B.; Sheng, X. D.; Shi, J. Y.; Song, H. C.; Stenkin, Yu. V.; Stepanov, V.; Su, Yang; Sun, Q. N.; Sun, Xiao-Na; Sun, Zhang‐Hua; Tam, P. H. T.; Tang, Z.; Wu, Tian; Wang, B. D.; Wang, C.; Wang, Hong Guang; Wang, H. G.; Wang, J. C.; Wang, J. S.; Wang, L. P.; Wang, L. Y.; Wang, R. N.; Wang, W.; Wang, Wei; Wang, X. G.; Wang, X. J.; Wang, Xiang-Yu; Wang, Yang; Wang, Y. D.; Wang, Y. J.; Wang, Y. P.; Wang, Zhongxiang; Wang, Z. X.; Wang, Zhen; Wang, Zheng; Wei, Da-Ming; Wei, J. J.; Wei, Y. J.; Wen, Tao; Wu, C. Y.; Wu, Hong; Wu, San; Wu, W. X.; Wu, Xue-Feng; Xi, Shao-Qiang; Xia, J.; Xiang, G. M.; Xiao, D. X.; Xiao, G. C.; Xiao, H. B.; Xin, G. G.; Xin, Y.; Xing, Yi; Xu, D. L.; Xu, R. X.; Xue, L.; Yan, Dahai; Yan, Jun; Yang, Chaowen; Yang, Fang; Yang, Jian-Huan; Yang, Lili; Yang, Min; Yang, R.; Yang, S. B.; Yao, Y. H.; Yao, Z. G.; Ye, Y. M.; Yin, L. Q.; Yin, Na; You, X. H.; You, Z. Y.; Yu, Y. H.; Yuan, Qiang; Zeng, Houdun; Zeng, Tingxuan; Zeng, W.; Zeng, Z. K.; Zha, M.; Zhai, X. X.; Zhang, Bin-Bin; Zhang, Hai-Ming; Zhang, H. Y.; Zhang, J. L.; Zhang, J. W.; Zhang, L. X.; Lu, Fang-Wu; Zhang, Lu; Zhang, P. F.; Zhang, P. P.; Zhang, R.; Zhang, S. R.; Zhang, S. S.; Zhang, Xiao; Zhang, X. P.; Zhang, Y. F.; Zhang, Y. L.; Zhang, Yi; Zhang, Yong; Zhao, Bing; Zhao, J.; Liu, Zhao; Zhao, S. P.; Zheng, F.; Zheng, Y.; Zhou, Bin; Zhou, H.; Zhou, Jianeng; Zhou, Ping; Zhou, Rong; Zhou, X. X.; Zhu, C. G.; Zhu, F. R.; Zhu, Hui; Zhu, K. J.; Zuo, Xin

doi:10.3847/2041-8213/ac2579

Cited by 38 publications

(32 citation statements)

References 26 publications

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“…The energies studied in this work are close to the knee of the cosmic ray spectrum, and events with such energies are generally assumed to have galactic origins, with the knee possibly representing a galactic energy limit. Recently, there have been reports of galactic gamma-ray sources with particle energies approaching those studied here [14,15]. Those source discoveries by HAWC and LHASSO relate to northern hemisphere galactic directions but the southern galaxy, which is viewed here, includes particularly interesting regions, such as the galactic centre and the inner galaxy.…”

Section: Discussionmentioning

confidence: 73%

A Search for Cosmic Ray Bursts at 0.1 PeV with a Small Air Shower Array

et al. 2022

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The Cosmic Ray Extremely Distributed Observatory (CREDO) pursues a global research strategy dedicated to the search for correlated cosmic rays, so-called Cosmic Ray Ensembles (CRE). Its general approach to CRE detection does not involve any a priori considerations, and its search strategy encompasses both spatial and temporal correlations, on different scales. Here we search for time clustering of the cosmic ray events collected with a small sea-level extensive air shower array at the University of Adelaide. The array consists of seven one-square-metre scintillators enclosing an area of 10 m × 19 m. It has a threshold energy ~0.1 PeV, and records cosmic ray showers at a rate of ~6 mHz. We have examined event arrival times over a period of over 2.5 years in two equipment configurations (without and with GPS timing), recording ~300 k events and ~100 k events. We determined the event time spacing distributions between individual events and the distributions of time periods which contained specific numbers of multiple events. We find that the overall time distributions are as expected for random events. The distribution which was chosen a priori for particular study was for time periods covering five events (four spacings). Overall, these distributions fit closely with expectation, but there are two outliers of short burst periods in data for each configuration. One of these outliers contains eight events within 48 s. The physical characteristics of the array will be discussed together with the analysis procedure, including a comparison between the observed time distributions and expectation based on randomly arriving events.

