The telescope to be onboard SPICA (Space Infrared Telescope for Cosmology and Astrophysics) has an aperture diameter of 2.5 m and its imaging performance is to be diffraction-limited at a wavelength of 20 μm at the operating temperature of <8 K. Because manufacturing precise autocollimating at mir- rors (ACFs) with sizes comparable to the SPICA telescope is not technically feasible, we plan to use sub-aperture stitching interferometry through ACFs for optical testing of the telescope. We have verified the applicability of the sub-aperture stitching technique to the SPICA telescope by performing stitching experiments in a vacuum at a room temperature, using the 800-mm telescope and a 300-mm ACF. We have also developed a new method to reduce uncertainties possibly caused by cryogenic and gravitational deformations of ACFs.

We present project updates of the next-generation infrared space mission SPICA (Space Infrared Tele- scope for Cosmology and Astrophysics) as of November 2015. SPICA is optimized for mid- and far-infrared astronomy with unprecedented sensitivity, which will be achieved with a cryogenically cooled (below 8 K), large (2.5 m) telescope. SPICA is expected to address a number of key questions in various fields of astrophysics, ranging from studies of the star-formation history in the universe to the formation and evolution of planetary systems. The international collaboration framework of SPICA has been revisited. SPICA under the new framework passed the Mission Definition Review by JAXA in 2015. A proposal under the new framework to ESA is being prepared. The target launch year in the new framework is 2027/28.

The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z1.3, 90% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field (5.4 deg2), using 10% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging (r ~25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute signicantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1< z <2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP eld in 5 broad bands (g; r; i; z; and y) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid- IR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust.

We performed Principle Component Analysis (PCA) over 264 galaxies in the IRAS Revised Bright Galaxy Sample (Sanders et al., 2003) using 12, 25, 60 and 100 μm ux data observed by IRAS and 9, 18, 65, 90 and 140 μm ux data observed by AKARI. We found that (i)the first principle component was largely contributed by infrared to visible ux ratio, (ii)the second principal component was largely contributed by the ux ratio between IRAS and AKARI, (iii)the third principle component was largely contributed by infrared colors.

Using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI we study the 3.3 μm polycyclic aromatic hydrocarbon (PAH) feature and its connection to active galactic nucleus (AGN) properties for a sample of 54 hard X-ray selected bright AGN, including both Seyfert 1 and Seyfert 2 type objects. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of the sources have known neutral hydrogen column densities (NH). The 3.3 μm PAH luminosity (L3:3μm) is used as a proxy for star-formation (SF) activity and hard X-ray luminosity (L14-195keV) as an indicator of the AGN power. We explore for possible dierence of SF activity between type 1 (un-absorbed) and type 2 (absorbed) AGN. We use several statistical analyses taking the upper-limits of the PAH lines into account utilizing survival analysis methods. The results of our log(L14-195keV) versus log(L3:3μm) regression shows a positive correlation and the slope for the type 1/unobscured AGN is steeper than that of type 2/obscured AGN at a 3σ level. Also our analysis shows that the circum-nuclear SF is more enhanced in type 2/absorbed AGN than type 1/un-absorbed AGN for low L14-195keV luminosity/low Eddington ratio AGN, while there is no significant dependence of SF activity on the AGN type in the high L14-195keV luminosities/Eddington ratios.

We performed systematic observations of the Hi Brα line (4.05 μm) in 51 nearby (z<0.3) ultraluminous infrared galaxies (ULIRGs), using AKARI near-infrared spectroscopy. The Brα line is predicted to be the brightest among the Hi recombination lines in ULIRGs with visual extinction higher than 15 mag. We detected the Brα line in 33 ULIRGs. In these galaxies, the relative contribution of starburst to the total infrared luminosity (LIR) is estimated on the basis of the ratio of the Brα line luminosity (LBrα) to LIR. The mean LBrα/LIR ratio in LINERs or Seyferts is significantly lower (~50%) than that in Hii galaxies. This result indicates that active galactic nuclei contribute signicantly (~50%) to LIR in LINERs, as well as Seyferts. We also estimate the absolute contribution of starburst to LIR using the ratio of star formation rates (SFRs) derived from LBrα (SFRBrα) and those needed to explain LIR (SFRIR). The mean SFRBrα/SFRIR ratio is only 0.33 even in Hii galaxies, where starburst is supposed to dominate the luminosity. We attribute this apparently low SFRBrα/SFRIR ratio to the absorption of ionizing photons by dust within Hii regions.

