14112264
Suzaku Spectroscopy of an X-Ray Reflection Nebula and a New Supernova Remnant Candidate in the SgrB1 Region
We made a 100 ks observation of the Sagittarius (Sgr) B1 region at (l, b) = (0.5, -0.1) near to the Galactic center (GC) with the Suzaku/XIS. Emission lines of S XV, Fe I, Fe XXV, and Fe XXVI were clearly detected in the spectrum. We found that the Fe XXV and Fe XXVI line emissions smoothly distribute over the Sgr B1 and B2 regions connecting from the GC. This result suggests that the GC hot plasma extends at least up to the Sgr B region with a constant temperature. There are two diffuse X-ray sources in the observed region. One of the two (G0.42-0.04) is newly discovered, and exhibits a strong S XV Ka emission line, suggesting a candidate for a supernova remnant located in the GC region. The other one (M0.51-0.10), having a prominent Fe I Ka emission line and a strongly absorbed continuum, is likely to be an X-ray reflection nebula. There is no near source bright enough to irradiate M0.51-0.10. However, the Fe I Ka emission can be explained if Sgr A* was ~ 10^6 times brighter 300 years ago, the light travel time for 100 pc to M0.51-0.10, than it is at present.
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.
53371172
Temporal and Spatial Analyses of Spectral Indices of Nonthermal Emissions Derived from Hard X-Rays and Microwaves
We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap Δδ between the electron spectral indices derived from HXRs δ X and those from microwaves δμ (Δδ = δ X – δμ) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index δ X evolve synchronously with those of the microwave spectral index δμ, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index δμ tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.
6264457
Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
We have observed the diffuse X-ray emission from the Galactic center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provide excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are Fe I Kat 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (Fe XXV K�) and hydrogenic (Fe XXVI Ly�) ions of iron. In addition, Klines from neutral or low ionization nickel (Ni I K�) and He-like nickel (Ni XXVII K�), and Fe I K�, Fe XXV K�, Fe XXVI Ly�, Fe XXV K and Fe XXVI Ly are detected for the first time. The line center energies and widths of Fe XXV Kand Fe XXVI Lyfavor a collisional excitation (CE) plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of Fe XXV-K�/ Fe XXV-Kis similar to the ionization temperature determined from that of Fe XXV-K�/FeXXVI-Ly�. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic, in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar.
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.
55146394
The X-ray Study of Small-Scale Shock Structures in the Non-thermal SNRs
The shock front of SNRs is the most probable acceleration site of high energy particles (up to, or more than TeV) as already confirmed by the hard X-ray observations of the synchrotron emission from accelerated electrons. The remarkable spatial resolution of the X-ray observatory Chandra enables us to investigate the small-scale structure of the spatial distribution of accelerated electrons close to the shock front, which may lead us to deep understanding of acceleration mechanism. We have found hard X-ray filaments having a sharp rise in upstream and rather slow decay in downstream from the shocked region of six SNRs (Cas A, Tycho, Kepler, SN 1006, RCW 86, and 30 Dor C) using the Chandra archive data. For all the SNRs, we found that the scale width of the filaments is significantly smaller than that of the thermal plasma derived from the Sedov solution, The scale width becomes larger as increasing radius of the SNR, which may be followed by the understanding of the history of acceleration and energy loss of electrons in the shock front.
6939385
The running coupling in lattice Landau gauge with unquenched Wilson fermion and KS fermion
The running coupling of the Wilson fermon(JLQCD/CP-PACS) and that of Kogut-Susskind(KS) fermion(MILC) are measured in the lattice Landau gauge QCD in MOM scheme. The quark propagator of the KS fermion is also measured and we find that it is infrared vanishing, which implies that quarks are confined. The renormalization factor of the running coupling and the tadpole renormalization define the scale of the quark wave function. Effects of the A 2 condensates of a few GeV 2 are observed in the running coupling and also in the quark propagator.
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%.
119243767
1/N Expansion of the 2D CPN−1 Model on Non(anti)commutative Superspace
We study UV properties of the two-dimensional supersymmetric CP N −1 model on non(anti)commutative superspace. We show that the deformed model has the same UV property as the ordinary model in the leading order of 1/N and that the deformation gives rise to UV divergence which cannot be dealt with in the next-to-leading order.
15189596
Numerical tests of the Kugo-Ojima color confinement criterion
The Kugo-Ojima color confinement criterion, which is based on the BRST symmetry of QCD is numerically tested by the lattice Landau gauge simulation. We first discuss the BRST symmetry on the lattice and the Gribov copy problem. The horizon function defined by Zwanziger based on the U-linear definition of the gauge field and that based on log U are compared. The parameter u which is expected to be $-1\delta^a_b$ in the continuum theory was found to be $-0.7\delta^a_b$ in the strong coupling region. There are about 20% difference between the two horizon functions, but in the weak coupling region, the expectation value of the horizon function is suggested to be zero or negative.
15292879
Numerical study of lattice Landau gauge QCD and the Gribov copy problem
The infrared properties of lattice Landau gauge QCD of SU(3) are studied by measuring gluon propagator, ghost propagator, QCD running coupling and Kugo-Ojima parameter of β = 6.0 on 16 4 , 24 4 , 32 4 and β = 6.4 on 32 4 , 48 4 , 56 4 lattices. From the larger lattice measurements, we observe that the runnning coupling measured by the product of the gluon dressing function and the ghost dressing function squared rescaled to the perturbative QCD results near the highest lattice momentum has a maximum of about 2.2 at around q = 0.5  GeV/c , and either approaches a constant or even decreases as q approaches zero. The magnitude of the Kugo-Ojima parameter is getting larger but staying around −0.83 in contrast to the expected value of −1 in the continuum theory. We observe, however, that there is an exceptional sample which has larger magnitude of the Kugo-Ojima parameter and stronger infrared singularity of the ghost propagator. The reflection positivity of the 1-d Fourier transform of the gluon propagator of the exceptional sample is manifestly violated. The Gribov noise problem was studied by performing a fundamental modular gauge (FMG) fixing by making use of the parallel tempering method with β = 2.2 on 16 4 SU(2) configurations. In conclusion we found that while the gluon propagator almost noise free, the Kugo-Ojima parameter and the ghost propagator in the FMG become ∼ 5% less in the infrared region therefore they are noisy. It is expected that these qualitative aspects seen in SU(2) will be reflected in the infrared properties of SU(3) QCD as well.