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Section: Discussionmentioning

confidence: 73%

A Search for Cosmic Ray Bursts at 0.1 PeV with a Small Air Shower Array

et al. 2022

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“…LHAASO J2108+5157 (Cao et al 2021a) and LHAASO J0341+5258 (Cao et al 2021c) are not yet found to be associated with any powerful pulsar or SNR, this motivates us to consider alternative scenarios. We have assumed there were explosions which injected both shock accelerated electrons and protons thousands of years ago.…”

Section: Resultsmentioning

confidence: 99%

“…LHAASO J2108 + 5157 is an UHE gamma ray source, discovered by Cao et al (2021a) after analysing the data from LHAASO-KM2A for 308.33 live days. This point-like source is located at R.A.=312.17 ± 0.07 stat , Dec. = 51.95 ± 0.05 stat .…”

Section: Lhaaso J2108+5157mentioning

confidence: 99%

“…Though there is a high energy gamma ray source 4FGL J2108.0+5155e spatially coincident with LHAASO J2108+5157, its flux is 10 times lower than the UHE gamma ray source. Based on the catalog of SIMBAD2, Cao et al (2021a) searched for possible cosmic accelerators within 0.8 • from the center of the LHAASO source. Though no SNR or PWN has been found, two young star clusters Kronberger 82 (Kronberger et al 2006) and Kronberger 80 (Kharchenko et al 2016) have been located.…”

Section: Lhaaso J2108+5157mentioning

confidence: 99%

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Ultra-high Energy Gamma-rays from Past Explosions in our Galaxy

Kar,

Gupta

2021

Preprint

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The discovery of the sources of ultra-high energy photons by High-Altitude Water Cerenkov Gamma ray Observatory and Large High Altitude Air Shower Observatory in our Galaxy has revolutionised the field of gamma ray astronomy in the last few years. These emissions are sometimes found in the vicinity of powerful pulsars or supernova remnants associated with giant molecular clouds. Inverse Compton emission by shock accelerated electrons emitted by pulsars and proton-proton interactions of shock accelerated protons emitted by supernova remnants with cold protons in molecular clouds are often identified as the causes of these emissions. In this paper we have selected two ultra-high energy photon sources LHAASO J2108+5157 and LHAASO J0341+5258 which are associated with giant molecular clouds, but no powerful pulsar or supernova remnant has been detected in their vicinity. We have proposed a scenario where shock accelerated electrons and protons are injected in the local environment of these sources from past explosions, which happened thousands of years ago. We show that the observed ultra-high energy photon flux can be explained with the secondary gamma rays produced by the time evolved relativistic electron and proton spectra.

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“…The most energetic photon ever observed is 1.4 PeV from the direction of Cygnus OB2, which was detected by the km 2 array (KM2A) of the Large High Altitude Air Shower Observatory (LHAASO) (Cao et al 2021a). LHAASO-KM2A also observed significant gammaray emission above 100 TeV from 12 sources (Cao et al 2021a;The LHAASO Collaboration et al 2021;Cao et al 2021b), which are probably the Galactic accelerators of PeV cosmic-rays, namely, PeVatrons. According to gamma-ray observations, various PeVatron candidates had been proposed, including, e.g., the Galactic center (e.g.…”

Section: Introductionmentioning

confidence: 96%

Neutrino Observations of LHAASO Sources: Present Constraints and Future Prospects

Huang,

2021

Preprint

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The Large High Altitude Air Shower Observatory (LHAASO) observed a dozen of gamma-ray sources with significant emission above 100 TeV, which are the possible accelerators of PeV cosmic-rays. The neutrino observations are required to answer whether these high energy gamma-rays are generated through hadronic process (by cosmic-rays) or leptonic process (by electrons). We use the Bayesian method and the ten-year (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) IceCube data to constrain the hadronic gamma-ray flux from LHAASO sources. The current observations constrain that the hadronic component contributes no more than ∼70% to the gamma-rays from Crab Nebula, which disfavors the hadronic origin of gamma-rays below hundreds of TeV. For other LHAASO sources, the 90% C.L. upper limits on hadronic gamma-ray flux are still higher than the gamma-ray flux observed. The uncertainties due to the source extension assumption and statistical approach are discussed quantitatively. We also evaluate the neutrino observation of LHAASO sources in the combined search using the current and future neutrino telescopes.

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Discovery of the Ultrahigh-energy Gamma-Ray Source LHAASO J2108+5157

Cited by 38 publications

References 26 publications

A Search for Cosmic Ray Bursts at 0.1 PeV with a Small Air Shower Array

A Search for Cosmic Ray Bursts at 0.1 PeV with a Small Air Shower Array

Ultra-high Energy Gamma-rays from Past Explosions in our Galaxy

Neutrino Observations of LHAASO Sources: Present Constraints and Future Prospects

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