Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyProfessor, Graduate Institute for Advanced Studies, The Graduate University for Advanced Studies (SOKENDAI)Visiting Professor, School of Science, Tokyo Institute of Technology
- Degree
- Ph. D.(The University of Tokyo)master's degree(The University of Tokyo)
- Researcher number
- 20280555
- ORCID ID
https://orcid.org/0000-0002-2374-7073- J-GLOBAL ID
- 200901095989600566
- researchmap Member ID
- 1000363020
I have been developing cryogenic high-resolution X-ray microcalorimeter spectrometers onboard X-ray astronomy satellite. It was achieved as the Resolve instrument onboard XRISM, which was launched in September, 2023.
Here are research themes I can provide. (1) Analyze high-resolution X-ray spectroscopy data obtained by XRISM satellite, and research motion of the hot gas in clusters of galaxies, in order to understand the formation of the large-scale structures of the Universe. (2) Conduct experimental studies, in anticipation of LiteBIRD mission, that aims for observing the polarization of the cosmic microwave background radiation.
Message to students: Through the research, develop an understanding of specific natural phenomena, and also learn the process to reach fundamental physics laws that underlie the complex phenomena, together with experimental and/or analytical methods.
Research Interests
6Research Areas
2Research History
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Mar, 2024 - Present
Education
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Apr, 1991 - Mar, 1995
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Apr, 1987 - Mar, 1991
Committee Memberships
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Apr, 2009 - Mar, 2011
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2009 - 2010
Awards
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2010
Papers
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Publications of the Astronomical Society of Japan, Oct 10, 2024Abstract We present an initial analysis of the X-Ray Imaging and Spectroscopy Mission (XRISM) first-light observation of the supernova remnant (SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band, which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of $\sigma _v \sim 450$ km s$^{-1}$. However, the Fe He$\alpha$ lines are substantially broadened with $\sigma _v \sim 1670$ km s$^{-1}$. This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He$\alpha$ emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be $-1000 \lesssim V_{\rm rs}$ (km s$^{-1}$) $\lesssim 3300$ (in the observer frame). We also find that Fe Ly$\alpha$ emission is redshifted with a bulk velocity of $\sim 890$ km s$^{-1}$, substantially larger than the radial velocity of the local interstellar medium surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.
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The Astrophysical Journal Letters, 973(1) L25-L25, Sep 1, 2024Abstract We present an analysis of the first two XRISM/Resolve spectra of the well-known Seyfert-1.5 active galactic nucleus (AGN) in NGC 4151, obtained in 2023 December. Our work focuses on the nature of the narrow Fe K α emission line at 6.4 keV, the strongest and most common X-ray line observed in AGN. The total line is found to consist of three components. Even the narrowest component of the line is resolved with evident Fe K α,1 (6.404 keV) and K α,2 (6.391 keV) contributions in a 2:1 flux ratio, fully consistent with neutral gas with negligible bulk velocity. Subject to the limitations of our models, the narrowest and intermediate-width components are consistent with emission from optically thin gas, suggesting that they arise in a disk atmosphere and/or wind. Modeling the three line components in terms of Keplerian broadening, they are readily associated with (1) the inner wall of the “torus,” (2) the innermost optical “broad-line region” (or “X-ray BLR”), and (3) a region with a radius of r ≃ 100 GM/c 2 that may signal a warp in the accretion disk. Viable alternative explanations of the broadest component include a fast-wind component and/or scattering; however, we find evidence of variability in the narrow Fe K α line complex on timescales consistent with small radii. The best-fit models are statistically superior to simple Voigt functions, but when fit with Voigt profiles the time-averaged lines are consistent with a projected velocity broadening of FWHM . Overall, the resolution and sensitivity of XRISM show that the narrow Fe K line in AGN is an effective probe of all key parts of the accretion flow, as it is currently understood. We discuss the implications of these findings for our understanding of AGN accretion, future studies with XRISM, and X-ray-based black hole mass measurements.
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 53-53, Aug 22, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 55-55, Aug 22, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 52-52, Aug 21, 2024
Misc.
