研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙物理学研究系 特任助教
- 学位
- Ph.D.(2017年6月 University of California, San Diego)
- 研究者番号
- 40867032
- ORCID ID
https://orcid.org/0000-0003-0041-6447- J-GLOBAL ID
- 201901016586407138
- researchmap会員ID
- B000373123
研究キーワード
3経歴
2-
2021年4月 - 現在
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2017年7月 - 2021年3月
学歴
2-
2010年9月 - 2017年6月
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2005年8月 - 2010年5月
受賞
2-
2013年11月
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2013年3月
論文
68-
Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 82-82 2024年8月23日
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 207-207 2024年8月23日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII 124-124 2024年8月16日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII 120-120 2024年8月16日
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Applied Optics 2024年8月8日
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Journal of Astronomical Telescopes, Instruments, and Systems 10(01) 2024年1月27日
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Review of Scientific Instruments 94(12) 2023年12月1日For cosmic microwave background (CMB) polarization observations, calibration of detector polarization angles is essential. We have developed a fully remote controlled calibration system with a sparse wire grid that reflects linearly polarized light along the wire direction. The new feature is a remote-controlled system for regular calibration, which has not been possible in sparse wire grid calibrators in past experiments. The remote control can be achieved by two electric linear actuators that load or unload the sparse wire grid into a position centered on the optical axis of a telescope between the calibration time and CMB observation. Furthermore, the sparse wire grid can be rotated by using a motor. A rotary encoder and a gravity sensor are installed on the sparse wire grid to monitor the wire direction. They allow us to achieve detector polarization angle calibration with an expected systematic error of 0.08°. The calibration system will be installed in small-aperture telescopes at Simons Observatory.
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Journal of Astronomical Telescopes, Instruments, and Systems 9(02) 2023年4月19日
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Ground test results of the electromagnetic interference for the x-ray microcalorimeter onboard XRISMJournal of Astronomical Telescopes, Instruments, and Systems 9(1) 18004 2023年1月1日Electromagnetic interference (EMI) for low-temperature detectors is a serious concern in many missions. We investigate the EMI caused by the spacecraft components to the x-ray microcalorimeter of the Resolve instrument onboard the x-ray imaging and spectroscopy mission, which is currently under development by an international collaboration and is planned to be launched in 2023. We focus on the EMI from (a) the low-frequency magnetic field generated by the magnetic torquers (MTQ) used for the spacecraft attitude control and (b) the radio-frequency (RF) electromagnetic field generated by the S and X band antennas used for communication between the spacecraft and the ground stations. We executed a series of ground tests both at the instrument and spacecraft levels using the flight-model hardware in 2021-2022 in a JAXA facility in Tsukuba. We also conducted electromagnetic simulations partially using the Fugaku high-performance computing facility. The MTQs were found to couple with the microcalorimeter, which we speculate through pick-ups of low-frequency magnetic field and further capacitive coupling. There is no evidence that the resultant energy resolution degradation is beyond the current allocation of noise budget. The RF communication system was found to leave no significant effect. We present the result of the tests and simulation in this article.
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 2022年8月31日
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave 2022年8月27日
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Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave 2022年8月27日
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Astrophys.J. 931(2) 101-101 2022年5月27日 査読有り
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Journal of Cosmology and Astroparticle Physics 2022(4) 2022年4月A methodology to provide the polarization angle requirements for different sets of detectors, at a given frequency of a CMB polarization experiment, is presented. The uncertainties in the polarization angle of each detector set are related to a given bias on the tensor-to-scalar ratio r parameter. The approach is grounded in using a linear combination of the detector sets to obtain the CMB polarization signal. In addition, assuming that the uncertainties on the polarization angle are in the small angle limit (lower than a few degrees), it is possible to derive analytic expressions to establish the requirements. The methodology also accounts for possible correlations among detectors, that may originate from the optics, wafers, etc. The approach is applied to the LiteBIRD space mission. We show that, for the most restrictive case (i.e., full correlation of the polarization angle systematics among detector sets), the requirements on the polarization angle uncertainties are of around 1 arcmin at the most sensitive frequency bands (i.e., ≈ 150 GHz) and of few tens of arcmin at the lowest (i.e., ≈ 40 GHz) and highest (i.e., ≈ 400 GHz) observational bands. Conversely, for the least restrictive case (i.e., no correlation of the polarization angle systematics among detector sets), the requirements are ≈ 5 times less restrictive than for the previous scenario. At the global and the telescope levels, polarization angle knowledge of a few arcmins is sufficient for correlated global systematic errors and can be relaxed by a factor of two for fully uncorrelated errors in detector polarization angle. The reported uncertainty levels are needed in order to have the bias on r due to systematics below the limit established by the LiteBIRD collaboration.
