13583595
New CTI Correction Method for Spaced-Row Charge Injection of the Suzaku X-Ray Imaging Spectrometer
The charge transfer inefficiency (CTI) of the X-ray CCDs on board the Suzaku satellite (X-ray Imaging Spectrometers; XIS) has increased since the launch due to radiation damage, and the energy resolution has been degraded. To improve the CTI, we have applied a spaced-row charge injection (SCI) technique to the XIS in orbit; by injecting charges into CCD rows periodically, the CTI is actively decreased. The CTI in the SCI mode depends on the distance between a signal charge and a preceding injected row, and the pulse height shows periodic positional variations. Using in-flight data of onboard calibration sources and of the strong iron line from the Perseus cluster of galaxies, we studied the variation in detail. We developed a new method to correct the variation. By applying the new method, the energy resolution (FWHM) at 5.9 keV at March 2008 is ~155 eV for the front-illuminated CCDs and ~175 eV for the back-illuminated CCD.
118367993
POSSIBLE CHARGE-EXCHANGE X-RAY EMISSION IN THE CYGNUS LOOP DETECTED WITH SUZAKU
X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant's rim are depleted to ~0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously enhanced abundances (up to ~1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the enhanced abundance regions commonly show a strong emission feature at ~0.7?keV. This feature is likely a complex of He-like O K(? + ? + ), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O K? appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently enhanced metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question.
15839314
X-Ray Spectroscopy of SN 1006 with Suzaku
We report on observations of SN 1006 with the X-ray Imaging Spectrometers (XIS) on board Suzaku. We firmly detected K-shell emission from Fe, for the first time, and find that the Fe ionization state is quite low. The broad band spectrum extracted from the southeast of the remnant is well fitted with a model consisting of three optically thin thermal non-equilibrium ionization plasmas and a power-law component. Two of the thermal models are highly overabundant in heavy elements and, hence, are likely due to ejecta. These components have different ionization parameters: $n_et \sim 1.4\times 10^{10}$ cm$^{-3}$ s and $n_et \sim 7.7\times 10^8$ cm$^{-3}$ s and it is the later one that produces the Fe-K emission. This suggests that Fe has been heated by the reverse shock more recently than the other elements, consistent with a picture where the ejecta are stratified by composition with Fe in the interior. On the other hand, the third thermal component is assumed to be solar abundance, and we associate it with emission from the interstellar medium (ISM). The electron temperature and ionization parameter are $kT_e \sim $0.5 keV and $n_et \sim 5.8\times 10^9$ cm$^{-3}$ s. The electron temperature is lower than that expected from the shock velocity which suggests a lack of collisionless electron heating at the forward shock. The extremely low ionization parameter and extreme non-equilibrium state are due to the low density of the ambient medium.
19609772
Monte Carlo Simulator and Ancillary Response Generator of Suzaku XRT/XIS System for Spatially Extended Source Analysis
We have developed a framework for the Monte-Carlo simulation of the X-Ray Telescopes (XRT) and the X-ray Imaging Spectrometers (XIS) onboard Suzaku, mainly for the scientific analysis of spatially and spectroscopically complex celestial sources. A photon-by-photon instrumental simulator is built on the ANL platform, which has been successfully used in ASCA data analysis. The simulator has a modular structure, in which the XRT simulation is based on a ray-tracing library, while the XIS simulation utilizes a spectral "Redistribution Matrix File" (RMF), generated separately by other tools. Instrumental characteristics and calibration results, e.g., XRT geometry, reflectivity, mutual alignments, thermal shield transmission, build-up of the contamination on the XIS optical blocking filters (OBF), are incorporated as completely as possible. Most of this information is available in the form of the FITS (Flexible Image Transport System) files in the standard calibration database (CALDB). This simulator can also be utilized to generate an "Ancillary Response File" (ARF), which describes the XRT response and the amount of OBF contamination. The ARF is dependent on the spatial distribution of the celestial target and the photon accumulation region on the detector, as well as observing conditions such as the observation date and satellite attitude. We describe principles of the simulator and the ARF generator, and demonstrate their performance in comparison with in-flight data.
16902285
Energy-Scale Calibration of the Suzaku X-Ray Imaging Spectrometer Using the Checker Flag Charge-Injection Technique in Orbit
The X-ray Imaging Spectrometer (XIS) aboard the Suzaku satellite is an X-ray CCD camera system that has superior performance, such as a low background, high quantum efficiency, and good energy resolution in the 0.2–12 keV band. Because of radiation damage in orbit, however, the charge-transfer inefficiency (CTI) has increased, and hence the energy scale and resolution of the XIS has been degraded since the launch in 2005 July. The CCD has a charge-injection structure, and the CTI of each column and the pulse-height dependence of the CTI are precisely measured by a checker flag charge-injection (CFCI) technique. Our precise CTI correction improved the energy resolution from 230 eV to 190 eV at 5.9 keV in 2006 December. This paper reports on CTI measurements with the CFCI experiments in orbit. Using the CFCI results, we have implemented the time-dependent energy scale and resolution to the Suzaku calibration database.
