The NeXT Mission

Takahashi, T.; Kelley, R. L.; Mitsuda, Kazuhisa; Kunieda, H.; Petre, R.; White, N. E.; Dotani, Tadayasu; Fujimoto, R.; Fukazawa, Yasushi; Hayashida, Kentaro; Ishida, M.; Ishisaki, Yoshitaka; Kokubun, M.; Makishima, Kazuo; Koyama, K.; Madejski, G.; Mori, Kunishiro; Mushotzky, R. F.; Nakazawa, K.; Ogasaka, Yasushi; Ohashi, T.; Ozaki, Masanobu; Tajima, H.; Tashiro, M.; Terada, Y.; Tsunemi, H.; Tsuru, Takeshi Go; Ueda, Yoshihiro; Yamasaki, Noriko Y.; Watanabe, S.; team, NeXT

doi:10.1117/12.789640

Cited by 33 publications

(9 citation statements)

References 25 publications

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“…However, such a comparison with simulated clusters in the central region would be practically difficult owing to over-cooling problems in cosmological hydrodynamical simulations, failing to reproduce the observed ICM features. If the ICM is not in thermal balance with the gravity and an additional pressure support is provided by the gas bulk/turbulent motions, as suggested by simulations, the X-ray micro-calorimeter instrument (SXS) on the next Japanese X-ray satellite ASTRO-H (Takahashi et al 2008) will directly detect them and measure their contributions to the pressure balance.…”

Section: Mass Comparisonmentioning

confidence: 99%

SUZAKUOBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE

Kawaharada

Okabe

Umetsu

et al. 2010

ApJ

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140

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We present results of new, deep Suzaku X-ray observations (160 ks) of the intracluster medium (ICM) in Abell 1689 out to its virial radius, combined with complementary data sets of the projected galaxy distribution obtained from the SDSS catalog and the projected mass distribution from our recent comprehensive weak and strong lensing analysis of Subaru/Suprime-Cam and HST/ACS observations. Faint X-ray emission from the ICM around the virial radius (r vir ∼ 15.′ 6) is detected at 4.0σ significance, thanks to low and stable X-ray background of Suzaku. The Suzaku observations reveal anisotropic gas temperature and entropy distributions in cluster outskirts of r 500 < ∼ r < ∼ r vir correlated with large-scale structure of galaxies in a photometric redshift slice around the cluster. The high temperature (∼ 5.4 keV) and entropy region in the northeastern (NE) outskirts is apparently connected to an overdense filamentary structure of galaxies outside the cluster. The gas temperature and entropy profiles in the NE direction are in good agreement, out to the virial radius, with that expected from a recent XMM-Newton statistical study and with an accretion shock heating model of the ICM, respectively. To the contrary, the other outskirt regions in contact with low density void environments have low gas temperatures (∼ 1.7 keV) and entropies, deviating from hydrostatic equilibrium. These anisotropic ICM features associated with large-scale structure environments suggest that the thermalization of the ICM occurs faster along overdense filamentary structures than along low-density void regions. We find that the ICM density distribution is fairly isotropic, with a threedimentional density slope of −2.29 ± 0.18 in the radial range of r 2500 < ∼ r < ∼ r 500 , and with −1.24in r 500 < ∼ r < ∼ r vir , which however is significantly shallower than the Navarro, Frenk, & White universal matter density profile in the outskirts, ρ ∝ r −3 . A joint X-ray and lensing analysis shows that the hydrostatic mass is lower than spherical lensing one (∼ 60 − 90%) but comparable to a triaxial halo mass within errors, at intermediate radii of 0.6r 2500 < ∼ r < ∼ 0.8r 500 . On the other hand, the hydrostatic mass within 0.4r 2500 is significantly biased as low as < ∼ 60%, irrespective of mass models. The thermal gas pressure within r 500 is, at most, ∼ 50-60% of the total pressure to balance fully the gravity of the spherical lensing mass, and ∼ 30-40% around the virial radius. Although these constitute lower limits when one considers the possible halo triaxiality, these small relative contributions of thermal pressure would require additional sources of pressure, such as bulk and/or turbulent motions.