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Publications of the Astronomical Society of Japan, 70(2), 2018We report a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary<br /> system with an extremely strong absorption of N_H~10^{24} cm^{-2}. Previous<br /> X-ray studies revealed that its spectrum is dominated by strong fluorescence<br /> lines of Fe as well as continuum emission. For physical and geometrical insight<br /> into the nature of the reprocessing material, we utilize the high spectroscopic<br /> resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer;<br /> SXS) and the wide-band sensitivity by the soft and hard X-ray imager (SXI and<br /> HXI) aboard Hitomi. Even though photon counts are limited due to unintended<br /> off-axis pointing, the SXS spectrum resolves Fe K{\alpha_1} and K{\alpha_2}<br /> lines and puts strong constraints on the line centroid and width. The line<br /> width corresponds to the velocity of 160^{+300}_{-70} km s^{-1}. This<br /> represents the most accurate, and smallest, width measurement of this line made<br /> so far from any X-ray binary, much less than the Doppler broadening and shift<br /> expected from speeds which are characteristic of similar systems. Combined with<br /> the K-shell edge energy measured by the SXI and HXI spectra, the ionization<br /> state of Fe is estimated to be in the range of Fe I--IV. Considering the<br /> estimated ionization parameter and the distance between the X-ray source and<br /> the absorber, the density and thickness of the materials are estimated. The<br /> extraordinarily strong absorption and the absence of a Compton shoulder<br /> component is confirmed. These characteristics suggest reprocessing materials<br /> which are distributed in a narrow solid angle or scattering primarily with warm<br /> free electrons or neutral hydrogen.
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Publications of the Astronomical Society of Japan, 70(6), 2018We present the results from the Hitomi Soft Gamma-ray Detector (SGD)<br /> observation of the Crab nebula. The main part of SGD is a Compton camera, which<br /> in addition to being a spectrometer, is capable of measuring polarization of<br /> gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray<br /> sources on the sky, and, the only source from which polarized X-ray photons<br /> have been detected. SGD observed the Crab nebula during the initial test<br /> observation phase of Hitomi. We performed the data analysis of the SGD<br /> observation, the SGD background estimation and the SGD Monte Carlo simulations,<br /> and, successfully detected polarized gamma-ray emission from the Crab nebula<br /> with only about 5 ks exposure time. The obtained polarization fraction of the<br /> phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1<br /> $\pm$ 10.6)% and, the polarization angle is 110.7$^o$ + 13.2 / $-$13.0$^o$ in<br /> the energy range of 60--160 keV (The errors correspond to the 1 sigma<br /> deviation). The confidence level of the polarization detection was 99.3%. The<br /> polarization angle measured by SGD is about one sigma deviation with the<br /> projected spin axis of the pulsar, 124.0$^o$ $\pm$0.1$^o$.
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Publications of the Astronomical Society of Japan, 70(2), 2018The present paper investigates the temperature structure of the X-ray<br /> emitting plasma in the core of the Perseus cluster using the 1.8--20.0 keV data<br /> obtained with the Soft X-ray Spectrometer (SXS) onboard the Hitomi Observatory.<br /> A series of four observations were carried out, with a total effective exposure<br /> time of 338 ks and covering a central region $\sim7'$ in diameter. The SXS was<br /> operated with an energy resolution of $\sim$5 eV (full width at half maximum)<br /> at 5.9 keV. Not only fine structures of K-shell lines in He-like ions but also<br /> transitions from higher principal quantum numbers are clearly resolved from Si<br /> through Fe. This enables us to perform temperature diagnostics using the line<br /> ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of<br /> the excitation temperature and ionization temperature in the Perseus cluster.<br /> The observed spectrum is roughly reproduced by a single temperature thermal<br /> plasma model in collisional ionization equilibrium, but detailed line ratio<br /> diagnostics reveal slight deviations from this approximation. In particular,<br /> the data exhibit an apparent trend of increasing ionization temperature with<br /> increasing atomic mass, as well as small differences between the ionization and<br /> excitation temperatures for Fe, the only element for which both temperatures<br /> can be measured. The best-fit two-temperature models suggest a combination of 3<br /> and 5 keV gas, which is consistent with the idea that the observed small<br /> deviations from a single temperature approximation are due to the effects of<br /> projection of the known radial temperature gradient in the cluster core along<br /> the line of sight. Comparison with the Chandra/ACIS and the XMM-Newton/RGS<br /> results on the other hand suggests that additional lower-temperature components<br /> are present in the ICM but not detectable by Hitomi SXS given its 1.8--20 keV<br /> energy band.
