A5017406871- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Neutrino Physics Research
- Gamma-ray bursts and supernovae
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
- Cosmology and Gravitation Theories
- Enterobacteriaceae and Cronobacter Research
- Terahertz technology and applications
- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Particle Detector Development and Performance
Special Astrophysical Observatory
2016-2025
Crimean Astrophysical Observatory
2024
Russian Academy of Sciences
2024
Astro Space Center
2022-2023
University College Cork
2022
Institute of Radio Astronomy
2011-2014
National Academy of Sciences of Ukraine
2012-2014
Abstract We analyze the variability of parsec-scale jet directions in active galactic nuclei (AGNs). Our analysis involves 317 AGNs at frequencies ranging from 2 to 43 GHz, and is made possible by developing an automatic direction measurement procedure. find strong significant variations a one quarter these AGNs; effect likely ubiquitous, not detected rest due limited sensitivity observations epoch coverage. Apparent rotation speeds range 0.21 deg yr−1 GHz 1.04 GHz. This frequency dependence...
Light curves for more than century optical photometric observations of the blazar OJ 287 reveals strong flares with a quasi-period about 12 years. For long time, this period has been interpreted by processes in binary black hole system. We propose an alternative explanation period, which is based on Doppler factor periodic variations emitting region caused jet helicity. Using multi-epoch very large baseline interferometry (VLBI) carried out framework MOJAVE (Monitoring Of Jets Active...
We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. use radio-to-optical data obtained by Whole Earth Blazar Telescope, 15 GHz from Owens Valley Radio Observatory, 91 and 103 Atacama Large Millimeter Array, near-infrared Rapid Eye Monitor telescope, as well Swift (optical-UV X-rays) Fermi ($\gamma$ rays) satellites to flux spectral variability correlation between changes at different wavelengths. Unprecedented $\gamma$-ray flaring activity was...
We study the jet physics of BL Lac object PKS 2233-148 making use synergy observational data sets in radio and gamma-ray energy domains. The four-epoch multi-frequency (4-43 GHz) VLBA observations focused on parsec-scale were triggered by a flare gamma-rays registered Fermi-LAT April 23, 2010. also used 15 GHz from OVRO 40-m telescope MOJAVE monitoring programs. Jet shape source is found to be conical scales probed setting lower limit about 0.1 its unknown redshift. Nuclear opacity dominated...
ABSTRACT The magnetic field plays a significant role in the phenomenon of highly collimated jets active galactic nuclei (AGN). Relativistic effects prevent direct reconstruction direction as transverse to electric vectors on radio maps. We determined topology B-field by modelling distributions total and linearly polarized intensity, polarization degree, deviation from local jet axis further comparison with observational data. consider (i) helical different twist angle (ii) toroidal...
ABSTRACT The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows prominent big blue bump and strong Compton dominance. We present the results of 2-yr multiwavelength campaign led by Whole Earth Blazar Telescope (WEBT) to study both quasar core beamed jet this source. WEBT data are complemented ultraviolet X-ray from Swift, γ-ray Fermi. modelled using optical near-infrared mean spectra obtained during campaign, together with templates. give prescriptions correct...
Abstract Multiband optical photometry data of blazar S5 0716+714 obtained from 2002 to 2019 reveal stable color index change with flux variability. We analyzed this trend under variability caused by the Doppler factor in presence a curved photon energy spectrum. A break spectrum emitting electrons, radiative losses, or log-parabolic electron distribution, synchrotron self-absorption acting compact jet part forms such explained observed geometric effects only assumption that radiating region...
The flat-spectrum radio quasar 4C $+$71.07 is a high-redshift ($z=2.172$), $\gamma$-loud blazar whose optical emission dominated by the thermal radiation from accretion disc. has been detected in outburst twice AGILE $\gamma$-ray satellite during period end of October - mid November 2015, when it reached flux order $F_{\rm E>100\,MeV} = (1.2 \pm 0.3)\times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$ and (3.1 0.6)\times s$^{-1}$, respectively, allowing us to investigate properties jet region. We...
Abstract The curved shape of the kiloparsec-scale jet blazar OJ 287 is analyzed in framework precession central engine, on existence which a large number studies over past decades are based. data necessary for analysis velocity and angle with line sight obtained based two competing assumptions about X-ray emission mechanism jet. Namely, there were both inverse Compton scattering cosmic microwave background under assumption relativistic source radiation. For latter one, we showed that...
We analyze the variability of parsec-scale jet directions in active galactic nuclei (AGNs). Our analysis involves 317 AGNs at frequencies ranging from 2 to 43 GHz, and is made possible by developing an automatic inner direction measurement procedure. find strong significant variations a one quarter these AGNs; effect likely ubiquitous, not detected rest due limited sensitivity observations epoch coverage. Average apparent rotation speeds range 0.21 deg/yr GHz 1.04 GHz. This frequency...
The blazar S5 1803+784 has a unique high temporal resolution data series for about year provided by the TESS satellite. By performing our aperture photometry of summarized on 10-30 full-frame image cuts to reduce Poisson noise, we obtained light curve from 01.2022 01.2023. Using new method determining shortest characteristic variability time and supplementing study with long-term multiband ZTF AZT-8 observations, trace evolution micro-variability parameters their correlation characteristics....
For the blazar BL Lac, we analyze data from TESS and multiband observations that were obtained using MTM-500 telescope of Crimean Astrophysical Observatory 1.09.2022 to 30.09.2022. During this period, Lac showed strong variability, both accompanied unaccompanied by changes in spectral index. The shortest characteristic variability times are mainly range 0.2 1 day do not depend on object brightness, index, average amplitude within corresponding intervals light curve. It indicates mechanisms...
The beamed inverse Compton/cosmic microwave background model has generally been used for the interpretation of X-ray radiation from kiloparsec-scale jets core-dominated quasars. Recent Fermi-LAT and HST observations have brought this into question. We examine assumption that X-rays jet quasar PKS 1127−145 are produced by Compton scattering central source emission. In context, we show both similarity distinction between observed radio spectral indices some knots can be explained under a...
The magnetic field plays a significant role in the phenomenon of highly collimated jets active galactic nuclei (AGN). Relativistic effects prevent direct reconstruction direction as transverse to electric vectors on radio maps. We determined topology B-field by modeling distributions total and linearly polarized intensity, polarization degree, deviation from local jet axis further comparison with observational data. consider (i) helical different twist angle; (ii) toroidal surrounded sheath...
The 1745+624 and PKS 1127−14 quasar jets are considered. X-ray emission of the near-central source knots is produced by inverse Compton scattering radiation, while on cosmic microwave background occurs at distant knots. competition these mechanisms has allowed to estimate angles between line sight. ratio radio flux densities shown conform theoretical dependence redshift.
The X-ray emission of the nearest to core 3C 273 kiloparsec jet knot A1 is shown be produced by inverse Compton scattering quasar rather than Thomson scattering. For last process, a large quantity thermal plasma required at knot, fact not confirmed polarization observations. Conclusion made that low-energy cut-off occurs power-law spectrum ultrarelativistic electrons in A1.