中川 貴雄

SPICA will provide the best sensitivity and image quality than ever at 5-210 mu m. This will revolutionize our understanding of exoplanets, protoplanetary disks, debris disks, and Solar system small bodies. This paper summarizes such key sciences with SPICA discussed so far among the Japanese SPICA Science Working Group, stressing on the planetary formation, and exoplanet detection and characterization.

We report the results of imaging spectroscopic observations of four giant Galactic star-forming regions with Fourier Transform Spectrometer (FTS) onboard AKARI. We obtained [O III] 88 mu m and [C II] 158 mu m line intensity maps for all the regions: G3.270-0.101, G333.6-0.2, NGC 3603, and M17. In G3.270-0.101, we obtained high spatial resolution of the [O III] 88 mu m line emission maps and the far-infrared continuum map for the first time. In G333.6-0.2, we found a local [O III] 88 mu m emission peak, which indicates the presence of an excitation source. We suggest that the [O III] 88 mu m emission locates the excitation sources better than the radio continuum emission does. We discuss the structure of the ISM and a possible embedded excitation source from these far-infrared line and mid-infrared continuum emission maps.

The Japanese infrared astronomical satellite AKARI has a far-infrared Fourier transform spectrometer (FTS), which is the first FTS with photoconductive detector arrays operated in space and provided unique datasets in astrophysics. © 2009 Optical Society of America.

The paper provides a summary of the results of the assessment study conducted on the SPICA Telescope Assembly (STA). SPICA (SPace Infrared telescope for Cosmology and Astrophysics) was selected for study as a mission of opportunity within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch in 2017. Observing in the 5 - 210 micron waveband, one of its major goals is the discovery of the origins of planets and galaxies. ESA's main contribution is the provision of the SPICA Telescope Assembly (STA) featuring a 3.5 m primary mirror cooled to < 6K. A nationally funded European FIR instrument (SAFARI) would also be part of SPICA's payload. Following an internal ESA study carried out in Q1 and Q2 2008, a parallel competitive industrial study (phase A level) has been performed. The main results achieved during this study are summarised. © 2009 Copyright SPIE - The International Society for Optical Engineering.

We describe the calibration of maps of diffuse Galactic Plane emission, and present detailed observations of several complexes. We also report observations of RCW82 H II region surrounded by a ring of dust emission with some embedded bright clumps, which reveal the expansion of material around H II regions as it interacts with the surrounding interstellar medium.

As a result of IRAS observations, main-sequence stars that have circumstellar debris disks and thus show infrared excess have been discovered. Since debris disks are thought to be the final stage of planet formation, it is very important to investigate the properties and evolution of debris disks statistically. Especially, mid-infrared observations become a key method for planet formation study because mid-infrared excess traces the thermal emission from debris dust in planet-forming regions. We are carrying on an unbiased survey of debris disk candidates that show mid-infrared excess by using the AKARI/ARC mid-infrared all-sky survey data. So far, we have identified seven new debris disk candidates that show large 18 gm excess. Here, we present the initial results of the debris disk survey.

Following the IRAS observations, many main-sequence stars that have circumstellar debris disks have been discovered through their infrared excesses. Since debris disks are thought trace the final stages of planet formation, it is very important to statistically investigate the properties and evolution of debris disks. Observations at mid-infrared wavelengths are important for planet formation studies because mid-IR excesses trace the thermal emission from debris dust in their planet forming regions. We are carrying on an unbiased survey of debris disk candidates showing mid-infrared excesses by using the AKARI/IRC mid-infrared all-sky survey data. So far, we have identified 7 new debris disk candidates that show large 18 mu m excess. Here, we present the initial results of the debris disk survey.

We present the results of our systematic infrared 2.5-35 mu m low-resolution spectroscopy of ultraluminous infrared galaxies (ULIRGs), using Subaru, AKARI and Spitzer. We detected the signatures of optically-elusive, but intrinsically luminous, buried AGNs in a significant fraction of ULIRGs classified optically as non-Seyferts. The energetic importance of buried AGN increases with increasing galaxy infrared luminosity, which may support the widely-proposed AGN feedback scenario as the origin of the galaxy downsizing phenomenon.

We have been investigating the formation and evolution of clusters of galaxies from low redshift to high redshift using the NIR/MIR images taken with the AKARI/IRC,C, as part of the AKARI mission program: CLEVL. We present an infrared view of these clusters. It is found that the cluster galaxies detected in MIR are divided into two groups: MIR-blue galaxies with (N3 - S11) < 0 and MIR-red galaxies with (N3 - S11) > 0. MIR-red galaxies are star forming galaxies with varying star formation rates, corresponding to late type galaxies. MIR-blue galaxies are red sequence galaxies with varying stellar ages or with low-level star formation activity. The fraction of the MIR-red galaxies varies significantly from cluster to cluster.

