LiteBIRD is a next-generation satellite mission to measure the polarization of the cosmic microwave background (CMB) radiation. On large angular scales the B-mode polarization of the CMB carries the imprint of primordial gravitational waves, and its precise measurement would provide a powerful probe of the epoch of inflation. The goal of LiteBIRD is to achieve a measurement of the characterizing tensor to scalar ratio r to an uncertainty of δr = 0.001. In order to achieve this goal we will employ a kilopixel superconducting detector array on a cryogenically cooled sub-Kelvin focal plane with an optical system at a temperature of 4 K. We are currently considering two detector array options; transition edge sensor (TES) bolometers and microwave kinetic inductance detectors (MKID). In this paper we give an overview of LiteBIRD and describe a TES-based polarimeter designed to achieve the target sensitivity of 2 µK·arcmin over the frequency range 50 to 320 GHz.

We studied the energy spectrum and the large-scale fluctuation of the X-ray background with the ASCA GIS instrument based on the ASCA Medium Sensitivity Survey and Large Sky Survey observations. A total of 91 fields with Galactic latitude |b| > 10 • were selected with a sky coverage of 50 deg 2 and 4.2 Ms of exposure. For each field, non X-ray events were carefully subtracted and sources brighter than ∼ 2 × 10 −13 erg cm −2 s −1 (2-10 keV) were eliminated. Spectral fits with a single power-law model for the individual 0.7-10 keV spectra showed a significant excess below ∼ 2 keV, which could be expressed by an additional thermal model with kT ≃ 0.4 keV or a steep power-law model with a photon index of Γ soft ≃ 6. The 0.5-2 keV intensities of the soft thermal component varied significantly from field to field by 1 σ = 52 +4 −5 %, and showed a maximum toward the Galactic Center. This component is considered to be entirely Galactic. As for the hard power-law component, an average photon index of 91 fields was obtained to be Γ hard = 1.412 ± 0.007 ± 0.025 and the average 2-10 keV intensity was calculated as F hard X = (6.38 ± 0.04 ± 0.64) × 10 −8 erg cm −2 s −1 sr −1 (1 σ statistical and systematic errors). The Galactic component is marginally detected in the hard band. The 2-10 keV intensities show a 1 σ deviation of 6.49 +0.56 −0.61 %, while deviation due to the reproducibility of the particle background is 3.2%. The observed deviation can be explained by the Poisson noise of the source count in the f.o.v. (∼ 0.5 deg 2 ), even assuming a single logN -logS relation on the whole sky. Based on the observed fluctuation and the absolute intensity, an acceptable region of the log N -log S relation was derived, showing a consistent feature with the recent Chandra and XMM-Newton results. The fluctuation of the spectral index was also examined; it implied a large amount of hard sources and a substantial variation in the intrinsic source spectra (Γ S ≃ 1.1 ± 1.0).

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X-ray spectra of the Galactic ridge emission in the Scutum arm region have been obtained with ASCA GIS and SIS in the energy range 0.7È10 keV. The observed spectra are basically of thermal emission from thin hot plasmas, and individual K emission lines from helium-like Mg, Si, S, and Fe ions are conÐrmed in both the GIS and SIS spectra. This means that the Galactic ridge X-ray emission cannot be explained by a single-temperature ionization-equilibrium plasma model. It cannot, however, be reproduced even if a nonequilibrium ionization model is introduced ; thus multiple plasma components are required. The GIS spectra are fairly well Ðtted by a double-temperature nonequilibrium ionization plasma model with temperatures of kT D 0.8 keV and kT D 7 keV. The softer component is found to be in an extremely low ionization state, with cm~3 s, while the harder component is in a relan e t D 109 tively high ionization state, though not yet in a full equilibrium. The GRXE properties obtained with the GIS are carefully reexamined by the highly resolved spectral-line features with the SIS.The soft and hard components are absorbed by equivalent hydrogen columns of 0.7 ] 1022 cm~2 and 4.6 ] 1022 cm~2, respectively. The surface brightness of the soft and hard components at b D 0¡ are estimated to be 1.9 ] 10~6 and 5.3 ] 10~7 ergs cm~2 s~1 sr~1 respectively, both in the 0.5È10 keV band. The surface brightness of the softer component extends toward signiÐcantly higher (D2¡) Galactic latitudes than the harder component, although their actual scale heights may be similar at D100 pc if the di †erences in their observable depths are taken into account. Spectral properties of the two components are seen to depend on the latitude ; the most noticeable e †ect is a rapid decrease in the Fe K line equivalent width seen in the hard component. Attempts are made to interpret the two components in terms of di †use hot plasmas Ðlling the interstellar space.

