Жарияланымдар / Публикации
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- Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Interaction of Black Hole Magnetospheres with Inclined Ambient FieldsMagnetic fields play a central role in black hole astrophysics, powering relativistic jets and other energetic phenomena. While near-horizon magnetic field is usually assumed to originate from the accretion flow, additional large-scale magnetic fields - such as those supplied by a companion neutron star in stellar-mass binaries or by galactic fields around supermassive black holes - may also affect the horizon-threading flux. In this work, we study the superposition of a weak arbitrarily inclined external uniform magnetic field with the internal Blandford-Znajek split-monopole field around a Schwarzschild black hole. This setup generically gives rise to magnetic null points, where the total field vanishes. We compute the magnetic flux through an arbitrarily tilted hemisphere of the event horizon and show that the flux can be substantially suppressed by the external field. In the axisymmetric case, the flux can even vanish completely. However, with nonzero inclination, complete cancellation becomes impossible, despite significant reduction. We further explore the ionization and subsequent particle acceleration from a Keplerian accretion disk, finding that efficient collimated outflows persist even under significant field inclination. We show that the acceleration is critically dependent on the external field orientation, with the escape fraction maximized at non-zero inclinations due to the destabilization of trapping zones and minimized in the anti-aligned configuration, where closed magnetic loops effectively suppress the outflow. We discuss the astrophysical implications of these findings, proposing that geometric flux cancellation can serve as a mechanism for jet quenching in compact binaries and offering an explanation for the lack of a prominent large-scale jet in Sgr A*. - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Interaction of Black Hole Magnetospheres with Inclined Ambient FieldsMagnetic fields play a central role in black hole astrophysics, powering relativistic jets and other energetic phenomena. While near-horizon magnetic field is usually assumed to originate from the accretion flow, additional large-scale magnetic fields - such as those supplied by a companion neutron star in stellar-mass binaries or by galactic fields around supermassive black holes - may also affect the horizon-threading flux. In this work, we study the superposition of a weak arbitrarily inclined external uniform magnetic field with the internal Blandford-Znajek split-monopole field around a Schwarzschild black hole. This setup generically gives rise to magnetic null points, where the total field vanishes. We compute the magnetic flux through an arbitrarily tilted hemisphere of the event horizon and show that the flux can be substantially suppressed by the external field. In the axisymmetric case, the flux can even vanish completely. However, with nonzero inclination, complete cancellation becomes impossible, despite significant reduction. We further explore the ionization and subsequent particle acceleration from a Keplerian accretion disk, finding that efficient collimated outflows persist even under significant field inclination. We show that the acceleration is critically dependent on the external field orientation, with the escape fraction maximized at non-zero inclinations due to the destabilization of trapping zones and minimized in the anti-aligned configuration, where closed magnetic loops effectively suppress the outflow. We discuss the astrophysical implications of these findings, proposing that geometric flux cancellation can serve as a mechanism for jet quenching in compact binaries and offering an explanation for the lack of a prominent large-scale jet in Sgr A*. - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Thin accretion-disc transfer functions in the q-metric spacetime: quadrupolar lensing signatures(Cornell University, 2026-09-07); ; ; Aliya TaukenovaWe study geometrically thin equatorial disc images in the static, axisymmetric q-metric spacetime using backward ray tracing. The Schwarzschild solution is recovered at $q=0$; for the nonzero deformations considered here, $r=2M$ is a curvature singularity rather than an event horizon. For a distant nearly face-on observer, we construct the first three equatorial transfer functions $r_m(b;q)$. In the {Schwarzschild} limit, the resolved third-crossing interval contains the critical impact parameter $b=3\sqrt{3}M$. As $q$ increases from $-0.3$ to $0.3$, the branch center shifts from $b_{3,c}/M\simeq3.716$ to $6.702$. In units of the physical monopole mass $\mathcal M=(1+q)M$, it instead decreases from $b_{3,c}/\mathcal M\simeq5.309$ to $5.156$. Much of the displacement in metric-parameter units therefore reflects the changing monopole scale. At fixed $\mathcal M$, the inclined first-intersection maps show that the contour dimensions increase with $q$, with larger relative changes near the inner disc. A prescribed power-law emissivity and relativistic frequency-shift weighting yield direct images whose integrated flux differs from the Schwarzschild value by at most $2.4\%$. Between the endpoint models, the horizontal median-flux position increases by $8.8\%$ and the interquartile width by $14.5\%$. Within this emission prescription, the residual deformation dependence appears mainly as a displacement and broadening of the brightness distribution. Higher-order radiative contributions are not included. - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, A shadows from the static black hole mimickers(Al-Farabi Kazakh National University, 2023-01-10); In this work, we study shadows from the naked singularity spacetime. The most analytical solutions of black hole shadows only investigated the case that the geodesic equations for photons can separate variables. We review the spherical null naked singularity metric and this spherically symmetric naked singularity spacetime metric is the solution of Einstein equations with an anisotropic fluid source which has no photon sphere. We also review a static, axially-symmetric singular solution of the vacuum Einstein’s equations without an event horizon which is can be used to describe the exterior gravitational field of a mass distribution with quadrupole moment. Moreover, the corresponding spacetime is characterized by the presence of naked singularities. It is theoretically known that not only a black hole can cast shadow, but other compact objects such as naked singularities, gravastar or boson stars can also cast shadows. We present the analytical calculation of shadows for both naked singularities spacetime and compare with the shadow of Schwarzschild static black hole, we show that this can serve as a black hole mimicker. Keywords: compact object, naked singularity, shadow.Цитирования (OpenAlex) 5 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Gravitational Refraction of Compact Objects with Quadrupoles(Multidisciplinary Digital Publishing Institute, 2023-02-28)Цитирования (OpenAlex) 10Цитирования (OpenCitations) 5 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Application of GBT theorem for Gravitational deflection of light by Compact Objects(Al-Farabi Kazakh National University, 2023-03-13)Цитирования (OpenAlex) 6Цитирования (OpenCitations) 3 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Stability Properties of Geometrothermodynamic Cosmological Models(Multidisciplinary Digital Publishing Institute, 2023-09-28); Цитирования (OpenAlex) 1Цитирования (OpenCitations) 1 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Nonlinear electrodynamical lensing of electromagnetic waves on the dipole magnetic field of the magnetar(World Scientific, 2023-12-01); ; Y. AimuratovWe study numerically a combined gravitational and nonlinear magnetic lensing effect on electromagnetic flux. A magnetar with a dipole magnetic field and background gravitational field is considered to deflect the light rays which passed through its magnetosphere. We assume a square wave front with sides [Formula: see text][Formula: see text]m as a grid with the [Formula: see text][Formula: see text]m dynamic step. At the nodes of this grid, the rays enter perpendicularly into the cubic area, which covers the main magnetic lensing region with a magnetar at the center. On the basis of general relativity (GR) and nonlinear vacuum electrodynamics, the distribution of rays by the deflection angle in the combined field of the magnetar was obtained. On the basis of the analysis of the obtained data, it is possible to assert that the magnetic field distorts the result of gravitational lensing. Therefore, the magnetar is regarded as a gravitational-magnetic lensing object, wherein the magnetic field induces axial distortion within [Formula: see text]. These results are expected to be detectable by modern instruments.Цитирования (OpenAlex) 5Цитирования (OpenCitations) 3 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Bending of Light by Magnetars within Generalized Born–Infeld Electrodynamics: Insights from the Gauss–Bonnet Theorem(Multidisciplinary Digital Publishing Institute, 2024-01-22); ; ; A.S. TaukenovaWe compute the weak bending angle of light within generalised Born–Infeld electrodynamics as it passes through the equatorial plane of a magnetic dipole. We start by considering the refractive index associated with the dipole within generalised Born–Infeld electrodynamics. Then, we calculate the Gaussian optical curvature based on these refractive indices. Using the Gauss–Bonnet theorem, we derive a formula to quantify the deflection angle in the presence of a strong magnetic field from a dipole. Our results align with results obtained through traditional geometric optics techniques, underscoring the importance of the Gauss–Bonnet theorem as a versatile tool for solving intricate problems in modern theoretical research. We apply our theoretical deflection angle formula to estimate the light bending in magnetars listed in the McGill catalogue, providing insights into the behaviour of light in environments with strong magnetic fields.Цитирования (OpenAlex) 5Цитирования (OpenCitations) 4 - Некоторые метрики заблокированы вашиминастройками согласия
Тип записи:Публикация, Black hole in a combined magnetic field: Ionized accretion disks in the jetlike and looplike configurations(American Physical Society, 2024-03-05); Цитирования (OpenAlex) 11Цитирования (OpenCitations) 8