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Publications of the Astronomical Society of Japan, 70(2), 2018The Hitomi SXS spectrum of the Perseus cluster, with $\sim$5 eV resolution in<br /> the 2-9 keV band, offers an unprecedented benchmark of the atomic modeling and<br /> database for hot collisional plasmas. It reveals both successes and challenges<br /> of the current atomic codes. The latest versions of AtomDB/APEC (3.0.8), SPEX<br /> (3.03.00), and CHIANTI (8.0) all provide reasonable fits to the broad-band<br /> spectrum, and are in close agreement on best-fit temperature, emission measure,<br /> and abundances of a few elements such as Ni. For the Fe abundance, the APEC and<br /> SPEX measurements differ by 16%, which is 17 times higher than the statistical<br /> uncertainty. This is mostly attributed to the differences in adopted<br /> collisional excitation and dielectronic recombination rates of the strongest<br /> emission lines. We further investigate and compare the sensitivity of the<br /> derived physical parameters to the astrophysical source modeling and<br /> instrumental effects. The Hitomi results show that an accurate atomic code is<br /> as important as the astrophysical modeling and instrumental calibration<br /> aspects. Substantial updates of atomic databases and targeted laboratory<br /> measurements are needed to get the current codes ready for the data from the<br /> next Hitomi-level mission.
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Publications of the Astronomical Society of Japan, 70(2), 2018We present Hitomi observations of N132D, a young, X-ray bright, O-rich<br /> core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a<br /> very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily<br /> detects the line complexes of highly ionized S K and Fe K with 16-17 counts in<br /> each. The Fe feature is measured for the first time at high spectral<br /> resolution. Based on the plausible assumption that the Fe K emission is<br /> dominated by He-like ions, we find that the material responsible for this Fe<br /> emission is highly redshifted at ~800 km/s compared to the local LMC<br /> interstellar medium (ISM), with a 90% credible interval of 50-1500 km/s if a<br /> weakly informative prior is placed on possible line broadening. This indicates<br /> (1) that the Fe emission arises from the supernova ejecta, and (2) that these<br /> ejecta are highly asymmetric, since no blue-shifted component is found. The S K<br /> velocity is consistent with the local LMC ISM, and is likely from swept-up ISM<br /> material. These results are consistent with spatial mapping that shows the<br /> He-like Fe concentrated in the interior of the remnant and the S tracing the<br /> outer shell. The results also show that even with a very small number of<br /> counts, direct velocity measurements from Doppler-shifted lines detected in<br /> extended objects like supernova remnants are now possible. Thanks to the very<br /> low SXS background of ~1 event per spectral resolution element per 100 ks, such<br /> results are obtainable during short pointed or slew observations with similar<br /> instruments. This highlights the power of high-spectral-resolution imaging<br /> observations, and demonstrates the new window that has been opened with Hitomi<br /> and will be greatly widened with future missions such as the X-ray Astronomy<br /> Recovery Mission (XARM) and Athena.
