A5074185836- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Statistical and numerical algorithms
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Nuclear Physics and Applications
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Cosmology and Gravitation Theories
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Particle Detector Development and Performance
- Methane Hydrates and Related Phenomena
- Advanced X-ray and CT Imaging
- Scientific Research and Discoveries
- Planetary Science and Exploration
- Space Science and Extraterrestrial Life
- Radiation Detection and Scintillator Technologies
- Spectroscopy and Chemometric Analyses
- Ionosphere and magnetosphere dynamics
- Radiation Therapy and Dosimetry
- Geomagnetism and Paleomagnetism Studies
Ludovika University of Public Service
2015-2025
HUN-REN Wigner Research Centre for Physics
2016-2022
Eötvös Loránd University
2008-2015
College of Charleston
2015
Sapienza University of Rome
2015
Konkoly Observatory
2008-2011
Chinese Academy of Sciences
2011
Yunnan Observatories
2011
Charles University
1996-2010
Military University
2006-2010
Two classes of gamma-ray bursts have been identified so far, characterized by T90 durations shorter and longer than approximately 2 s. We show here that the BATSE 3B data allow a good fit with three Gaussian distributions in log T90. The χ2 statistic indicates 40% probability for two-Gaussian fits, whereas three-Gaussian is 98%. Using another statistical method, it argued third class random fluctuation less 0.02%.
Context. Research over the past three decades has revolutionized cosmology while supporting standard cosmological model. However, principle of Universal homogeneity and isotropy always been in question, since structures as large survey size have found each time increased. Until 2013, largest known structure our Universe was Sloan Great Wall, which is more than 400 Mpc long located approximately one billion light years away. Aims. Gamma-ray bursts are most energetic explosions Universe. As...
We analysed the different aspects of spatial distribution 542 Gamma-Ray Bursts with precisely determined positions and spectroscopic redshifts. The data were divided according to origin redshift (afterglow or host galaxy). yearly rate afterglow host-based observations are different, only a few in recent years. Since launch Swift, fall exponentially by 50 % 15 years, potentially affecting all planned GRB missions. also rest-frame T90 values from Swift BAT FERMI GBM catalogues data. host-...
Several studies over the last two decades have used canonical correlation analysis (CCA) to study relationships between main γ-ray (e.g. fluence, peak flux, and duration) X-ray (flux, decay spectral index, hydrogen column density) data from gamma-ray bursts (GRBs). In this paper, we revisit approach using a much larger dataset identify potential new insights into these relationships. We CCA investigate interrelationship of aforementioned parameters. Using derived variables, calculated their...
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.
According to the cosmological principle (CP), Universal large-scale structure is homogeneous and isotropic. The observable Universe, however, shows complex structures even on very large scales. recent discoveries of significantly exceeding transition scale 370 Mpc pose a challenge CP. We report here discovery largest regular formation in Universe; ring with diameter 1720 Mpc, displayed by 9 gamma-ray bursts (GRBs), factor 5 isotropic distribution. has major 43° minor 30° at distance 2770...
Two classes of gamma-ray bursts have been identified so far, characterized by durations shorter and longer than approximately 2 seconds. In 1998 two independent papers indicated the existence third class roughly duration between 10 this paper, using full BATSE Catalog, maximum likelihood estimation is presented, which gives a 0.5% probability to having only subclasses. The Monte-Carlo simulation confirms probability, too.
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%...
Context. Two classes of gamma-ray bursts have been identified in the BATSE catalogs characterized by durations shorter and longer than about 2 s. There are, however, some indications for existence a third class. Swift satellite detectors different spectral sensitivity pre-Swift ones bursts. Therefore we reanalyze their distribution also classification GRBs.
Clustering is an important tool to describe gamma-ray bursts (GRBs). We analysed the Final BATSE catalog using Gaussian-mixture-models-based clustering methods for six variables (durations, peak flux, total fluence, and spectral hardness ratios) that contain information on clustering. Our analysis found five kinds of GRBs previously by other authors are only cut groups well-known three types (short, long, intermediate in duration). The two short duration differ mostly flux. Therefore,...
Abstract At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors massive stars, they provide a tracer star formation and star-forming galaxies over whole cosmic history. Their bright power-law afterglows ideal backlights for absorption studies interstellar intergalactic medium back to reionization era. The proposed THESEUS mission is designed detect large samples GRBs at z > 6 in 2030s, time when supporting...
Several large structures, including the Sloan Great Wall, Huge Large Quasar Group, and a gamma-ray burst cluster referred to as Hercules-Corona Borealis appear exceed maximum structural size predicted by Universal inflationary models. The existence of very structures such these might necessitate cosmological model modifications. Gamma-ray bursts are most luminous sources found in nature. They associated with stellar endpoints massive stars near distant galaxies. Since they viable indicators...
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....
Gamma-ray bursts are usually classified through their high-energy emission into short-duration and long-duration bursts, which presumably reflect two different types of progenitors. However, it has been shown on statistical grounds that a third, intermediate population is needed in this classification scheme, although an extensive study the properties class so far not done. The large amount follow-up studies generated during Swift era allows us to have suficient sample attempt third prompt...
The Hercules-Corona Borealis Great Wall is a statistically significant clustering of gamma-ray bursts around redshift 2. Motivated by recent theoretical results indicating that maximal Universal structure size may indeed coincide with its estimated (2-3Gpc), we reexamine the question this Wall's existence from both observational and perspectives. Our statistical analyses confirm clustering's presence in most reliable data set currently available, present video showing what looks like in~3D....
The Fermi collaboration identified a possible electromagnetic counterpart of the gravitational wave event September 14, 2015. Our goal is to provide an unsupervised data analysis algorithm identify similar events in Fermi's Gamma-ray Burst Monitor CTTE stream. We are looking for signals that typically weak. Therefore, they can only be found by careful count rates all detectors and energy channels simultaneously. Automatized Detector Weight Optimization (ADWO) method consists search signal,...
Abstract Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with potential span vast range of redshifts. The growing synergies between different probes opening new frontiers, which promise profound insights into several aspects fundamental physics and cosmology. In this context, THESEUS will play central role during 2030s in detecting localizing electromagnetic counterparts gravitational wave neutrino sources that unprecedented sensitivity next generation...
Mercury's southern inner magnetosphere is an unexplored region as it was not observed by earlier space missions. In October 2021, BepiColombo mission has passed through this during its first Mercury flyby. Here, we describe the observations of SERENA ion sensors nearby and inside magnetosphere. An intermittent high-energy signal, possibly due to interplanetary magnetic flux rope, been downstream Mercury, together with low energy solar wind. Low ions, satellite outgassing, were detected...