Spatial Distributions of Cold and Warm Interstellar Dust in M101 Resolved with AKARI/Far-Infrared Surveyor (FIS)

The nearby face-on spiral galaxy M101 has been observed with the Far-Infrared Surveyor (FIS) onboard AKARI. The far-infrared four-band images reveal fine spatial structures of M101, which include global spiral patterns, giant HII regions embedded in outer spiral arms, and a bar-like feature crossing the center. The spectral energy distribution of the whole galaxy shows the presence of the cold dust component (18 K) in addition to the warm dust component (55 K). The distribution of the cold dust is mostly concentrated near the center, and exhibits smoothly distributed over the entire extent of the galaxy, whereas the distribution of the warm dust indicates some correlation with the spiral arms, and has spotty structures such as four distinctive bright spots in the outer disk in addition to a bar-like feature near the center tracing the CO intensity map. The star-formation activity of the giant HII regions that spatially correspond to the former bright spots is found to be significantly higher than that of the rest of the galaxy. The latter warm dust distribution implies that there are significant star-formation activities in the entire bar filled with molecular clouds. Unlike our Galaxy, M101 is a peculiar normal galaxy with extraordinary active star-forming regions.Comment: 18 pages, 9 figures, accepted for publication in PASJ AKARI special issu

Wide-Area Mapping of 155 Micron Continuum Emission from the Orion Molecular Cloud Complex

We present the results of a wide-area mapping of the far-infrared continuum emission toward the Orion complex by using a Japanese balloon-borne telescope. The 155-um continuum emission was detected over a region of 1.5 deg^2 around the KL nebula with 3' resolution similar to that of the IRAS 100-um map. Assuming a single-temperature model of the thermal equilibrium dust, maps of the temperature and the optical depth were derived from the 155 um intensity and the IRAS 100 um intensity. The derived dust temperature is 5 - 15 K lower and the derived dust optical thickness were derived from the 155-um intensity and the IRAS 100-um intensity. The derived dust temperature is 5 - 15 K lower and the derived dust optical depth is 5 - 300 times larger than those derived from the IRAS 60 and 100-um intensities due to the significant contribution of the statistically heated very small grains to the IRAS 60-um intensity. The optical-thickness distribution shows a filamentary dust ridge that has a 1.5 degrees extent in the north - south direction and well resembles the Integral-Shaped Filament (ISF) molecular gas distribution. The gas-to-dust ratio derived from the CO molecular gas distribution along the ISF is in the range 30 - 200, which may be interpreted as being an effect of CO depletion due to the photodissociation and/or the freezing on dust grains.Comment: 23 pages, 7 figures, 1 table, to appear in PASJ, Vol. 56, No.

AKARI-CAS --- Online Service for AKARI All-Sky Catalogues

The AKARI All-Sky Catalogues are an important infrared astronomical database for next-generation astronomy that take over the IRAS catalog. We have developed an online service, AKARI Catalogue Archive Server (AKARI-CAS), for astronomers. The service includes useful and attractive search tools and visual tools. One of the new features of AKARI-CAS is cached SIMBAD/NED entries, which can match AKARI catalogs with other catalogs stored in SIMBAD or NED. To allow advanced queries to the databases, direct input of SQL is also supported. In those queries, fast dynamic cross-identification between registered catalogs is a remarkable feature. In addition, multiwavelength quick-look images are displayed in the visualization tools, which will increase the value of the service. In the construction of our service, we considered a wide variety of astronomers' requirements. As a result of our discussion, we concluded that supporting users' SQL submissions is the best solution for the requirements. Therefore, we implemented an RDBMS layer so that it covered important facilities including the whole processing of tables. We found that PostgreSQL is the best open-source RDBMS products for such purpose, and we wrote codes for both simple and advanced searches into the SQL stored functions. To implement such stored functions for fast radial search and cross-identification with minimum cost, we applied a simple technique that is not based on dividing celestial sphere such as HTM or HEALPix. In contrast, the Web application layer became compact, and was written in simple procedural PHP codes. In total, our system realizes cost-effective maintenance and enhancements.Comment: Yamauchi, C. et al. 2011, PASP..123..852

The Far-Infrared Properties of Spatially Resolved AKARI Observations

We present the spatially resolved observations of IRAS sources from the Japanese infrared astronomy satellite AKARI All-Sky Survey during the performance verification (PV) phase of the mission. We extracted reliable point sources matched with IRAS point source catalogue. By comparing IRAS and AKARI fluxes, we found that the flux measurements of some IRAS sources could have been over or underestimated and affected by the local background rather than the global background. We also found possible candidates for new AKARI sources and confirmed that AKARI observations resolved IRAS sources into multiple sources. All-Sky Survey observations are expected to verify the accuracies of IRAS flux measurements and to find new extragalactic point sources.Comment: 11 pages, 7 figures, accepted publication in PASJ AKARI special issu