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Publications of the Astronomical Society of Japan, 70(2), 2018The origin of the narrow Fe-K{\alpha} fluorescence line at 6.4 keV from<br /> active galactic nuclei has long been under debate; some of the possible sites<br /> are the outer accretion disk, the broad line region, a molecular torus, or<br /> interstellar/intracluster media. In February-March 2016, we performed the first<br /> X-ray microcalorimeter spectroscopy with the Soft X-ray Spectrometer (SXS)<br /> onboard the Hitomi satellite of the Fanaroff-Riley type I radio galaxy NGC 1275<br /> at the center of the Perseus cluster of galaxies. With the high energy<br /> resolution of ~5 eV at 6 keV achieved by Hitomi/SXS, we detected the<br /> Fe-K{\alpha} line with ~5.4 {\sigma} significance. The velocity width is<br /> constrained to be 500-1600 km s$^{-1}$ (FWHM for Gaussian models) at 90%<br /> confidence. The SXS also constrains the continuum level from the NGC 1275<br /> nucleus up to ~20 keV, giving an equivalent width ~20 eV of the 6.4 keV line.<br /> Because the velocity width is narrower than that of broad H{\alpha} line of<br /> ~2750 km s$^{-1}$, we can exclude a large contribution to the line flux from<br /> the accretion disk and the broad line region. Furthermore, we performed pixel<br /> map analyses on the Hitomi/SXS data and image analyses on the Chandra archival<br /> data, and revealed that the Fe-K{\alpha} line comes from a region within ~1.6<br /> kpc from the NGC 1275 core, where an active galactic nucleus emission<br /> dominates, rather than that from intracluster media. Therefore, we suggest that<br /> the source of the Fe-K{\alpha} line from NGC 1275 is likely a low-covering<br /> fraction molecular torus or a rotating molecular disk which probably extends<br /> from a pc to hundreds pc scale in the active galactic nucleus system.
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Publications of the Astronomical Society of Japan, 70(2), 2018Extending the earlier measurements reported in Hitomi collaboration (2016,<br /> Nature, 535, 117), we examine the atmospheric gas motions within the central<br /> 100~kpc of the Perseus cluster using observations obtained with the Hitomi<br /> satellite. After correcting for the point spread function of the telescope and<br /> using optically thin emission lines, we find that the line-of-sight velocity<br /> dispersion of the hot gas is remarkably low and mostly uniform. The velocity<br /> dispersion reaches maxima of approximately 200~km~s$^{-1}$ toward the central<br /> active galactic nucleus (AGN) and toward the AGN inflated north-western `ghost'<br /> bubble. Elsewhere within the observed region, the velocity dispersion appears<br /> constant around 100~km~s$^{-1}$. We also detect a velocity gradient with a<br /> 100~km~s$^{-1}$ amplitude across the cluster core, consistent with large-scale<br /> sloshing of the core gas. If the observed gas motions are isotropic, the<br /> kinetic pressure support is less than 10\% of the thermal pressure support in<br /> the cluster core. The well-resolved optically thin emission lines have Gaussian<br /> shapes, indicating that the turbulent driving scale is likely below 100~kpc,<br /> which is consistent with the size of the AGN jet inflated bubbles. We also<br /> report the first measurement of the ion temperature in the intracluster medium,<br /> which we find to be consistent with the electron temperature. In addition, we<br /> present a new measurement of the redshift to the brightest cluster galaxy<br /> NGC~1275.
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Publications of the Astronomical Society of Japan, 70(2), 2018Thanks to its high spectral resolution (~5 eV at 6 keV), the Soft X-ray<br /> Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure<br /> of spatially resolved emission lines from highly ionized ions in galaxy<br /> clusters for the first time. In this series of papers, using the SXS we have<br /> measured the velocities of gas motions, metallicities and the multi-temperature<br /> structure of the gas in the core of the Perseus cluster. Here, we show that<br /> when inferring physical properties from line emissivities in systems like<br /> Perseus, the resonant scattering (RS) effect should be taken into account. In<br /> the Hitomi waveband, RS mostly affects the FeXXV He$\alpha$ line ($w$) - the<br /> strongest line in the spectrum. The flux measured by Hitomi in this line is<br /> suppressed by a factor ~1.3 in the inner ~30 kpc, compared to predictions for<br /> an optically thin plasma; the suppression decreases with the distance from the<br /> center. The $w$ line also appears slightly broader than other lines from the<br /> same ion. The observed distortions of the $w$ line flux, shape and distance<br /> dependence are all consistent with the expected effect of the resonant<br /> scattering in the Perseus core. By measuring the ratio of fluxes in optically<br /> thick ($w$) and thin (FeXXV forbidden, He$\beta$, Ly$\alpha$) lines, and<br /> comparing these ratios with predictions from Monte Carlo radiative transfer<br /> simulations, the velocities of gas motions have been obtained. The results are<br /> consistent with the direct measurements of gas velocities from line broadening<br /> described elsewhere in this series, although the systematic and statistical<br /> uncertainties remain significant. Further improvements in the predictions of<br /> line emissivities in plasma models, and deeper observations with future X-ray<br /> missions will enable RS measurements to provide powerful constraints on the<br /> amplitude and anisotropy of clusters gas motions.
