堂谷 忠靖

We are developing the Soft X-ray Imager (SXI), a charge-coupled device (CCD) camera system to be deployed onboard the ASTRO-H satellite. Using an engineering model system in which design specifications were the same as those of the flight model, we measured charge transfer inefficiency (ETU and the effects of charge [railing. The CCD was irradiated with monochromatic X-rays produced by a radio isotope (Fe-55) and X-ray generator using alpha particles from Am-241. We used four targets for the X-ray generator: (C2F4)(n), SiO2, Ti, and Ge. Since CTl degrades energy resolution, we adopted the charge-injection technique to the SM. With this technique, injected charges till traps, and subsequent signal charges are transferred with less loss of charge. However, the charge-injection technique can cause positional variations in gain on the CCD chip. Thus, we constructed a method for correcting CTl. We also evaluated the charge trailing effect and tested a method for correcting its effects. After applying these corrections to charge injection, variations in gain improved from 0.5% to 0.1% over the CCD chip, and the energy resolution (FWHM) improved from similar to 220 eV to similar to 180 eV at 5.9 KeV. (C) 2014 Elsevier B.V. All rights reserved,

PolariS (Polarimetry Satellite) is a Japanese small satellite mission dedicated to polarimetry of X-ray and γ-ray sources. The primary aim of the mission is to perform hard X-ray (10-80 keV) polarimetry of sources brighter than 10 mCrab. For this purpose, PolariS employs three hard X-ray telescopes and scattering type imaging polarimeters. PolariS will measure the X-ray polarization for tens of sources including extragalactic ones mostly for the first time. The second purpose of the mission is γ-ray polarimetry of transient sources, such as γ-ray bursts (GRBs). Wide field polarimeters based on similar concept as that used in the IKAROS/GAP but with higher sensitivity will be used, and polarization measurement of 10 GRBs per year is expected.

PolariS (Polarimetry Satellite) is a Japanese small satellite mission dedicated to polarimetry of X-ray and gamma-ray sources. The primary aim of the mission is to perform hard X-ray (10-80 keV) polarimetry of sources brighter than 10 mCrab. For this purpose, PolariS employs three hard X-ray telescopes and scattering type imaging polarimeters. PolariS will measure the X-ray polarization for tens of sources including extragalactic ones mostly for the first time. The second purpose of the mission is gamma-ray polarimetry of transient sources, such as gamma-ray bursts (GRBs). Wide field polarimeters based on similar concept as that used in the IKAROS/GAP but with higher sensitivity will be used, and polarization measurement of 10 GRBs per year is expected.

Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched in 2015. The SXI camera contains four CCD chips, each with an imaging area of 31 mm x31 mm, arrayed in mosaic, covering the whole FOV area of 38' x 38'. The CCDs are a P-channel back-illuminated (BI) type with a depletion layer thickness of 200 pm. High QE of 77% at 10 keV expected for this device is an advantage to cover an overlapping energy band with the Hard X-ray Imager (HXI) onboard ASTRO-H. Most of the flight components of the SXI system are completed until the end of 2013 and assembled, and an end-to-end test is performed. Basic performance is verified to meet the requirements. Similar performance is confirmed in the first integration test of the satellite performed in March to June 2014, in which the energy resolution at 5.9 keV of 160 eV is obtained. In parallel to these activities, calibrations using engineering model CCDs are performed, including QE, transmission of a filter, linearity, and response profiles.

X-ray CCD operated onboard satellite are contaminated by outgas from organic material used in satellites. This contamination causes a significant reduction in the detection sensitivity of X-ray detectors. In order to prevent such contamination to the Back-IlluminatedCCD (BI-CCD) of the Soft X-ray Imager (SXI) onboard ASTRO-H, we have developed a Contamination Blocking Filter (CBF), which consists of similar to 30nm thick Aluminum and similar to 200nm thick Polyimide. The CBF is be placed on the top of the CCD camera hood and is required to have a high X-ray transmission in order to take advantage of the high detection efficiency of BI-CCD.We measured the X-ray transmission of three fight candidates of the CBF last October at the SPring-8 and obtained the X-ray transmission of three CBFs in the soft X-ray energy from 0.2 to 1.8 keV which covers the absorption edges around C-K, N-K, O-K, and Al-K including X-ray absorption fine structure (XAFS). In these measurements, we found three CBFs have high X-ray transmission below 2ke V, e.g. similar to 70% at around 0.5 keV, and determined the thickness of Al and Polyimide to be 220 nm and similar to 50 nm, respectively. We will calculate the response function of SXI including these results.