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The Astrophysical Journal 926(1) 54 2022年2月1日<jats:title>Abstract</jats:title> <jats:p>CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, <jats:italic>r</jats:italic>, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for <jats:italic>r</jats:italic> > 0.003 at greater than 5<jats:italic>σ</jats:italic>, or in the absence of a detection, of reaching an upper limit of <jats:italic>r</jats:italic> < 0.001 at 95% CL.</jats:p>
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Ground test results of the electromagnetic interference for the x-ray microcalorimeter onboard XRISMSPACE TELESCOPES AND INSTRUMENTATION 2022: ULTRAVIOLET TO GAMMA RAY 12181 2022年Electromagnetic interference (EMI) for low-temperature detectors is a serious concern in many missions. We investigate the EMI caused by the spacecraft components to the x-ray microcalorimeter of the Resolve instrument onboard the X-Ray Imaging and Spectroscopy Mission (XRISM), which is currently under development by an international collaboration and is planned to be launched in 2023. We focus on the EMI from (a) the low-frequency magnetic field generated by the magnetic torquers used for the spacecraft attitude control and (b) the radio-frequency (RF) electromagnetic field generated by the S and X band antennas used for communication between the spacecraft and the ground stations. We executed a series of ground tests both at the instrument and spacecraft levels using the flight model hardware in 2021-2022 in a JAXA facility in Tsukuba. We also conducted electromagnetic simulations partially using the Fugaku high-performance computing facility. The magnetic torquers were found to couple with the microcalorimeter, but there is no evidence that the resultant degradation is beyond the current allocation of noise budget. The RF communication system was found to leave no significant effect. We present the result of the tests and simulation in this article.
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SPACE TELESCOPES AND INSTRUMENTATION 2022: OPTICAL, INFRARED, AND MILLIMETER WAVE 12180 2022年LiteBIRD is a JAXA-led international project that aims to test representative inflationary models by performing an all-sky cosmic microwave background radiation (CMB) polarization survey for 3 years at the Sun-Earth Lagrangian point L2. We aim to launch LiteBIRD in the late 2020s. The payload module (PLM) is mainly composed of the Low-Frequency Telescope (LFT), the Mid-Frequency Telescope and High-Frequency Telescope (MHFT), and a cryo-structure. To conduct the high-precision and high-sensitivity CMB observations, it is required to cool the telescopes down to less than 5 K and the detectors down to 100 mK. The high temperature stability is also an important design factor. It is essential to design and analyze the cryogenic thermal system for PLM. In this study, the heat balance, temperature distribution, and temperature stability of the PLM for the baseline design are evaluated by developing the transient thermal model. The effect of the Joule-Thomson (JT) coolers cold tip temperature variation, the periodical changes in subK Adiabatic Demagnetization Refrigerator (ADR) heat dissipation, and the satellite spin that generates the variable direction of solar flux incident are implemented in the model. The effect of contact thermal conductance in the LFT and the emissivity of the V-groove on the temperature distribution and heat balance are investigated. Based on the thermal analysis, it was confirmed that the PLM baseline design meets the requirement of the temperature and the cooling capability of the 4K-JT cooler. In addition, the temperatures of the V-groove and the LFT 5-K frame are sufficiently stable for the observation. The temperature stability of the Low Frequency Focal Plane (LF-FP) is also discussed in this paper.