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Publications of the Astronomical Society of Japan, 70(2), 2018© The Author(s) 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 σ fluctuations of the X-ray fluxes at the pulse peaks, and the 3 σ upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2-300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and 70-300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) × 10−11 erg cm−2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions.
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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewedThe Soft X-ray Spectrometer (SXS) onboard the Hitomi (ASTRO-H) satellite observed several celestial objects. All the observations with the SXS were performed through a beryllium (Be) window installed on the gate-valve of the SXS dewar. However, the Be window had not been well calibrated before launching. Therefore, we measured the transmission of a spare Be window, which is from the same lot as the flight material. The measurements were preformed in 3.8-30 keV range with BL01B1 at SPring-8, and in 2.5-12 keV range combined with BL11B and BL7C at KEK-PF. In this paper, we report mainly the results of the KEK-PF experiment. With the KEK-PF, we measured five places of the Be window. Their estimated thicknesses are consistent with each other within 1.3 μm. In the five transmission data, we confirmed absorption edges by Fe-K, Ni-K and Mn-K and six edge like features at 3460, 6057, 6915, 7590, 8790 and 9193 eV, which can be interpreted as Bragg diffraction by Be polycrystal. By combining the transmissions measured at KEK-PF and at SPring-8, we estimated Be thickness of 259.73±0.01 μm. The amounts of contaminated materials are roughly comparable with the provided values from the provider. We also performed scanning measurements of whole surface in the Be window. In the results, thickness of Be window was found to be uniform in ±1μm from the measurement with 4 keV X-rays.
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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewedDuring the Hitomi (Astro-H) commissioning observations the SXS dewar gate valve (GV) remained closed to protect the instrument from initial spacecraft outgassing. As a result, the optical path of the observations included the Be window installed on the GV. Both x-ray fluorescence (XRF) analysis and x-ray transmission measurements were performed in June 2016 on the flight-spare Be window which is the same lot as the flight material at SPring-8 in Japan. The beamline operating range is 3.8-30 keV. We used a beam spot size of 1 mm × 0.2 mm to measure two positions on the Be window, at the center of the window and at one position 6.5 mm off-center. We used simultaneous transmission measurements of standard materials for energy calibration. The transmission data clearly showed Fe and Ni K-edges, plus a marginal detection of the Mn K-edge. We found that our transmission data was best fit using the following component Be: 261.86±0.01μm, Cr: 3nm (fixed), Mn: 3.81±0.05nm, Fe: 10.83±0.05nm, Ni: 16.48±0.03nm, Cu: 5nm (fixed). The transmission is reduced 1% at the Fe K-edge. The amount of contaminated materials are comparable to the values of the value provided by the vender. The surface transmission is strained with σ = 0.11% of the unbiased standard deviation calculated variation in the residuals between the measured value and the model.
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Astrophysical Journal Letters, 837(1), 2017X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E approximate to 3.5 keV emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S XVI (E similar or equal to 3.44 keV rest-frame)-a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.
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SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY, 9905, 2016 Peer-reviewedThe calorimeter array of the JAXA Astro-H (renamed Hitomi) Soft X-ray Spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV, enabling essential plasma diagnostics. The properties that make the SXS array a powerful x-ray spectrometer also make it sensitive to photons from the entire electromagnetic band, and particles as well. If characterized as a bolometer, it would have a noise equivalent power (NEP) of < 4x10(-18) W/(Hz)(0.5). Thus it was imperative to shield the detector from thermal radiation from the instrument and optical and UV photons from the sky. Additionally, it was necessary to shield the coldest stages of the instrument from the thermal radiation emanating from the warmer stages. Both of these needs are addressed by a series of five thin-film radiation-blocking filters, anchored to the nested temperature stages, that block long-wavelength radiation while minimizing x-ray attenuation. The aperture assembly is a system of barriers, baffles, filter carriers, and filter mounts that supports the filters and inhibits their potential contamination. The three outer filters also have been equipped with thermometers and heaters for decontamination. We present the requirements, design, implementation, and performance of the SXS aperture assembly and blocking filters.