X-ray CCDs are widely used as the focal plane detectors of the X-ray telescopes. Among them, backside illuminated CCDs with a deep depletion layer are preferred because of their high quantum efficiency in both soft and hard X-ray bands. However, they tend to have poorer energy resolution and higher background due to the relatively large charge diffusion. We carried out simple experiments to apply a magnetic field of 0.25 T or 0.4 T to the CCD, which is expected to suppress the charge diffusion very slightly and to bring subtle improvement in the performance of the CCD. We found unexpectedly that grade branching ratios of Grade 3 and Grade 4, both are horizontal split events, symmetrically changed depending on the direction of the applied magnetic field. Although the cause of the change is not understand yet, it clearly demonstrate that the charge cloud in the CCD is affected by the externally applied magnetic field. We also found a decrease of Grade 7 only in the experiment 2. We consider this may be caused by the supress of the charge diffusion by the magnetic field, although other possibilities can not be excluded. No significant improvement was detected in the energy resolution. We could show with these experiments that the charge cloud in the CCD may be controlled by the externally applied magnetic field. Magnetic field may become useful tool in future to improve the performance of CCDs.

© 2014 SPIE.The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.

We report on a proton radiation damage experiment on P-channel CCD newly developed for an X-ray CCD camera onboard the ASTRO-H satellite. The device was exposed up to 10(9) protons cm(-2) at 6.7 MeV. The charge transfer inefficiency (CTI) was measured as a function of radiation dose. In comparison with the CTI currently measured in the CCD camera onboard the Suzaku satellite for 6 years, we confirmed that the new type of P-channel CCD is radiation tolerant enough for space use. We also confirmed that a charge-injection technique and lowering the operating temperature efficiently work to reduce the CTI for our device. A comparison with other P-channel CCD experiments is also discussed. (C) 2013 Elsevier B.V. All rights reserved.

We detected hard X-ray emission from the unidentified Galactic bulge source 1RXS J175721.2-304405 with ASCA. The observed absorption column, flux and power-law index led us to consider that 1RXS J175721.2-304405 may be a new low-mass X-ray binary located near the Galactic center. Furthermore, the X-ray light-curve shows a step-function-like time variability, which is likely due to the occultation of a companion star. Future follow-up observations by missions such as ASTROSAT may reveal a periodic eclipse from 1RXS J175721.2-304405 if it is covered long enough. Since the long orbital period suggests a giant companion, follow-up observations will give firm evidence that 1RXS J175721.2-304405 is a new and rare eclipsing low-mass X-ray binary with a giant companion. (C) 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.

The Soft X-ray Imager, SXI, is an X-ray CCD camera onboard the ASTRO-H satellite to be launched in 2015. ASTRO-H will carry two types of soft X-ray detector. The X-ray calorimeter, SXS, has an excellent energy resolution with a narrow field of view while the SXI has a medium energy resolution with a large field of view, 38' square. We employ 4 CCDs of P-channel type with a depletion layer of 200 mu m. Having passed the CDR, we assemble the FM so that we can join the final assembly. We present here the SXI status and its expected performance in orbit.

We have newly developed the back-illuminated (BI)-CCD which has an Optical Blocking Layer (OBL) directly coating its X-ray illumination surface with Aluminum-Polyimide-Aluminum instead of Optical Blocking Filter (OBF). OBL is composed of a thin polyimide layer sandwiched by two Al layers. Al and Polyimide has a capability to cut visible light and EUV, respectively. To evaluate the performance of OBL that cut off EUV as well as transmit soft X-ray, we measured the EUV and Soft X-ray transmission of both OBL at various energy range between 15-2000 eV by utilizing beam line located at the Photon Factory in High Energy Accelerator Research Organization. We obtained the EUV transmission to be similar to 3% at 41eV which is as same as expected transmission from the designed thickness of polyimide layer, and found no significant change of the EUV transmission of polyimide found during 9month. We also obtained the Soft X-ray transmission of OBL, and found the X-ray transmission of OBL was consistent with the result expected from the thickness of OBL. We also measured the Optical transmission of OBL between 500-900 nm to evaluate the performance of Al that cut off optical light, and obtained the optical transmission to be less than 4x10(-5).

Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched in 2014. The SXI camera contains four CCD chips, each with an imaging area of 31mmx31 mm, arrayed in mosaic, which cover the whole FOV area of 38'x38'. The SXI CCDs are a P-channel back-illuminated (BI) type with a depletion layer thickness of 200 mu m. High QE of 77% at 10 keV expected for this device is an advantage to cover an overlapping energy band with the Hard X-ray Imager (HXI) onboard ASTRO-H. Verification with engineering model of the SXI has been performed since 2011. Flight model design was fixed and its fabrication has started in 2012.

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-Throughput spectrometer sensitive over 0.3-12 keV with high spectral resolution of ?E 5 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes. © 2012 SPIE.

A deep X-ray observation of the unidentified very high energy (VHE) gamma-ray source HESS J1702-420, for the first time, was carried out by Suzaku. No bright sources were detected in the XIS field of view (FOV), except for two faint point-like sources. The two sources, however, are considered not to be related to HESS J1702-420, because their fluxes in the 2-10 keV band (similar to 10(-14) erg s(-1) cm(-2)) are similar to 3 orders of magnitude smaller than the VHF gamma-ray flux in the 1-10 TeV band (F-TeV = 3.1 x 10(-11) erg s(-1) cm(-2)). We compared the energy spectrum of diffuse emission, extracted from the entire XIS FOV with those from nearby observations. If we consider the systematic error of background subtraction, no significant diffuse emission was detected with an upper limit of F-X < 2.7 x 10(-12) erg s(-1) cm(-2) in the 2-10 keV band for an assumed power-law spectrum of Gamma = 2.1 and a source size same as that in the VHE band. The upper limit of the X-ray flux is twelve-times as small as the VHE gamma-ray flux. The large flux ratio (F-TeV/F-X) indicates that HESS J1702-420 is another example of a "dark" particle accelerator. If we use a simple one-zone leptonic model, in which VHE gamma-rays are produced through inverse Compton scattering of the cosmic microwave background and interstellar far-infrared emission, and the X-rays via the synchrotron mechanism, an upper limit of the magnetic field (1.7 mu AG) is obtained from the flux ratio. Because the magnetic field is weaker than the typical value in the galactic plane (3-10 mu G), the simple one-zone model may not work for HESS J1702-420 and a significant fraction of the VHE gamma-rays may originate from protons.

Pulsar systems are very good experimental laboratories for the fundamental physics in extreme environments which cannot be achieved on ground. For example, the systems are under conditions of high magnetic field strength, large gravitational potential, and fast rotation, representing highly-ionized hot plasmas with particle acceleration etc. We can test phenomena related to these extreme condition in the X-ray to sub-MeV bands. In future, we will get fantastic capabilities of higher sensitivities, larger effective area, higher energy resolutions, and X-ray imaging capabilities with wider energy band than current missions, in addition to opening new eyes of polarization measurements, and deep all sky monitoring capabilities, with future X-ray missions including ASTRO-H, eRossita, NuSTAR, GEMS, International X-ray Observatory (IXO) and so on. In this paper, we summarize current hot topics on pulsars and discuss expected developments by these future missions, especially by ASTRO-H and IXO, based on the current design parameters.

We present the development of the data acquisition system for the X-ray CCD camera (SXI: Soft X-ray Imager) onboard the ASTRO-H satellite. Two types of breadboard models (BBMs) of SXI electronics have been produced to verify the functions of each circuit board and to establish the data acquisition system from CCD to SpaceWire (SpW) I/F. Using BBM0, we verified the basic design of the CCD driver, function of the Sigma S-ADC, data acquisition of the frame image, and stability of the SpW communication. We could demonstrate the energy resolution of 164 eV (FWHM) at 5.9 keV. Using BBM1, we verified acquisition of the housekeeping information and the frame images.

Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched in 2012. The SXI camera contains four CCD chips, each with an imaging aread of 31 mm x 31 mm, arrayed in mosaic, which cover the whole FOV area of 38'x38'. The SXI CCD of which model name is HPK Pch-NeXT4 is a P-channel type, back-illuminated, fully depleted device with a thickness of 200 mu m. We have developed an engineering model of the SXI camera body with coolers, and analog electronics for them. Combined with the bread board digital electronics, we succeeded in operation the whole the SXI system. The CCDs are cooled down to -120 degrees C with this system, and X-rays from Fe-55 sources are detected. Although optimization of the system is in progress, the energy resolution of typical 200eV and best 156eV (FWHM) at 5.9 keV are obtained. The readout noise is 10e(-) to 15e(-), and to be improved its goal value of 5e(-). On-going function tests and environment tests reveal some issues to be solved until the production of the SXI flight model in 2012.