Combining the AKARI Point Source Catalog and the 37-month Monitor of All-sky X-ray Image (MAXI) catalog, the infrared and X-ray properties of nearby active galactic nuclei were investigated. The 37-month MAXI catalog tabulates 100 nearby Seyfert galaxies, 73 of which are categorized into Seyfert I galaxies. Among these Seyfert galaxies, 69 ones were found to have an AKARI infrared counterpart. For the Seyfert I galaxies in this sample, a well-known correlation was found between the infrared and X-ray luminosities. However, the observed X-ray luminosity of the Seyfert II galaxies tends to be lower for the infrared luminosity than the Seyfert I galaxies. This suggests that the X-ray absorption is significant in the Seyfert II galaxies. The Seyfert II galaxies seem to have a bimodal distribution of the IR color between 18 μm and 90 μm. Especially, a large fraction of the Seyfert II galaxies exhibits a redder IR color than the Seyfert I galaxies. A possible origin of the redder IR color is brie y discussed, in relation to the star formation activity in the host galaxy, and to the X-ray absorption.

In order to reveal physical conditions of molecular gas in active galaxies (active galaxies mean both starbursts and AGNs in this paper), we carried out systematic observations (R = 19 ~ 120) of CO funda- mental band at 4.7 m in absorption with AKARI. We also made follow-up CO absorption observations at higher spectral resolution (R = 5000 ~ 1000) with Subaru. Recently, Herschel made extensive ob- servations of highly-excited CO lines in emission in the far-infrared. The two data sets (absorption and emission) sometimes provide us with apparently inconsistent results. One case is starburst galaxies: Sub- aru observations showed low temperature of molecular gas toward the starburst NGC 253, while Herschel detected highly excited CO lines in the starburst. This suggests that warm molecular clouds are more deeply embedded than newly formed star clusters. The other case is obscured AGNs; Herschel detected highly excited CO lines in emission in nearby AGNs, while AKARI and Subaru observations showed CO absorption only in some of the obscured AGNs. This could re ect the dierence of nature of molecular tori in these AGNs. We propose the combination of the absorption and emission observations as an eective tool to reveal geometry of warm molecular clouds in active galaxies.

Utilizing a unique capability of AKARI that allows deep spectroscopy at 2.5 - 5.0 μm, we performed a spectroscopy study of more than 200 quasars through one of the AKARI mission programs, QSONG (Quasar Spectroscopic Observation with NIR Grism). QSONG targeted 155 high redshift (3:3 < z < 6:42) quasars and 90 low redshift active galactic nuclei (0:002 < z < 0:48). In order to provide black hole mass estimates based on the rest-frame optical spectra, the high redshift part of QSONG is designed to detect the Hα line and the rest-frame optical spectra of quasars at z > 3:3. The low redshift part of QSONG is geared to uncover the rest-frame 2.5 - 5.0 μm spectral features of active galactic nuclei to gain useful information such as the dust-extinction-free black hole mass estimators based on the Brackett lines and the temperatures of the hot dust torus. We outline the program strategy, and present some of the scientific highlights from QSONG, including the detection of the Hα line from a quasar at z > 4:5 which indicates a rigorous growth of black holes in the early universe, and the Brβ-based black hole mass estimators and the hot dust temperatures (~ 1100 K) of low redshift AGNs.

