N. G. Pulatova

Main Astronomical Observatory

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L. Zadorozhna

Taras Shevchenko National University of Kyiv

A. V. Tugay

Taras Shevchenko National University of Kyiv

I. B. Vavilova

National Academy of Sciences of Ukraine

Victor Doroshenko

University of Tübingen

S. V. Nazarov

Crimean Astrophysical Observatory

СГ

С. Г. Сергеев

Special Astrophysical Observatory

ГА

Г. А. Борман

Crimean Astrophysical Observatory

A. A. Vasylenko

National Academy of Sciences of Ukraine

I. S. Troitsky

St Petersburg University

V. M. Larionov

St Petersburg University

Cooperative Institutions

The Ohio State University

University of Turku

Max Planck Institute for Astronomy

Taras Shevchenko National University of Kyiv

Max Planck Society

National Institute for Astrophysics

National Academy of Sciences of Ukraine

Max Planck Institute for Radio Astronomy

Turku Centre for Computer Science

St Petersburg University

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The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT★

Monthly Notices of the Royal Astronomical Society (2013)

C. M. Raiteri M. Villata F. D’Ammando V. M. Larionov Mark Gurwell

Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily gamma-ray observations by Fermi. Discrete correlation analysis between the optical and gamma-ray emission reveals correlation with a time lag of 0 +- 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time scales than corresponding gamma-ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiation is located downstream from the optical and gamma-ray-emitting zone in the jet. The mean optical degree of polarisation slightly decreases over the considered period and in general it is higher when the flux is lower. The optical electric vector polarisation angle (EVPA) shows a preferred orientation of about 15 deg, nearly aligned with the radio core EVPA and mean jet direction. Oscillations around it increase during the 2011-2012 outburst. We investigate the effects of a geometrical interpretation of the long-term flux variability on the polarisation. A helical magnetic field model predicts an evolution of the mean polarisation that is in reasonable agreement with the observations. These can be fully explained by introducing slight variations in the compression factor in a transverse shock waves model.

Flare

10.1093/mnras/stt1672

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Citations (108)

NUMERICAL ESTIMATOR FOR LARGE-SCALE COSMIC STRUCTURES

Odessa Astronomical Publications (2018)

A. V. Tugay N. G. Pulatova A. D. Zhoga

Components of large-scale structure (LSS) of Universe includes galaxy clusters , walls , filaments , groups and field galaxies. The question of spatial organization of all these components remains open despite of a number of recently developed methods of LSS analysis. In this paper we introduce new continuous structural parameter of galaxy distribution for the determining of the type of LSS surrounding. This parameter is based on comparison of the radial distribution of galaxies around the certain point with the uniform one. Our method for structure parameter calculation is based on the distribution of 1000 closets galaxies to the selected one. Such number was selected because most galaxy clusters contains up to 1000 galaxies. When we exceed 1000th closest galaxy we will leave possible cluster or filament and will pass to another type of LSS. We suppose that in uniform distribution of galaxies their number should increase as third power a distance, similar to luminosity. Therefore the inverse dependence of galaxy distance from number should be cubic root. New structural parameter was introduced as the difference of this dependence of cubic root. The main type of cosmic surrounding for a galax is defined by the value and the sign of such structural parameter. If a galaxy lies in a cluster the distances of nearby galaxies will be less than cubic root. We integrated distance difference for all 1000 galaxies and get negative structural parameter in this case. If a galaxy lies in a void, the distances of surrounding galaxies will be larger than cubic root. In such case the structural parameter will be positive. New parameter was calculated for sky distribution of SDSS galaxies at distances from 50 to 150 Mpc. Analyzing obtained values, we come to conclusion that our structural parameter can be used for the division of LSS components and extragalactic filament detection.

10.18524/1810-4215.2018.31.144738

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Radio properties of the low-redshift isolated galaxies with active nuclei

Kinematika i fizika nebesnyh tel (Online) (2023)

N. G. Pulatova I. B. Vavilova A. A. Vasylenko O. M. Ulyanov

Âëàñòèâîñò³ ³çîëüîâàíèõ ãàëàêòèê ³ç àêòèâíèìè ÿäðàìè íà z < 0.05 ó ðàä³îä³àïàçîí³Ìåòà ðîáîòè.Äîñë³äaeóþòüñÿ âëàñòèâîñò³ 61 ³çîëüîâàíî¿ ãà ëàê òèêè ç àêòèâíèìè ÿäðàìè (³çîëüîâàí³ ÀßÃ) â ðàä³îä³àïàçîí³ íà ÷åðâî íèõ çì³ùåííÿõ z < 0.05.Âèá³ðêó áóëî îòðèìàíî øëÿõîì ïåðåõðåñíî¿ êîðåëÿö³¿ êàòàëîãó 2MIG (êàòàëîã ³çîëüîâàíèõ ãàëàêòèê íà áàç³ îãëÿäó íåáà 2MASS) ³ç êàòàëîãîì êâàçàð³â/ÀßÃ Veron-Cetty ³ îáìåaeåíà çà çîðÿíîþ âåëè÷èíîþ 4 m < K s £ 12 m , ïðîìåíåâîþ øâèäê³ñòþ V r < < 15 000 êì/ñ òà â³äñòàííþ äî íàéáëèae÷î¿ çíà÷èìî¿ ãàëàêòèêè.Ö³ îáìåaeåííÿ ñâ³ä÷àòü, ùî ³çîëüîâàí³ ÀßÃ íå ìàëè ç³òêíåíü