We report on the development of the X-ray CCD for the soft X-ray imager (SXI) onboard ASTRO-H. SXI CCDs are P-channel, back-illuminated type manufactured by Hamamatsu Photonics K. K.. Experiments with the prototype CCD for the SXI shows the device has a depletion layer as thick as 200 mu m, high quantum efficiency for hard X-ray band. At the same time, we found a significant low energy tail in the soft X-ray response of the SXI prototype CCD by irradiating soft X-rays to the prototype CCD for the SXI. We made smaller size of CCDs than the flight model with several types of the surface treatment in order to evaluate the X-ray responce in detail. CCDs with one of the surface layers treatment show a low energy tail of which intensity is one order of magnitude smaller than that of the original SXI prototype CCD for 0.5 keV X-ray incidence. The same treatment will be applied to the flight model CCDs of the SXI. We also performed the experiments to inject charge with the SXI prototype CCD, which is needed to mitigate the radiation damage in the orbit. We investigated the operation conditions of the charge injection. Using the potential equilibration method, charges are injected in each column homogeneously, though the amount of the charge must be larger than 20 ke(-).

We report instrument outline as well as science of the photon-counting soft X-ray telescope that we have been studying as a possible scientific payload for the Japanese Solar-C mission whose projected launch around 2019. Soft X-rays (~1- 10 keV) from the solar corona include rich information on (1) possible mechanism(s) for heating the bright core of active regions seen in soft X-rays (namely, the hottest portion in the non-flaring corona), (2) dynamics and magnetohydrodynamic structures associated with magnetic reconnection processes ongoing in flares, and even (3) generation of supra-thermal distributions of coronal plasmas associated with flares. Nevertheless, imaging-spectroscopic investigation of the soft X-ray corona has so far remained unexplored due to difficulty in the instrumentation for achieving this aim. With the advent of recent remarkable progress in CMOS-APS detector technology, the photon-counting X-ray telescope will be capable of, in addition to conventional photon-integration type exposures, performing imaging-spectroscopic investigation on active regions and flares, thus providing, for example, detailed temperature information (beyond the sofar- utilized filter-ratio temperature) at each spatial point of the observing target. The photon-counting X-ray telescope will emply a Wolter type I optics with a piece of a segmented mirror whose focal length 4 meters, combined with a focal-plane CMOS-APS detector (0.4-0.5"/pixel) whose frame read-out rate required to be as high as 1000 fps. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

During the search for counterparts of very high energy gamma-ray sources, we screndipitously discovered large, extended, low surface brightness emission from pulsar wind nebulae (PWNe) around pulsars with the ages up to similar to 100 kyr, a discovery made possible by the low and stable background of the Suzaku X-ray satellite. A systematic study of a sample of eight of these PWNe, together with Chandra data sets, has revealed that the nebulae keep expanding up to similar to 100 kyr, although the timescale of the synchrotron X-ray emission is only similar to 60 yr for typical magnetic fields of 100 mu G. Our result suggests that the accelerated electrons up to similar to 80 TeV can escape from the PWNe without losing most energies. Moreover, in order to explain the observed correlation between the X-ray size and the pulsar spin-down age, the magnetic field strength in the PWNe must decrease with time.

The Suzaku observation of LMC X-3 gives the best data to date on the shape of the accretion disk spectrum. This is due to the combination of very low absorbing column density along this line of sight, which allows the shape of the disk emission to be constrained at low energies by the CCDs while the tail can be simultaneously determined up to 30 keV by the high-energy detectors. These data clearly demonstrate that the observed disk spectrum is broader than a simple "sum of blackbodies," and relativistic smearing of the emission is strongly required. However, the intrinsic emission should be more complex than a (color-corrected) sum of blackbodies as it should also contain photoelectric absorption edges from the partially ionized disk photosphere. These are broadened by the relativistic smearing, but the models predict similar to 3%-5% deviations for 1/3-1 solar abundance around the edge energies, significantly stronger than observed. This indicates that the models need to include more physical processes such as self-irradiation, bound-bound (line) absorption, and/or emission from recombination continua and/or lines. Alternatively, if none of these match the data, it may instead require that the accretion disk density and/or emissivity profile with height is different to that assumed. Thus, these data demonstrate the feasibility of observational tests of our fundamental understanding of the vertical structure of accretion disks.