We describe observational characteristics of three Extremely Red MIR-bright Objects (ERMOs, satisfying R - [15] >= 6.5 AB mag) found in the AKARI North Ecliptic Pole (NEP) deep field at z=1.5-2.2, showing broad Mg II emission (similar to 5000 km sec(-1)) while their broad-band spectral energy distributions (SEDs) at optical and mid-infrared are power-law, similar to that of the type-2 AGN. Since their SEDs cannot be explained solely by any AGN dust torus templates, we propose that the stellar population co-exists with the AGN dust torus. The interstellar dust clouds associated with the stellar population may be responsible for the extinction of the broad-line regions.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimised for mid- and far-infrared astronomy with a cryogenically cooled 3.5 m telescope. Its high spatial resolution and unprecedented sensitivity in the mid- and far-infrared will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3 m class cooled (5 K) telescope in space with moderate total weight (3 t). SPICA is proposed as a Japanese-led mission together with extensive international collaboration. The assessment study on the European contribution to the SPICA project has started under the framework of the ESA Cosmic Vision 2015-2025. US and Korean participations are also under discussion. The target launch year of SPICA is 2017.

We present an overview of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is an astronomical mission optimized for mid-and far-infrared astronomy with a cryogenically cooled 3-m class (3.5 m in the current design) telescope. Its high spatial resolution and unprecedented sensitivity will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3-m class cooled (5 K) telescope in space with moderate total weight (4t). SPICA is an international mission. Japan is in charge of the whole integration of the system, and its activity is now approved as a pre-project at JAXA. The assessment study on the European contribution to the SPICA project has been carried out under the framework of the ESA Cosmic Vision 2015-2025. US and Korean participations are also being discussed extensively. The target launch year of SPICA is 2018.

We present our latest results on near- to mid-infrared observations of supernovae within one year after the explosion with Infrared Camera (IRC) on board AKARI In this project, we aim to explore the dust formation scenario in the ejecta of core-collapse supernovae. So far, observations of several recent supernovae including SN2006jc and SN2008ax have been carried out as part of the Directors Time of AKARI. At the same time, we have set about the near-infrared slit-less spectroscopic observations of nearby galaxies with high supernovae frequency in preparation for a future supernova in the AKARI Phase-3 Open Time Program "Near-infrared Slit-less Spectroscopy of Nearby Galaxies; Waiting for Supernovae Momentarily (NEWSY)" (P.I. Sakon, I.). The obtained near- to mid-infrared spectral energy distribution (SED) of early-time supernovae is quite valuable and unique to investigate the properties of dust formed around the massive star and will further deepen our knowledge on the origin of dust especially in the early universe.

The AKARI far-infrared deep cosmological survey has been carried out toward the region with the lowest cirrus density in the whole sky, near the South Ecliptic Pole (AKARI Deep Survey South: ADF-S). We present the details of this survey, and show the obtained galaxy number counts. More than 2200 galaxies were detected down to a flux level of 10 mJy at 90 mu m, and suggest the necessity for a new model to explain galaxy evolution.

We investigate the relation between the surface densities of the gas and stars in various regions in the disks of M101 and M81 to investigate the Kennicutt-Schmidt law. The galaxies were observed with the Far-Infrared Surveyor (FIS) onboard AKARI at central wavelengths of 65, 90, 140 and 160 mu m. The spectral energy distribution of the whole galaxies shows the presence of a cold dust component in addition to a warm dust component. The cold and warm dust components can be related to the gas mass and newly-formed stellar mass, respectively, whose relation in various regions shows a power-law correlation. There are significant differences in the power-law index between outer arms with four giant H-II regions and inner arms in M101, while the power-law index for spiral arms of M81 is similar to that for inner arms in M101.

We present a progress report on two deep radio surveys to support the AKARI North and South Ecliptic Pole Deep fields, and a first correlation between the extragalactic radio source population and their 20 cm fluxes.

We present a first look at the Galactic Plane source populations, and show some early results from the AKARI Diffuse mapping programme to recover the extended galactic emission.

We have observed the Quintuplet- and Arches-cluster regions with the Fourier Transform Spectrometer (FTS) of the Far-Infrared Surveyor (FIS) aboard AKARI to investigate the physical conditions of interstellar matter around the clusters. The FIS-FTS mapping data reveal differences in the spatial distribution among the far-infrared [O III], [N II], and [CII] line emissions near the Arches cluster; the emission of an ionic line with a higher ionization potential is distributed closer to the Arches cluster. This clearly indicates that UV photons from the Arches cluster are ionizing the surface of nearby molecular clouds, and penetrating deeper to dissociate the cloud. We have estimated the effective temperature of the Arches cluster to be about 34000 K from the ratio of the [O III]/[N II] lines. ©2009. Astronomical Society Of Japan.

