arXiv subjects
Publications and source records attributed to M. V. Sazhin.
A lower limit for a neutral black hole size is obtained in the frames of the string gravity model with the second order curvature correction. It is shown that this effect remains when the third order curvature correction is also taken into account and argued that such restriction does exist in all perturbative orders of curvature expansions.
The Sky Polarization Observatory (SPOrt) is presented as a project aimed to measure the diffuse sky polarized emission, from the International Space Station, in the frequency range 20-90 GHz with 7 degrees of HPBW. The SPOrt experimental configuration is described with emphasis on the aspects that make SPOrt the first European scientific payload operating at microwave wavelengths.
We present the cosmological and astrophysical objectives of the SPOrt mission, which is scheduled for flying on the International Space Station (ISS) in the year 2002 with the purpose of measuring the diffuse sky polarized radiation in the microwave region. We discuss the problem of disentangling the cosmic background polarized signal from the Galactic foregrounds.
We study the possible contribution of a stochastic gravitational wave background to the anisotropy of the cosmic microwave background (CMB) in cold and mixed dark matter (CDM and MDM) models. We test this contribution against recent detections of CMB anisotropy at large and intermediate angular scales. Our likelihood analysis indicates that models with blue power spectra ($n \simeq 1.2$) and a tensor to the scalar quadrupole ratio of $R = C_2^T /C_2^S \sim 2$ are most consistent with the anisotropy data considered here. We find that by including the possibility of such background in CMB data analysis it can drastically alter the conclusion on the remaining cosmological parameters.
We consider the dependence of the internal structure of a neutron star in a close binary system on the semi-major axis of the binary orbit, focusing on the case when the Roche lobes of the components are nearly filled. We adopt a polytropic equation of state. The temporal evolution of the semi-major axis and its dependence on the mass ratio of the binary components and the polytropic index are determined. The calculation are carried out right up to the moment of contact, when quasi-stationary model becomes invalid. We analyze differences in the shapes of the pulses of gravitational radiation emitted by a pair of point masses and by a binary neutron star, taking into account its internal structure and tidal deformations.
The cosmic microwave background (CMB) polarization, whose experimental detection must become the next natural step in the study of the CMB radiation, depends on the dynamics of hydrogen recombination in the Universe, on the relation between the power of scalar perturbations and gravitational waves, and on the presence or absence of secondary ionization. The spectrum of the CMB anisotropy is currently known with an accuracy that is high enough to draw some conclusions about the cosmological parameters and about the presence of secondary ionization of matter. The reduction of observational data strongly suggests the presence of secondary ionization. We consider the effect of this ionization at redshifts $z<100$ on the CMB polarization generated by the scalar mode on various angular scales.
The fluctuation of the angular positions of reference extragalactic radio and optical sources under the influence of the irregular gravitational field of visible Galactic stars is considered. It is shown that these angular fluctuations range from a few up to hundreds of microarcseconds. This leads to a small rotation of the celestial reference frame. The nondiagonal coefficients of the rotation matrix are of the order of a microarcsecond. The temporal variation of these coefficients due to the proper motion of the foreground stars is of the order of one microsecond per 20 years. Therefore, the celestial reference frame can be considered inertial and homogeneous only to microarcsecond accuracy. Astrometric catalogues with microarcsecond accuracy will be unstable, and must be reestablished every 20 years.
An internal singularity of a string four-dimensional black hole with second order curvature corrections is discussed. A restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization of the surrounding space-time caused by this minimal-size black hole is also discussed.