arXiv subjects

Z. N. Osmanov

Publications and source records attributed to Z. N. Osmanov.

16 recordsLinked to original sources

arXiv2025

Maximum possible energies of electrons accelerated in magnetospheres of rotating black holes

Our aim is to evaluate the maximum attainable energies of electrons accelerated by means of the magneto-centrifugal mechanism. We examine how the range of maximum possible energies, as well as the primary limiting factors, vary with black hole mass. Additionally, we analyse the dependence of the maximum relativistic factor on the initial distance from the black hole and its spin factor in the range 0.1 - 0.2. We model the acceleration of electrons on rotating magnetic field lines and apply several constraining mechanisms: the inverse Compton scattering, curvature radiation, and the breakdown of the bead-on-the-wire approximation. As a result, the maximum Lorentz factors for electron acceleration vary with the type of black hole. For stellar-mass black holes, electrons can be accelerated up to the Lorentz factors 1.3 * 10^3 - 1.3 * 10^4 with only co-rotation constrain affecting the maximum relativistic factor; In intermediate-mass black holes, the Lorentz factors are in the interval 1.3 * 10^4 - 1.1 * 10^5; For the supermassive black holes the Lorentz factors range from 7 * 10^4 to 1.7 * 10^5; while the ultra-massive black hole located at the center of Abell 1201 can accelerate electrons up to 10^6 with both the co-rotation and Inverse Compton in Thomson regime determining the final Lorentz factor for the last three categories.

astro-ph.HE↗

arXiv2025

The possibility for panspermia in the galaxy by means of planetary dust grains

By obtaining the assumption that planetary dust particles can escape from the gravitational attraction of a planet, we consider the possibility for the dust grains to leave the star's system by means of the radiation pressure. By taking the typical dust parameters into account, we consider their dynamics and show that they can reach the deep cosmos, taking part in panspermia. It has been shown that, during $5$ billion years, the dust grains will reach $10^5$ stellar systems, and by taking the Drake equation into account, it has been shown that the whole galaxy will be full of planetary dust particles.

astro-ph.EP↗

arXiv2025

Can the solar atmosphere generate very high energy cosmic rays?

The origin and acceleration of high-energy particles in space (cosmic rays), constitute important topics in modern astrophysics. Among the The origin and acceleration of high-energy particles, constituting cosmic rays, is likely to remain an important topic in modern astrophysics. Among the two categories - galactic and solar cosmic rays - the latter are much less investigated. Primary source of solar cosmic ray particles are impulsive explosions of the magnetized plasma known as solar flares and coronal mass ejections. These particles, however, are characterized by relatively low energies compared to their galactic counterparts. In this work, we explore resonance wave-wave (RWW) interaction between the polarized electromagnetic radiation emitted by the solar active regions, and the quantum waves associated with high-energy, relativistic electrons generated during solar flares. Mathematically, the RWW interaction problem boils down to analyzing a Klein-Gordon equation (spin less electrons) embedded in the electromagnetic field. We find that RWW could accelerate the relativistic electrons to enormous energies even comparable to energies in the galactic cosmic rays.

astro-ph.SR↗

arXiv2023

Are we visible to advanced alien civilizations?

We considered the question of how our artificial constructions are visible to advanced extraterrestrial civilizations. Taking the universality of the laws of physics, we found that the maximum distance where the detection is possible is of the order of $3000$ ly and under certain conditions Type-II advanced alien societies might be able to resolve this problem.

physics.pop-ph↗

arXiv2023

Excitation of Langmuir waves in the magnetospheres of AGN

In the paper we study the process of excitation of Langmuir waves in the magnetospheres of active galactic nuclei (AGN), by taking a general-relativistic expression of the Goldreich-Julian density into account. We considered the linearised set of equations which describe dynamics of the studied mechanism: the Euler equation, the continuity equation and the Poisson equation. After solving the dispersion relation and obtaining the instability growth rate, we explored it versus several physical parameters: electron's and proton's relativistic factors and the mass and luminosity of AGN, which are supposed to be Kerr black holes. We showed that the parametric process of energy pumping into the Langmuir waves is very efficient and the electrostatic field's amplitude will be exponentially amplifying, which might account for pair creation, particle acceleration and plasma heating processes in the nearby regions of AGN.