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Nature, 535(7610) 117-121, 2016Clusters of galaxies are the most massive gravitationally-bound objects in<br /> the Universe and are still forming. They are thus important probes of<br /> cosmological parameters and a host of astrophysical processes. Knowledge of the<br /> dynamics of the pervasive hot gas, which dominates in mass over stars in a<br /> cluster, is a crucial missing ingredient. It can enable new insights into<br /> mechanical energy injection by the central supermassive black hole and the use<br /> of hydrostatic equilibrium for the determination of cluster masses. X-rays from<br /> the core of the Perseus cluster are emitted by the 50 million K diffuse hot<br /> plasma filling its gravitational potential well. The Active Galactic Nucleus of<br /> the central galaxy NGC1275 is pumping jetted energy into the surrounding<br /> intracluster medium, creating buoyant bubbles filled with relativistic plasma.<br /> These likely induce motions in the intracluster medium and heat the inner gas<br /> preventing runaway radiative cooling; a process known as Active Galactic<br /> Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus<br /> cluster core, which reveal a remarkably quiescent atmosphere where the gas has<br /> a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from<br /> the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s<br /> is found across the 60 kpc image of the cluster core. Turbulent pressure<br /> support in the gas is 4% or less of the thermodynamic pressure, with large<br /> scale shear at most doubling that estimate. We infer that total cluster masses<br /> determined from hydrostatic equilibrium in the central regions need little<br /> correction for turbulent pressure.
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Proceedings of SPIE - The International Society for Optical Engineering, 8443, Dec 1, 2012one of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high-spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor (TES) and absorbers that consist of metal and semi-metal layers and a multiplexed SQUID readout. The array (32 x 32 pixels) provides an energy resolution of < 3 eV. Due to the large collection area of the Athena optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. Compared to the requirements for the same instrument on IXO, the performance requirements have been relaxed to fit into the much more restricted boundary conditions of Athena. In this paper we illustrate some of the science achievable with the instrument. We describe the results of design studies for the focal plane assembly and the cooling systems. Also, the system and its required spacecraft resources will be given. © 2012 SPIE.
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Proceedings of SPIE - The International Society for Optical Engineering, 8443, Dec 1, 2012We present the development status of the Pulse Shape Processor (PSP), which is the on-board digital electronics responsible for the signal processing of the X-ray microcalorimeter spectrometer instrument (the Soft X-ray Spectrometer; SXS) for the ASTRO-H satellite planned to be launched in 2014. We finished the design and fabrication for the engineering model, and are currently undertaking a series of performance verification and environmental tests. In this report, we summarize the results obtained in a part of the tests completed in the first half of this year. © 2012 SPIE.
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Meeting abstracts of the Physical Society of Japan, 67(1) 141-141, Mar 5, 2012
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Proceedings of SPIE - The International Society for Optical Engineering, 7732, 2010 Peer-reviewed
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AIP Conference Proceedings, 1185 442-445, Dec 1, 2009Performance test of a Ti/Au bilayer TES microcalorimeter has been made in combination with a continuous adiabatic demagnetization refrigerator (CADR). The CADR has four stages of ADR to produce continuous cooling by recycling them in dedicated order, and is cryogen-free utilizing a 4K-GM refrigerator We installed a Ti/Au bilayer TES microcalorimeter and 420-series SQUID array to readout the X-ray signal on the 1st (coldest) stage of the CADR. We successfully operated the CADR at temperature of 120 mK in continuous mode more than 27 hr, however, FWHM energy resolution of the TES microcalorimeter was degraded to 45 eV at 6 keV, as compared to 10 eV when measured in a dilution refrigerator. This is mainly because the temperature stability was not good enough (about 0.6 mK) and the operation temperature was not sufficiently lower than the transition temperature Tc = 135 mK of the TES. We operated the TES microcalorimeter at the operation temperature of 105 mK in one-shot mode and the resolution was improved to 30 eV. We also found that the operating point of the TES was affected by the magnetic field of the 3rd and 4th ADR recycle. More complete shielding of the magnetic field is essential for further improvement of the performance of the TES microcalorimeter © 2009 American Institute of Physics.
