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HADAR (High Altitude Detection of Astronomical Radiation)是一个基于大气切伦科夫成像技术的地面望远镜阵列, 其采用大口径折射式水透镜系统来收集大气切伦科夫光, 以实现对10 GeV—10 TeV能量段的伽马射线和宇宙线的探测. HADAR具有低阈能和大视场的优势, 因此可以对天区进行连续扫描和观测, 在观测活动星系核(Active Galactic Nuclei, AGN)等银河系外伽马射线源方面具有明显优势. 本文研究了HADAR实验对AGN的探测能力. 基于费米望远镜(Fermi Large Area Telescope, Fermi-LAT)的AGN源能谱信息, 将观测能量外推至甚高能能段, 同时加入河外背景光的吸收效应, 以计算HADAR对AGN源观测的统计显著性. 研究结果显示, HADAR运行一年时间, 预计将有31个Fermi-LAT AGN源以高于5倍显著性被观测到, 其中大部分为蝎虎状天体类型.The High Altitude Detection of Astronomical Radiation (HADAR) experiment is a refracting terrestrial telescope array based on the atmospheric Cherenkov imaging technique. It is a hybrid array consisting of four water-lens telescopes and a surrounding scintillation detector array for observing Cherenkov light induced by 10 GeV–10 TeV cosmic rays and gamma rays in the atmosphere. The water-lens telescope mainly consists of a hemispherical lens with a diameter of 5 m acting as a Cherenkov light collector, a cylindrical metal tank with a 4 m radius and 7 m height, and an imaging system at the bottom of the tank. The sky region covered by HADAR is much larger than the current generation of Imaging Atmospheric Cherenkov Telescopes, and even the CTA. The field-of-view (FOV) of HADAR can reach up to 60 degrees. The HADAR experiment possesses the advantages of a large field-of-view and low energy threshold, so it can continuously scan wide portions of the sky and easily observe extragalactic gamma-ray sources. The majority of the extragalactic gamma-ray sources detected at very high energy (VHE) energies are active galactic nuclei (AGNs). In this study, we present the potential of using the HADAR experiment for detecting AGN. Based on the AGN catalog sources of the Fermi Large Area Telescope (Fermi-LAT), the observed energy is extrapolated to the VHE range. The VHE gamma rays propagating over cosmological distances can interact with the low-energy of the extragalactic background light (EBL) and produce electron-positron pairs. Therefore, we consider the absorption effects of different EBL models when calculating the expected gamma ray spectra of the AGN sample. We select the sample with redshift measurements and locations inside the FOV of HADAR from 4LAC catalog. In total, there are 375 BL Lacertae objects (BL Lacs) and 289 flat-spectrum radio quasars (FSRQs) satisfying the selection conditions. The integral gamma ray spectra are derived and compared with the sensitivity curve of HADAR, the number of sources with fluxes above the sensitivity of HADAR is counted. Further, we calculate the statistical significance of HADAR for AGN source observation based on the equi-zenith angle sky scanning analysis method. The simulation results reveal that a total of 31 sources of Fermi-LAT AGN can be detected by HADAR with a significance greater than five standard deviations over a one-year survey period, most of which are BL Lacs.
