A5086673311- Gamma-ray bursts and supernovae
- Statistical and numerical algorithms
- Cosmology and Gravitation Theories
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Relativity and Gravitational Theory
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Scientific Research and Discoveries
- Nuclear Physics and Applications
- Astronomical Observations and Instrumentation
- Methane Hydrates and Related Phenomena
- Advanced X-ray and CT Imaging
- Advanced Mathematical Theories and Applications
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Geomagnetism and Paleomagnetism Studies
- Spectroscopy and Chemometric Analyses
- Computational Physics and Python Applications
Charles University
2010-2019
Czech Academy of Sciences, Astronomical Institute
2010-2019
Astronomical Institute of the Slovak Academy of Sciences
2009-2019
National Taiwan University
2017
Sungkyunkwan University
2015
Sapienza University of Rome
2015
Konkoly Observatory
1998-2011
Max Planck Institute for Extraterrestrial Physics
2008-2011
Eötvös Loránd University
2000-2011
Military University
2010
Gamma-ray bursts can be divided into three groups ("short", "intermediate", "long") with respect to their durations. This classification is somewhat imprecise, since the subgroup of intermediate duration has an admixture both short and long bursts. In this paper a physically more reasonable definition group presented, using also hardnesses It shown again that existence real, no further are needed. The softest one. From new it follows 11% all belong group. An anticorrelation between hardness...
Earlier classification analyses found three types of gamma-ray bursts (short, long and intermediate in duration) the BATSE sample. Recent works have shown that these groups are also present RHESSI BeppoSAX databases. The duration distribution analysis observed by Swift satellite favors three-component model. In this paper, we extend data with spectral information. We show, using hardness simultaneously, maximum likelihood method against two-component shows a fourth component is not needed.
Gamma-ray bursts are the most luminous events in Universe. Going beyond short-long classification scheme we work context of three burst populations with third group intermediate duration and softest spectrum. We looking for physical properties which discriminate from other two classes. use maximum likelihood fits to establish memberships duration-hardness plane. To confirm these results also k-means hierarchical clustering. Monte-Carlo simulations test significance existence find it 99.8%...
A sample of 427 gamma-ray bursts (GRBs), measured by the RHESSI satellite, is studied statistically with respect to duration and hardness ratio. Standard statistical tests are used, such as $\chi^2$, F-test maximum likelihood ratio test, in order compare number GRB groups database that BATSE database. Previous studies based on Catalog claim existence an intermediate group, besides long short groups. Using only $T_{90}$ information $\chi^2$ or F-test, we have not found any significant group...
The durations of 388 gamma-ray bursts, detected by the Swift satellite, are studied statistically in order to search for their subgroups. Then results compared with obtained earlier from BATSE database. standard chi^2 test is used. Similarly database, short and long subgroups well also data. Also intermediate subgroup seen whole sample GRBs gives a support three
We argue that the distributions of both intrinsic fluence and duration gamma-ray emission in bursts from BATSE sample are well represented by log-normal distributions, which dispersion is much larger than cosmological time dilatation redshift effects. perform separate bivariate distribution fits to short long burst samples. The behaviour results an ellipsoidal distribution, whose major axis determines overall statistical relation between duration. show this fit provides evidence for a...
In the article a test is developed, which allows to null-hypothesis of intrinsic randomness in angular distribution gamma-ray bursts collected at Current BATSE Catalog. The method modified version well-known counts-in-cells test, and fully eliminates non-uniform sky-exposure function instrument. Applying this case all no non-randomness found. also did not find non-randomnesses for short long bursts, respectively. On other hand, using new intermediate subclass 181 rejected on 96.4% confidence...
The primary scientific goal of the GRIPS mission is to revolutionize our understanding early universe using γ-ray bursts. We propose a new generation gamma-ray observatory capable unprecedented spectroscopy over wide range energies (200 keV–50 MeV) and polarimetry (200–1000 keV). sensitivity nuclear absorption features enables measurement column densities as high 1028cm − 2. Secondary goals achievable by this include direct measurements all types supernova interiors through γ-rays from...
We have studied the complete randomness of angular distribution gamma-ray bursts (GRBs) detected by Burst and Transient Source Experiment (BATSE). Because GRBs seem to be a mixture objects different physical nature, we divided BATSE sample into five subsamples (short1, short2, intermediate, long1, long2) based on their durations peak fluxes, distributions separately. used three methods, Voronoi tesselation, minimal spanning tree multifractal spectra, search for non-randomness in subsamples....
A sample of 427 gamma-ray bursts from a database (February 2002 - April 2008) the RHESSI satellite is analyzed statistically. The spectral lags and peak-count rates, which have been calculated for first time in this paper, are studied completing an earlier analysis durations hardness ratios. has already inferred existence third group with intermediate duration, apart so-called short long groups. First aim article to discuss properties these intermediate-duration terms rates lags. Second...
