| 2 | East Asian VLBI Network observations of active galactic nuclei jets:imaging with KaVA+Tianma+Nanshan显示文摘The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions.After the combination of the Korean VLBI Network(KVN) and the VLBI Exploration of Radio Astrometry(VERA) into Ka VA,further expansion with the joint array in East Asia is actively promoted.Here we report the first imaging results(at 22 and 43 GHz) of bright radio sources obtained with Ka VA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China.To test the EAVN imaging performance for different sources,we observed four active galactic nuclei(AGN) having different brightness and morphology.As a result,we confirmed that the Tianma 65-m Radio Telescope(TMRT) significantly enhances the overall array sensitivity,a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of Ka VA only.The addition of the Nanshan 26-m Radio Telescope(NSRT) further doubled the east-west angular resolution.With the resulting high-dynamic-range,high-resolution images with EAVN(Ka VA+TMRT+NSRT),various fine-scale structures in our targets,such as the counter-jet in M87,a kink-like morphology of the 3 C 273 jet and the weak emission in other sources are successfully detected.This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general.Ongoing expansion of EAVN will further enhance the angular resolution,detection sensitivity and frequency coverage of the network. | 崔玉竹 Kazuhiro Hada Motoki Kino Bong-Won Sohn Jongho Park Hyun-Wook Ro Satoko Sawada-Satoh Wu Jiang Lang Cui Mareki Honma 沈志强 Fumie Tazaki 安涛 Ilje Cho Guang-Yao Zhao Xiao-Peng Cheng Kotaro Niinuma Kiyoaki Wajima Ying-Kang Zhang Noriyuki Kawaguchi Juan-Carlos Algaba Shoko Koyama Tomoya Hirota Yoshinori Yonekura Nobuyuki Sakai Bo Xia Yong-Bin Jiang Lin-Feng Yu Wei Gou Ju-Yeon Hwang Yong-Chen Jiang Yun-Xia Sun Dong-Kyu Jung Hyo-Ryoung Kim Jeong-Sook Kim Hideyuki Kobayashi Jee-Won Lee Jeong-Ae Lee Hua Zhang Guang-Hui Li Zhi-Qiang Xu Peng Li Jung-Hwan Oh Se-Jin Oh Chung-Sik Oh Tomoaki Oyama Duk-Gyoo Roh Katsunori-M.Shibata 郭文 Rong-Bing Zhao Wei-Ye Zhong Jin-Qing Wang Wen-Jun Yang 闫浩 Jae-Hwan Yeom Bin Li 李笑飞 Jian-Ping Yuan Jian Dong Zhong Chen Kazunori Akiyama Keiichi Asada Do-Young Byun Yoshiaki Hagiwara Jeffrey Hodgson Tae-Hyun Jung Kee-Tae Kim Sang-Sung Lee Kunwoo Yi Qing-Hui Liu Xiang Liu Ru-Sen Lu Masanori Nakamura Sascha Trippe Na Wang Xue-Zheng Wang 张波 | 2021 | Research in Astronomy and Astrophysics2021，21，8： | 0 |
| 3 | An accurate and efficient radiative transfer model for simulating all-sky images from Fengyun satellite radiometers显示文摘Forward radiative transfer models(RTM)are an indispensable tool for quantitative applications of satellite radiometers,e.g.,for data calibration,instrument development,retrieval,and so on.In this study,we develop an accurate and efficient RTM for radiometers onboard Fengyun satellites,namely FYRTM(RTM for Fengyun Radiometers).Correlated k-distribution models are developed to improve the computational efficiency for gas absorption,and the effects of cloud and aerosol multiple scattering and emission are accelerated with pre-computed look-up tables.FYRTM is evaluated with a rigorous simulation based on discrete ordinate radiative transfer model(DISORT)as well as a popular fast forward model,i.e.,the Community Radiative Transfer Model(CRTM).Results indicate that FYRTM-based simulations are two to three orders of magnitudes faster than the DISORT-based simulations.Compared to the rigorous model,FYRTM relative errors are within 2%at solar channels,and brightness temperatures(BT)differences are within 1 K at infrared channels.Compared with CRTM,FYRTM is computationally similar at solar channels,but three times faster at infrared channels.Furthermore,simulated reflectances/BTs using FYRTM are in a good agreement with the satellite observations.Overall,FYRTM is capable to simulate satellite observations under different atmospheric conditions,and can be extended to other radiometers onboard the Fengyun satellites(both geostationary and polarorbiting satellites).It is expected to play important roles in future applications with Fengyun observations. | Bin YAO Chao LIU Shiwen TENG Lei BI Zhiqing ZHANG Peng ZHANG Byung-Ju SOHN | 2020 | Science China Earth Sciences2020，63，11： | 0 |
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