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. (arXiv:1902.02800v1 [astro-ph.GA])

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. (arXiv:1902.02800v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chiang_C/0/1/0/all/0/1">Chia-Ying Chiang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goto_T/0/1/0/all/0/1">Tomotsugu Goto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hashimoto_T/0/1/0/all/0/1">Tetsuya Hashimoto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_S/0/1/0/all/0/1">Seong-Jin Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matsuhara_H/0/1/0/all/0/1">Hideo Matsuhara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oi_N/0/1/0/all/0/1">Nagisa Oi</a>

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$_{rm AGN}$) shows no sign of strong redshift
evolution. Instead, F$_{rm AGN}$ increases with increasing IR luminosity in
all redshifts bins ($0

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$_{rm AGN}$) shows no sign of strong redshift
evolution. Instead, F$_{rm AGN}$ increases with increasing IR luminosity in
all redshifts bins ($0<z<2$).

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