A. Tsvetkova
A5012238660- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- SAS software applications and methods
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Geomagnetism and Paleomagnetism Studies
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Environmental Monitoring and Data Management
- Nuclear Physics and Applications
- earthquake and tectonic studies
- Earthquake Detection and Analysis
- Image Processing and 3D Reconstruction
- User Authentication and Security Systems
- Advanced Research in Science and Engineering
- Medical Imaging Techniques and Applications
- Laser-Plasma Interactions and Diagnostics
- Computational Physics and Python Applications
- Particle Accelerators and Free-Electron Lasers
Ioffe Institute
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari
2022-2024
University of Cagliari
2022-2024
Osservatorio di Astrofisica e Scienza dello Spazio
2024
Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
2024
Max Planck Institute for Extraterrestrial Physics
2022
Physico-Technical Institute
2013-2020
Abstract GRB 221009A has been referred to as the brightest of all time (BOAT). We investigate veracity this statement by comparing it with a half century prompt gamma-ray burst observations. This is ever detected measures peak flux and fluence. Unexpectedly, highest isotropic-equivalent total energy identified, while luminosity at ∼99th percentile known distribution. explore how such can be powered discuss potential implications for ultralong high-redshift bursts. By geometric extrapolation...
Abstract We report on Konus-WIND (KW) and Mikhail Pavlinsky Astronomical Roentgen Telescope – X-ray Concentrator (ART-XC) observations analysis of a nearby GRB 221009A, the brightest γ -ray burst (GRB) detected by KW for >28 yr observations. The prompt, pulsed phase emission lasts ∼600 s is followed steady power-law decay lasting more than 25 ks. From ART-XC light curves spectral data, we derive time-averaged peak energy E p ≈ 2.6 MeV, at 3.0 total 20 keV–10 MeV fluence ≈0.22 erg cm −2 ,...
Abstract The most energetic gamma-ray bursts (GRBs) are remarkable sources releasing huge amounts of energy on short timescales. Their prompt emission, which usually lasts a few seconds, is so bright that it visible across the whole observable universe. Studying these extreme events may provide clues nature GRB progenitors and physical processes at work in relativistic jets. In this paper, we study end isotropic distribution long GRBs. We use two samples GRBs with redshift detected by Fermi...
Cadmium Zinc Telluride Imager (CZTI) aboard AstroSat has been regularly detecting Gamma-Ray Bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI attempt spectro-polarimetric studies of GRBs. Here, we present the first catalog GRB made by during five years operation. This presents time integrated prompt emission 20 GRBs energy range 100-600 keV. The sample includes bright which were detected within an angle 0-60 degree and...
Abstract Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor Γ init below the ∼ 100 required to produce long-duration gamma-ray burst (LGRB), but which could still optical emission resembling LGRB afterglows. Here we present results search for on-axis afterglows using Zwicky Transient Facility (ZTF). Our yielded seven transients that resemble in terms their red colors ( g − r > 0 mag), faint host galaxies 23 rapid fading dr / dt...
Context. The variety and complexity of long duration gamma-ray burst (LGRB) light curves (LCs) encode a wealth information about the way LGRB engines release their energy following collapse progenitor massive star. Thus far, attempts to characterise GRB LCs have focused on number properties, such as minimum variability timescale power density spectra (both ensemble average individual), or considering different definitions variability. In parallel, characterisation stochastic process has been...
Gamma-ray bursts (GRBs) occurring in the local Universe constitute an interesting sub-class of GRB family, since their luminosity is on average lower than that cosmological analogs. We aim to contribute study by reporting case 171205A. This source was discovered Swift Burst Alert Telescope (BAT) 2017, December 5 and soon associated with a low redshift host galaxy (z=0.037), emerging SN (SN 2017iuk). analyzed full Swift, dataset, comprising UV-Optical (UVOT), X-ray (XRT) BAT data. In...
Abstract Discovered more than 50 years ago, gamma-ray burst (GRB) prompt emission remains the most puzzling aspect of GRB physics. Its complex and irregular nature should reveal how newborn engines release their energy. In this respect, possibility that could operate as self-organized critical (SOC) systems has been put forward. Here, we present energy, luminosity, waiting time, duration distributions individual pulses GRBs with known redshift detected by Fermi Gamma-ray Burst Monitor. This...
Abstract In this catalog, we present the results of a systematic study gamma-ray bursts (GRBs) with reliable redshift estimates detected in triggered mode Konus- Wind (KW) experiment during period from 1997 February to 2016 June. The sample consists 150 GRBs (including 12 short/hard bursts) and represents largest set cosmological studied date over broad energy band. From temporal spectral analyses sample, provide burst durations, lags, fits two model functions, total fluences, peak fluxes....