Suzaku observed the region including HESS J1809-193, a TeV unidentified source, and confirmed the existence of extended hard X-ray emission previously reported by ASCA, as well as hard X-ray emission from PSR J1809-1917 in this region. A one-dimensional profile of the diffuse emission is represented along with a Gaussian model with a best-fit sigma of 7' +/- 1'. The diffuse emission extends for at least 21 pc (at the 3 sigma level, assuming a distance of 3.5 kpc), and has a hard spectrum with a photon index of Gamma similar to 1.7. The hard spectrum suggests a pulsar wind nebula origin, which is also strengthened by the hard X-ray emission from PSR J1809-1917, itself. Thanks to the low background of Suzaku XIS, we were able to investigate the spatial variation of the energy spectrum, but no systematic spectral change in the extended emission was found. These results imply that the X-ray emitting pulsar wind electrons can travel up to 21 pc from the pulsar without any noticeable energy loss via synchrotron emission.

著者人数: 22人(含チーム1)資料番号: AA0064574177レポート番号: JAXA-SP-09-008E

著者人数: 22人資料番号: AA0064574161レポート番号: JAXA-SP-09-008E

Suzaku has enabled us to study wide-band spectral and timing properties of black-hole binaries and AGNs more accurately than ever, and revealed how the continuum definition can affect Fe-K line profiles. We have reproduced 0.5-300 keV spectra of Cyg X-1 and GRO J1655-40 in terms of thermal Comptonization in highly inhomogeneous coronae. In both objects, R-in was constrained by the Fe-K line profile and soft excess as similar to 10 R-g, as opposed to the relativistic Fe-K line reported in the literature. We also re-analyzed the 0.7-300 keV Suzaku spectra of OX 339-4, and found that a careful modeling of the continuum leads to R-in > R-g(Yamada et al. 2009), again in disagreement with Miller et al. (2008). Furthermore, through a systematic analysis of AGNs, we discovered a hard spectral component in the HXD-PIN band, which varies independently of the powerlaw. Taking this into account, the time-averaged spectra of MCG-6-30-15 have been explained by invoking neither a large refection fraction, nor an extreme broad Fe-K line. The essence here is that the hard X-ray (20-40 keV) bump may be partially explained as an additional Comptonization component. Our results indicate that the extremely relativistic Fe-K line reported for some objects is not a unique solution, and depends in many cases on the continuum modeling.

We have developed a new back-illuminated (BI) CCD which has an Optical Blocking Layer (OBL) directly coating its X-ray illumination surface with Aluminum-Polyimide-Aluminum instead of Optical Blocking Filter (OBF). OBL is composed of a thin polyimide layer sandwiched by two Al layers. Polyimide and Al has a capability to cut EUV and optical light, respectively. The X-ray CCD is affected by large doses of extreme ultraviolet (EUV) radiation from Earth sun-lit atmosphere (airglow) in orbit as well as the optical light.In order to evaluate the performance of the EUV-attenuating polyimide of the OBL, we measured the EUV transmission of both the OBL and the OBF at energies between 15-72 eV by utilizing a beam line located at the Photon Factory in High Energy Accelerator Research Organization (KEK-PF). We obtained the EUV transmission to be 3% at 41 eV which is the same as the expected transmission from the designed thickness of the polyimide layer. We also found no significant change of the EUV transmission of polyimide over the nine month interval spanned by out two experiments.We also measured the optical transmission of the OBL at wavelengths between 500-900 angstrom to evaluate the performance of the Al that attenuates optical light, and found the optical transmission to be less than 4x10(-5).

We are designing an X-ray CCD camera (SXI) for ASTRO-H, including many new items. We have developed the CCD, CCD-NeXT4, that is a P-channel type CCD. It has a thick depletion layer of 200 mu m with an imaging area of 30mm square. Since it is back-illuminated, it has a good low energy response and is robust against the impact of micro-meteorites. We will employ 4 chips to cover the area of 60mm square. A mechanical rather than peltier cooler will be employed so that we can cool the CCD to -120 degrees C. We will also introduce an analog ASIC that is placed very close to the CCD. It performs well, having a similar noise level to that assembled by using individual parts used on SUZAKU. We also employ a modulated X-ray source (MXS), that improves the accuracy of the calibration. The SXI will have one of the largest SO among various satellites.