The Far-Infrared Surveyor (FIS) for AKARI

The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and uses two kinds of array detectors. The FIS arrays and optics are designed to sweep the sky with high spatial resolution and redundancy. The actual scan width is more than eight arcmin, and the pixel pitch is matches the diffraction limit of the telescope. Derived point spread functions (PSFs) from observations of asteroids are similar to the optical model. Significant excesses, however, are clearly seen around tails of the PSFs, whose contributions are about 30% of the total power. All FIS functions are operating well in orbit, and its performance meets the laboratory characterizations, except for the two longer wavelength bands, which are not performing as well as characterized. Furthermore, the FIS has a spectroscopic capability using a Fourier transform spectrometer (FTS). Because the FTS takes advantage of the optics and detectors of the photometer, it can simultaneously make a spectral map. This paper summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japa

AKARI/FIS All-sky survey point source catalogues

The AKARI Infrared Astronomical Satellite observed the whole sky in the far infrared (50-180µm) and the mid-infrared (9 and 18µm) between May 2006 and August 2007 (Murakami et al. 2007PASJ...59S.369M) The AKARI/FIS All-Sky Survey Bright Source Catalog Version 1.0 provides positions and fluxes for 427071 point sources in the 4 far-infrared wavelengths centered at 65, 90, 140 and 160µm (see filter characteristics in the "Note (1)" section below

AKARI all-sky bright source catalogue: far-infrared luminous quasars and the optical far-infrared correlation

We have identified 22 quasars in the AKARI far-infrared all-sky Bright Source Catalogue, using a matching radius of 1 are magnified with respect to the predicted far-infrared luminosity, and consider this may be due to gravitational lensing. If confirmed, this would provide a new way to identify lenses; if not, we may have identified an interesting new population of extreme starbursting quasars

Diffuse far-infrared [

The Far-Infrared Line Mapper (FILM) onboard the Infrared Telescope in Space (IRTS) made a survey for the far-infrared [\ion{C}{ii}] 158 μm line emission with high sensitivity and moderate spatial resolution. We have found that diffuse [\ion{C}{ii}] line emission extends to high Galactic latitude regions. The [\ion{C}{ii}] line intensity at $\vert b\vert \sim 60^{\circ}$ ranges from $2\times10^{-7}$ to $1.5\times10^{-6}$ \mbox{erg cm}^{-2}~\mbox{ s}^{-1}~\mbox{sr}^{-1}. Comparisons of the distribution of the [\ion{C}{ii}] line emission with those of the \ion{H}{i} column density and far-infrared radiation show some correlations, but the [\ion{C}{ii}] line emission differs from the far-IR and HI emission at high Galactic latitudes. These differences suggest that the [\ion{C}{ii}] line primarily comes from ionized gas in the high-latitude regions. The intensities of the [\ion{C}{ii}] line emission on the southern side ($b < 0^{\circ}$) of the Galactic plane are systematically larger than those on the northern side ($b > 0^{\circ}$). We infer from this difference that there is a displacement of the Sun with respect to the center of interstellar medium from which the [\ion{C}{ii}] line comes. When an exponential distribution is assumed for the [\ion{C}{ii}] emitting gas, it is expected that the Sun is located at the distance of about 17% of the scale height above the center of the gas. This is consistent with the previously reported displacement of the Sun from the Galactic plane

Journal of The Korean Astronomical Society

We present the results of an rocket-borne observation of far-infrared [CII] line at 157.7¯m from the diffuse interstellar medium in the Ursa Major. We also introduce a part of results on the [CII] emission recently obtained by the IRTS, a liquid-helium cooled 15cm telescope onboard the Space Flyer Unit. From the rocket-borne observation we obtained the cooling rate of the diffuse HI gas due to the [CII] line emission, which is 1:3 \Sigma 0:2 \Theta 10 \Gamma26 ergss \Gamma1 H \Gamma1 atom . We also observed appreciable [CII] emission from the molecular clouds, with average CII/CO intensity ratio of 420. The IRTS observation provided the [CII] line emission distribution over large area of the sky along great circles crossing the Galactic plane at l = 50 ffi and l = 230 ffi . We found two components in their intensity distributions, one concentrates on the Galactic plane and the another extends over at least 20 ffi in Galactic latitude. We ascribe one component to the emissio..