arXiv subjects

T. Regimbau

Publications and source records attributed to T. Regimbau.

24 records · Page 2Linked to original sources

arXiv2005

Expected coalescence rates of NS-NS binaries for laser beam interferometers

The coalescence rate of two neutron stars (NS) is revisited. For estimation of the number of bound NS-NS and the probability of their coalescence in a timescale $τ$, the galactic star formation history, directly derived from observations, and the evolution of massive stars are considered. The newly established galactic merging rate is $(1.7\pm 1.0) \times 10^{-5} yr^{-1}$, while the local merging rate, including the contribution of elliptical galaxies, is about a factor of two higher, $3.4 \times 10^{-5} yr^{-1}$. Using the present data basis on galaxy distribution in the local universe and the expected sensitivity of the first generation of laser beam interferometers, we estimate that one event should occur every 125 years for LIGO and one event each 148 years for VIRGO. The situation is considerably improved for advanced-LIGO since we predict that 6 events per year should be detected whereas for a recently proposed VIRGO new configuration, the event rate might increase up to 3 events every two years.

astro-ph↗

arXiv2005

Expected Coalescence Rate of Double Neutron Stars for Ground Based Interferometers

In this paper we present new estimates of the coalescence rate of neutron star binaries in the local universe and we discuss its consequences for the first generations of ground based interferometers. Our approach based on both evolutionary and statistical methods gives a galactic merging rate of 1.7 10$^{-5}$ yr$^{-1}$, in the range of previous estimates 10$^{-6}$ - 10$^{-4}$ yr$^{-1}$. The local rate which includes the contribution of elliptical galaxies is two times higher, in the order of 3.4 10$^{-5}$ yr$^{-1}$. We predict one detection every 148 and 125 years with initial VIRGO and LIGO, and up to 6 events per year with their advanced configuration. Our recent detection rate estimates from investigations on VIRGO future improvements are quoted.

gr-qc↗

arXiv2004

Optimal combination of signals from co-located gravitational wave interferometers for use in searches for a stochastic background

This article derives an optimal (i.e., unbiased, minimum variance) estimator for the pseudo-detector strain for a pair of co-located gravitational wave interferometers (such as the pair of LIGO interferometers at its Hanford Observatory), allowing for possible instrumental correlations between the two detectors. The technique is robust and does not involve any assumptions or approximations regarding the relative strength of gravitational wave signals in the detector pair with respect to other sources of correlated instrumental or environmental noise. An expression is given for the effective power spectral density of the combined noise in the pseudo-detector. This can then be introduced into the standard optimal Wiener filter used to cross-correlate detector data streams in order to obtain an optimal estimate of the stochastic gravitational wave background. In addition, a dual to the optimal estimate of strain is derived. This dual is constructed to contain no gravitational wave signature and can thus be used as on "off-source" measurement to test algorithms used in the "on-source" observation.

gr-qc↗

arXiv2001

Cosmic Background of Gravitational Waves from Rotating Neutron Stars

The extragalactic background of gravitational waves produced by tri-axial rotating neutron stars was calculated, under the assumption that the properties of the underlying pulsar population are the same of those of the galactic population, recently derived by Regimbau & de Freitas Pacheco (2000). For an equatorial ellipticity of $ε$ = 10$^{-6}$, the equivalent density parameter due to gravitational waves has a maximum amplitude in the range 2$\times10^{-11}-3\times10^{-9}$, around 0.9-1.5 kHz. The main reasons affecting the theoretical predictions are discussed. This background is comparable to that produced by the ''ring-down'' emission from distorted black holes. The detection possibility of this background by a future generation of gravitational antennas is also examined.

astro-ph↗

arXiv2001

Population Synthesis of Pulsars: Magnetic Field Effects

New results based on methods of population synthesis, concerning magnetic field effects on the evolution of pulsars are reported. The present study confirms that models with timescales for the magnetic field decay longer than the pulsar lifetime are in better agreement with data. These new simulations indicate that the diagram log($P\dot P$) - log($t_s$) alone cannot be used to test field decay models. The dispersion of the values of the initial period and magnetic field can explain the observed behaviour of the data points in such a diagram. The simulations also indicate that the statistical properties of anomalous X-ray pulsars and soft-gamma repeaters (magnetar candidates) are compatible with those derived for objects born in the high side tail of the magnetic field distribution. The predicted birth rate of neutron stars having field strengths in excess of 10$^{14}$ G is one object born each 750 yr.

astro-ph↗

arXiv2000

Gravitation Wave Emission from Radio Pulsars Revisited

We report a new pulsar population synthesis based on Monte Carlo techniques, aiming to estimate the contribution of galactic radio pulsars to the continuous gravitational wave emission. Assuming that the rotation periods of pulsars at birth have a Gaussian distribution, we find that the average initial period is 290 ms. The number of objects with periods equal to or less than 0.4 s, and therefore capable of being detected by an interferometric gravitational antenna like VIRGO, is of the order of 5100-7800. With integration times lasting between 2 and 3 yr, our simulations suggest that about two detections should be possible, if the mean equatorial ellipticity of the pulsars is $ε$ =10$^{-6}$. A mean ellipticity an order of magnitude higher increases the expected number of detections to 12-18, whereas for $ε< 10^{-6}$, no detections are expected

astro-ph↗