The Role of AGNs in the (Ultra)Luminous Infrared Galaxy

• Main Authors: Lin, Ming-Yi, 林明儀
• Other Authors: Hashimoto, Yasuhiro
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/00812957755424133539

碩士 === 國立臺灣師範大學 === 地球科學系 === 101 === In order to understand the mutual influence between active galactic nuclei (AGN) and star formation during the evolution of galaxies, we investigate 142 galaxies detected in both X-ray and 70μm observations in the COSMOS (Cos- mic Evolution Survey) field. All of our data are obtained from archive, X-ray point source catalogs from Chandra and XMM-Newton observation; far-infrared 70μm point source catalog from Spitzer-MIPS observation. Although the IRAC [3.6μm]-[4.5μm] vs. [5.8μm]-[8.0μm] colors of our sample indicate the existence of star formation, the ratio of rest frame 2-10 keV luminosity to total infrared lu- minosity (8-1000μm) shows comparatively higher X-ray flux than submillimeter galaxies for a given total infrared luminosity, indicating the possibility of higher AGN activity relative to star formation. When we characterize ”obscured AGN” by X-ray hardness ratio, we find that sources with exhibit both 70μm and X-ray emissions tend to have a higher hardness ratio compared to X-ray sources without 70μm emission, suggesting possible connection between the dust and gas across the various physical scales inside a galaxy. We also find that 70μm detected galaxies with X-ray emission and without X-ray emission show no significant dif- ference in cold dust temperature, suggesting that the AGN activity and the dust temperature may not be directly correlated.