We have observed the Quintuplet- and Arches-cluster regions with the Fourier Transform Spectrometer (FTS) of the Far-Infrared Surveyor (FIS) onboard AKARI to investigate the physical conditions of the interstellar matter around the clusters. The FIS-FTS mapping data reveal differences in spatial distribution among the far-infrared [OIII], [NII], and [CII] line emissions near the Arches-cluster; the emission of an ionic line with a higher ionization potential is distributed closer to the Arches-cluster. This clearly indicates that UV photons from the Arches-cluster are ionizing the surface of nearby molecular clouds and penetrating deeper to dissociate the cloud. We have estimated the effective temperature of the Arches-cluster to be about 34000 K from the ratio of [OIII]/[NII] lines. We have also estimated the dust color temperature to be about 30 K from the continuum ratio of 88/122 mu m.

AKARI, the Japanese infrared astronomical satellite, was launched on 2006 February 21 (UT) and put into a sun-synchronous polar orbit at an altitude of 700 km. Cosmic radiations, particularly protons in the South Atlantic Anomaly (SAA), were expected to affect the performance of the stressed Ge:Ga array far-infrared detector on board AKARI. One of the influences is the radioactivation of the detector housing; γ-rays from the radioactivated detector housing interact with Ge:Ga elements, producing spikes (so-called glitches) in the electric outputs of the detector. Prior to the launch, we performed a 100 MeV proton-beam irradiation test for an engineering model of the stressed Ge:Ga array, which simulated the SAA passage. In the test, we observed glitches in the detector output that were due to the radioactivation of the detector housing. By investigating the test data, we have computed the glitch rate of the flight array detector expected in the AKARI orbit, including its change with time from the launch to the end of the AKARI mission. After the launch of AKARI, we have compared the performance observed in the orbit to that predicted by the proton-beam test. The glitch rate really changed with time after the launch; we have found that the in-orbit behavior is consistent with the prediction. © 2008. The Astronomical Society of the Pacific. All rights reserved.

We present a careful analysis of the point-source detection limit of the AKARI All-Sky Survey in the WIDE-S 90-μm band near the North Ecliptic Pole (NEP). Timeline analysis is used to detect IRAS (Infrared Astronomy Satellite) sources and then a conversion factor is derived to transform the peak timeline signal to the interpolated 90-μm flux of a source. Combined with a robust noise measurement, the point-source flux detection limit at signal-to-noise ratio (S/N) > 5 for a single detector row is 1.1 ± 0.1 Jy which corresponds to a point-source detection limit of the survey of ∼0.4 Jy. Wavelet transform offers a multiscale representation of the Time Series Data (tsd). We calculate the continuous wavelet transform of the tsd and then search for significant wavelet coefficients considered as potential source detections. To discriminate real sources from spurious or moving objects, only sources with confirmation are selected. In our multiscale analysis, IRAS sources selected above 4σ can be identified as the only real sources at the Point Source Scales. We also investigate the correlation between the non-IRAS sources detected in timeline analysis and cirrus emission using wavelet transform and contour plots of wavelet power spectrum. It is shown that the non-IRAS sources are most likely to be caused by excessive noise over a large range of spatial scales rather than real extended structures such as cirrus clouds. © 2008 The Authors.

The AKARI satellite (formerly known as ASTRO-F) is Japan's first infrared astronomical satellite. AKARI is equipped with the infrared camera (IRC) and the far-infrared surveyor (FIS), which are cooled below 7 K. The AKARI's 68.5 cm telescope, which is made of SiC, is also cooled below 7 K. A unique feature of the AKARI cryostat is that it uses both cryogen and mechanical coolers. Using mechanical coolers, the helium lifetime can be greater than one year with 170 L of liquid helium. AKARI was launched on February 21, 2006 (UT), from the Uchinoura Space Center (USC). It has been performing successfully in orbit. © 2008 Elsevier Ltd. All rights reserved.

The next Japanese infrared space telescope SPICA features a large 3.5-m-diameter primary mirror and an optical bench cooled to 4.5 K with advanced mechanical cryocoolers and effective radiant cooling instead of using a massive and short-lived cryogen system. To obtain a sufficient thermal design margin for the cryogenic system, cryocoolers for 20 K, 4 K, and 1 K have been modified for higher reliability and higher cooling power. The latest results show that all mechanical cryocoolers achieve sufficient cooling capacity for the cooling requirement of the telescope and detectors on the optical bench at the beginning of life. Consequently, the feasibility of the SPICA cryogenic system concept was validated, while attempts to achieve higher reliability, higher cooling capacity and less vibration have continued for stable operations at the end of life. © 2008 Elsevier Ltd. All rights reserved.

A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ballbearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes. © 2008 Optical Society of America.