astro-ph.GA↗

arXiv2022

On the fraction of particles involved in magneto-centrifugally generated ultra-high energy electrons in the Crab pulsar

The earthward journey of ultra high energy electrons ($\sim 600$ TeV) produced in the Pulsar atmosphere by Landau damping of magneto-centrifugally excited Langmuir waves (drawing energy form the rotational slowdown) on primary electrons, is charted. It is shown, that just as they escape the light cylinder zone, the ultra-high energy particles, interacting with the medium of the Crab nebula, rapidly loose their energy via the quantum synchrotron process, producing highly energetic gamma rays ~ $\sim 0.6$PeV. Interacting with the cosmic background radiation in the interstellar medium, only a tiny fraction of these ultra high energy photons (via the $γγ$ channel) are, then transformed into electron-positron pairs. Detected flux of these photons imposes an upper limit on the fraction ($4\times 10^{-7}$) of the magnetospheric particles involved in the process of generation of ultra-high energy photons (up to $600$ TeV).

astro-ph.HE↗

arXiv2022

Dynamics of a particle in the generalised Ellis-Bronnikov wormhole on the rotating Archimede's spiral

A particle moving on curved magnetic field lines in the wormhole metrics is considered. The dynamics of a single particle is studied on a co-rotating parameterized magnetic field line. Being interested in the force-free dynamics we choose the rotating Archimedes' spiral embedded in the generalized Ellis-Bronnikov metrics. By analysing the phase space, we explore how the physical parameters affect the motion of the particle and it is shown that the particles may reach the force free regime, eventually escaping the wormhole.

gr-qc↗

arXiv2022

Resonant energization of particles by radio AGN

A new mechanism of particle acceleration, based on the resonant interaction of a classical electromagnetic wave (EM) with a quantum wave (associated with a relativistic particle), is explored. In a model illustrative calculation, we study the fate of a Klein Gordon wave subjected to the intense radio frequency waves generated in the vicinity of an active galactic nuclei (AGN). In the framework of the paper we examine a quantum wave associated with a relativistic particle, and it is shown that the group velocity of the wave approaches the speed of light, implying that the particles resonantly exchange energy with EM waves, eventually leading to acceleration of particles to very high energies. For typical parameters of under accreting Eddington radio AGN, it is shown that the resonant energization could catapult particles to extreme energies $\sim 10^{16-20}$eV.

astro-ph.HE↗

arXiv2022

Prospects of SETI by small size optical telescopes

In the present manuscript we consider the possibility of SETI by the small size (with diameters less than 1 m) optical telescopes. Calculations are performed for typical parameters of the mentioned type of telescopes. In particular, we show that the techno-signatures of Type-2.x and Type-3.x civilizations might be detected. It is demonstrated that it is possible to detect as hot megastructures (up to 4000 K) built around main sequence stars and pulsars as well as von Neumann extraterrestrial probes.

physics.pop-ph↗

arXiv2022

The synchrotron mechanism and the high energy flair from PKS 1510-089

In order to understand the role of the synchrotron emission in the high energy gamma-ray flares from PKS 1510-089, we study generation of the synchrotron emission by means of the feedback of cyclotron waves on the particle distribution via the diffusion process. The cyclotron resonance causes the diffusion of particles along and across the magnetic field lines. This process is described by the quasi-linear diffusion (QLD) that leads to the increase of pitch angles and generation of the synchrotron emission. We study the kinetic equation which defines the distribution of emitting particles. The redistribution is conditioned by two major factors, QLD and the dissipation process, that is caused by synchrotron reaction force. The QLD increases pitch angles, whereas the synchrotron force resists this process. The balance between these two forces guarantees the maintenance of the pitch angles and the corresponding synchrotron emission process. The model is analyzed for a wide range of physical parameters and it is shown that the mechanism of QLD provides the generation of high energy (HE) emission in the GeV energy domain. According to the model the lower energy, associated with the cyclotron modes, provokes the synchrotron radiation in the higher energy band.

