119203321
STATISTICAL PROPERTIES OF MULTIPLE OPTICAL EMISSION COMPONENTS IN GAMMA-RAY BURSTS AND IMPLICATIONS
Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are complied from the literature. Multiple optical emission components are extracted with power-law function fits to these lightcurves. We present a systematical analysis for statistical properties and their relations to prompt gamma-ray emission and X-ray afterglow for each component. We show that peak luminosity in the prompt and late flares are correlated and the evolution of the peak luminosity may signal the evolution of the accretion rate. No tight correlation between the shallow decay phase/plateau and prompt gamma-ray emission is found. Assuming that they are due to a long-lasting wind injected by a compact object, we show that the injected behavior favors the scenarios of a long-lasting wind powered by a Poynting flux from a black hole via the Blandford-Znajek mechanism fed by fall-back mass or by the spin-down energy release of a magnetar after the main burst episode. The peak luminosity of the afterglow onset is tightly correlated ...
100860790
A curve-based material recognition method in MeV dual-energy X-ray imaging system
High-energy dual-energy X-ray digital radiography imaging is mainly used in the material recognition of cargo inspection. We introduce the development history and principle of the technology and describe the data process flow of our system. The system corrects original data to get a dual-energy transparence image. Material categories of all points in the image are identified by the classification curve, which is related to the X-ray energy spectrum. For the calibration of classification curve, our strategy involves a basic curve calibration and a real-time correction devoted to enhancing the classification accuracy. Image segmentation and denoising methods are applied to smooth the image. The image contains more information after colorization. Some results show that our methods achieve the desired effect.
54197110
A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. II. AFTERGLOW ONSET AND LATE RE-BRIGHTENING COMPONENTS
We continue our systematic statistical study of various components of gamma-ray burst (GRB) optical light curves. We decompose the early onset bump and the late re-brightening bump with empirical fits and analyze their statistical properties. Among the 146 GRBs that have well-sampled optical light curves, the onset and re-brightening bumps are observed in 38 and 26 GRBs, respectively. It is found that the typical rising and decaying slopes for both the onset and re-brightening bumps are similar to 1.5 and similar to-1.15, respectively. No early onset bumps in the X-ray band are detected to be associated with the optical onset bumps, while an X-ray re-brightening bump is detected for half of the re-brightening optical bumps. The peak luminosity is anti-correlated with the peak time L-p proportional to t(p)(-1.81 +/- 0.32) for the onset bumps and L-p proportional to t(p)(-0.83 +/- 0.17) for the re-brightening bumps. Both L-p and the isotropic energy release of the onset bumps are correlated with E-gamma,E- iso, whereas no similar correlation is found for the re-brightening bumps. These results suggest that the afterglow onset bumps are likely due to the deceleration of the GRB fireballs. Taking the onset bumps as probes for the properties of the fireballs and their ambient medium, we find that the typical power-law index of the relativistic electrons is 2.5 and the medium density profile behaves as n proportional to r(-1) within the framework of the synchrotron external shock models. With the medium density profile obtained from our analysis, we also confirm the correlation between the initial Lorentz factor (Gamma(0)) and E-iso,E-gamma in our previous work. The jet component that produces the re-brightening bump seems to be on-axis and independent of the prompt emission jet component. Its typical kinetic energy budget would be about one order of magnitude larger than the prompt emission component, but with a lower Gamma(0), typically several tens.
119302057
REVISITING THE EMISSION FROM RELATIVISTIC BLAST WAVES IN A DENSITY-JUMP MEDIUM
Re-brightening bumps are frequently observed in gamma-ray burst afterglows. Many scenarios have been proposed to interpret the origin of these bumps, of which a blast wave encountering a density-jump in the circumburst environment has been questioned by recent works. We develop a set of differential equations to calculate the relativistic outflow encountering the density-jump by extending the work of Huang et al. This approach is a semi-analytic method and is very convenient. Our results show that late high-amplitude bumps cannot be produced under common conditions, rather only a short plateau may emerge even when the encounter occurs at an early time (< 10(4) s). In general, our results disfavor the density-jump origin for those observed bumps, which is consistent with the conclusion drawn from full hydrodynamics studies. The bumps thus should be caused by other scenarios.