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Section: Mass Comparisonmentioning

confidence: 99%

SUZAKUOBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE

Kawaharada

Okabe

Umetsu

et al. 2010

ApJ

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140

189

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“…An image of 137 Cs obtained from the Compton reconstruction with electron tracking [30] the background to the limit achieved by the configuration of active shield and collimator [23,24]. In order to further reduce the background and thus to improve the sensitivity, we have proposed a new detector called the Soft Gamma-ray Detector (SGD) for the NeXT mission.…”

Section: Fig 11mentioning

confidence: 99%

A Si/CdTe Compton Camera for gamma-ray lens experiment

Takahashi

2006

Exp Astron

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Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) have been regarded as promising semiconductor materials for hard X-ray and γ -ray detection. However, a considerable amount of charge loss in these detectors results in a reduced energy resolution. We have achieved a significant improvement in the spectral properties by forming the Schottky junction on the Te side of the CdTe wafer. With the further reduction of leakage current by an adoption of guard ring structure, we have demonstrated a CdTe pixel detector with high energy resolution and full charge collection capabilty. The detector has a pixel size of a few mm and a thickness of 0.5 − 1 mm. We apply this high resolution detector to a new silicon and CdTe Compton Camera which features high angular resolution. We also describe a concept of the stack detector which consists of many thin CdTe layers and provides sufficient efficiency for hard X-rays and gamma-rays up to several hundred keV maintaining good energy resolution. A narrow-FOV Compton telescope can be realized by installing a Si/CdTe Compton Camera inside the deep well of an active shield. This configuration is very suitable as focal plane detector for future focusing gamma-ray missions.

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“…Maintaining pointing performance is one of the major requirements for space science missions using large and precise space telescopes. However, it is very difficult to maintain the precise pointing performance of large structures such as the next international X-ray astronomy satellite (ASTRO-H) being developed by JAXA (Takahashi et al, 2010). In this research, therefore, we control the shape of the truss structure, which is generally used as a support structure on orbit, focusing on the pointing performance.…”

Section: Introductionmentioning

confidence: 99%

Application of preview information to pointing control of truss structure using artificial thermal expansion on orbit

Funakoshi

Ishimura

Ogi

et al. 2014

Journal of Intelligent Material Systems and Structures

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The pointing performance of a truss structure on orbit that is used for a large space telescope is discussed. To achieve advanced science missions, large and precise support structures such as truss structures are needed. However, the preciseness of the structure might be lost due to various disturbances on orbit. Therefore, to realize ultra-large and precise support structures, active shape control of the structures is needed. To control the shape, we use artificial thermal expansion caused by heaters instead of mechanical actuators. Control systems without mechanical mechanisms have high reliability, which is very attractive for use on orbit. However, there are some constraints regarding the usage of heaters. The control input is restricted to positive inputs because heaters can give off heat but cannot dissipate heat actively, and there will be upper limits on the heat input. To improve the control performance under such constraints, we apply "Model Predictive Control (MPC)" as a feedforward control method with preview information. In this paper, we mainly show the effectiveness of MPC compared with PI control, which is one of the typical feedback control methods. We developed a structural mathematical model and a thermal mathematical model in order to evaluate the performance of the control system. It is confirmed through numerical simulations that the total error is reduced by MPC compared with PI control.

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The NeXT Mission

Cited by 33 publications

References 25 publications

SUZAKUOBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE

SUZAKUOBSERVATION OF A1689: ANISOTROPIC TEMPERATURE AND ENTROPY DISTRIBUTIONS ASSOCIATED WITH THE LARGE-SCALE STRUCTURE

A Si/CdTe Compton Camera for gamma-ray lens experiment

Application of preview information to pointing control of truss structure using artificial thermal expansion on orbit

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