Title: Far-infrared Line Observations in Nearby and High-z Galaxies

Speaker: Yinghe Zhao, Yunnan Astronomical Observatories, Chinese Academy of Science

Host: Junfeng Wang

Time: 14:30, Thursday,  Dec. 31

Location: Physics Building 552

Abstract: 

Far-infrared (FIR) emission lines, such as the [C II] 158 μm, [N II] 122 and 205 μm, mid-J CO lines, are important for cooling the interstellar medium (ISM) and for providing critical diagnostic tools for the study of the star-forming ISM. This talk will show our recent works on these lines, observed in nearby and high-z galaxies, including ellipticals, normal galaxies and luminous infrared galaxies (LIRGs). The main results are (1) The luminosity of the [NII] 205 micron (LNII) has a nearly linear correlation with star formation rate (SFR), albeit the intercept of such relation varies somewhat with f60/f100, suggesting that [NII]205 emission can serve as a useful SFR indicator with an accuracy of ~0.4 dex, or ~0.2 dex if f60/f100 is known independently. (2) The two [CI] lines are good tracers of total molecular gas mass both in LIRGs and normal galaxies. (3) CO(7-6) is a good tracer of SFR. (4) The combination of two or three of the CO(7-6), [NII]205, [CII]158 and [CI] lines can measure both SFR and FIR color, e.g., surface SFR density. (5) Nearby infrared luminous QSOs also contain abundant molecular gas. (6) High resolution observation of CO(6-5) line shows that CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset, suggesting that the gas and dust emissions may have different heating mechanisms.

Bio: 

赵应和，2002年和2008年分别获得南京大学学士和博士学位，2009年获得江苏省优秀博士学位论文奖。在中科院紫金山天文台星系中的恒星形成团组从事博士后研究工作后于2011年获聘副研究员，随后（2011.11-2015.10）在美国加州理工学院、国家射电天文台任访问学者。2015年底至今任中科院云南天文台研究员，2018年获云南省首批高层次青年人才项目支持。主要研究领域是多波段观测星系的形成和演化，如星系中的恒星形成活动、星际介质性质、星系和黑洞的共同演化等。迄今已发表学术论文近60篇，论文被引用800余次，H指数18。主持或参与面上、重大和重点研发等项目。主要研究成果有（1）证实蓝致密矮星系是年老的、正在进行星暴活动的星系，并指出这些星系大多经历过气体的内外流活动；（2）首次提出利用氮离子在远红外波段的发射线作为恒星形成率定标；（3）首次观测上证实碳原子发射线可以作为总分子气体示踪剂并给出定标。这三项研究工作所发表的7篇论文，篇均引用近30次。