astro-ph.GA↗

arXiv2021

Electromagnetic vortex beam dynamics in degenerate electron-positron astrophysical plasmas

For degenerate astrophysical electron-positron plasmas we have considered dynamics of electromagnetic beams carrying angular momentum. It is found for arbitrary level of degeneracy such a beam having the power exceeding a certain critical value breaks up into many filaments, eventually leading to the formation of stable spatial solitons keeping zero field in the center of the structure.

physics.plasm-ph↗

arXiv2021

On the simultaneous generation of radio and soft X-ray emission by AXP 4U 0142+61

In the present paper we study the possibility of a simultaneous generation of radio waves and soft $X$-rays by means of the quasi-linear diffusion (QLD) in the anomalous pulsar AXP 4U 0142+61. Considering the magnetosphere composed of the so-called beam component and the plasma component respectively, we argue that the frozen-in condition will inevitably lead to the generation of the unstable cyclotron waves. These waves, via the QLD, will in turn influence the particle distribution function, leading to certain values of the pitch angles, thus to an efficient synchrotron mechanism, producing soft $X$-ray photons. We show that for physically reasonable parameters of magnetospheric plasmas, the QLD can provide generation of radio waves in the following interval $40$ MHz-$111$ MHz connected to soft $X$-rays for the domain $0.3$keV-$1.4$keV.

astro-ph.HE↗

arXiv2021

Solitary structure formation and self-guiding of electromagnetic beam in highly degenerate electron plasma

In the present paper we consider the nonlinear interaction of high frequency intense electromagnetic (EM) beam with degenerate electron plasmas. In a slowly varying envelop approximation the beam dynamics is described by the couple of nonlinear equations for the vector and scalar potentials. Numerical simulations demonstrate that for an arbitrary level of degeneracy the plasma supports existence of axially symmetric 2D solitons which are stable against small perturbations. The solitons exist if the power trapped in the structures, being the growing function of soliton amplitude, is above a certain critical value but below the value determining by electron cavitation. The robustness of obtained soliton solutions was verified by simulating the dynamics of initial Gaussian beams with parameters close to the solitonic ones. After few diffraction lengths the beam attains the profile close to the profile of the ground state soliton and propagates for a long distance without detectable distortion. The simulations have been performed for the input Gaussian beams with parameters far from ground state solutions. It is shown that the beam parameters are oscillating near the parameters of the ground soliton solution and thus the formation of oscillating waveguide structures takes place.

physics.plasm-ph↗

arXiv2021

Synchrotron emission from a nearby zone of SgrA$^*$

Quasi-linear diffusion (QLD), driven by the cyclotron instability, is proposed as a mechanism for the possible generation of synchrotron emission in the nearby zone of SgrA$^*$. For physically reasonable parameters, the QLD, by causing non-zero pitch angle scattering lets electrons with the relativistic factors of the order of $10^8$ emit synchrotron radiation in the hard $X$-ray spectral band $\sim120$ keV.

astro-ph.HE↗

arXiv2021

Relativistic effects of rotation in $γ$-ray pulsars -- Invited Review

In this paper we consider relativistic effects of rotation in the magnetospheres of $γ$-ray pulsars. The paper reviews the progress achieved in this field during the last three decades. For this purpose we examine direct centrifugal acceleration of particles and corresponding limiting factors: constraints due to the curvature radiation and the inverse Compton scattering of electrons against soft photons. Based on the obtained results generation of parametrically excited Langmuir waves and the corresponding Landau-Langmuir-centrifugal drive is studied.

astro-ph.HE↗

arXiv2021

Fluid Dynamics in the Ellis Wormhole

In the Ellis wormhole metrics we study characteristics of fluid dynamics and the properties of linear sound waves. By implying the energy-momentum equation and the continuity equation in the general relativistic manner we examine the flow dynamics and solve the corresponding equations for a relatively simple case - radial flow. To study the linear sound waves the equations governing the mentioned physical system are linearized and solved and interesting characteristic properties are found.

gr-qc↗