A5057339596- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Distributed and Parallel Computing Systems
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- Relativity and Gravitational Theory
- CCD and CMOS Imaging Sensors
- Satellite Image Processing and Photogrammetry
- Multidisciplinary Science and Engineering Research
- IoT and Edge/Fog Computing
- Superconducting Materials and Applications
- Astrophysics and Star Formation Studies
- Advanced Measurement and Metrology Techniques
- Particle physics theoretical and experimental studies
- Second Language Learning and Teaching
Czech Academy of Sciences, Astronomical Institute
2010-2024
Czech Academy of Sciences, Institute of Physics
2023
University of Geneva
2023
Charles University
2003-2023
National Academy of Sciences of Ukraine
2023
Czech Academy of Sciences
2005-2023
University of Duisburg-Essen
2019
Institute of Applied Astronomy
2019
Institute of Astronomy
2019
Czech Technical University in Prague
2013-2018
ABSTRACT OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in binary black hole model. The model predicted major outburst 2015 December. We found the did occur within expected time range, peaking on December 5 at magnitude 12.9 R -band. Based Swift /XRT satellite measurements and polarization data, we find it included thermal component. Its timing provides an accurate estimate for spin of primary hole, . present also...
Abstract Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission gravitational waves (GWs). We show that observations associated binary black hole (BBH) central engine blazar OJ 287 demand inclusion radiation reaction effects beyond quadrupolar order. It turns out even certain hereditary contributions to GW required predict impact flare timings 287. develop an approach incorporates this effect into BBH...
Abstract We present the results of our power spectral density analysis for BL Lac object OJ 287, utilizing Fermi -LAT survey at high-energy γ -rays, Swift -XRT in X-rays, several ground-based telescopes and Kepler satellite optical, radio GHz frequencies. The light curves are modeled terms continuous-time autoregressive moving average (CARMA) processes. Owing to inclusion data, we were able construct first time optical variability spectrum a blazar without any gaps across ∼6 dex temporal Our...
Abstract We report the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in blazar OJ 287. In binary black hole model, it is associated with an impact secondary accretion disk primary. Our multifrequency observing campaign was set up to search for such signature based prediction made 8 yr earlier. The first I -band results have already been reported by Kishore et al. (2024). Here we combine these data our monitoring R -band. There big change – spectral index 1.0 ± 0.1...
The bright blazar OJ~287 routinely parades high brightness bremsstrahlung flares, which are explained as being a result of secondary supermassive black hole (SMBH) impacting the accretion disc more massive primary SMBH in binary system. is not rigid but rather bends calculable way due to tidal influence secondary. Below we refer this phenomenon variable level. We begin by showing that these flares occur at times predicted simple analytical formula, based on general relativity inspired...
Context . Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (ɀ), pinpointing locations earliest star-forming galaxies and providing bright backlights with simple featureless power-law spectra that can be used to spectrally fingerprint intergalactic medium host galaxy during period reionization. Future missions such as Gamow Explorer (hereafter Gamow) being proposed unlock this potential by increasing rate identification high-ɀ (ɀ > 5) GRBs in order rapidly trigger...
We observed an optical afterglow of GRB 200131A obtaining the first photometric point 63 s after satellite trigger. This early observation shows a steep decay, suggesting either internal engine activity or reverse shock. By fitting this data set, we show that fit well as shock component modeled thin shell expanding into constant density interstellar matter. The also good agreement with catalogued Milky Way galactic extinction and leaves only little space for further in host galaxy. judging...
Abstract The SST-1M (webpage: https://sst-1m.space ) is a Small-Sized Telescope (SST) designed to provide cost-effective and high-performance solution for gamma-ray astrophysics, particularly energies beyond few TeV. goal integrate this telescope into an array of similar instruments, leveraging its lightweight design, earthquake resistance, established Davies-Cotton configuration. Additionally, optical system function without protective dome, allowing it withstand the harsh atmospheric...
We observed an optical afterglow of GRB200131A obtaining the first photometric point 63 s after satellite trigger. This early observation shows a steep decay, suggesting either internal engine activity or reverse shock. By fitting this data set, we show that fit well as shock component GRB modeled thin shell expanding into constant density interstellar matter. The also good agreement with catalogued Milky Way galactic extinction and leaves little room for further in host galaxy. judging...
A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves this event, 42 of which yielded a central flash detection. aimed at constraining Triton's atmospheric structure seasonal variations its pressure since Voyager 2 epoch (1989). also shape lower atmosphere analysis. used Abel inversions direct ray-tracing code to provide density, pressure, temperature profiles in altitude range $\sim$8 km...