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Fermi Source Assoc. R.A./(°) Dec./(°) z $N_0/(\rm TeV^{-1}{\cdot}cm^{-2}{\cdot}s^{-1})$ $ E_0 $/GeV α β Livetime/hrs S/σ 4FGL J0112.1+2245 S2 0109+22 18.03 22.75 0.265 1.399× 10–5 0.76 1.99 0.057 277.8 8.9 4FGL J0222.6+4302 3C66A 35.67 43.04 0.444 1.008×10–5 1.21 1.88 0.045 264.2 21.5 4FGL J0319.8+1845 1E 0317.0+1835 49.97 18.75 0.190 1.618×10–8 5.98 1.67 0.0 257.8 5.1 4FGL J0650.7+2503 1ES 0647+250 102.70 25.05 0.203 6.587×10–7 2.06 1.66 0.035 286.0 25.3 4FGL J0738.1+1742 PKS 0735+17 114.54 17.71 0.424 2.640×10–6 1.54 1.97 0.065 251.3 7.4 4FGL J0809.8+5218 1ES 0806+524 122.46 52.31 0.138 2.222×10–6 1.30 1.80 0.041 193.9 15.1 4FGL J0915.9+2933 Ton 0396 138.99 29.55 0.190 1.068×10–6 1.35 1.74 0.083 294.7 7.8 4FGL J1015.0+4926 1H 1013+498 153.77 49.43 0.212 7.019×10–6 1.01 1.76 0.041 220.0 29.9 4FGL J1058.6+5627 TXS 1055+567 164.67 56.46 0.143 2.525×10–6 1.06 1.87 0.040 149.4 6.3 4FGL J1104.4+3812 Mkn 421 166.12 38.21 0.030 1.842×10–5 1.29 1.72 0.023 284.9 529.6 4FGL J1117.0+2013 RBS 0958 169.27 20.23 0.139 4.167×10–7 1.84 1.95 0.0 266.1 5.7 4FGL J1150.6+4154 RBS 1040 177.66 41.91 0.320 5.965×10–7 1.73 1.65 0.091 270.0 6.6 4FGL J1217.9+3007 B2 1215+30 184.48 30.12 0.130 7.113×10–6 1.07 1.88 0.040 295.1 31.6 4FGL J1221.3+3010 PG 1218+304 185.34 30.17 0.184 1.742×10–7 4.44 1.71 0.0 295.2 31.3 4FGL J1221.5+2814 W Comae 185.38 28.24 0.102 3.516×10–6 1.06 2.16 0.0 293.1 6.6 4FGL J1224.4+2436 MS 1221.8+2452 186.12 24.61 0.219 2.417×10–7 2.36 1.89 0.0 284.6 5.5 4FGL J1224.9+2122 4C +21.35 186.23 21.38 0.434 2.187×10–4 0.39 2.27 0.045 271.8 5.4 4FGL J1230.2+2517 ON 246 187.56 25.30 0.135 6.100×10–6 0.82 1.99 0.061 286.7 6.0 4FGL J1231.7+2847 B2 1229+29 187.93 28.79 0.236 7.991×10–7 1.58 1.99 0.0 293.9 5.1 4FGL J1427.0+2348 PKS 1424+240 216.76 23.80 0.604 6.508×10–6 1.23 1.70 0.060 281.8 23.8 4FGL J1428.5+4240 H 1426+428 217.13 42.68 0.129 2.772×10–8 5.02 1.66 0.0 266.1 9.7 4FGL J1555.7+1111 PG 1553+113 238.93 11.19 0.360 3.325×10–6 1.85 1.54 0.070 199.5 58.9 4FGL J1653.8+3945 Mkn 501 253.47 39.76 0.033 4.439×10–6 1.48 1.71 0.018 279.5 258.4 4FGL J1725.0+1152 1H 1720+117 261.27 11.87 0.180 7.214×10–7 2.22 1.76 0.056 205.9 13.9 4FGL J1728.3+5013 I Zw 187 262.08 50.23 0.055 1.950×10–7 3.01 1.78 0.0 213.2 24.1 4FGL J1838.8+4802 GB6J1838+4802 279.71 48.04 0.300 3.198×10–7 2.55 1.85 0.0 231.3 6.1 4FGL J2116.2+3339 B2 2114+33 319.06 33.66 0.350 1.068×10–6 1.71 1.74 0.102 294.4 7.2 4FGL J2202.7+4216 BL Lac 330.69 42.28 0.069 4.498×10–5 0.75 2.18 0.060 268.2 15.0 4FGL J2250.0+3825 B3 2247+381 342.51 38.42 0.119 2.881×10–8 5.33 1.72 0.060 284.2 9.9 4FGL J2253.9+1609 3C 454.3 343.50 16.15 0.859 6.408×10–4 0.52 2.39 0.0 240.7 14.7 4FGL J2323.8+4210 1ES 2321+419 350.97 42.18 0.059 2.926×10–7 2.47 1.90 0.0 268.7 13.4 
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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53]
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