High-sensitivity wide-band X-ray spectroscopy is the key feature of the Suzaku X-ray observatory, launched on 2005 July 10. This paper summarizes the spacecraft, in-orbit performance, operations, and data processing that are related to observations. The scientific instruments, the high-throughput X-ray telescopes, X-ray CCD cameras, non-imaging hard X-ray detector are also described.

We have developed a framework for the Monte-Carlo simulation of the X-Ray Telescopes (XRT) and the X-ray Imaging Spectrometers (XIS) onboard Suzaku, mainly for the scientific analysis of spatially and spectroscopically complex celestial sources. A photon-by-photon instrumental simulator is built on the ANL platform, which has been successfully used in ASCA data analysis. The simulator has a modular structure, in which the XRT simulation is based on a ray-tracing library, while the XIS simulation utilizes a spectral "Redistribution Matrix File" (RMF), generated separately by other tools. Instrumental characteristics and calibration results, e.g., XRT geometry, reflectivity, mutual alignments, thermal shield transmission, build-up of the contamination on the XIS optical blocking filters (OBF), are incorporated as completely as possible. Most of this information is available in the form of the FITS (Flexible Image Transport System) files in the standard calibration database (CALDB). This simulator can also be utilized to generate an "Ancillary Response File" (ARF), which describes the XRT response and the amount of OBF contamination. The ARF is dependent on the spatial distribution of the celestial target and the photon accumulation region on the detector, as well as observing conditions such as the observation date and satellite attitude. We describe principles of the simulator and the ARF generator, and demonstrate their performance in comparison with in-flight data.

The soft diffuse X-ray emission of twelve fields observed with Suzaku are presented together with two additional fields from previous analyses. All have galactic longitudes 65$^\circ $$\lt$$\ell$$\lt$ 295$^\circ $ to avoid contributions from the very bright diffuse source that extends at least 30$^\circ $ from the Galactic center. The surface brightnesses of the Suzaku nine fields for which apparently uncontaminated ROSAT All Sky Survey (RASS) were available were statistically consistent with the RASS values, with an upper limit for differences of 17 $\times$ 10$^{-6}$cs$^{-1}$arcmin$^{-2}$ in R45-band. The OVII and OVIII intensities are well correlated to each other, and OVII emission shows an intensity floor at $\sim$2 photonss$^{-1}$cm$^{-2}$str$^{-1}$ (LU). The high-latitude OVIII emission shows a tight correlation with excess of OVII emission above the floor, with (OVIII intensity) $=$ 0.5 $\times$ [(OVII intensity) $-$ 2LU], suggesting that temperatures averaged over different line-of-sight show a narrow distribution around $\sim$0.2 keV. We consider that the offset intensity of OVII arises from the Heliospheric solar wind charge exchange and perhaps from the local hot bubble, and that the excess OVII (2–7LU) is emission from more distant parts of the Galaxy. The total bolometric luminosity of this galactic emission is estimated to be 4 $\times$ 10$^{39}$ergs$^{-1}$, and its characteristic temperature may be related to the virial temperature of the Galaxy.

We present Suzaku spectra of X-ray emission in the fields just off the LMC X-3 sight line. O VII, O VIII, and Ne IX emission lines are clearly detected, suggesting the presence of an optically thin thermal plasma with an average temperature of 2.4 ×10 6 K. This temperature is significantly higher than that inferred from existing Xray absorption line data obtained with Chandra grating observations of LMC X-3, strongly suggesting that the gas is not isothermal. We then jointly analyze these data to characterize the spatial and temperature distributions of the gas. Assuming a vertical exponential Galactic disk model, we estimate the gas temperature and density at the Galactic plane and their scale heights as 3.6(2.9, 4.7) × 10 6 K and 1.4(0.3, 3.4) × 10 −3 cm −3 and 1.4(0.2, 5.2) kpc and 2.8(1.0, 6.4) kpc, respectively. This characterization can account for all the O VI line absorption, as observed in a FUSE spectrum of LMC X-3, but only predicts less than one tenth of the O VI line emission intensity typically detected at high Galactic latitudes. The bulk of the O VI emission most likely arises at interfaces between cool and hot gases.