Context.A high contrast coronagraph is expected to provide one of the promising ways to directly observe extra-solar planets. We present the newest results of our laboratory experiment investigating "rigid" coronagraph with a binary shaped checkerboard pupil mask, which should offer a highly stable solution for telescopes without adaptive optics (AO) for wavefront correction in space missions.Aims. The primary aim of this work was to study the stability of the coronagraph, and to demonstrate its performance without adaptive wavefront correction. Estimation of both the raw contrast and the gain of the point spread function (PSF) subtraction were needed. The limiting factor of the contrast was also important. Methods. A binary shaped pupil mask of a checkerboard type has been designed. The mask, consisting of an aluminum film on a glass substrate, was manufactured using nano-fabrication techniques with electron beam lithography. Careful evaluation of coronagraphic performance, including PSF subtraction, was carried out in air using the developed mask. Results. A contrast of was achieved for the raw coronagraphic image by areal averaging of all of the observed dark regions. Following PSF subtraction, the contrast reached . Speckles were a major limiting factor throughout the dark regions of both the raw image and the PSF subtracted image. Conclusions. A rigid coronagraph with PSF subtraction without AO is a useful method to achieve high contrast observations. Applications of a rigid coronagraph to a Space Infrared telescope for Cosmology and Astrophysics (SPICA) and other platforms are discussed. © 2008 ESO.

Context. The Galactic center region is luminous in the far-infrared (FIR), but dominant sources of this luminosity are still controversial. Aims. We investigate physical conditions of the diffuse interstellar medium in the Galactic center region by multi-line spectroscopy in the FIR. Methods. We analyze the archival data of the Galactic center region obtained with the Long-Wavelength Spectrometer on board the Infrared Space Observatory. We detect strong continuum emission and fine-structure emission lines from photo-dissociation and H II regions, including [O I] and [C II] lines that are dominant coolants of interstellar clouds. Results. The observations show that the [C II]/FIR ratio is systematically low whereas the [O I]/FIR ratio is almost constant toward the Galactic center region. By using a photo-dissociation region model with observed FIR parameters, we obtain radiation an effective temperature of K in the Galactic center region, which is significantly lower than K in the Galactic disk region. Conclusions. Dominant sources of the FIR luminosity in the Galactic center region are not likely to be young OB stars but rather cool stars, K and M giants, which implies that the current star-formation activity is rather low in the Galactic center region. © 2008 ESO.

We present a preliminary optical design and layout for the mid-infrared (4-18 μm) high-resolution spectrograph for SPICA, Japanese next-generation space IR observatory with 3.5 m telescope. MIR high-resolution spectroscopy is a powerful probe to study gas-phase molecules/atoms in a variety of astronomical objects. Space observation provides a great opportunity to study many molecular lines especially in between the atmospheric windows. SPICA gives us a chance to realize MIR high-resolution spectroscopy from space with the large telescope aperture. The major technical challenge is the size of the spectrograph, which tends to be too large for space. We hope to overcome this problem with a novel MIR immersion grating, which can make the instrument smaller by a factor of the refractive index of the grating material. We plan to fabricate a large pitch ZnSe (n = 2.4) immersion grating with the fly-cutting technique at LLNL (see Poster paper 7018-183 by Ikeda et al.1 and 7018-181 by Kuzmenko et al.2 in the proceedings of this conference). We show our preliminary spectrograph designs with a spectral resolution of ∼30,000 in 4-8 μm (short mode) and 12-18 μm (long mode). The instrument size can be as small as 200 × 400 mm thanks to the MIR immersion gratings. With unprecedented spectral resolution in space, which is 10-times higher than ISO-SWS, the high-resolution spectrograph for SPICA (SPICA-HIRES) could be a unique instrument that can provide most sensitive and clear spectra of this kind.

The SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is a infrared space-borne telescope mission of the next generation following AKARI. SPICA will carry a telescope with a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 5 K. SPICA is planned to be launched in 2017, into the sun-earth L2 libration halo orbit by an H II-A rocket and execute infrared observations at wavelengths mainly between 5 and 200 micron. The large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch gives us with the SPICA mission a unique opportunity for coronagraphic observation. We have started development of a coronagraphic instrument for SPICA. The primary target of the SPICA coronagraph is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph are set to be 5-27 micron (3.5-5 micron is optional), 10(-6), and a few lambda/D (and as small as possible), respectively, in which lambda is the observation wavelength and D is the diameter of the telescope aperture (3.5m). For our laboratory demonstration, we focused first on a coronagraph with a binary shaped pupil mask as the primary candidate for SPICA because of its feasibility. In an experiment with a binary shaped pupil coronagraph with a He-Ne laser (lambda=632.8nm), the achieved raw contrast was 6.7x10(-8), derived from the average measured in the dark region without active wavefront control. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was initiated in an attempt to achieve better performance, i.e., smaller IWA and higher throughput. A laboratory experiment was performed using a He-Ne laser with active wavefront control, and a raw contrast of 6.5x10(-7) was achieved. We also present recent progress made in the cryogenic active optics for SPICA. Prototypes of cryogenic deformable by Micro Electro Mechanical Systems (MEMS) techniques were developed and a first demonstration of the deformation of their surfaces was performed with liquid nitrogen cooling. Experiments with piezo-actuators for a cryogenic tip-tilt mirror are also ongoing.