Continuous searches for other possible white dwarf (WD) pulsars like AE Aquarii[l 2] with Suzaku and INTEGRAL have been performed. After picking up WDs with known magnetic field strengths and spin periods from catalogs of CVs and isolated WDs, objects whose induced electric potentials exceed 10(12) volts and dipole radiations over 10(29) erg s(-1) are selected; AM Her, EUVE J0317-85, P01031+234, LHS1734, PG1015+014 etc. Their X-rays were studied with INTEGRAL archive data and/or Suzaku follow-up observations. A promising non-thermal emission from an object, AM Her in a very low state, has been found with Suzaku at the X-ray luminosity of 6.6 x 10(29) erg s(-1).

The wide-band Suzaku spectra of the black hole (BH) binary GX 339-4, acquired in 2007 February during the Very High state, were reanalyzed. Effects of event pileup (significant within similar to 3' of the image center) and telemetry saturation of the X-ray Imaging Spectrometer (XIS) data were carefully considered. The source was detected up to similar to 300 keV, with an unabsorbed 0.5-200 keV luminosity of 3.8 x 10(38) erg s(-1) at 8 kpc. The spectrum can be approximated by a power law of photon index 2.7, with a mild soft excess and a hard X-ray hump. When using the XIS data outside 2' of the image center, the Fe K line appeared extremely broad, suggesting a high BH spin as already reported by Miller et al. based on the same Suzaku data and other CCD data. When the XIS data accumulation is further limited to > 3' to avoid event pileup, the Fe K profile becomes narrower, and a marginally better solution appears which suggests that the inner disk radius is 5-14 times the gravitational radius (1 sigma), though a maximally spinning BH is still allowed by the data at the 90% confidence level. Consistently, the optically thick accretion disk is inferred to be truncated at a radius 5-32

We present ASCA and Suzaku studies of the TeV source HESS J1837-069, which has not been identified in other wavelengths. We confirm the presence of two X-ray sources in the Suzaku XIS image, AX J1838.0-0655 and AX J1837.3-0652, near both ends of the elongated TeV emission region. The XIS spectra of the two sources were reproduced by an absorbed power-law model, whose parameters are all consistent with those determined by the ASCA data. Recently, 70.5 ms X-ray Pulsation has been detected with RXTE in the sky region including HESS J1837-069 (Gotthelf & Halpern 2008, ApJ, 681, 515). Using the ASCA GIS data, which has both timing and imaging capabilities, we identified the pulsation Source as AX J1838.0-0655. The pulse periods determined by ASCA and Suzaku, and that reported with RXTE indicate steady spin-down at 4.917(4) x 10(-14) s s(-1). These results suggest that AX J1838.0-0655 is an intrinsically stable source, and presumably a pulsar wind nebula (PWN). We discuss the possibility that AX J1838.0-0655 is associated with HESS J1837-069 and the VHE gamma-ray ernission is originated from the PWN.

The black-hole binary Cygnus X-1 was observed for 17 ks with the Suzaku X-ray observatory in 2005 October, while it was in a low/hard state with a 0.7-300 keV luminosity of 4.6 x 10(37) ergs(-1). The XIS and HXD spectra, spanning 0.7-400 keV, were reproduced successfully, incorporating a cool accretion disk and a hot Comptonizing corona. The corona is characterized by an electron temperature of similar to 100 keV, and two optical depths of similar to 0.4 and similar to 1.5, which account for the softer and harder continua, respectively. The disk has an innermost temperature of similar to 0.2keV, and is thought to protrude half way into the corona. The disk not only provides seed photons to the Compton cloud, but also produces a soft spectral excess, a mild reflection hump, and a weakly broadened iron line. A comparison with the Suzaku data on GRO J1655-40 reveals several interesting spectral differences, which can mostly be attributed to inclination effects, assuming that the disk has a flat geometry while the corona is grossly spherical. An intensity-sorted spectroscopy indicates that the continuum becomes less Comptonized when the source flares up on time scales of 1-200 s, while the underlying disk remains unchanged.

