Galactic Binary Gravitational Wave Noise within LISA Frequency Band

Gravitational wave noise associated with unresolved binary stars in the Galaxy is studied with the special aim of determining the upper frequency at which it stops to contribute at the rms noise level of the proposed space-born interferometer (LISA). The upper limit to this background is derived from the statistics of SN Ia explosions, part of which can be triggered by binary white dwarf coalescences. The upper limiting frequency at which binary stochastic noise crosses LISA rms sensitivity is found to lie within the range 0.03-0.07 Hz, depending on the galactic binary white dwarf coalescence rate. To be reliably detectable by LISA, the energy density of relic cosmological background per logarithmic frequency interval should be Omega_{GW}h_{100}^2>10^{-8} at f>0.03 Hz.Comment: 16 pages with 1 eps figure, aasms4.sty, to appear in the ApJ vol. 494 February 20, 1998 issu

Neutron star spin-kick velocity correlation effect on binary neutron star coalescence rates and spin-orbit misalignment of the components

We study the effect of the neutron star spin -- kick velocity alignment observed in young radio pulsars on the coalescence rate of binary neutron stars. Two scenarios of the neutron star formation are considered: when the kick is always present and when it is small or absent if a neutron star is formed in a binary system due to electron-capture degenerate core collapse. The effect is shown to be especially strong for large kick amplitudes and tight alignments, reducing the expected galactic rate of binary neutron star coalescences compared to calculations with randomly directed kicks. The spin-kick correlation also leads to a much narrower NS spin-orbit misalignment.Comment: 7 pages, 5 figures, accepted for publiction in MNRA

Luminosity function of binary X-ray sources calculated using the Scenario Machine

Using the ``Scenario Machine'' we have carried out a population synthesis of X-ray binaries for the purpose of modelling of X-ray luminosity functions (XLFs) in different types of galaxies: star burst, spiral, and elliptical. This computer code allows to calculate, by using Monte Carlo simulations, the evolution of a large ensemble of binary systems, with proper accounting for the spin evolution of magnetized neutron stars. We show that the XLF has no universal type. It depends on the star formation rate in the galaxy. Also it is of importance to take into account the evolution of binary systems and life times of X-ray stages in theoretical models of such functions. We have calculated cumulative and differential XLFs for the galaxy with the constant star formation rate. Also we have calculated cumulative luminosity functions for different intervals of time after the star formation burst in the galaxy and curves depicting the evolution of the X-ray luminosity after the star formation burst in the galaxy.Comment: 22 pages, 13 figure