An extinction-free AGN census by 23 space-based infrared band SED fitting

Ting-Wen Wang^1*, Tomotsugu Goto¹, Seong Jin Kim¹, Tetsuya Hashimoto¹, Denis Burgarella², Matthew Malkan³, Nagisa Oi⁴, Chien-Chang Ho¹

¹Institute of Astronomy, National Tsing Hua University, Hsinchu City, Taiwan
²Aix Marseille Univ. CNRS, CNES, LAM Marseille, France
³Department of Physics and Astronomy, UCLA, Los Angeles, CA, USA
⁴Tokyo University of Science, Tokyo, Japan

* Presenter:Ting-Wen Wang, email:tinattw0127@gapp.nthu.edu.tw

How active galactic nucleus (AGN) impact upon the total infrared (IR) luminosity is one of the critical issues to study galaxy-AGN coevolution. However, AGNs are often missed in optical, UV and soft X-ray observations. An mid-IR survey is one of the best ways to study AGNs because it is extinction-free. The uniqueness of AKARI enables us to search for hidden AGNs: the AKARI satellite performs continuous near- to mid-IR observation with 9 filters. WISE and SPITZER cannot separate star forming galaxy (SFG)-AGN well at certain redshift ranges due to the filter gaps in the mid-IR. In this work, we derive how much portion of the energy released from the active nucleus contributes to the total infrared luminosity of a galaxy. To decompose AGN emission from the whole energy distribution, we use the state-of-the-art modeling software based on the energy balance scheme between the obscured UV/optical and the reemitted IR emission by dust. There are 1955 sources in our AKARI sample; however, previously there were only 15 spectroscopically/X-ray classified AGNs. With our approach, 44 AGNs are recovered from the sample. Also, we found there is a redshift dependence of the AGN evolution, which implies more AGNs in the high-z universe. With the upcoming large IR surveys, e.g. JWST, we expect to find more AGNs and have a comprehensive understanding of the accretion history of supermassive black holes.

Keywords: galaxies: active, galaxies: infrared