We have analyzed 200 Rossi X-ray Timing Explorer observations of the black hole candidate GX 339-4, all from bright hard state periods between 1996 and 2005. The purpose of our study is to investigate the radiation mechanisms in the hard state of GX 339-4. The broadband 3-200keV spectra were successfully modeled by a simple analytic model, power-law with an exponential cut-off modified with a smeared edge. The obtained energy cut-off (E-cut) was distributed over 50-200 keV, and the photon index over 1.4-1.7. We found a clear anti-correlation (E-cut alpha L-0.70 +/- 0.06) between the X-ray luminosity (L) in 2-200 keV and E-cut, when L is larger than 7 x 10(37) erg s(-1) (assuming a distance of 8 kpc), while E-cut is roughly constant at around 200 keV when L is smaller than 7 x 10(37) ergs(-1). This anti-correlation remained unchanged by adopting a more physical thermal Comptonization model, which resulted in an anti-correlation that can be expressed as kT(e) alpha L-0.24 +/- 0.06. These anti-correlations can be quantitatively explained by a picture in which the energy-flow rate from protons to electrons balances with inverse Compton cooling.

A fast rotating magnetized white dwarf, AE Aquarii, was observed with Suzaku, in 2005 October-November and 2006 October with exposures of 53.1 and 42.4ks, respectively. In addition to clear spin modulation in the 0.5-10 keV band of the XIS data at the barycentric period of 33.0769 +/- 0.0001 s, the 10-30 keV HXD data in the second half of the 2005 observation also showed statistically significant periodic signals at a consistent period. On that occasion, the spin-folded HXD light curve exhibited two sharp spikes separated by similar to 0.2 cycles in phase, in contrast to approximately sinusoidal profiles observed at energies below similar to 4 keV. The folded 4-10 keV XIS light curves are understood to be a superposition of those two types of pulse profiles. The phase-averaged 1.5-10 keV spectra can be reproduced by two thermal components with temperatures of 2.0(-0.16)(+0.20) keV and 0.53(-0.13)(+0.14) keV but the 12-25 keV HXD data show a significant excess above the extrapolated model. This excess can be explained by either a power-law model with a photon index of 1.12(-0.62)(+0.63) or a third thermal component with a temperature of 54(-47)(+26) keV. At a distance of 102pc, the 4-30keV luminosities of the thermal and the additional components become 1.7(-0.6)(+1.3) and 5.3(-0.3)(+15.3) X 10(29) erg s(-1), respectively. The latter corresponds to 0.09% of the spin-down energy of the object. Possible emission mechanisms of the hard pulsations are discussed, including non-thermal ones, in particular.

The NeXT (New exploration X-ray Telescope), the new Japanese X-ray Astronomy Satellite following Suzakii, is an international X-ray mission which is currently planed for launch in 2013. NeXT is a combination of wide band X-ray spectroscopy (3-80 keV) provided by multi-layer coating, focusing hard X-ray mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-10 keV) provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane detector for a soft X-ray telescope and a non-focusing soft gamma-ray detector. With these instruments, NeXT covers very wide energy range from 0.3 keV to 600 keV. The micro-calorimeter system will be developed by international collaboration lead by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of ΔE ∼7 eV by the micro-calorimeter will enable a wide variety of important science themes to be pursued.

The X-ray Imaging Spectrometer (XIS) on board the Suzaku satellite is an X-ray CCD camera system that has features of a low background, high quantum efficiency, and good energy resolution in the 0.2-12 keV band. Because of the radiation damage, however, the energy resolution of the XIS has been degraded since Suzaku was launched (July 2005). In order to improve the energy resolution, one of the major advantages of the XIS over the other X-ray CCDs in orbit is the provision of a precision charge injection (CI) capability. We applied this Cl in two ways. First, in order to measure the precise charge transfer inefficiency (CTI), we applied the checker-flag Cl, and measured the CTI of each CCD column. Furthermore, we obtained the pulse height dependency of the CTI. Our precise CTI correction using these results improved the energy resolution from 193 eV to 173 eV in FWHM at 5.9 keV in July 2006 (one year after the launch). Second, the energy resolution can be improved also by reducing the CTI. For this purpose, we applied the spaced-row charge injection (SCI); periodically injected artificial charges work as if they compensate radiation-induced traps and prevent electrons produced by X-rays from being captured by the charge traps. Using this method, the energy resolution improved from 210 eV to 150 eV in FWHM at 5.9 keV in September 2006, which is close to the resolution just after the launch (140 eV). We report the current in-orbit calibration status of the XIS data using these two techniques. We present the time history of the gain and energy resolution determined from onboard calibration sources (Fe-55) and observed calibration objects like E0102-72.