Red shift

10.15407/kfnt2023.02.047

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BVRI CCD-photometry of comparison stars in the fields of active galaxies. V

Astrophysics (2013)

В.Т. Дорошенко С. Г. Сергеев Yu. S. Efimov G. A. Borman D. N. Okhmat

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Statistical study of isolated and non-isolated AGNs in the Local Universe

Proceedings of the International Astronomical Union (2012)

N. G. Pulatova I. B. Vavilova Peter Berczik

Abstract We present the main results of statistical study of general properties of isolated AGN hosts and AGN hosts in pairs at z <0.05 as concerns with the environmental influence on the nuclear galaxy activity. With this aim we compiled the sample of 61 isolated AGNs selected from 2MIG Catalog and Catalog Veron+2010, and the sample of 109 AGNs in pairs selected from NED database. We found a significant excess content of Sy 2 type galaxies in comparison with Sy 1 type galaxies in both samples (44% and 11% among isolated AGNs, 48% and 6% among AGNs in pairs, respectively). Isolated AGN hosts of all spectral types are located, in average, at the more far distances and have a more complicated structure than AGNs in pairs as well as they are mostly of late morphological types. Our statistical analysis shows that the observed nuclear activity of isolated 2MIG AGNs during last 3 billions years and more, first of all, is connected with the internal galaxy parameters (relative mass/size, dark/visible matter content, multi-wavelength properties of gas-dust medium in accretion disks, tor's structure, central black hole mass etc.).

10.1017/s1743921312020091

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X-ray spectral features and classification of selected QSOs

arXiv (Cornell University) (2021)

L. Zadorozhna Anatolii Tugay N. G. Pulatova O. I. Maluy

We present the results of a systematic analysis of the XMM-Newton spectra of nearby optically bright QSOs. The objects have been selected from X-ray Galaxy Catalog Xgal20. It is a catalog of 1172 manually identified and classified galaxies, obtained as a cross-correlation between the 4XMM-DR9 catalog and the Hyper-Linked Extragalactic Databases and Archives (HyperLeda) with an X-ray flux greater than 1E-13 erg/cm^2/s. The goal of this work is to characterize the X-ray spectral properties of selected QSOs in the 0.1 - 10 keV energy band. The majority of the sources (6 out of 11), are classified as radio-quiet QSOs. We studied optical spectra, hardness ratios and performed X-ray spectral fits for the 10 brighter sources. In most cases, the power law model with absorption is good enough to simulate observed continua. Although the details of the spectrum in some sources significantly complicate the model for fitting. The majority of sources have steep spectra Gamma > 2.1. Extremely steep photon index 2.4 - 2.5 in our sample occurs for three radio-loud type I quasars. We detected Fe K-alpha line for two radio-loud type II quasars. We find no strong evidence for spectral hardening above 2 keV neither for quasars of type I nor for obscured type II. For each quasar its type was established both based on the features and details of observed X-ray spectrum and previous data.

QSOS

Spectral index

10.48550/arxiv.2110.07373

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Advanced morphology of VIPERS galaxies

arXiv (Cornell University) (2021)

Olexandr Gugnin Anatolii Tugay N. G. Pulatova L. Zadorozhna

We calculated morphological parameters for 70821 galaxies from VIPERS (spectroscopic galaxy survey performed on VIMOS spectroscope at VLT). These parameters includes Gini, M20, Concentration, Asymmetry and Smoothness. Results correlate with the distribution of these parameters for other simulated and observed samples. We also studied dependence of these parameters with Sersic power index of radial distribution of surface brightness of galaxy image. Our aim was to find a clear separation of VIPERS galaxies on elliptical and spiral. This is necessary for testing the method of Sersic index (ns) calculation in statmorph program. To find such bimodality we use B-V color index from VIPERS database. To perform the error analysis of morphological parameters we simulated galaxy images with random background of different magnitude and estimated the errors as dispersion of the parameters. We also found asymptotic values of errors of morphological parameters by increasing the numbers of mock images. To analyse the possible variation of each morphological parameter during the convolution of close galactic images, we have simulated them to research. In the result of this investigation we have analysed the dependence of the every morphological parameter from CAS and Gini/M20 statistics from the distance between galactic centers. The differences between our results for VIPERS and Gini-M20 distribution for PanStarrs galaxies at z<0.5 could be explained it by cosmological evolution of galaxies. We found out that in modern Universe there are much more elliptical galaxies than at z>0.5 which corresponds to VIPERS sample. Also we concluded that galaxy mergers were more frequent in the early Universe.

Smoothness

Surface brightness fluctuation

Bimodality

Shape parameter

10.48550/arxiv.2110.11666

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Multi-wavelength properties and SMBH's masses of the isolated AGNs in the Local Universe

I. B. Vavilova A. A. Vasylenko Iu. Babyk N. G. Pulatova

10.5281/zenodo.60643

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