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Research Notes of the American Astronomical Society 2021年4月The Simons Observatory is a Cosmic Microwave Background experiment to observe the microwave sky in six frequency bands from 30 to 290 GHz. The Observatory—at ∼5200 m altitude—comprises three Small Aperture Telescopes and one Large Aperture Telescope (LAT) at the Atacama Desert, Chile. This research note describes the design and current status of the LAT along with its future timeline....
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Applied Optics 60(4) 823-837 2021年2月1日We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope, allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics that are now being built. We describe nonsequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tracing simulations of the telescope structure that allow us to determine geometries that minimize detector loading and mitigate spurious near-field effects that have not been resolved by the internal baffling. We also describe physical optics simulations, performed over a range of frequencies and field locations, that produce estimates of monochromatic far-field beam patterns, which in turn are used to gauge general optical performance. Finally, we describe simulations that shed light on beam sidelobes from panel gap diffraction.
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Applied Optics 60(4) 864-864 2021年1月26日Controlling stray light at millimeter wavelengths requires special optical design and selection of absorptive materials that should be compatible with cryogenic operating environments. While a wide selection of absorptive materials exists, these typically exhibit high indices of refraction and reflect/scatter a significant fraction of light before absorption. For many lower index materials such as commercial microwave absorbers, their applications in cryogenic environments are challenging. In this paper, we present a new tool to control stray light: metamaterial microwave absorber tiles. These tiles comprise an outer metamaterial layer that approximates a lossy gradient index anti-reflection coating. They are fabricated via injection molding commercially available carbon-loaded polyurethane (25% by mass). The injection molding technology enables mass production at low cost. The design of these tiles is presented, along with thermal tests to 1 K. Room temperature optical measurements verify their control of reflectance to less than 1% up to angles of incidence, and control of wide angle scattering below 0.01%. The dielectric properties of the bulk carbon-loaded material used in the tiles is also measured at different temperatures, confirming that the material maintains similar dielectric properties down to 3 K.
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PROCEEDINGS OF THE 14TH ASIA-PACIFIC PHYSICS CONFERENCE 2319 2021年POLARBEAR-2A is the first receiver for the Simons Array cosmic micmwave background polarization experiment. POLARBEAR-2A has transition-edge sensor bolometers on the focal plane. Signals from bolometers arc multiplexed and read out by a single SQUID. The receiver was deployed in late 2018 in Atacama, Chile, and operation started in 2019, where rapid confirmation of correspondence between bolometers and multiplexed readout channels was important as an initial step of performance validation. For this purpose, we devised a method using a coherent source that allows us to identify the frequency band and polarization sensitivity angle for each readout channel without detailed bolometer tuning.
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Ground-based and Airborne Telescopes VIII 2020年12月18日
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Review of Scientific Instruments 91(12) 124503-124503 2020年12月1日 査読有り
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The Astrophysical Journal 904(1) 65-65 2020年11月20日 査読有り
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Journal of Low Temperature Physics 200(5-6) 461-471 2020年9月 査読有り
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The Astrophysical Journal 893(1) 85-85 2020年4月17日 査読有り
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Internal Delensing of Cosmic Microwave Background Polarization B-Modes with the POLARBEAR ExperimentPhysical Review Letters 124(13) 2020年4月1日 査読有り
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Review of Scientific Instruments 90(11) 115115-115115 2019年11月1日 査読有り筆頭著者責任著者
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The Astrophysical Journal 882(1) 62-62 2019年9月4日 査読有りWe present the first measurement of cross-correlation between the lensing potential, reconstructed from cosmic microwave background (CMB) polarization data, and the cosmic shear field from galaxy shapes. This measurement is made using data from the Polarbear CMB experiment and the Subaru Hyper Suprime-Cam (HSC) survey. By analyzing an 11 deg2 overlapping region, we reject the null hypothesis at 3.5σ and constrain the amplitude of the cross-spectrum to , where is the amplitude normalized with respect to the Planck 2018 prediction, based on the flat Λ cold dark matter cosmology. The first measurement of this cross-spectrum without relying on CMB temperature measurements is possible owing to the deep Polarbear map with a noise level of ∼6 μK arcmin, as well as the deep HSC data with a high galaxy number density of . We present a detailed study of the systematics budget to show that residual systematics in our results are negligibly small, which demonstrates the future potential of this cross-correlation technique.