197507608
Correlation between the Peak Spectral Energy of Gamma-Ray Bursts and the Peak Luminosity of the Underlying Supernovae: Implication for the Nature of GRB-SN Connection
10999058
Improved correlation between the variability and peak luminosity of gamma-ray bursts
A new procedure for smoothing a gamma-ray burst (GRB) light curve and calculating its variability is presented. Applying the procedure to a sample of 25 long GRBs, we have obtained a very tight correlation between the variability and the peak luminosity. The only significant outlier in the sample is GRB 030329. With this outlier excluded, the data scatter is reduced by a factor of ∼3 compared to that of Guidorzi et al., measured by the deviation of fit. Possible causes for the outlier are discussed.
119231659
The effects of ultraviolet photometry and binary interactions on photometric redshift and galaxy morphology
Using the HYPERZ code and a template spectral library, which consists of four observed galaxy spectra from Coleman, Wu & Weedman (CWW) and eight spectral families built with evolutionary population synthesis models, we present photometric redshift (photo-z) estimates for a spectroscopic sample of 6531 galaxies. Spectroscopic redshifts are also available, and are selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and the Galaxy Evolution Explorer (GALEX) Data Release 4 (DR4). There are also morphologies for a morphological sample of 1502 bright galaxies, which are from the catalogue of Fukugita et al., and these are also matched with SDSS DR7 and GALEX DR4. We find that the inclusion of F(UV) or N(UV), or both, decreases the number of catastrophic identifications (| z.(phot) - z.(spec)| > 1.0). If catastrophic identifications are removed, the inclusion of both FUV and NUV photometry mainly increases the number of non-catastrophic identifications in the low-redshift, g-r less than or similar to 0.8 and fainter r-magnitude regions. The inclusion of binary interactions mainly increases the number of non-catastrophic identifications and decreases the deviations in the 0.3 <= g-r <= 0.8 region when only using optical photometry. Based on the morphological galaxy sample, we find that the inclusion of ultraviolet (UV) photometry decreases and increases the probability that early types are classified as burst and E types, respectively. This increases the probability that late types are classified as CWW-Sbc and CWW-Scd types. If catastrophic identifications are excluded, the inclusion of UV data mainly increases the identifications of late types in all redshift, bluer g-r and r greater than or similar to 14 regions. Moreover, binary interactions mainly affect the determinations of E and S0 types. In comparison, we find that the reliability and completeness for early-and late-type selection by the HYPERZ code are less than those by the concentration index C = 2.6, the profile likelihood P(exp) - P(de)V = 0 and colour u-r = 2.22 criteria. Moreover, we find that N(UV)-u = 1.94 and 5.77 - 1.47(u-r) = F(UV)-u discriminators can be used as morphology selection indicators. These two criteria have comparable reliability and completeness for selecting early- and late-type galaxies to C = 2.6 criterion and higher completeness for early-type selection than the u-r = 2.22 criterion.
122993825
Field measurement of PEP-II LER dipoles and quadrupoles at IHEP
The field measurement of 209 dipoles and 320 quadrupoles for PEP-II LER will be finished at IHEP in June 1997. This paper covers the details of the magnetic measurement devices developed to measure these magnets as well as the results of the measurements.
120944465
QCD inspired relativistic effective Hamiltonian model for mesons
Abstract A QCD inspired relativistic effective Hamiltonian model for mesons has been proposed based on light-front QCD effective Hamiltonian. The squared invariant rest mass operator is used as the effective Hamiltonian. The model has been improved significantly in four major aspects: i) it is proved that in constituent rest frame and in internal Hilbert subspace, the total angular momentum of mesons is conserved, the mass eigen equation can be expressed in total angular momentum representation and in terms of a set of coupled radial eigen equations; ii) a relativistic confining potential is introduced to describe the excited states; iii) an SU(3) flavor mixing interaction is included and a set of coupled mass eigen equations are obtained for different flavor components; iv) the L – S coupling and the tensor interaction are taken into full account. The model has been applied to describe the whole meson spectra of about 265 mesons with available data. The meson masses, squared radii, and decay constants are calculated, and the agreement with data is satisfying. For the mesons whose mass data have large experimental uncertainty, the model produces certain mass values for test. For some mesons whose total angular momenta and parities are not assigned experimentally, the model gives a prediction of their spectroscopic configuration L J 2 S + 1 . The radial excitation spectra are also analyzed, the discrepancy between the calculated spectra and the data indicates angular momentum effect and higher Fock space effect for some mesons. The relation between our model and the infrared conformal scaling invariance as well as the holographic light front QCD meson model is discussed.