We present a concept for BLISS, a sensitive far-IR-submillimeter spectrograph for SPICA. SPICA is a JAXA-led mission featuring a 3.5-meter telescope actively cooled to below 5K, envisioned for launch in 2017. The low-background platform is especially compelling for moderate-resolution survey spectroscopy, for which BLISS is designed. The BLISS / SPICA combination will offer line sensitivities below 10 Wm in modest integrations, enabling rapid survey spectroscopy of galaxies out to redshift 5. The far-IR fine-structure and molecular transitions which BLISS / SPICA will measure are immune to dust extinction, and will unambiguously reveal these galaxies' redshifts, stellar and AGN contents, gas properties, and heavy-element abundances. Taken together, such spectra will reveal the history of galaxies from 1 GY after the Big Bang to the present day. BLISS is comprised of five sub-bands, each with two R ∼ 700 grating spectrometer modules. The modules are configured with polarizing and dichroic splitters to provide complete instantaneous spectral coverage in two sky positions. To approach background-limited performance, BLISS detectors must have sensitivities at or below 5 × 10 WHz , and the format is 10 arrays of several hundred pixels each. It is anticipated that these requirements can be met on SPICA's timescale with leg-isolated superconducting (TES) bolometers cooled with a 50 mK magnetic refrigerator. -20 -2 -20 -1/2

SPICA (SPace Infrared telescope for Cosmology and Astrophysics) was selected for study as a mission of opportunity within the science programme Cosmic Vision 2015-2025 of the European Space Agency, with a planned launch in 2017. Observing in the 5 - 210 micron waveband, one of its major goals is the discovery of the origins of planets and galaxies. ESA's contribution is the provision of the SPICA Telescope Assembly (STA) featuring a 3.5 m primary mirror cooled to < 5K, and instrument engineering and management of a nationally funded European FIR instrument {SAFARI) as part of SPICA's payload. SAFARI is an imaging spectrometer operating at 30-210 micron, baselined as a Mach-Zehnder (MZ) Fourier Transform Spectrometer (FTS). An internal ESA study has been carried out to address the specific challenges associated in particular with STA and SAFARI, taking into account resource margins and interface specifications driven by the overall spacecraft design. This paper provides a summary of the preliminary results achieved during this study.

We report the results of mid- to far-infrared spectroscopic observations of Galactic star-forming regions with ISO, Spitzer, and AKARI. Owing to the high sensitivity of the IRS onboard Spitzer, we detected [Si II]35 μm, [Fe II] 26 μm, and [Fe III] 23μm lines widely in low-density star-forming regions, and derived gas-phase Si and Fe abundances as 3-100% and <22%, respectively. With the FTS onboard AKARI, we obtained the spatial distribution of the [O III] 88μm emission in two star-forming regions. © 2008 EAS EDP Sciences.

Spatially resolved X-ray spectroscopy with high spectral resolution allows the study of astrophysical processes in extended sources with unprecedented sensitivity. This includes the measurement of abundances, temperatures, densities, ionisation stages as well as turbulence and velocity structures in these sources. An X-ray calorimeter is planned for the Russian mission Spektr Röntgen-Gamma (SRG), to be launched in 2011. During the first half year (pointed phase) it will study the dynamics and composition of of the hot gas in massive clusters of galaxies and in supernova remnants (SNR). During the survey phase it will produce the first all sky maps of line-rich spectra of the interstellar medium (ISM). Spectral analysis will be feasible for typically every 5° × 5° region on the sky. Considering the very short time-scale for the development of this instrument it consists of a combination of well developed systems. For the optics an extra eROSITA mirror, also part of the Spektr-RG payload, will be used. The detector will be based on spare parts of the detector flown on Suzaku combined with a rebuild of the electronics and the cooler will be based on the design for the Japanese mission NeXT. In this paper we will present the science and give an overview of the instrument.

The SXS (Soft X-ray Spectrometer) onboard the coming Japanese X-ray satellite NeXT (New Exploration Xray Telescope) and the SXC (Spectrum-RG X-ray Calorimeter) in Spectrum-RG mission are microcalorimeter array spectrometers which will achieve high spectral resolution of ~ 6 eV in 0.3-10.0 keV energy band. These spectrometers are well-suited to address key problems in high-energy astrophysics. To achieve these high spectral sensitivities, these detectors require to be operated under 50 mK by using very efficient cooling systems including adiabatic demagnetization refrigerator (ADR). For both missions, we propose a two-stage series ADR as a cooling system below 1 K, in which two units of ADR consists of magnetic cooling material, a superconducting magnet, and a heat switch are operated step by step. Three designs of the ADR are proposed for SXS/SXC. In all three designs, ADR can attain the required hold time of 23 hours at 50 mK and cooling power of 0.4μW with a low magnetic fields (1.5/1.5 Tesla or 2.0/3.0 Tesla) in a small configuration (180 mmφ× 319 mm in length). We also fabricated a new portable refrigerator for a technology investigation of two-stage ADR. Two units of ADR have been installed at the bottom of liquid He tank. By using this dewar, important technologies such as an operation of two-stage cooling cycle, tight temperature control less than 1 μK (in rms) stability, a magnetic shielding, saltpills, and gas-gap heat switches are evaluated.

