Does AGN Fraction Depend on Redshift or Luminosity? An Extinction-Free Test by 18-band Mid-infrared SED Fitting in the AKARI NEP Wide Field

Abstract

Revealing what fraction of galaxies harbor AGN is central in understanding black hole accretion history of the Universe. However, optical and soft X-ray surveys miss the most highly obscured AGNs. Infrared (IR), instead, is more robust against absorption. Previous IR photometric surveys, however, only had 4 or 5 filters in mid-IR. Our AKARI North Ecliptic Pole (NEP) wide field sample has 18 filters in mid-IR (9 from AKARI, 4 from WISE, and 5 from Spitzer), for the first time, allowing a sophisticated mid-IR SED fitting diagnosis for a statistical number of sources (89178 over 5.4 deg${}^2$). By using a SED fitting technique, we investigate the evolution of AGN fraction as a function of redshift and IR (8-1000 $\mu$m) luminosity in an extinction-free way. We found that the AGN fraction (F${}_{\mathrm{AGN}}$) shows no sign of strong redshift evolution. Instead, F${}_{\mathrm{AGN}}$ increases with increasing IR luminosity in all redshifts bins ($0<z<2$).

accepted for publication in PASJ AKARI special issue. A related talk is at https://www.youtube.com/watch?v=bWJfyZWKi3U

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• Dynamical properties of Ultraluminous Infrared Galaxies. II. Traces of dynamical evolution and end products of local ultraluminous mergers
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Cited by in corpus (5)

• Search for Optically Dark Infrared Galaxies without Counterparts of Subaru Hyper Suprime-Cam in the AKARI North Ecliptic Pole Wide Survey Field
• Lower AGN Abundance in Galaxy Clusters at z < 0.5
• Identification of AKARI infrared sources by Deep HSC Optical Survey: Construction of New Band-Merged Catalogue in the NEP-Wide field
• Environmental Effects on AGN activity via Extinction-free Mid-Infrared Census
• The OTELO survey: Revealing a population of low-luminosity current/active star-forming galaxies at z$\sim 0.9$