The zodiacal light emission is the thermal emission from the interplanetary dust and the dominant diuse radiation in the mid- to far-infrared wavelength region. Even in the far-infrared, the contribution of the zodiacal emission is not negligible at the region near the ecliptic plane. The AKARI far-infrared all-sky survey covered 97% of the whole sky in four photometric bands with band central wavelengths of 65, 90, 140, and 160 m. AKARI detected the small-scale structure of the zodiacal dust cloud, such as the asteroidal dust bands and the circumsolar ring, in far-infrared wavelength region. Although the most part of the zodiacal light structure in the AKARI far-infrared all-sky image can be well reproduced with the DIRBE zodiacal light model, there are discrepancies in the small-scale structures. In particular, the intensity and the ecliptic latitude of the peak position of the asteroidal dust bands cannot be repro- duced precisely with the DIRBE models. The AKARI observational data during more than one year has advantages over the 10-month DIRBE data in modeling the full-sky zodiacal dust cloud. The resulting small-scale zodiacal light structure template has been used to subtract the zodiacal light from the AKARI all-sky maps.

The Infrared Camera onboard the AKARI satellite carried out spectroscopic observations with a grism mode named NG, whose wavelength coverage was 2.5{5.0 m. We reinvestigate the current ux calibration for the NG grism mode, with which calculated ux density implausibly decreases at 4.9 m especially for red objects due to the second-order light contamination. We perform a new spectral response calibration using blue and red standard objects simultaneously. New response curves which contain both the rst- and second-order light are able to separate each contribution consistently and useful for studies of red objects such as CO ro-vibrational absorption in active galactic nuclei.

We present the AKARI far-infrared (FIR) all-sky maps and describe its characteristics, calibration accuracy and scientic capabilities. The AKARI FIR survey has covered 97% of the whole sky in four photometric bands, which cover continuously 50{180 micron with band central wavelengths of 65, 90, 140, and 160 microns. The data have been publicly released in 2014 (Doi et al., 2015) with improved data quality that have been achieved since the last internal data release (Doi et al., 2012). The accuracy of the absolute intensity is  10% for the brighter regions. Quantitative analysis of the relative intensity accuracy and its dependence upon spatial scan numbers has been carried out. The data for the rst time reveal the whole sky distribution of interstellar matter with arcminute- scale spatial resolutions at the peak of dust continuum emission, enabling us to investigate large-scale distribution of interstellar medium in great detail. The lamentary structure covering the whole sky is well traced by the all-sky maps. We describe advantages of the AKARI FIR all-sky maps for the study of interstellar matter comparing to other observational data.

This paper provides an overview of the AKARI mission, which was the rst Japanese satellite dedicated to infrared astronomy. The AKARI satellite was launched in 2006, and performed both an all-sky survey and pointed observations during its 550 days in the He-cooled mission phases (Phases 1 and 2). After the He ran out, we continued near-infrared observations with mechanical cryocoolers (Phase 3). Due to a failure of its power supply, AKARI was turned o in 2011. The AKARI data are unique in terms of the observed wavelengths as well as the sky coverage, and provide a unique legacy resource for many astronomical studies. Since April 2013, a dedicated new team has been working to rene the AKARI data processing. The goal of this activity is to provide processed datasets for most of the AKARI observations in a Science Ready form, so that more users can utilize the AKARI data in their astronomical research. The data to be released will include revised All-Sky Point Source Catalogues, All-Sky Image Maps, as well as high-sensitivity images and spectra obtained by pointed observations. We expect that the data will be made public by in the Spring of 2016.

We present the current status (as of August 2014) of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is a mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3m-class telescope. SPICA is expected to achieve high spatial resolution and unprecedented sensitivity in the mid- and far-infrared, which 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. We have carried out the "Risk Mitigation Phase" activity, in which key technologies essential to the realization of the mission have been extensively developed. Consequently, technical risks for the success of the mission have been significantly mitigated. Along with these technical activities, the international collaboration framework of SPICA has been revisited, which resulted in la arger contribution from ESA than that in the original plan. To enable the ESA participation under the new framework, a SPICA proposal to ESA is under consideration as a medium-class mission under the framework of the ESA Cosmic Vision. The target launch year of SPICA under the new framework is the mid-2020s.