The transient X-ray binary pulsar A0535+262 was observed with Suzaku on 2005 September 14 when the source was in the declining phase of the August-September minor outburst. The similar to 103 s X-ray pulse profile was strongly energy dependent, with a double-peaked profile in the soft X-ray energy band (< 3 keV) and a single-peaked smooth profile in hard X-rays. The width of the primary dip is found to increase with energy. The broadband energy spectrum of the pulsar is well described with a negative and positive power law with exponential (NPEX) continuum model, along with a blackbody component for soft excess. A weak iron K alpha emission line with an equivalent width similar to 25 eV was detected in the source spectrum. The blackbody component is found to be pulsating over the pulse phase, implying that the accretion column and/or the inner edge of the accretion disk may be the possible emission site of the soft excess in A0535+262. The higher value of the column density is believed to be the cause of the secondary dip in the soft X-ray energy band. The iron line equivalent width is found to be constant (within errors) over the pulse phase. However, a sinusoidal type of flux variation of the iron emission line, in phase with the hard X-ray flux, suggests that the inner accretion disk is the possible emission region of the iron fluorescence line.

Although rotating neutron stars (NSs) have been regarded as being textbook examples of astrophysical particle acceleration sites for decades, details of the acceleration mechanism remain a mystery; for example, we cannot yet observationally distinguish "polar cap" models from "outer gap" models. To solve the model degeneracy, it is useful to study similar systems with much different physical parameters. Strongly magnetized white dwarfs (WDs) are ideal for this purpose, because they have essentially the same system geometry as NSs, but differ largely from NSs in the system parameters, including the size, magnetic field, and the rotation velocity, with the induced electric field expected to reach 10(13)-10(14) eV. Based on this idea, the best candidate among WDs, AE Aquarii, was observed with the fifth Japaneses X-ray satellite, Suzaku. The hard X-ray detector (HXD) on-board Suzaku has the highest sensitivity in the hard X-ray band over 10 keV. A marginal detection in the hard X-ray band was achieved with the HXD, and was separated from the thermal emission. The flux corresponds to about 0.02% of its spin-down energy. If the signal is real, this observation must be a first case of the detection of non-thermal emission from WDs. (C) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

The Soft X-ray Imager (SXI) is the X-ray CCD detector system on board the NeXT mission that is to be launched around 2013. The system consists of a camera, an SXI-specific data processing unit (SXI-E) and a CPU unit commonly used throughout the NeXT satellite. All the analog signal handling is restricted within the camera unit, and all the I/O of the unit are digital. The camera unit and SXI-E are connected by multiple LVDS lines, and SXI-E and the CPU unit will be connected by a SpaceWire (SpW) network. The network can connect SXI-E to multiple CPU units (the formal SXI CPU and neighbors) and all the CPU units in the network have connections to multiple neighbors: with this configuration, the SXI system can work even in the case that one SpW connection or the formal SXI CPU is down. The main tasks of SXI-E are to generate the CCD driving pattern, the acquisition of the image data stream and HK data supplied by the camera and transfer them to the CPU unit with the Remote Memory Access Protocol (RMAP) over SpW. In addition to them, SXI-E also detects the pixels whose values are higher than the event threshold and both adjacent pixels in the same line, and send their coordinates to the CPU unit. The CPU unit can reduce its load significantly with this information because it gets rid of the necessity to scan whole the image to detect X-ray events.

We studied how the configuration parameters of a CCD (pixel size and depletion layer thickness) affect the instrumental background of an X-ray CCD camera in the space environment through the Monte-Carlo simulation. X-ray detectors are in general sensitive not only to X-rays but also to charged particles. The latter produce pseudo-signal indistinguish able from that of X-rays, which is called instrumental background. It is essential to reduce the instrumental background for the observations of dim and diffuse X-ray sources, but the low background was not considered as a, design goal of an X-ray CCD camera so far. We utilized the Monte-Carlo simulator, which could successfully reproduce the Suzaku XIS background, for the current analysis. We found that thicker depletion layer tends to increase the background except for the >5 keV band of the backside-illuminated CCD. On the other hand, pixel-size dependence was different between the frontside and backside illuminated CCDs. These results are interpreted in terms Of the interaction of cosmic/X-rays with the CCD.