Prolate (Pupil) Apodized Lyot Coronagraphs (PPALC) are known to offer optimal performances for a Lyot-type Coronagraph configuration, i.e. with an opaque occulting focal mask. One additional benefit of PPALC is its possible use in a multi-stage configuration. In theory, the coronagraphic performance can be QN, where Q is the energy rejection factor of one stage (the first one), and N the number of stages. Several ground-based telescopes are considering PPALC as an option for their high-contrast instrumentation (e.g. Gemini/GPI, EELT/EPICS, Subaru HiCIAO). Although the PPALC suffers from several limitations, several works are currently focused on fabricating entrance pupil apodizers and trying to find ways to overcome chromatism issues. In this work, we present the first experimental results from Multi- Stage PPALC (MS-PPALC) that was done in the context of the japanese space telescope SPICA coronagraph project. Our entrance pupil apodizers use small diameter High Energy Beam Sensitive glass (HEBS-glass) from Canyon Materials Inc. The current results show modest coronagraphic performance due to uncompensated phase aberrations inherent to HEBS-glass material. In addition, and due to these uncompensated phase aberrations, the present optical configuration is an altered version of the originally planned set-up. However, we can demonstrate the validity the MSPPALC concept and compare it to numerical simulations.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for midand far-infrared astronomy with a cryogenically cooled 3.5 m telescope. Its high spatial resolution and unprecedented sensitivity in the mid- and far-infrared will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3.5- m class cooled (5 K) telescope in space with moderate total weight (3t). SPICA is proposed as a Japanese-led mission together with extensive international collaboration. The assessment study on the European contribution to the SPICA project has started under the framework of the ESA Cosmic Vision 2015-2025. US and Korean participations are also being discussed extensively. The target launch year of SPICA is 2017.

We report on the results of systematic infrared 2.5-5 μm spectroscopy of 45 nearby ultraluminous infrared galaxies (ULIRGs) at z < 0.3 using AKARI IRC. This paper investigates whether the luminosities of these ULIRGs are dominated by starburst activity, or alternatively, whether optically elusive buried active galactic nuclei (AGNs) are energetically important, based on the strengths of 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission and dust absorption features at 3-4 μm. Because of the AKARI IRC's spectroscopic capability in the full 2.5-5 μm wavelength range, we can apply this energy diagnostic method to ULIRGs at z > 0.15. We estimate the intrinsic luminosities of extended (several kpc), modestly obscured (Ay < 15 mag) starburst activity based on the observed 3.3 μm PAH emission luminosities measured in AKARIIRC slitless spectra, and confirm that such starbursts are energetically unimportant in nearby ULIRGs. In roughly half of the observed ULIRGs classified optically as non-Seyferts, we find signatures of luminous buried AGNs. The fraction of ULIRGs with detectable buried AGN signatures increases with increasing infrared luminosity. Our overall results support the scenario that luminous buried AGNs are important in many ULIRGs at z < 0.3 classified optically as non-Seyferts, and that the optical undetectability of such buried AGNs occurs merely because of a large amount of nuclear dust, which can make the sightline of even the lowest dust column density opaque to the ionizing radiation of the AGNs. © 2008. Astronomical Society of Japan.

AKARI is the first Japanese astronomical infrared satellite mission orbiting around the Earth in a sun-synchronous polar orbit at the altitude of 700 km. One of the major observation programs of the AKARI is an all-sky survey in the mid- to far-infrared spectral regions with 6 photometric bands. The mid-infrared part of the AKARI All-Sky Survey was carried out with the Infrared Camera (IRC) at the 9 and 18 μm bands with the sensitivity of about 50 and 120 mJy (5σ per scan), respectively. The spatial resolution is about 9.4" at both bands. AKARI mid-infrared (MIR) all-sky survey substantially improves the MIR dataset of the IRAS survey of two decades ago and provides a significant database for studies of various fields of astronomy ranging from star-formation and debris disk systems to cosmology. This paper describes the current status of the data reduction and the characteristics of the AKARI MIR all-sky survey data.

We report the in-orbit performance of the AKARI/Far-Infrared Surveyor Ge:Ga photoconductors, focusing on the transient response and the radiation effects, to perform the characterization of these effects for data analyses. The behavior for these effects is found to be significantly different between the Short-Wavelength and Long-Wavelength array detectors of the FIS, most probably due to the difference in the array configuration. We discuss cosmic-ray radiation effects, referring to the results of pre-flight proton-beam irradiation measurements. We also describe our efforts to correct the slow transient response of the detectors by adopting a physical approach.