118498255
SUZAKU OBSERVATIONS OF THE TYPE 2 QSO IN THE CENTRAL GALAXY OF THE PHOENIX CLUSTER
We report the Suzaku/XIS and HXD and Chandra/ACIS-I results on the X-ray spectra of the Phoenix cluster at the redshift z = 0.596. The spectrum of the intracluster medium (ICM) is well reproduced with the emissions from low-temperature (~3.0 keV and ~0.76 solar) and high-temperature (~11 keV and ~0.33 solar) plasmas; the former is localized at the cluster core, while the latter distributes over the cluster. In addition to these ICM emissions, a strongly absorbed power-law component is found, which is due to an active galactic nucleus (AGN) in the cluster center. The absorption column density and unobscured luminosity of the AGN are ~3.2 × 1023 cm–2 and ~4.7 × 1045 erg s–1 (2-10 keV), respectively. Furthermore, a neutral iron (Fe I) K-shell line is discovered for the first time with the equivalent width (EW) of ~150 eV at the rest frame. The column density and the EW of the Fe I line are exceptionally large for such a high-luminosity AGN, and hence the AGN is classified as a type 2 quasi-stellar object (QSO). We speculate that a significant fraction of the ICM cooled gas would be consumed to maintain the torus and to activate the type 2 QSO. The Phoenix cluster has a massive starburst in the central galaxy, indicating that suppression in the cooling flow is less effective. This may be because the onset of the latest AGN feedback has occurred recently and has not yet been effective. Alternatively, the AGN feedback is predominantly in radiative mode, not in kinetic mode, and the torus may work as a shield to reduce its effect.
18268747
Central charges in non(anti)commutative N=2 supersymmetric U(N) gauge theory
Abstract We study the central charge of the deformed N = ( 1 , 0 ) supersymmetry algebra in non(anti)commutative N = 2 supersymmetric U ( N ) gauge theory. In the cases of N = 1 / 2 superspace and N = 2 harmonic superspace with the singlet deformation, we find that the central charge is deformed by the non(anti)commutative parameters but depends on the electric and magnetic charges. For generic deformation of N = 2 harmonic superspace, we compute the O ( C ) correction to the central charges in the case of U ( 1 ) gauge group.
118101462
Infrared Features of Lattice Landau Gauge QCD and the Gribov Copy Problem
Infrared features of gluon propagator, ghost propagator, QCD running coupling and the Kugo‐Ojima parameter in lattice Landau gauge QCD are presented. The framework of PMS analysis suggests that there appear infrared, intermediate and ultraviolet regions specified by ΛMS, β0 and β1. The propagators and the running coupling of q > 1GeV are fitted by the MO∼M scheme using the factorization scale as the scale parameter. The running coupling data of q < 14GeV are fitted by the contour improved perturbation method. The Gribov copy problem is studied in SU (2), β = 2.2 samples by comparing the data gauge fixed by the parallel tempering method and the data gauge fixed by the straightforward gauge fixing. The Gribov noise effect turned out to be about 2%.
115158728
Noncommutative supertori in two dimensions
First we consider the deformations of superspaces with = (1, 1) and = (2, 2) supersymmetries in two dimensions. Among these the construction of noncommutative supertorus with odd spin structure is possible only in the case of = (2, 2) supersymmetry broken down to = (1, 1). However, for the even spin structures the construction of noncommutative supertorus is possible for both = (1, 1) and = (2, 2) cases. The spin structures are realized by implementing the translational properties along the cycles of commutative supertorus in the operator version: Odd spin structure is realized by the translation in the fermionic direction in the same manner as in the construction of noncommutative torus, and even spin structures are realized with appropriate versions of the spin angular momentum operator.
122154679
A Study of tunneling in Hamiltonian systems via Monte Carlo simulation and Rayleigh-Ritz variation
Abstract Energy spectra of Hamiltonian systems which contain potential barriers are studied in the Monte Carlo simulation and the Rayleigh-Ritz variation. The onset of tunneling and splitting of the eigenergies are observed as the coupling constant increases. Consistency of the results of the Monte Carlo simulation is checked by two independent data fittings.
13161330
A new algorithm for numerical simulation of Langevin equations
Abstract Formulated is a new systematic method for obtaining higher order corrections in numerical simulation of stochastic differential equations (SDEs), i.e., Langevin equations. Random walk step algorithms within a given order of finite Δt , are obtained so as to reproduce within that order a corresponding transition density of the Fokker-Planck equations, in the weak Taylor approximation scheme [1]. A great advantage of our method is its straightforwardness such that direct perturbative calculations produce the algorithm as an end result, so that the procedure is tractable by computer. Examples in general form for curved space cases as well as flat space cases are given in some order of approximations. Simulations are performed for specific examples of U(1) system and SU(2) systems, respectively.