Photometric Redshifts in the North Ecliptic Pole Wide Field based on a
  Deep Optical Survey with Hyper Suprime-Cam
  The $AKARI$ space infrared telescope has performed near- to mid-infrared
(MIR) observations on the North Ecliptic Pole Wide (NEPW) field (5.4 deg$^2$)
for about one year. $AKARI$ took advantage of its continuous nine photometric
bands, compared with NASA's $Spitzer$ and WISE space telescopes, which had only
four filters with a wide gap in the MIR. The $AKARI$ NEPW field lacked deep and
homogeneous optical data, limiting the use of nearly half of the IR sources for
extra-galactic studies owing to the absence of photometric redshifts
(photo-zs). To remedy this, we have recently obtained deep optical imaging over
the NEPW field with 5 bands ($g$, $r$, $i$, $z$, and $Y$) of the Hyper
Suprime-Camera (HSC) on the Subaru 8m telescope. We optically identify AKARI-IR
sources along with supplementary $Spitzer$ and WISE data as well as
pre-existing optical data. In this work, we derive new photo-zs using a
$\chi^2$ template-fitting method code ($Le$ $Phare$) and reliable photometry
from 26 selected filters including HSC, $AKARI$, CFHT, Maidanak, KPNO,
$Spitzer$ and WISE data. We take 2026 spectroscopic redshifts (spec-z) from all
available spectroscopic surveys over the NEPW to calibrate and assess the
accuracy of the photo-zs. At z < 1.5, we achieve a weighted photo-z dispersion
of $\sigma_{\Delta{z/(1+z)}}$ = 0.053 with $\eta$ = 11.3% catastrophic errors.
