Initial result from mid-infrared spectroscopic survey by AKARI
 -- Property of PAH emission from galaxies out to z=0.5 --

Youichi Ohyama

ASIAA, Taiwan


Abstract: The PAH emission in the mid-infrared wavelengths is thought
to be a good star formation rate indicator, which is less sensitive to
the effect of dust extinction compared to the tracers in the
UV/Optical wavelengths.

The robustness of the PAH/SFR relationship, however, is still not be
established well because of lack of unbiased, large number of spectral
samples of PAH emission from galaxies.

We will present the initial results from the unbiased slit-less
spectroscopic survey of galaxies (SPICY) in the near- and mid-infrared
wavelengths by AKARI.

The survey is conducted by the Infrared Camera (IRC) onboard AKARI in
the slit-less spectroscopy mode (R=50).  We have covered over 1000
sq. arcmin. within the AKARI deep field toward the North Ecliptic Pole
(NEP) with a sensitivity down to 1mJy (5 sigma) for continuum at 9um,
and obtained more than 100 samples of mid-infrared spectra of galaxies
with good S/N ratio.

We will discuss property of the PAH features of these galaxies, and
relationship between  NIR/MIR color and the PAH features.