We have developed an imaging Fourier transform spectrometer (FTS) for space-based far-infrared astronomical observations. The FTS employs newly developed photoconductive detector arrays with a capacitive trans-impedance amplifier, which makes the FTS a completely unique instrument. The FTS was installed as a function of the far-infrared instrument (FIS: Far-Infrared Surveyor) aboard the Japanese astronomical satellite, AKARI, which was launched on 2006 February 21 (UT) from Uchinoura Space Center. The FIS-FTS had been operated for more than one year before liquid helium ran out on 2007 August 26. The FIS-FTS was operated nearly six hundreds times, which corresponds to more than one hundred hours of astronomical observations and almost the same amount of time for calibrations. As expected from laboratory measurements, the FIS-FTS performed well and has produced a large set of astronomical data for valuable objects. Meanwhile, it has become clear that the detector transient effect is a considerable factor for FTSs with photoconductive detectors. In this paper, the instrumentation of the FIS-FTS and interesting phenomena related to FTS using photoconductive detectors are described, and future applications of this kind of FTS system are discussed. © 2008. Astronomical Society of Japan.

We have developed an imaging Fourier transform spectrometer (iFTS) for space-based far-infrared astronomical observations. The iFTS employs newly developed photoconductive detector arrays with a capacitive trans-impedance amplifier, which makes the iFTS a completely unique instrument. The iFTS was installed as a function of the far-infrared instrument (FIS: Far-Infrared Surveyor) on the Japanese astronomical satellite, AKARI, which was launched on February 21, 2006 (UT) from the Uchinoura Space Center. The iFTS had worked properly in the space environment as well as in laboratory for more than one year before liquid helium ran out on August 26, 2007. The iFTS was operated nearly six hundreds of pointed observations. More than one hundred hours of astronomical observations and almost the same amount of time for calibrations have been carried out in the mission life. Meanwhile, it becomes clear that the detector transient effect is a considerable factor for FTSs with photoconductive detectors. In this paper, the instrumentation of the iFTS and interesting phenomena related to FTSs using photoconductive detectors are described, and the calibration strategy of the iFTS is discussed briefly.

The SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is a infrared space-borne telescope mission of the next generation following AKARI. SPICA will carry a telescope with a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 5 K. SPICA is planned to be launched in 2017, into the sun-earth L2 libration halo orbit by an H II-A rocket and execute infrared observations at wavelengths mainly between 5 and 200 micron. The large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch gives us with the SPICA mission a unique opportunity for coronagraphic observation. We have started development of a coronagraphic instrument for SPICA. The primary target of the SPICA coronagraph is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph are set to be 5-27 micron (3.5-5 micron is optional), 10 , and a few λ/D (and as small as possible), respectively, in which λ is the observation wavelength and D is the diameter of the telescope aperture (3.5m). For our laboratory demonstration, we focused first on a coronagraph with a binary shaped pupil mask as the primary candidate for SPICA because of its feasibility. In an experiment with a binary shaped pupil coronagraph with a He-Ne laser (λ=632.8nm), the achieved raw contrast was 6.7×10 , derived from the average measured in the dark region without active wavefront control. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was initiated in an attempt to achieve better performance, i.e., smaller IWA and higher throughput. A laboratory experiment was performed using a He-Ne laser with active wavefront control, and a raw contrast of 6.5×10 was achieved. We also present recent progress made in the cryogenic active optics for SPICA. Prototypes of cryogenic deformable by Micro Electro Mechanical Systems (MEMS) techniques were developed and a first demonstration of the deformation of their surfaces was performed with liquid nitrogen cooling. Experiments with piezo-actuators for a cryogenic tip-tilt mirror are also ongoing. -6 -8 -7

Next generation space telescopes, which are currently being developed in the US and Europe, require large-scale light-weight reflectors with high specific strength, high specific stiffness, low CTE, and high thermal conductivity. To meet budget constraints, they also require materials that produce surfaces suitable for polishing without expensive over-coatings. HB-Cesic® - a European and Japanese trademark of ECM - is a Hybrid Carbon-Fiber Reinforced SiC composite developed jointly by ECM and MELCO to meet these challenges. The material's mechanical performance, such as stiffness, bending strength, and fracture toughness are significantly improved compared to the classic ECM Cesic® material (type MF). Thermal expansion and thermal conductivity of HB-Cesic® at cryogenic temperatures are now partly established; and excellent performance for large future space mirrors and structures are expected. This paper presents the design and manufacturing of an 800-mm mirror for space application, starting with the C/C raw material preparation to the finishing of the components, including the polishing of the mirror. The letters "HB" in HB-Cesic® stand for "hybrid" to indicate that the C/C raw material is composed of a mixture of different types of chopped, short carbon-fibers.

