arXiv subjects

A. O. Zaporozhchenko

Publications and source records attributed to A. O. Zaporozhchenko.

7 recordsLinked to original sources

arXiv2026

Damping of dynamical friction force in self-interacting ultralight dark matter and Fornax timing problem

The dynamics of globular clusters in the Fornax dwarf galaxy pose a challenge for the standard cold dark matter and can be used to test other models of dark matter. We study this dynamics in the context of an ultralight bosonic dark matter model, accounting for the damping term in a generalized Gross-Pitaevskii equation. Employing analytic formulas for the dynamical friction force, the infall time and evolution of globular clusters are compared in the cases with and without the damping term. It is argued that the damping term plays an important role in the Fornax timing problem in ultralight dark matter (ULDM) models. We found that the ULDM model with repulsive self-interaction can solve the Fornax timing problem in the absence of or with very small self-interaction, even if the initial position of the globular cluster is not far from the center of the galaxy. Still, the problem is resolved for strongly interacting repulsive ULDM, even for the most pressing case of globular cluster GC3, if its starting position exceeds 1.5 kpc.

astro-ph.GA↗

arXiv2026

Impact of space-time curvature coupling on the vacuum energy induced by a magnetic topological defect in flat space-time of arbitrary dimension

We have investigated vacuum polarization of a quantized charged massive scalar field in the presence of a magnetic topological defect, modeled as an impenetrable tube of finite thickness carrying magnetic flux. At the tube's surface, we imposed a general Robin boundary condition. Our analysis demonstrates that, in flat space-time, the total induced vacuum energy is independent of the coupling $ξ$ of the scalar field's interaction with the space-time curvature only in the special cases of Dirichlet and Neumann boundary conditions. For general Robin boundary conditions, however, the total induced vacuum energy depends on the coupling $ξ$ in a flat space-time and exhibits a nontrivial dependence on the parameter of the Robin boundary condition. We investigated the dependence of this effect not only on Robin's boundary condition parameter, but also on the tube thickness and the space-time dimensionality. We conclude that careful measurements of vacuum polarization effects in flat space-time may, in principle, provide an independent way to probe the $ξ$ coupling.

hep-th↗

arXiv2025

Analytic calculation of dynamical friction for Plummer sphere in ultralight dark matter

The dynamical friction force acting on a spatially extended probe (globular clusters and dwarf galaxies) moving in the environment of ultralight bosonic dark matter in the state of the Bose-Einstein condensate is determined. Modeling the probe as a Plumer sphere of radius $l_p$, the radial and tangential components of the dynamic friction force are found in an analytic form, which reduce in the limit $l_p \to 0$ to the corresponding analytic expressions obtained in the literature in the case of a point probe. The dependence of the dynamical friction force on boson particle mass $m$ was analyzed and found to be non-monotonous in the interval $10^{-23} - 10^{-21}$eV.

astro-ph.GA↗

arXiv2025

Magnetic field in vacuum of quantum spinor matter induced by a cosmic string in three-dimensional space

A linear magnetic topological defect (cosmic string) is modeled as a magnetic flux-carrying tube that is impenetrable to external spinor matter. The matter field is quantized in the background of this tube, with the most general set of boundary conditions ensuring both the tube's impenetrability and the self-adjointness of the Dirac Hamiltonian operator. We compute the induced vacuum magnetic flux along the tube in (3+1)-dimensional space-time. It was shown that the requirement for the total induced vacuum magnetic flux to be finite restricts the admissible boundary conditions to only one choice: the MIT quark bag boundary condition. The dependence of the effect on the transverse size of the tube and the flux inside the tube was also analyzed.

hep-th↗

arXiv2025

Dynamical friction in ultralight dark matter: Plummer sphere perspective

In models of dark matter composed of feebly interacting ultralight bosons in the state of Bose-Einstein condensate, the dynamical friction force acting on circularly moving globular clusters modelled as Plummer spheres is determined. Analytic expressions for both radial and tangential components of the dynamical friction force are given. We reveal that the dynamical friction force for the Plummer sphere deviates from that for a point probe of the same mass for a significantly large ratio of the Plummer sphere radius to its orbital radius, as well as for large values of the Mach number.

astro-ph.GA↗

arXiv2025

Dependence of scalar matter vacuum energy, induced by a magnetic topological defect, on the coupling to space-time curvature

We considered the vacuum polarization of a quantized charged scalar matter field in the background of a topological defect modeled by a finite-thickness tube with magnetic flux inside. The tube is impenetrable for quantum matter, and a generalized boundary condition of the Robin type is imposed at its surface. We have shown that in the flat space-time, the total induced vacuum energy does not depend on the coupling $(ξ)$ of the scalar field's interaction with the space-time curvature, only for the partial cases of the Dirichlet and Neumann boundary conditions on the tube's edge. However, for generalized Robin boundary conditions, the total induced energy depends on the coupling $ξ$ in flat space-time, at least for negative values of the boundary condition parameter $-π/2<θ<0$.

hep-th↗

arXiv2024

Dynamical friction in rotating ultralight dark matter galactic cores

Dynamical friction and stellar orbital motion in spiral galaxies with dark matter composed of ultralight bosons in the state of rotating Bose-Einstein condensate (BEC) are studied. It is found that the dynamical friction force is significantly affected by the topological charge of the vortex structure of the BEC core with the strongest effect at distances near the galactic center. It is also shown that the ultralight dark matter self-interaction plays an important role in studying the dynamical friction.

astro-ph.GA↗