Environmental Effects on AGN Activities via Extinction-Free Mid-Infrared Census

Daryl Joe Santos^1*, Tomotsugu Goto¹, Ting-Wen Wang¹, Chien-Chang Ho¹, Ting-Chi Huang¹, Seong Jin Kim¹

¹Institute of Astronomy, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Daryl Joe Santos, email:daryl_santos@gapp.nthu.edu.tw

How the environment affects the AGN activity along with galaxy evolution is one of the interesting issues in modern astronomy. However, it cannot be completed without any efforts to reveal the hidden/obscured population of AGNs. The AKARI satellite is more powerful than the other current IR telescopes (e. g. WISE and Spitzer) due to its 9-band filter coverage, which is more effective compared to WISE’s 4-band coverage and Spitzer’s 5-band coverage. Continuous near- to mid-IR (MIR) photometry obtained by the AKARI survey towards the northern sky allows us to tackle this issue in an extinction- free way since MIR provides the distinctive diagnostic for discriminating the hidden AGN activities. We utilized an extinction-free AGN classification of AKARI-detected galaxies in the North Ecliptic Pole. The CIGALE is a code that uses spectral energy distribution (SED) fitting to model the optical to sub-mm emission of each source, and it was used to identify hidden AGN activities. The photometric redshift data of the sample galaxies were estimated using LEPHARE, a χ2 template-fitting code, and their local density values were derived from a separate catalog. We report on the evolution of AGN activities as a function of environment, redshift, and total infrared (IR) luminosity.

Keywords: Mid-infrared, active galactic nucleus (AGN), environmental effects