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3.5 m telescope. Its high spatial resolution and unprecedented sensitivity in the mid- and far-infrared will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. To reduce the mass of the whole mission, SPICA will be launched at ambient temperature and cooled down on orbit by mechanical coolers on board with an efficient radiative cooling system, a combination of which allows us to have a 3.5-m class cooled (5 K) telescope in space with moderate total weight (3t). SPICA is proposed as a Japanese-led mission together with extensive international collaboration. The assessment study on the European contribution to the SPICA project has started under the framework of the ESA Cosmic Vision 2015-2025. US and Korean participations are also being discussed extensively. The target launch year of SPICA is 2017.

Infrared Camera (IRC) onboard AKARI satellite has carried out more than 4000 pointed observations during the phases 1 and 2, a significant amount of which were performed in the spectroscopic mode. In this paper, we investigate the properties of the spectroscopic data taken with MIR-S channel and propose a new data reduction procedure for slit-less spectroscopy of sources embedded in complicated diffuse background structures. The relative strengths of the 0 to 1 order light as well as the efficiency profiles of the 2 order light are examined for various objects taken with MIR-S dispersers. The boundary shapes of the aperture mask are determined by using the spectroscopic data of uniform zodiacal emission. Based on these results, if the appropriate template spectra of zodiacal light emission and the diffuse background emission are prepared and the geometries of the diffuse structures are obtained by the imaging data, we can reproduce the slit-less spectroscopic patterns made by a uniform zodiacal emission and the diffuse background emission by a convolution of those template profiles. This technique enables us to obtain the spectra of infrared sources in highly complicated diffuse background and/or foreground structures, such as in the Galactic plane and in nearby galaxies. th st nd

The AKARI far-infrared deep survey has been carried out toward the region with the lowest cirrus density in the whole sky, near the South Ecliptic Pole. We present the details of this survey, and show the obtained galaxy counts. More than 2,200 galaxies were detected down to a flux level of 20 mJy, and suggest the necessity for a new model to explain galaxy evolution.

We present the in-orbit performance of slow-scan observation of the Far-Infrared Surveyor (FIS) onboard the AKARI satellite. The FIS, one of the two focal-plane instruments of AKARI, has four photometric bands from 50-180 μm with two kinds of Ge:Ga array detectors. In addition to the All-Sky Survey, the FIS also took images of specific targets by the slow-scan. Because of the longer exposure time on a targeted source, the sensitivity in the slow-scan mode is 1-2 orders of magnitude better than that in the All-Sky Survey mode. In order to evaluate the point spread functions (PSFs), several bright point-like objects such as asteroids, stars, and galaxies were observed. Though significant enhancements are seen at the tails of the PSFs, the derived full width at the half maximum (FWHM) are consistent with those expected from the optical simulation and the laboratory measurements; ∼40″ for two shorter wavelength bands and ∼60″ for two longer wavelength bands, respectively. The absolute photometric calibration has been performed by observing well established photometric calibration standards (asteroids and stars) in a wide range of fluxes. After the establishment for the method of the aperture photometry, the photometric accuracy for point sources is less than 10% in all bands.

The SPICA mission has been proposed to JAXA as the second Japanese IR space telescope to be launched in 2017. The SPICA spacecraft, launched with an H-IIA launch vehicle, is to be transferred into a halo orbit around the Sun-Earth L2, where effective radiant cooling is feasible owing to solar rays and radiant heat fluxes from the Earth constantly coming from the same direction. That optimal thermal environment enables this IR space telescope to use a large 3.5-m-diameter-single-aperture primary mirror cooled to 4.5 K with advanced mechanical cryocoolers and effective radiant cooling instead of a massive and short-lived cryogen. As a result of thermal and structural analyses, the thermal design of cryogenic system was obtained. Then, mechanical cryocoolers have been developed to meet cooling requirement at 1.7 K, 4.5 K and 20 K. The latest results of upgrading of the 20 K-class two-stage Stirling cooler, the 4K-class JT cooler, and the 1K-class JT cooler indicate that all cryocoolers gain a sufficient margin of cooling capacity with unprecedentedly low power consumption for the cooling requirement. It is concluded that the feasibility of the SPICA mission was confirmed for the critical cryogenic system design, while some attempts to achieve higher reliability, higher cooling capacity and less vibration have been continued for stable operations throughout the entire mission period.

The Japanese led Space Infrared telescope for Cosmology and Astrophysics (SPICA) will observe the universe over the 5 to 210 micron band with unprecedented sensitivity owing to its cold (∼5 K) 3.5m telescope. The scientific case for a European involvement in the SPICA mission has been accepted by the ESA advisory structure and a European contribution to SPICA is undergoing an assessment study as a Mission of Opportunity within the ESA Cosmic Vision 1015-2015 science mission programme. In this paper we describe the elements that are being studied for provision by Europe for the SPICA mission. These entail ESA directly providing the cryogenic telescope and ground segment support and a consortium of European insitutes providing a Far Infrared focal plane instrument. In this paper we describe the status of the ESA study and the design status of the FIR focal plane instrument.