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AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at <i>z</i> ≲ 0.5
Ohyama, Y.,Wada, T.,Matsuhara, H.,Takagi, T.,Malkan, M.,Goto, T.,Egami, E.,Lee, H.-M.,Im, M.,Kim, J.H.,Pearson, C.,Inami, H.,Oyabu, S.,Usui, F.,Burgarella, D.,Mazyed, F.,Imanishi, M.,Jeong, W.-S.,Miya EDP Sciences 2018 Astronomy and astrophysics Vol.618 No.-
<P><I>Context.</I> Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift <I>z</I> ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy.</P><P><I>Aims.</I> We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to <I>z</I> ≃ 0.5, by paying particular attention to their PAH properties.</P><P><I>Methods.</I> We conducted a low-resolution (<I>R</I> ≃ 50) slitless spectroscopic survey at 5-13 <I>μ</I>m of 9 <I>μ</I>m flux-selected sources (>0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 <I>μ</I>m features at <I>z</I> < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 <I>μ</I>m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 <I>μ</I>m PAH feature over the 3.5 <I>μ</I>m stellar component of the SEDs.</P><P><I>Results.</I> The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 <I>μ</I>m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at <I>z</I> ≳ 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.</P>
A PANORAMIC VIEW OF THE ASTEROIDS IN THE INNER SOLAR SYSTEM WITH AKARI
Usui, F.,Kuroda, D.,Muller, T.G.,Hasegawa, S.,Ishiguro, M.,Ootsubo, T.,Ueno, M.,AKARI SOSOS team, AKARI SOSOS team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We constructed an unbiased asteroid catalog from the mid-infrared part of the All-Sky Survey with the Infrared Camera (IRC) on board AKARI. About 20% of the point source events recorded in the IRC All-Sky Survey observations were not used for the IRC Point Source Catalog in its production process because of a lack of multiple detection by position. Asteroids, which are moving objects on the celestial sphere, are included in these "residual events" We identified asteroids out of the residual events by matching them with the positions of known asteroids. For the identified asteroids, we calculated the size and albedo based on the Standard Thermal Model. Finally we had a new brand of asteroid catalog, which contains 5,120 objects, about twice as many as the IRAS asteroid catalog.
RETRIEVAL OF LOCAL INTERPLANETARY DUST EMISSIVITY BY ASTRO-F
HONG S. S.,KWON S. M.,PYO J.,UENO M.,ISHIGURO M.,USUI F.,WEINBERG J. L. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.4
This is a proposal to probe local part of the interplanetary dust (IPD) cloud complex and retrieve mean volume emissivity of the local IPDs at mid-infrared wavelengths. This will be done by monitoring, with Infrared Camera (IRC) aboard the ASTRO-F, the annual modulation of the zodiacal emission. In pointing mode of the ASTRO-F mission the spacecraft can make attitude maneuvering over approximately ${\pm}1^{\circ}$ range centered at solar elongation $90^{\circ}$ in the ecliptic plane. The attitude maneuvering combined with high sensitivity of the IRC will provide us with a unique opportunity observationally to take derivatives of the zodiacal emission brightness with respect to the solar elongation. From the resulting differential of the brightness over the ${\pm}1^{\circ}$ range, one can directly determine the mean volume emissivity of the local IPDs with a sufficient accuracy to de-modulate the annual emissivity variations due to the Earth's elliptical motion and the dis-alignment of the maximum IPD density plane with respect to the ecliptic. The non-zero eccentricity ($e_{\oplus}$= 0.0167) of the Earth's orbit combined with the sensitive temperature dependence of the Planck function would bring modulations of amplitude at least $3.34\%$ to the zodiacal emission brightness at mid-infrared wavelengths, with which one may determine the IPD temperature T(r) and mean number density n(r) as functions of heliocentric distance r. This will in turn fix the power-law exponent $\delta$ in the relation $T(r) = T_o(r/r_o)^{-\delta}$ for the dust temperature and v in $n(r) = n_o(r/r_o)^-v$ for the density. We discuss how one may de-couple the notorious degeneracy of cross-section, density, reference temperature $T_o$ and exponent $\delta$.
Visible-wavelength spectroscopy of subkilometer-sized near-Earth asteroids with a low delta-v
Kuroda, D.,Ishiguro, M.,Takato, N.,Hasegawa, S.,Abe, M.,Tsuda, Y.,Sugita, S.,Usui, F.,Hattori, T.,Iwata, I.,Imanishi, M.,Terada, H.,Choi, Y.-J.,Watanabe, S.-i.,Yoshikawa, M. Astronomical Society of Japan 2014 Publications of the Astronomical Society of Japan Vol.66 No.3
AKARI NEAR-INFRARED SPECTROSCOPIC SURVEY FOR COMETARY VOLATILES
Ootsubo, T.,Kawakita, H.,Kobayashi, H.,Usui, F.,AKARI SOSOS team, AKARI SOSOS team The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We performed a spectroscopic survey for cometary volatiles with the Infrared Camera onboard the Japanese infrared satellite AKARI. The observations were carried out in the near-infrared wavelength range in the period from 2008 June to 2010 January. In this paper, we summarize the observations and results of the AKARI survey for the mixing ratios of major volatiles in comets. We derived the $2.5-5{\mu}m$ spectra of 18 comets including both Oort cloud comets and Jupiter-family comets. Prominent emission bands in the observed spectra are the fundamental vibrational bands of water ($H_2O$) at $2.7{\mu}m$ and carbon dioxide ($CO_2$) at $4.3{\mu}m$. The fundamental vibrational band of carbon monoxide (CO) at $4.7{\mu}m$ and the broad emission feature probably related to C-H bearing molecules can also be recognized around the $3.4-3.5{\mu}m$ region in some comets. We detect $CO_2$ in 17 out of 18 comets, and derived gas production rate ratios of $CO_2$ with respect to $H_2O$ in 17 comets. We detect a reliable CO emission band only in three of the comets. Our data set provides the largest homogeneous database of $CO_2/H_2O$ ratios in comets obtained so far.