Valentin N. Rudenko

Very high frequency gravitational wave background in the universe

Astrophysical sources of high frequency gravitational radiation are considered in association with a new interest in the very sensitive HFGW receivers required for the laboratory GW Hertz experiment. Special attention is paid to the phenomenon of primordial black-hole evaporation. It acts as a black body to all kinds of radiation, including gravitons, and, therefore, emits an equilibrium spectrum of gravitons during its evaporation. A limit on the density of high frequency gravitons in the universe is obtained, and the possibility of detecting them is briefly discussed.

Reception frequency bandwidth of a gravitational resonant detector with optical readout

A gravitational resonant bar detector with a large scale Fabry-Perot (FP) cavity as an optical readout and a mechanical displacement transformer is considered. We calculate, in a fully analytical way, the final receiver bandwidth in which the potential sensitivity, limited only by the bar thermal noise, is maintained despite the additional thermal noise of the transformer and the additive noise of the optical readout. We also discuss an application to the OGRAN project, where the bar is instrumented with a 2 m long FP cavity.

Gravitational free mass antenna as an angular gravity gradiometer

Abstract In the low frequency region 10 −4 –10 −5 Hz a long base gravitational-wave interferometer is considered as a differential tiltmeter insensitive to perturbations of the local normal to the land. The effect of variations of the reciprocal deflection of two pendulum-mirrors is estimated for three conceivable scenarios of the earth core movements. The possibility of measurement of this effect is discussed according to the noise background estimate typical for modern gravitational antenna projects.

Search for astro-gravitational correlations

A special arrangement of a gravity-wave experiment, in which the noise background of the gravity detector is investigated near time markers corresponding to the detection of astrophysical events accompanying neutron or gamma bursts, is studied. A general algorithm is developed for analyzing the traces for the case of resonant solid-state detectors. The efficiency of the algorithm is demonstrated in a reanalysis of old data concerning the “neutron-gravity correlation” effect associated with the explosion of the SN1987A Supernova. Modifications of the algorithm for searching for gamma-gravity correlations are proposed.A new approach in the gravitational wave experiment is considered. In addition to the old method of searching for coincident reactions of two separated gravitational antennae it was proposed to seek perturbations of the gravitational detector noise background correlated with astrophysical events such as neutrino and gamma ray bursts which can be relaibly registered by correspondent sensors. A general algorithm for this approach is developed. Its efficiency is demonstrated in reanalysis of the old data concerning the phenomenon of neutrino-gravity correlation registered during of SN1987A explosion.

Low-frequency signals of large-scale gravitational-wave interferometers

The applicability of large-scale gravitational-wave interferometers for measuring low-frequency geophysical signals is considered. The main goal of this paper is to study the mechanism for the penetration of quasi-static geophysical perturbations to the high-frequency interferometer port. Attention is drawn to the parametric nature of this effect related to slow variations of the optical transfer function. The geophysical modulation index is calculated for all harmonics of the output spectrum and for the photon circulation frequency resulting from the noise illumination of neighboring optical modes near the central resonance. The model of an interferometer with a two-component pump is analyzed in an effort to improve the geophysical signal recording quality. Numerical estimates for various operating regimes of the instrument are presented, along with discussions of the possibility of recording weak gravitational effects.

The status of the gravitational wave setups at moscow university

Abstract The program of developing experimental gravitational wave research at SAI (MSU) was started in 1990 (the general perspective was reported at the Australian EFVV-conference). This program was declared in cooperation with Nuclear Research Institute of Russian Ac. of Sciences (NRI) and was stimulated by observational results during the SN 1987A explosion. The economical problems of our country did not permit the development of that program as it had been planned initially but nevertheless some steps have been made. In this report we present briefly the status of the gravitational setups which have been already installed and some which are in progress.

Analysis of the Noise Background of the ULITKA Gravitational Antenna

A long-term analysis of the noise background of the “ULITKA” gravitational-wave antenna is presented in connection with searches for anomalous impulsive signals and slow solar-terrestrial correlations with a period of 27 days. Automated selection and estimation algorithms are used, including nonparametric criteria for the statistical dependence of samples uniform in time. The upper limit for the gravitational-noise background is confirmed by the observational statistics. The presence of slow, anomalous correlations is not confirmed.

Dynamics of a free mass interferometric gravitational antenna with small loss suspensions

Abstract Fine dynamical effects in laser interferometric gravitational antennas are considered. It is shown that for high quality factors of the mirrors suspension an instability can arise during long continuous operation of an antenna.

Detection of gravitational geodynamic effects with gravitational-wave interferometers

We study the operation of the laser gravitational-wave long-base interferometer as a detector of tidal variations of the Earth’s gravitational field. Empirical estimates of the low-frequency noise level of that detector, as well as an estimate of the magnitude of the detected signal accompanying the Earth’s inner core oscillations have been obtained.

Algorithms for data analysis in gravitational-wave experiments

The detection of gravitational radiation from relativistic objects in the Universe is discussed. Modern programs designed to search for such signals based on current astrophysical concepts about the nature of the sources are considered. A comparative analysis indicates that available gravitational-wave detectors, whose sensitivity to metric perturbations is on the order of 10−21, are unlikely to be able to detect cosmic gravitational waves. However, the detector sensitivity can be increased using a multichannel method to search for astro-gravitational correlations, in which the noise background of the gravitational-wave detectors is analyzed in parallel with data from neutrino and gamma-ray detectors.