We report on the bright burst detected by four Interplanetary network (IPN) spacecraft 2015 April 12. The IPN localization of source is consistent with position recently discovered soft gamma-repeater SGR 1935+2154. From Konus-Wind (KW) observation, we derive temporal and spectral parameters emission, energetics. rather long duration (∼1.7 s) large measured energy fluence (∼2.5 × 10−5 erg cm−2) put it in class rare 'intermediate' (SGR) flares, this first one observed from A search for...
We report the early discovery of optical afterglow gamma-ray burst (GRB) 140801A in 137 deg$^2$ 3-$\sigma$ error-box Fermi Gamma-ray Burst Monitor (GBM). MASTER is only observatory that automatically react to all alerts. GRB one few GRBs whose counterpart was discovered solely from its GBM localization. The found by Global Robotic Net 53 sec after receiving alert, making it fastest detection a error-box. Spectroscopy obtained with 10.4-m Gran Telescopio Canarias and 6-m BTA SAO RAS reveals...
Abstract We present a database of solar flares registered by the Konus-Wind instrument during more than 27 yr operation, from 1994 November to now (2022 June). The constantly updated (hereafter KW-Sun) contains over 1000 events detected in instrument’s triggered mode and is accessible online at http://www.ioffe.ru/LEA/kwsun/ . For each flare, provides time-resolved energy spectra range ∼20 keV ∼15 MeV FITS format along with count-rate light curves three wide-energy bands, G1 (∼20–80 keV), G2...
A sizeable fraction of gamma-ray burst (GRB) light curves (LCs) feature a sequence peaks that hold information on the unknown way energy is released and dissipated into gamma-rays over time. Traditionally, searches for periodic signals in GRB LCs have turned out to be inconclusive, partly because they are challenging as consequence short-lived, coloured-noise, non-stationary nature themselves. Yet, recent claims revived issue. We aim search components through new approach GRBs avoids most...
Context. Positive lags between the arrival time of different photon energies are commonly observed in prompt phase gamma-ray bursts (GRBs), where soft photons lag behind harder ones. However, a fraction GRBs display opposite behavior. In particular, Fermi Large Area Telescope (LAT) observations revealed that high-energy often characterized by delayed onset. Aims. We explore potential spectral as diagnostic tool to identify distinct emission components or processes. By analyzing data from...
Two classes of gamma-ray bursts (GRBs) corresponding to the short-hard and long-soft events, with a putative intermediate class, are typically considered in observer frame. However, when considering GRB characteristics cosmological rest frame, boundary between becomes blurred. The goal this research is check for evidences third `intermediate' class GRBs investigate how transformation from frame affects hardness-duration-based classification. We applied fits skewed non-skewed (symmetric)...
GRB 110918A is the brightest long detected by Konus-WIND during its 19 years of continuous observations and most luminous ever observed since beginning cosmological era in 1997. We report on final IPN localization this event detailed multiwavelength study with a number space-based instruments. The prompt emission characterized typical duration, moderare $E_{peak}$ time-integrated spectrum, strong hard-to-soft evolution. high energy fluence yields, at z=0.984, huge isotropic-equivalent...
ABSTRACT In this catalog, we present the results of a systematic study 295 short gamma-ray bursts (GRBs) detected by Konus- Wind (KW) from 1994 to 2010. From temporal and spectral analyses sample, provide burst durations, lags, fits with three model functions, total energy fluences, peak fluxes bursts. We discuss evidence found for an additional power-law component presence extended emission in fraction KW GRBs. Finally, consider obtained context Type I (merger-origin)/Type II...
We present a detailed follow-up of the very energetic GRB 210905A at high redshift z = 6.312 and its luminous X-ray optical afterglow. Following detection by Swift Konus- Wind , we obtained photometric spectroscopic in near-infrared (NIR), covering both prompt afterglow emission from few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release E iso 1.27 −0.19 +0.20 × 10 54 erg, lies top ∼7% bursts (GRBs) catalogue terms released. Its is among most ever observed, and,...
Gamma-ray bursts (GRBs) bridge relativistic astrophysics and multimessenger astronomy. Space–based γ - X-ray wide-field detectors have proven essential for detecting localizing the highly variable GRB prompt emission, which is also a counterpart of gravitational wave events. We studied capability long short GRBs with High Energy Rapid Modular Ensemble Satellites (HERMES) Pathfinder (HP) SpIRIT, namely swarm six 3U CubeSats to be launched in early 2025, 6U CubeSat on December 1 2023....
At the dawn of gamma--ray burst (GRB) afterglow era, a Cepheid-like correlation was discovered between time variability $V$ and isotropic-equivalent peak luminosity $L_ iso $ prompt emission about dozen long GRBs with measured redshift available at that time. Soon afterwards, confirmed in sample 30 GRBs, even though it affected by significant scatter. Unlike minimum timescale (MVT), measures relative power short-to-intermediate timescales. We aim to test using 200 spectroscopically redshift,...