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Journal of Cosmology and Astroparticle Physics 2019(02) 056-056 2019年2月27日 査読有りThe Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping ≈ 10% of the sky to a white noise level of 2 μK-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio,r, at a target level of σ(r)=0.003. The large aperture telescope will map ≈ 40% of the sky at arcminute angular resolution to an expected white noise level of 6 μK-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from thePlancksatellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.
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The Astrophysical Journal 870(2) 102-102 2019年1月14日 査読有り
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Astrophysical Journal 886(1) 38-38 2019年
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Journal of Low Temperature Physics 193(5-6) 758-770 2018年12月 査読有り© 2018, Springer Science+Business Media, LLC, part of Springer Nature. We present on the status of POLARBEAR-2 A (PB2-A) focal plane fabrication. The PB2-A is the first of three telescopes in the Simons Array, which is an array of three cosmic microwave background polarization-sensitive telescopes located at the POLARBEAR site in Northern Chile. As the successor to the PB experiment, each telescope and receiver combination is named as PB2-A, PB2-B, and PB2-C. PB2-A and -B will have nearly identical receivers operating at 90 and 150 GHz while PB2-C will house a receiver operating at 220 and 270 GHz. Each receiver contains a focal plane consisting of seven close-hex packed lenslet-coupled sinuous antenna transition edge sensor bolometer arrays. Each array contains 271 dichroic optical pixels, each of which has four TES bolometers for a total of 7588 detectors per receiver. We have produced a set of two types of candidate arrays for PB2-A. The first we call Version 11 (V11) uses a silicon oxide (SiOx) for the transmission lines and crossover process for orthogonal polarizations. The second we call Version 13 (V13) uses silicon nitride (SiNx) for the transmission lines and cross-under process for orthogonal polarizations. We have produced enough of each type of array to fully populate the focal plane of the PB2-A receiver. The average wirebond yield for V11 and V13 arrays is 93.2% and 95.6%, respectively. The V11 arrays had a superconducting transition temperature (Tc) of 452±15 mK, a normal resistance (Rn) of 1.25±0.20Ω, and saturation powers of 5.2 ± 1.0 pW and 13 ± 1.2 pW for the 90 and 150 GHz bands, respectively. The V13 arrays had a superconducting transition temperature (Tc) of 456 ± 6 mK, a normal resistance (Rn) of 1.1±0.2Ω, and saturation powers of 10.8 ± 1.8 pW and 22.9 ± 2.6 pW for the 90 and 150 GHz bands, respectively. Production and characterization of arrays for PB2-B are ongoing and are expected to be completed by the summer of 2018. We have fabricated the first three candidate arrays for PB2-C but do not have any characterization results to present at this time.
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Journal of Low Temperature Physics 193(5-6) 851-859 2018年12月 査読有り
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 2018年8月6日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 2018年7月31日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 2018年7月9日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 2018年7月9日
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX 2018年7月9日 筆頭著者
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Ground-based and Airborne Telescopes VII 2018年7月6日
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Ground-based and Airborne Telescopes VII 2018年7月6日
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The Astrophysical Journal 848(2) 121-121 2017年10月23日 査読有り
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Astrophysical Journal 794(2) 2017年10月10日 査読有りWe report a measurement of the B-mode polarization power spectrum in the cosmic microwave background (CMB) using the Polarbear experiment in Chile. The faint B-mode polarization signature carries information about the universe's entire history of gravitational structure formation, and the cosmic inflation that may have occurred in the very early universe. Our measurement covers the angular multipole range 500 < l < 2100 and is based on observations of an effective sky area of 25 deg2 with 3′.5 resolution at 150 GHz. On these angular scales, gravitational lensing of the CMB by intervening structure in the universe is expected to be the dominant source of B-mode polarization. Including both systematic and statistical uncertainties, the hypothesis of no B-mode polarization power from gravitational lensing is rejected at 97.2% confidence. The band powers are consistent with the standard cosmological model. Fitting a single lensing amplitude parameter ABB to the measured band powers, ABB = 1.12 ± 0.61(stat)-0.12 +0.04 (sys) ± 0.07(multi), where ABB = 1 is the fiducial wmap-9 ΛCDM value. In this expression, "stat" refers to the statistical uncertainty, "sys" to the systematic uncertainty associated with possible biases from the instrument and astrophysical foregrounds, and "multi" to the calibration uncertainties that have a multiplicative effect on the measured amplitude ABB.
