118654045
Imaging Spectroscopy on Preflare Coronal Nonthermal Sources Associated with the 2002 July 23 Flare
We present a detailed examination on the coronal nonthermal emissions during the preflare phase of the X4.8 flare that occurred on 2002 July 23. The microwave (17 GHz and 34 GHz) data obtained with Nobeyama Radioheliograph, at Nobeyama Solar Radio Observatory and the hard X-ray (HXR) data taken with RHESSI obviously showed nonthermal sources that are located above the flare loops during the preflare phase. We performed imaging spectroscopic analyses on the nonthermal emission sources both in microwaves and in HXRs, and confirmed that electrons are accelerated from several tens of keV to more than 1 MeV even in this phase. If we assume the thin-target model for the HXR emission source, the derived electron spectral indices (~4.7) is the same value as that from microwaves (~4.7) within the observational uncertainties, which implies that the distribution of the accelerated electrons follows a single power law. The number density of the microwave-emitting electrons is, however, larger than that of the HXR-emitting electrons, unless we assume low-ambient plasma density of about 1.0 × 109 cm–3 for the HXR-emitting region. If we adopt the thick-target model for the HXR emission source, on the other hand, the electron spectral index (~6.7) is much different, while the gap of the number density of the accelerated electrons is somewhat reduced.
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.
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.
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.
2668770
Coupling between M2-branes and form fields
In the context of low-energy effective theory of multiple M2-branes, we construct the interaction terms between the world-volume fields of M2-branes and the antisymmetric tensor fields of three- and six-forms. By utilizing the compactification procedure, we show coincidence between the dimensionally reduced coupling and the R-R coupling to D-branes in type II string theory. We also discuss that a cubic term proportional to six-form field reproduces the quartic mass-deformation term in the world-volume theory of multiple M2-branes.
120689000
Singular Lagrangian and the Dirac-Faddeev Method Existence Theorem of Constraints in 'Standard Form'
121927270
Spontaneous breaking of chiral symmetry in a vector-gluon model
Solutions of the self-consistent equation for fermion propagator in a vector-gluon model are fully examined. The equation is characterized by a set of parameters, i.e., the coupling constant g, the bare mass of the fermion mo and the cutoff A. It is proved that with a suitable gauge chosen, the equation without ~utoff has solutions ·only in the case mo=O, It is then shown that, if g'/4n Bn, the "normal-state" solution for the equation without cutoff, even if it existed, should necessarily have an unphysical singularity. This fact implies that the "normal-state" solution becomes unstable for a su.fficiently large value of g'. § l. Introduction The. reason for success of low energy theorems obtained by current algebra and PCAC-treatment may be well understood in terms of chiral symmetry in which the pseudoscalar mesons play a special role among hadtons as the Nambu­ Goldstone (NG) bosons1l transforming nonlinearly under chiral transformation. On the other hand, in the composite hadron models based on SU(3) or SU(6), it is clear that there is no vital distinction between pseudoscalar mesons and others such as vector- and tensor-mesons. It is therefore worth expecting that the pseudoscalar NG bosons can also be interpreted as the bound states in con­ formity with the viewpoint of the composite model. . This homogeneity and· heterogeneity ot the pseudoscalar mesons to other mesons should rather be in­ vestigated by comparing their internal structure with composite particles· . . In this respect it would be meaningful to study a model in which spontaneous breaking of chiral symmetry is realized by a composite NG boson: The Nambu­ Jona-Lasinio model2l is known as such an example. However, the use of chain approximation and the momentum cutoff inevitable for the local four-fermion
18167287
A test of the Kugo–Ojima confinement criterion by lattice Landau gauge QCD simulations
in the strong coupling region. The data isanalysed in connection with the theory of Zwanziger. In the weak coupling region, theexpectation value of the horizon function is negative or consistent to 0.1. IntroductionThere are various manifestation of colour conﬁnement in QCD. One is the linear poten-tial between quarks, which appears in the quenched lattice QCD simulation. A mechanismfor the appearance of the linear potential was proposed as well by Gribov [1] about 20years ago. He showed that the Landau gauge ﬁxing or the Coulomb gauge ﬁxing does notﬁx the gauge ﬁeld A
16425609
Numerical studies of confinement in the lattice Landau gauge
Critical conjectures on confinement in the Landau gauge is numerically tested in focus to Gribov copy effects. One of the subjects is of the Kugo-Ojima confinement criterion and the other is of various viewpoints in the Gribov-Zwanziger theory. We use the smearing gauge as a reference gauge free of Gribov copy, and performed three types of simulations, log U, U-linear and log U in the smearing gauge. It is found that Gribov copy effect on the Kugo-Ojima parameter is small. log U and U-linear simulations yield only global scale factor difference in gluon propagator, but nontrivial difference of momentum behaviour in ghost propagator, and about 10% difference in Kugo-Ojima parameter. The horizon function defined by Zwanziger is evaluated in three types of gauge field and compared. All data show the negative horizon function as expected.