arXiv subjects

Anton Smirnov

Publications and source records attributed to Anton Smirnov.

10 recordsLinked to original sources

arXiv2026

Boxy/Peanut Bulges: Comparative Analysis of EGIPS Galaxies and TNG50 Models

We investigated the properties of boxy/peanut-shaped (B/PS) bulges in a sample of 71 galaxies from the Edge-on Galaxies in the Pan-STARRS Survey (EGIPS) and 20 simulated galaxies from Illustris TNG50 using multicomponent photometric decomposition. For each real and simulated galaxy, we obtained a suitable photometric model in which the B/PS bulge was represented by a dedicated 2D photometric function. For real galaxies, we found that more flattened X-structures are generally residing in larger B/PS bulges. When tested against the galaxy masses, we verified that both larger bulges and more flattened X-structures are typically found in more massive galaxies. Since large bars are also known to reside in more massive galaxies, we conclude that the flatness of X-structures in larger B/PS bulges has a physical origin, rather than being solely a result of projection effects due to differences in observed bar viewing angles. When comparing the properties of B/PS bulges between EGIPS galaxies and TNG50 galaxies, with bars rotated for different viewing angles, we found that B/PS bulges in TNG50 are considerably smaller and less luminous in terms of total intensity. This is consistent with previous studies of bar properties in TNG50, indicating the B/PS bulges in TNG50 differ from those in real galaxies, as do their parent bars.

astro-ph.GA↗

arXiv2026

Comparison of Static and Evolving Potentials in the Orbital Dynamics of Globular Clusters in the Central Region of the Galaxy

A comparative analysis of the dynamics of the orbital motion (regular or chaotic) of 45 globular clusters in the central region of the Galaxy with a radius of 3.5 kpc is carried out. The static and evolving (based on the semi-analytical cosmological model of Gomez et al. (2010) and Hagi et al. (2015)) potentials of the Galaxy are considered both in the form of an axisymmetric and non-axisymmetric potential of the Galaxy with a rotating elongated bar with the following parameters at the present time: mass $10^{10} M_\odot$, length of the major semi-axis 5 kpc, rotation angle of the bar axis 25$^o$, angular velocity of rotation 40 km s$^{-1}$ kpc$^{-1}$ . To form the 6D-phase space required for integrating the orbits, the most accurate astrometric data to date from the Gaia satellite (Vasiliev \& Baumgardt, 2021), as well as new refined average distances (Baumgardt \& Vasiliev, 2021) were used. We used a frequency method for analysis of the chaotic/regular orbital motion of all 45 GCs. The results are summarized in the table, which provides an overview of each GC in our sample, the degree of chaotization in both the static and evolving potentials, and the influence of the central rotating bar on the degree of orbital chaotization in both cases. It is shown that the orbital dynamics have undergone minor changes during the transition from the static to the evolving potential. This confirms our previously obtained result that changes in the masses and sizes of the gravitational potential components act on orbital parameters in opposite ways, and at small galactocentric distances this influence is maximally compensated, while the orbits of distant objects and objects with large apocentric distances experience the greatest influence.

astro-ph.GA↗

arXiv2025

Relationship between Poincaré Sections and Spectral Characteristics of Orbits of Globular Clusters in the Central Region of the Galaxy

In the paper, orbital dynamics, regular or chaotic, of globular clusters (GCs) in the central region of the Galaxy, which is subject to the greatest influence of the rotating bar, has been studied. Such methods for determining chaos as Poincaré sections and spectral methods have been compared. The relationship between the Poincaré sections and the spectral characteristics of the orbits has been estimated. The sample includes 45 globular clusters in the central region of the Galaxy with a radius of 3.5 kpc. To form the 6D-phase space required for integrating the orbits, the most accurate astrometric data to date from the Gaia satellite, as well as new refined average distances, have been used. The following, most realistic, bar parameters have been adopted: mass $10^{10} M_\odot$, length of the major semi-axis of the bar model in the form of a triaxial ellipsoid is 5 kpc, angle of rotation of the bar axis is $25^o$, rotation velocity is 40 km s$^{-1}$ kpc $^{-1}$. The result of the study is that a 100\% correlation between the classification by Poincaré sections and the spectral characteristics of the orbits has been established. Consequently, the classification by Poincaré sections can be replaced by a more visual analysis of the amplitude spectra of the orbits. Thus, two lists of GCs: with regular and chaotic dynamics have been compiled. The GCs with varying degrees of orbital chaos have separately been distinguish.

astro-ph.GA↗

arXiv2025

Spectral Analysis of the Orbital Dynamics of Globular Clusters in the Central Region of the Milky Way