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Meeting abstracts of the Physical Society of Japan, 64(2) 31-31, Aug 18, 2009
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日本物理学会講演概要集, 64(2) 31-31, Aug 18, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 92-92, Mar 3, 2009
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Experimental Astronomy, 23(1) 67-89, 2009 Peer-reviewedHow structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysical cosmology. EDGE (Piro et al., 2007) will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions, through the period of galaxy cluster formation, down to the very low redshift Universe, when between a third and one half of the baryons are expected to reside in cosmic filaments undergoing gravitational collapse by dark matter (the so-called warm hot intragalactic medium). In addition EDGE, with its unprecedented capabilities, will provide key results in many important fields. These scientific goals are feasible with a medium class mission using existing technology combined with innovative instrumental and observational capabilities by: (a) observing with fast reaction Gamma-Ray Bursts with a high spectral resolution. This enables the study of their star-forming and host galaxy environments and the use of GRBs as back lights of large scale cosmological structures; (b) observing and surveying extended sources (galaxy clusters, WHIM) with high sensitivity using two wide field of view X-ray telescopes (one with a high angular resolution and the other with a high spectral resolution). The mission concept includes four main instruments: a Wide-field Spectrometer (0.1-2.2 eV) with excellent energy resolution (3 eV at 0.6 keV), a Wide-Field Imager (0.3-6 keV) with high angular resolution (HPD = 15") constant over the full 1.4 degree field of view, and a Wide Field Monitor (8-200 keV) with a FOV of A1/4 of the sky, which will trigger the fast repointing to the GRB. Extension of its energy response up to 1 MeV will be achieved with a GRB detector with no imaging capability. This mission is proposed to ESA as part of the Cosmic Vision call. We will outline the science drivers and describe in more detail the payload of this mission.
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Meeting abstracts of the Physical Society of Japan, 63(2) 90-90, Aug 25, 2008
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Meeting abstracts of the Physical Society of Japan, 63(1) 108-108, Feb 29, 2008
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SPACE TELESCOPES AND INSTRUMENTATION 2008: ULTRAVIOLET TO GAMMA RAY, PTS 1 AND 2, 7011, 2008The Spectrum-RG (SRG) mission, to be launched in 2011. will conduct the first all-sky survey in the 0.1-15 keV band via two imaging telescope systems, eROSITA and ART-XC. These will enable the detection of about 100 thousand clusters of galaxies and the mapping of the large scale structure of the Universe. They will also discover all obscured accreting Black Holes in nearby galaxies and about 3 million new, distant AGNs. In the course of the survey mode two sky regions around the celestial polar zones will be observed with much higher sensitivity. Then, selected sources and dedicated sky regions will be observed in a pointing mode with high sensitivity in order to investigate the nature of dark matter and dark energy. An X-Ray Calorimeter, the SXC experiment, will permit observations of the brightest clusters of galaxies with record energy resolution in pointing mode and mapping of the hot intergalactic medium in the survey mode.
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Proceedings of SPIE - The International Society for Optical Engineering, 7011, 2008 Peer-reviewedMultiplexed readout of TES (Transition Edge Sensor) signals is one of the key technologies needed to realize large format arrays of microcalorimeters in future X-ray missions. In the FDM (Frequency-Domain Multiplexing) approach using MHz biasing frequencies, a wide band-width FLL (Flux Locked Loop) circuit is essential to compensate the phase delay between the TES sensor and the room temperature circuits. An analog feedback circuit using a lock-in amplifier technique and phase shifters with a very low noise pre-amplifier is being developed. This circuit will be tested with an actual TES array and an 8-input SQUID in the EURECA project.
