AI 中文总结
本研究利用KVN的VLBI技术，在89GHz频段探测到朝向四个河外致密射电源的HCO⁺与HCN分子吸收线，其柱密度比与现有观测趋势一致，验证了VLBI用于分子吸收研究的可行性。
AI 中文摘要
作为以高角分辨率探索银河系前景星际介质（ISM）的第一步，我们研究了甚长基线干涉测量（VLBI）对分子吸收线的探测能力。本文报道了利用韩国甚长基线干涉测量网络（KVN）对四个河外致密射电源开展的首次观测，探测到了HCO⁺ J=1-0和HCN J=1-0分子吸收线。所有方向均探测到HCO⁺吸收线，三个方向探测到HCN吸收线；其中除两次HCO⁺探测外，其余均为VLBI首次报道。我们发现，利用VLBI得到的柱密度比N(HCN)/N(HCO⁺)与连接元件干涉仪观测建立的趋势一致，证明了未来开展分子吸收VLBI研究的可行性。
英文摘要
As the first step to explore the Galactic foreground interstellar medium (ISM) with high angular resolution, we investigated the detectability of molecular absorption lines with very long baseline interferometry (VLBI). This paper reports our first observations of HCO+ J=1-0 and HCN J=1-0 molecular absorption lines toward four extragalactic compact radio sources with the Korean VLBI Network (KVN). HCO+ absorption lines were detected in all directions and HCN absorption lines in three directions. All of these detections, except for two HCO+ detections, are reported here for the first time with VLBI. We find that the column density ratio N(HCN)/N(HCO+) obtained with VLBI is consistent with the trend established from observations with connected-element interferometers, demonstrating the feasibility of future VLBI studies of molecular absorption.
Comments5 pages, 2 figures, 3 tables. Accepted for publication in PASJ