A new method for determining the nature of the orbital motion (chaotic or regular) of globular clusters in the central region of the Galaxy with a radius of 3.5 kpc, which are most affected by the bar, is proposed. The method is based on calculating the orbital power spectrum as a function of time and calculating the entropy of the power spectrum as a measure of orbital chaos. The sample includes 45 globular clusters. To form the 6D phase space required for integrating the orbits, the most accurate astrometric data to date from the Gaia satellite (Vasiliev \& Baumgardt, 2021) were used, as well as new refined average distances (Baumgardt \& Vasiliev, 2021). Orbits of globular clusters are obtained in a non-axisymmetric potential with a bar in the form of a triaxial ellipsoid embedded in an axisymmetric potential, traditionally used by us to construct orbits of globular clusters, described in detail in the paper by Bajkova et al. (2023a). The following, most realistic, bar parameters are adopted: mass $10^{10} M_\odot$, length of the major semi-axis 5 kpc, angle of rotation of the bar axis 25$^o$, angular velocity of rotation 40 km s$^{-1}$ kpc$^{-1}$. A list of 23 globular clusters with regular dynamics and 22 globular clusters with chaotic dynamics is determined. The correlation of the obtained classification of globular clusters with the classification obtained by us using other methods in the work of Bajkova et al. (2024a) was determined.

astro-ph.GA↗

arXiv2024

The influence of the bar on the chaotic dynamics of globular clusters in the central region of the Galaxy

The paper is devoted to the analysis of the influence of the galactic bar on the nature of the orbital motion (chaotic or regular) of globular clusters in the central region of the Galaxy with a radius of 3.5 kpc, which are subject to the greatest influence of the bar. The sample includes 45 globular clusters. To form the 6D phase space required for integrating the orbits, the most accurate astrometric data to date from the Gaia satellite (Vasiliev, Baumgardt, 2021) were used, as well as new refined average distances (Baumgardt, Vasiliev, 2021). The orbits of the globular clusters were obtained both in an axisymmetric potential and in a potential including the bar. The following, most realistic, bar parameters were adopted: mass $10^{10} M_\odot$, semi-major axis length 5 kpc, bar axis rotation angle 25$^o$, angular rotation velocity 40 km s$^{-1}$ kpc$^{-1}$. The analysis of the chaoticity/regularity of the orbital motion in both potentials was carried out using one of the most effective methods, namely, the frequency method, which consists in calculating the drift of fundamental frequencies. As a result, the influence of the bar on the dynamics of each GC of the sample was assessed. It is established that 8 GCs changed regular dynamics to chaotic under the influence of the bar, and 9 GCs changed chaotic dynamics to regular one.

astro-ph.GA↗

arXiv2024

Scaling Transformers for Low-Bitrate High-Quality Speech Coding

The tokenization of speech with neural audio codec models is a vital part of modern AI pipelines for the generation or understanding of speech, alone or in a multimodal context. Traditionally such tokenization models have concentrated on low parameter-count architectures using only components with strong inductive biases. In this work we show that by scaling a transformer architecture with large parameter count to this problem, and applying a flexible Finite Scalar Quantization (FSQ) based bottleneck, it is possible to reach state-of-the-art speech quality at extremely low bit-rates of $400$ or $700$ bits-per-second. The trained models strongly out-perform existing baselines in both objective and subjective tests.

eess.AS↗

arXiv2024

Analysis of regularity/chaoticity of the globular clusters dynamics on the central region of the Milky Way

We analyzed the regularity/chaoticity of the orbits of 45 globular clusters in the central region of the Galaxy with a radius of 3.5 kpc, which are subject to the greatest influence from an elongated rotating bar. Various analysis methods were used, namely, methods for calculating the Highest Lyapunov Exponents, the method of Poincar$\acute{e}$ sections, the frequency method based on the calculation of fundamental frequencies, as well as the visual assessment method. Bimodality was discovered in the histogram of the distribution of positive Lyapunov exponents, calculated in the classical version, without renormalization of the shadow orbit, which makes it possible to implement a probabilistic method of GC classification. To construct the orbits of globular clusters, we used a gravitational potential model with a bar in the form of a triaxial ellipsoid, described in detail in the work of Bajkova et al., Izvestiya Glavnoi astronomicheskoi observatorii v Pulkove, {\bf 228}, 1 (2023). The following bar parameters were adopted: mass $10^{10} M_\odot $, semimajor axis length 5 kpc, bar viewing angle 25$^o$, rotation velocity 40 km s$^{-1}$ kpc$^{-1}$. To form the 6D-phase space required for orbit integration, the most accurate astrometric data to date from the Gaia satellite (EDR3) (Vasiliev, Baumgardt, 2021), as well as new refined average distances to globular clusters (Baumgardt, Vasiliev, 2021) were used. A classification is made of globular clusters with regular and chaotic dynamics. As the analysis showed, globular clusters with small pericentric distances and large eccentricities are most susceptible to the influence of the bar and demonstrate the greatest chaos. It is shown that the results of classifying globular clusters by the nature of their orbital dynamics, obtained using the various methods of analysis considered in the work, correlate well with each other.