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Astrophysical Journal, 680(2) 1049-1052, 2008About half of the baryons in the local universe are thought to reside in the so-called warm-hot intergalactic medium (WHIM) at temperatures of 0.1-10 MK. Thermal soft excess emission in the spectrum of some cluster outskirts that contains O vu and/or O VIII emission lines is regarded as evidence of the WHIM, although the origin of the lines is controversial due to strong Galactic and solar system foreground emission. We observed the Coma-11 field, where the most prominent thermal soft excess has been reported, with Suzaku XIS in order to clarify the origin of the excess. We did not confirm O VII or O VIII excess emission. The O VII and O VIII intensity in Coma-11 is more than 5 σ below that reported before, and we obtained 2 σ upper limits of 2.8 and 2.9 photons cm-2 s-1 sr-1for O VII and O VIII, respectively. The intensities are consistent with those in another field (Coma-7) that we measured, and with other measurements in the Coma outskirts (Coma-7 and X Com field with XMM-Newton). We did not confirm the spatial variation. within Coma outskirts. The strong oxygen emission lines previously reported are likely due to solar wind charge exchange. © 2008. The American Astronomical Society. All rights reserved.
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Meeting abstracts of the Physical Society of Japan, 62(2) 110-110, Aug 21, 2007
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The Astronomical herald, 100(7) 321-329, Jun 20, 2007
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IEEE Nuclear Science Symposium Conference Record, 4 2526-2531, 2007We report in-flight status of the X-ray detectors on board the Suzaku observatory, the 5th X-ray astronomy satellite of Japan launched on July 10, 2005. Suzaku is equipped with two types of Instruments: one is the X-ray Imaging Spectrometers (XISs) and the other is Hard X-ray Detector (HXD). XIS utilizes the X-ray CCD camera in combination with the grazing-incidence X-ray telescope. HXD is a non-imaging, hybrid detector utilizing Si PIN diodes and GSO/BGO phoswich counters. Suzaku takes a low-earth, circular orbit with an altitude of 560 km and an inclination of 31 deg. This means that Suzaku goes through the south atlantic anomaly about 1/3 of its revolutions. This has a large impact on the in-flight performance of XIS and HXD, which is reported in detail in the present paper. © 2007 IEEE.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY III, 6688(No.) 4, 2007How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysics. EDGE(1) will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions, through the period. of galaxy cluster formation, down to the very low redshift Universe, when between a third and one half of the baryons are expected to reside in cosmic filaments undergoing gravitational collapse by dark matter (the so-called warm hot intragalactic medium). In addition EDGE, with its unprecedented capabilities, will provide key results in many important fields. These scientific goals are feasible with a medium class mission using existing technology combined with innovative instrumental and observational capabilities by: (a) observing with fast reaction Gamma-Ray Bursts with a high spectral resolution (R similar to 500). This enables the study of their (star-forming) environment and the use of GRBs as back lights of large scale cosmological structures; (b) observing and surveying extended sources (galaxy clusters, WHIM) with high sensitivity using two wide field of view X-ray telescopes (one with a high angular resolution and the other with a high spectral resolution). The mission concept includes four main instruments: a Wide-field Spectrometer with excellent energy resolution (3 eV at 0.6 keV), a Wide-Field Imager with high angular resolution (HPD 15") constant over the full 1.4 degree field of view, and a Wide Field Monitor with a FOV of 1/4 of the sky, which will trigger the fast repointing to the GRB. Extension of its energy response up to 1 MeV will be achieved with a GRB detector with no imaging capability. This mission is proposed to ESA as part of the Cosmic Vision call. We will briefly review the science drivers and describe in more detail the payload of this mission.
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Progress of Theoretical Physics Supplement, (169) 79-83, 2007Joint analysis of Suzaku/Chandra emission/absorption lines were conducted to constrain the density and geometry of hot gas along two lines of sights of LMC X-3 and 4U 1820-303. Because significant foreground line emissions may exist, the Suzaku emission data must be analyzed with spacial cares. The present results imply the hot gas to extend to the galacticdisk scale or more for the LMC X-3 direction. However, the present simple model fails to explain the results for the 4U1820-303 directions.
Professional Memberships
4Research Projects
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科学研究費助成事業 基盤研究(C), 日本学術振興会, Apr, 2023 - Mar, 2026
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科学研究費助成事業 新学術領域研究(研究領域提案型), 日本学術振興会, Apr, 2019 - Mar, 2021
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Japan Society for the Promotion of Science, Apr, 2013 - Mar, 2017
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, Apr, 2011 - Mar, 2014
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科研費 挑戦的萌芽研究, Apr, 2008 - Mar, 2011