We present a detailed prompt emission and early optical afterglow analysis of the two very high energy (VHE) detected bursts GRB 201015A 201216C, their comparison with subset similar bursts. Time-resolved spectral multi-structured 201216C using Bayesian binning algorithm revealed that during entire duration burst, low index ($\alpha_{\rm pt}$) remained below limit synchrotron line death. However, statistically some bins supported additional thermal component. Additionally, evolution...
Identifying black holes is essential for our understanding of the development stars and can reveal novel principles physics. Gravitational microlensing provides an exceptional opportunity to examine undetectable population in Milky Way. In particular, long-lasting events are likely be associated with massive lenses, including holes. We present analysis Gaia18ajz event reported by Gaia Science Alerts system. a long-timescale exhibiting features indicative annual parallax effect. Our objective...
Context. Long gamma-ray bursts (GRBs) are produced by the collapse of some very massive stars, that emit ultra-relativistic jets. When jets collide with interstellar medium they decelerate and generate so-called afterglow emission, which has been observed to be polarised. Aims. We study polarimetric evolution GRB 210610B afterglow, at z = 1.1341. This allows us evaluate role geometric and/or magnetic mechanisms in polarisation. Methods. using imaging polarimetry CAFOS on 2.2 m Calar Alto...
We present a summary of the results OJ 287 observational campaign, which was carried out during 2021/2022 season. This season is special in binary model because major axis precessing happens to lie almost exactly plane accretion disc primary. leads pairs identical impacts between secondary black hole and disk 2005 2022. In 2005, flare called “blue flash” observed 35 days after impact, should have also been verifiable did observe similar flash were able obtain more details its properties....
Events such as GRB130606A at z=5.91, offer an exciting new window into pre-galactic metal enrichment in these very high redshift host galaxies. We study the environment and galaxy of GRB 130606A, a high-z event, context population GRBs. have obtained multiwavelength observations from radio to gamma-ray, concentrating particularly on X-ray evolution well optical photometric spectroscopic data analysis. With initial Lorentz bulk factor range Γ_0 ~ 65-220, afterglow can be explained by...
We analyse the light curve in R band of blazar OJ287, gathered during 2015/2016 observing season. did a search for quasi-periodic oscillations (QPOs) using several methods over wide range timescales. No statistically significant periods were found high-frequency domain both ground-based data and Kepler observations. In longer-period domain, Lomb–Scargle periodogram revealed peaks above 99% significance level. The longest one—about 95 days—corresponds to innermost stable circular orbit (ISCO)...
Identifying black holes is essential for comprehending the development of stars and uncovering novel principles physics. Gravitational microlensing provides an exceptional opportunity to examine undetectable population in Milky Way. In particular, long-lasting events are likely be associated with massive lenses, including holes. We present analysis Gaia18ajz event, reported by Gaia Science Alerts system, which has exhibited a long timescale features indicative annual parallax effect. Our...
The High Energy Astrophysics group of the stellar department Astronomical Institute in Ondřejov operates two small aperture robotic telescopes called BART and D50. Both are capable making automatic followup observation gamma‐ray burst optical counterparts. This paper deals with smaller telescope BART.
Following the detection of a long GRB 190919B by INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory), we obtained an optical photometric sequence its counterpart. The light curve emission exhibits unusually steep rise ~100 s after initial trigger. This behaviour is not expected from 'canonical' afterglow. As explanation, propose scenario consisting two superimposed flares: flare originating inner engine activity followed hydrodynamic peak external shock. inner-engine nature first...
Aims. We investigate the photometric activity of cataclysmic variable (CV) V795 Her. pay attention to time evolution length its superhump cycle Psh. how well profile is reproduced in individual phases Φsh also analyze mutual relation intensity light and superimposed rapid variations.
We report on a detection of an early rising phase optical afterglow (OA) long GRB 090726. resolve complicated profile the light curve. also investigate relation and X-ray emission this event. make use photometry OA obtained by 0.5 m telescope AI AS CR, supplemented data other observers, Swift/XRT data. The peaked at ~ 17.5 mag (R) t-T0 500 s. find complex curve during OA: approximately power-law rise, rapid transition to plateau, weak flare superimposed center slowly steepening decline...
The highly variable blazar OJ~287 is commonly discussed as an example of a binary black hole system. 130 year long optical light curve well explained by model where the central body massive 18.35$\times$10$^9$ solar mass that supports thin accretion disc. secondary 0.15$\times$10$^9$ impacts disc twice during its 12 orbit, and causes observable flares. Recently, it has been argued with typical AGN rate above mentioned should be at least six magnitudes brighter than OJ~287's host galaxy would...
RTS2, or Remote Telescope System 2nd Version, is an open-source, distributed and modular observatory control system. During the course of its development lasting over a decade, original goal to develop software capable searches for optical transients γ-ray bursts changed system full large observatories executing complex observing scenarios. In this presentation, we would like share our experience with meta-queues scheduling, developed primarily automation FLWO 1.2m telescope. Meta-queues...