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ASTROPHYSICAL JOURNAL 848(1) 2017年10月 査読有り
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Journal of Cosmology and Astroparticle Physics 2017(05) 008-008 2017年5月3日 査読有り
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Astronomy & Astrophysics 600 A60-A60 2017年4月 査読有りAnalysis of cosmic microwave background (CMB) datasets typically requires some filtering of the raw time-ordered data. For instance, in the context of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/or scan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguously remove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We show that such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimated simultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can render an unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice of map-making and power spectrum estimation approaches in the context of <italic>B</italic>-mode polarization studies. Specifically, we have studied the effects of time-domain filtering on the noise correlation structure in the map domain, as well as impact it may haveon the performance of the popular pseudo-spectrum estimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation of the sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal and special care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domain filtering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused on polarization-sensitive measurements targeting the <italic>B</italic>-mode component of the CMB signal and apply the proposed methods to realistic simulations based on characteristics of an actual CMB polarization experiment, POLARBEAR. Our analysis and conclusions are however more generally applicable.
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII 9914 2016年8月8日POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment that will be located in the Atacama highland in Chile at an altitude of 5200 m. Its science goals are to measure the CMB polarization signals originating from both primordial gravitational waves and weak lensing. PB-2 is designed to measure the tensor to scalar ratio, r, with precision σ(r) > 0:01, and the sum of neutrino masses, Σmz, with σ(Σmv) < 90 meV. To achieve these goals, PB-2 will employ 7588 transition-edge sensor bolometers at 95 GHz and 150 GHz, which will be operated at the base temperature of 250 mK. Science observations will begin in 2017.
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Journal of Low Temperature Physics 184(3-4) 805-810 2016年8月 査読有りWe present an overview of the design and status of the Polarbear-2 and the Simons Array experiments. Polarbear-2 is a cosmic microwave background polarimetry experiment which aims to characterize the arc-minute angular scale B-mode signal from weak gravitational lensing and search for the degree angular scale B-mode signal from inflationary gravitational waves. The receiver has a 365 mm diameter focal plane cooled to 270 mK. The focal plane is filled with 7588 dichroic lenslet–antenna-coupled polarization sensitive transition edge sensor (TES) bolometric pixels that are sensitive to 95 and 150 GHz bands simultaneously. The TES bolometers are read-out by SQUIDs with 40 channel frequency domain multiplexing. Refractive optical elements are made with high-purity alumina to achieve high optical throughput. The receiver is designed to achieve noise equivalent temperature of 5.8 μ KCMBs in each frequency band. Polarbear-2 will deploy in 2016 in the Atacama desert in Chile. The Simons Array is a project to further increase sensitivity by deploying three Polarbear-2 type receivers. The Simons Array will cover 95, 150, and 220 GHz frequency bands for foreground control. The Simons Array will be able to constrain tensor-to-scalar ratio and sum of neutrino masses to σ(r) = 6 × 10 - 3 at r= 0.1 and ∑ mν(σ= 1) to 40 meV.
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Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII 2016年7月20日
MISC
39講演・口頭発表等
46共同研究・競争的資金等の研究課題
2-
日本学術振興会 科学研究費助成事業 2020年4月 - 2023年3月
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日本学術振興会 科学研究費助成事業 2017年10月 - 2020年3月
