Conveners
Extragalactic astrophysics and cosmology
- Dmytro Orikhovskyi (Taras Shevchenko National University of Kyiv, Kyiv, Ukraine)
A connection between Supermassive Black Holes (SMBH) and galaxy growth has been suggested by a number of studies, based on empirical correlations between BH mass and integrated galaxy properties as galaxy bulge mass, total stellar mass, velocity dispersion and star formation rate (SFR). In particular current studies show that SFR and AGN activity appear to follow similar patterns with cosmic...
We present the results of photometric observations and research of blazar PKS1222+216 with high temporal resolution (30–60 s) in the B, V and R filters of Johnson/Bessel system. The observations were performed with the AZT-8 (D = 0,7 m; F = 2.8 m; CCD PL4710-1-BB-E2V) telescope of the observation station Lisnyky of Astronomical Observatory of Taras Shevchenko National University of Kyiv during...
Blazar variability appears to be stochastic in nature. However, a possibility of low-dimensional chaos was considered in the past, but with no unambiguous detection so far. If present, it would constrain the emission mechanism by suggesting an underlying dynamical system. We rigorously searched for signatures of chaos in \textit{Fermi}-Large Area Telescope light curves of 11 blazars. The data...
Hereby we present the results of photometric observations and research of two BL Lacertae objects: Markarian 501 and Markarian 421. The observations were performed with the AZT-8 (D = 70 cm, F = 2.8 m) telescope of the observation station Lisnyky of Astronomical Observatory of Taras Shevchenko National University of Kyiv during 2018-2020. The AZT-8 equipped with the PL4710-1-BB-E2V CCD and...
Thanks to the last years great success of the European Space Agency space mission GAIA and the latest data release of the 3D stellar positions and velocities in our Galaxy we now have a very accurate and homogenous data for the Milky Way Globular Cluster (GC) system space positions and velocities up to 200 kpc of Galactocentric distances. Based of the GC system current coordinates and...
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We use different machine learning techniques to create and compare classifiers for the search of compact star-forming galaxies (CSFGs). The methods considered were: k-nearest neighbours, deep neural network, and gradient...
We consider a data driven approach as an alternative to the traditional photometric techniques to determine distance moduli m-M to the galaxies. In our first work (Elyiv et al., 2020, Astron. & Astrophys.) we tested the five machine learning regression techniques for inference of $m-M$: linear, polynomial, k-nearest neighbors, Gradient boosting, and artificial neural network and obtained rms...
The 4XMM-DR10 catalogue is the largest database of X-ray sources, the last version of which contains 575158 unique X-ray. The aim of our work was to obtain a sample of X-ray galaxies. To reach this goal, we created the sample based on the HyperLEDA database that consists of 7181 objects. In the current work, we present general properties of the sample, namely the distribution in equatorial...
We calculated morphological parameters for test sample of 4659 galaxies from VIPERS survey. 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.
Black holes are one of the most mysterious objects in the universe. These objects(as you know) attracts particles towards it. It’s is formed when a heavy star dies,it forms a 4d curve in the space-time and attracts everything towards it. With this curvature,time is also effected. The more we go closer to the black hole the more the time gets dilated. This is explained by Einstein’s famous twin...
Galaxies interact with each other forming bigger galaxies, following the hierarchical scenario, where bigger structures evolve from smaller ones. Here, I will explore how signatures of hierarchical evolution can be found in the distribution of light, kinematics and dynamics of nearby galaxies while in the meantime understand the difficulties on the carried out research that is done in this field.
Investigating period changes of classical Cepheids through the framework of $O-C$ diagrams provides a unique insight to the evolution and nature of these variable stars. In this work, we carried out the $O-C$ diagram calculation of 148 Galactic Cepheids with century long coverage. In multiple cases we observed peculiar $O-C$ behaviours that indicated the possible presence of a formerly...
Galaxies evolve embedded in a vast gaseous halo that dwarfs the mass and spatial extent of stars in the galactic disk. Photoionization modeling suggests that cold circumgalactic gas has significantly lower densities than expected by theoretical predictions based on thermal pressure equilibrium with hot CGM gas. In this talk, I will demonstrate the impact of cosmic ray physics on the formation...
