Using the pseudo-Newtonian (PN) potential, we estimate the influence of
the repulsive cosmological constant Ʌ ~ 1.3×10-56
cm-2 implied by recent cosmological tests onto the motion of
both Small and Large Magellanic Clouds (SMC and LMC) in the
gravitational field of the Milky Way. The role of the cosmological
constant is most conspicuous when binding mass is estimated for the
satellite galaxies. We have found a strong influence of cosmic repulsion
on the total binding mass for both galaxies. We have found that in some
cases, the effect of the cosmic repulsion can be even comparable to the
effects of the dynamical friction and the Andromeda galaxy.
Read More
We study acceleration of current-carrying string loops governed by presence of an outer tension barrier and an inner angular momentum barrier in the field of black holes. Relativistic current carrying strings moving axisymmetrically along the axis of a black hole could in a simplified way represent plasma that exhibits associated string-like behavior. We demonstrate that string loops can be scattered near the black hole horizon and the energy of string oscillations can be efficiently converted to the energy of their linear motion. Such a transmutation effect can potentially represent acceleration of jets in active galactic nuclei and microquasars.
Read More
Kerr naked singularities (superspinars) have to be efficiently converted to a black hole due to accretion from Keplerian discs. In the final stages of the conversion process the near-extreme Kerr naked singularities (superspinars) provide a variety of extraordinary physical phenomena. Such superspinning Kerr geometries can serve as an efficient accelerator for extremely high-energy collisions enabling direct and clear demonstration of the outcomes of the collision processes. We shall discuss the efficiency and visibility of the ultra-high energy collisions in the deepest parts of the gravitational well of superspinning near-extreme Kerr geometries for the whole variety of particles freely falling from infinity. We demonstrate that the ultra high-energy processes can be obtained with no fine tuning of the motion constants and the products of the collision can escape to infinity with efficiency higher than in the case of the near-extreme black holes.
Read More
We investigate possible signatures of a Kerr naked singularity (superspinar) in the profiled spectral lines of radiation emitted by monochromatically and isotropically radiating point sources forming a Keplerian ring or disc around such compact object. We have found out that the profiled spectral line of the radiating Keplerian ring can be splitted into two parts due to the fact that there is no event horizon in the naked singularity spacetimes.
Read More
Using the pseudo-Newtonian (PN) potential, we estimate the influence of the repulsive cosmological constant Ʌ ~ 1.3×10-56 cm-2 implied by recent cosmological tests onto the motion of both Small and Large Magellanic Clouds (SMC and LMC) in the gravitational field of the Milky Way. The role of the cosmological constant is most conspicuous when binding mass is estimated for the satellite galaxies. We have found a strong influence of cosmic repulsion on the total binding mass for both galaxies. We have found that in some cases, the effect of the cosmic repulsion can be even comparable to the effects of the dynamical friction and the Andromeda galaxy.
Read More
We have previously applied several models of high-frequency
quasi-periodic oscillations (HF QPOs) to estimate the spin of the
central Kerr black hole in the three Galactic microquasars, GRS
1915+105, GRO J1655-40, and XTE J1550-564. Here we explore the
alternative possibility that the central compact body is a
super-spinning object (or a naked singularity) with the external
space-time described by Kerr geometry with a dimensionless spin
parameter a ≡ cJ/GM2> 1. We calculate the relevant
spin intervals for a subset of HF QPO models considered in the previous
study. Our analysis indicates that for all but one of the considered
models there exists at least one interval of a> 1 that is compatible
with constraints given by the ranges of the central compact object mass
independently estimated for the three sources. For most of the models,
the inferred values of a are several times higher than the extreme Kerr
black hole value a = 1. These values may be too high since the spin of
superspinars is often assumed to rapidly decrease due to accretion when
a ≫ 1. In this context, we conclude that only the epicyclic and the
Keplerian resonance model provides estimates that are compatible with
the expectation of just a small deviation from a = 1.
Read More
We introduce a pseudo-Newtonian gravitational potential describing the gravitational field of Schwarzschild black hole surrounded by a quintessential field. We also show, how the geodesic motion reflected in behaviour of general relativistic effective potential can be alternatively described by the pseudo-Newtonian one.
Read More
We present a detailed comparison of several integration schemes applied to the dynamic system consisting of a charged particle on the Kerr background endowed with the axisymmetric electromagnetic test field. In particular, we compare the performance of the symplectic integrator with several non-symplectic routines and discuss under which circumstances we should choose the symplectic one and when we should switch to some other scheme. We are basically concerned with two crucial, yet opposing aspects - accuracy of the integration and CPU time consumption. The latter is generally less critical in our application while the highest possible accuracy is strongly demanded.
Read More
We study transition from regular to chaotic motion in the neighbourhood of stable equilibrium point of a relativistic current-carrying string-loop located around Schwarzschild black hole. We demonstrate successive transfer from the purely regular, periodic motion through quasi-periodic motion to purely chaotic motion of the string loop, with increasing of its energy. We also calculated quasi-periodic fundamental frequencies, which are important for survival of corresponding KAM tori. Using maximal Lyapunov exponent we show how the chaoticity of the string loop motion changes with increase of the string loop energy
Read More
Relativistic current-carrying string loop moving axisymmetrically along the axis of a Schwarzschild black hole is investigated as model of relativistic jet formation. Acceleration of the string loop along its axis of symmetry shows regular and also irregular dependence on initial conditions. We will apply the theory of chaotic scattering on this problem.
Read More
