Classification of BeppoSAX's Gamma-Ray Bursts

The BeppoSAX Catalog has been very recently published. In this paper we analyze - using the Maximum Likelihood (ML) method - the duration distribution of the 1003 GRBs listed in the catalog with duration. The ML method can identify the long and the intermediate duration groups. The short population of the bursts is identified only at a 96% significance level. MC simulation has been also applied and gives a similar significance level; 95%. However, the existence of the short bursts is not a scientific question after the Compton Gamma-Ray Observatory's observation. Our minor result is this well-known fact that in the BeppoSAX data the short bursts are underrepresented, mainly caused by the different triggering system. Our major result is the identification of the intermediate group in the BeppoSAX data. Therefore, four different satellites (CGRO, Swift, RHESSI and BeppoSAX) observed the intermediate type Gamma-Ray Burst.Comment: Accepted for publication in Astrophysics & Space Scienc

The duration distribution of Swift Gamma-Ray Bursts

Decades ago two classes of gamma-ray bursts were identified and delineated as having durations shorter and longer than about 2 s. Subsequently indications also supported the existence of a third class. Using maximum likelihood estimation we analyze the duration distribution of 888 Swift BAT bursts observed before October 2015. Fitting three log-normal functions to the duration distribution of the bursts provides a better fit than two log-normal distributions, with 99.9999% significance. Similarly to earlier results, we found that a fourth component is not needed. The relative frequencies of the distribution of the groups are 8% for short, 35% for intermediate and 57% for long bursts which correspond to our previous results. We analyse the redshift distribution for the 269 GRBs of the 888 GRBs with known redshift. We find no evidence for the previously suggested difference between the long and intermediate GRBs' redshift distribution. The observed redshift distribution of the 20 short GRBs differs with high significance from the distributions of the other groups.Comment: accepte

Cosmological Brightness Distribution Fits of Gamma Ray Burst Sources

We discuss detailed fits of the BATSE and PVO gamma-ray burst peak-flux distributions with Friedman models taking into account possible density evolution and standard candle or power law luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and we derive the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable.Comment: Ap.J. in press, uuencoded .ps file, 9 pages manuscript plus 5 figure

Low-dimensional long-range topological structure in the QCD vacuum

Lattice topological charge associated with Ginsparg-Wilson fermions exhibits generic topological stability over quantum ensemble of configurations contributing to the QCD path integral. Moreover, the underlying chiral symmetry leads to the suppression of ultraviolet noise in the associated topological charge densities ("chiral smoothing"). This provides a solid foundation for the direct study of the role of topological charge fluctuations in the physics of QCD vacuum. Using these tools it was recently demonstrated that: (a) there is a well-defined space-time structure (order) in topological charge density (defined through overlap fermions) for typical configurations contributing to QCD path integral; (b) this fundamental structure is low-dimensional, exhibiting sign-coherent behavior on subsets of dimension less than four and not less than one; (c) the structure has a long-range global character (spreading over maximal space-time distances) and is built around the locally one-dimensional network of strong fields (skeleton). In this talk we elaborate on certain aspects and implications of these results.Comment: 3 pages, 1 figure; Lattice2003(topology

Macroeconomic implications of virtual shopping : a theoretical approach

Recently, parallel to developments in the communication technology, online shopping has become increasingly popular for many products, like books, CDs, software, and computers. Most analysts conjecture that the future will witness a wider basket of products and a higher trade volume via the Internet. This paper investigates the economic implications of Internet shopping in a Ricardian equilibrium framework. First, it shows the necessary and sufficient condition for the shift to Internet shopping. Next, it indicates that macroeconomic variables like consumption and income rise when this shift takes place. Thus, this paper shows that the economic implications of Internet shopping will be higher than the current experience and Internet shopping will become an important element of the `new economy\' when the bulky part of the shopping is done via the Internet.

Analysis of the BATSE Continuous MER data

The CGRO/BATSE database includes many types of data such as the 16-channel continuous background or medium energy resolution burst data (CONT and MER data types). We have calculated some four hundred burst's medium energy resolution spectra and Principal Component Analysis has been applied. We found five components can describe GRBs' spectra.Comment: 4 pages, 2 figures, accepted in Nuovo Ciment