The Cosmological Principle is the assumption that universe spatially homogeneous and isotropic in large-scale average. In year 1998 author, together with his two colleagues, has shown BATSE's short gamma-ray bursts are not distributed isotropically on sky. This claim was then followed by other papers confirming both existence of anisotropies angular distribution huge Gpc structures spatial distribution. These observational facts contradiction Principle, because large scale averaging hardly...
Until 6 October 2005 sixteen redshifts had been measured of long gamma-ray bursts discovered by the Swift satellite. Further 45 have other satellites. Here we perform five statistical tests comparing redshift distributions these two samples assuming as null hypothesis an identical distribution for samples. Three (Student's t-test, Mann-Whitney test, Kolmogorov-Smirnov test) reject at significance levels between 97.19 and 98.55%. Two different comparisons medians show extreme % rejection....
view Abstract Citations (34) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Brightness Distribution of Bursting Sources in Relativistic Cosmologies Meszaros, P. ; A. We present analytical solutions for the integral distribution arbitrary bursting or steady source counts as a function peak photon count rate within Friedmann cosmological models. discuss both standard candle and truncated power-law luminosity cases with density evolution....
view Abstract Citations (40) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmological Evolution and Luminosity Function Effects on Number Counts, Redshift, Time Dilation of Bursting Sources Meszaros, A. ; P. We present analytic formulae for the integral number count distribution cosmological bursting or steady sources valid over entire range fluxes, including density evolution either standard candle a power-law luminosity function. These...
view Abstract Citations (34) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmological Brightness Distribution FITS of Gamma-Ray Burst Sources Horvath, I. ; Meszaros, P. A. We discuss detailed fits the BATSE and PVO gamma-ray burst peak- flux distributions with Friedmann models taking into account possible density evolution standard candle or power-law luminosity functions. A χ^2^ analysis is used to estimate goodness fits, we derive...
The anisotropy of the sky distribution 2025 gamma-ray bursts (GRBs) collected in Current BATSE catalog is confirmed. It shown that quadrupole term being proportional to non-zero with a probability 99.9%. occurrence this ani sot ropy then supported by binomial test even 99.97%. also argued cannot be caused exclusively instrumental effects due non-uniform exposure instrument; there should exist some intrinsic angular GRBs. Separating GRBs into short and long subclasses, it 251 ones are...
It is known that the soft tail of gamma-ray bursts' spectra show excesses from exact power-law dependence. In this article we departure can be detected in peak flux ratios different BATSE DISCSC energy channels. This effect allows to estimate redshift bright long bursts Catalog. A verification these redshifts obtained for 8 GRB which have both data and measured optical spectroscopic redshifts. There good correlation between estimated redshifts, average error . The method similar photometric...
Aims.The redshift distribution of gamma-ray bursts collected in the BATSE Catalog is compared with star formation rate. We aim to clarify accordance between them. also study case comoving number density monotonously increasing up .
We analyze the spectral lags of a sample bright gamma-ray burst pulses observed by CGRO BATSE and compare these with results high-resolution spectroscopical investigations. find that hard spectra have largest lags, there is similar, but weaker correlation between hardness-intensity index, η, lag. also differ considerably within burst. Furthermore, peak energy mainly decreases increasing Assuming lag-luminosity relation as suggested Norris et al., will thus be positive luminosity–peak-energy...
Several claims have been put forward that an essential fraction of long-duration BATSE gamma-ray bursts should lie at redshifts larger than 5. This point-of-view follows from the natural assumption fainter objects should, on average, redshifts. However, 5 are rare for observed by Swift, seemingly contradicting estimates. The purpose this article is to clarify contradiction. We derive cosmological relationships between and emitted quantities, we arrive a prediction can be tested ensembles...
We have carried out a principal component analysis for 625 gamma-ray bursts in the BATSE 3B catalog which nonzero values exist nine measured variables. This shows that only two of three basic quantities duration, peak flux, and fluence are independent, even if this relation is strongly affected by instrumental effects, these account 91.6% total information content. The next most important variable fourth energy channel (at energies above 320 keV). has larger variance less correlated with...
Two groups recently deduced the positive value for cosmological constant, concluding at a high (≥99%) confidence level that universe should be accelerating. This conclusion followed from statistical analysis of dozens high-redshift supernovae. In this paper is discussed. From conservative frequentist's point view, validity null hypothesis zero constant tested by classical χ2 test 60 supernovae listed in Perlmutter et al. sample contains 42 objects discovered frame Supernova Cosmology Project...