astro-ph.GA↗

arXiv2023

The problem of dust attenuation in photometric decomposition of edge-on galaxies and possible solutions

The presence of dust in spiral galaxies affects the ability of photometric decompositions to retrieve the parameters of their main structural components. For galaxies in an edge-on orientation, the optical depth integrated over the line-of-sight is significantly higher than for those with intermediate or face-on inclinations, so it is only natural to expect that for edge-on galaxies, dust attenuation should severely influence measured structural parameters. In this paper, we use radiative transfer simulations to generate a set of synthetic images of edge-on galaxies which are then analysed via decomposition. Our results demonstrate that for edge-on galaxies, the observed systematic errors of the fit parameters are significantly higher than for moderately inclined galaxies. Even for models with a relatively low dust content, all structural parameters suffer offsets that are far from negligible. In our search for ways to reduce the impact of dust on retrieved structural parameters, we test several approaches, including various masking methods and an analytical model that incorporates dust absorption. We show that using such techniques greatly improves the reliability of decompositions for edge-on galaxies.

astro-ph.GA↗

arXiv2023

Structure formation and thermal conduction in polymer-based composites obtained by fused filament fabrication

Fused filament fabrication (FFF) is widely used to obtain polymer-based composites with improved mechanical and thermal conduction properties. The effective properties of the composites are sensitive to its structure including the shape, distribution, and orientation of inclusions in the matrix and FFF-specific defects. The present work aims to study the formation of composite structure and relate it to the measured effective thermal conduction properties. Polymer flow in the hot end and the structure of printed samples are studied by metallography. The effective thermal diffusivity is measured by the laser flash method and analyzed by the Maxwell Garnett theory. Fibers in a polymer-matrix composite visualize polymer flow in the hot end of the FFF printer. In the nozzle, fibers are generally oriented parallel to the flow direction while gas bubbles may locally disturb flow and disorient fibers. Printed composite Carbon fiber/TPU inherits preferential orientation of fibers observed in the filament. Disorientation of fibers relative to the alignment direction increases after printing. In the printed Al2O3/PA composite, there is a lattice of triangle-based cylindrical pores parallel to the extrusion direction. Al2O3 particles are of irregular shape and approximately equiaxed. No segregation or agglomeration are observed. Significant anisotropy of thermal diffusivity is observed in the printed samples of 5%vol. Carbon fiber/TPU composite. The measured effective thermal diffusivity of printed Al2O3/PA composites is essentially isotropic and significantly increases with the volume fraction of inclusions. In the studied FFF-printed composites, the effective thermal diffusivity is proportional to the thermal diffusivity of polymer matrix, which is sensitive to its structure formed in non-equilibrium conditions of rapid quenching from liquid phase.

cond-mat.mtrl-sci↗

arXiv2020

The Halos and Environments of Nearby Galaxies (HERON) II: The outer structure of edge-on galaxies

The HERON project is aimed at studying halos and low surface brightness details near galaxies. In this second HERON paper we consider in detail deep imaging (down to surface brightness of ~28 mag/arcsec$^2$ in the r band) for 35 galaxies, viewed edge-on. We confirm a range of low surface brightness features previously described in the literature but also report new ones. We classify the observed outer shapes of the galaxies into three main types (and their prototypes): disc/diamond-like (NGC891), oval (NGC4302), and boxy (NGC3628). We show that the shape of the outer disc in galaxies does not often follow the general 3D model of an exponential disc: 17 galaxies in our sample exhibit oval or even boxy isophotes at the periphery. Also, we show that the less flattened the outer disc is, the more oval or boxy its structure. Many galaxies in our sample have an asymmetric outer structure. We propose that the observed diversity of the galaxy outer shapes is defined by the merger history and its intensity: if no recent multiple minor or single major merging took place, the outer shape is diamond-like or discy. On the contrary, interacting galaxies show oval outer shapes, whereas recent merging appears to transform the outer shape to boxy.

astro-ph.GA↗