High resolution observations of the 6cm H_2CO maser in NGC 6240

作     者：Jun-Zhi Wang Zhi-Yu Zhang Yu Gao 

作者机构：School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Purple Mountain Observatory Chinese Academy of Sciences Max-Planck-Institut für Radioastronomie Graduate University of Chinese Academy of Sciences 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2013年第13卷第3期

页      面：270-276页

核心收录：

学科分类：07[理学] 070402[理学-天体测量与天体力学] 0704[理学-天文学] 

基　　金：supported by the National Basic Research Program of China (973 Program, 2012CB821800) the Natural Science Foundation of China(Grant Nos. 10833006 and 11173013) 

主　　题：galaxies: ISM    galaxies: kinematics and dynamics    galaxies: individual (NGC 6240) 

摘      要：We present high resolution （- 1″） H2CO maser and 5 GHz radio continuum observations toward nearby merging galaxy NGC 6240 made with the Very Large Array in an A configuration. Two concentrations of H2CO emission at about a 6or level have been detected, one of which is associated with the strongest CO peak in the overlap region while the other is about 2″ southwest of the southem galaxy. Both H2CO concentrations are associated with near infrared H2 emission, which is thought to be from shocked molecular gas. The total H2CO line luminosity in NGC 6240 is about 60% of that in Arp 220. Based on the distribution of H2CO emission in NGC 6240, which has both active galactic nuclei and an extreme starburst, the H2CO megamaser is likely to be related to the effect of the starburst instead of nuclear activity. Radio continuum cannot be the inversion mechanism of H2CO megamasers, because the two H2CO concentrations in NGC 6240 are not associated with radio continuum emission. Instead, with the association of near infrared H2 emission, shock dynamics may produce the inverted population of H2CO needed to generate megamasers.