A. Królak

Data analysis of gravitational-wave signals from spinning neutron stars. I. The signal and its detection

We present a theoretical background for the data analysis of the gravitational-wave signals from spinning neutron stars for Earth-based laser interferometric detectors. We introduce a detailed model of the signal including both the frequency and the amplitude modulations. We include the effects of the intrinsic frequency changes and the modulation of the frequency at the detector due to Earths motion. We estimate the effects of the stars proper motion and of relativistic corrections. Moreover we consider a signal consisting of two components corresponding to a frequency

Nature of Singularities in Gravitational Collapse

f

The Mock LISA Data Challenges: from Challenge 1B to Challenge 3

and twice that frequency. From the maximum likelihood principle we derive the detection statistics for the signal and we calculate the probability density function of the statistics. We obtain the data analysis procedure to detect the signal and to estimate its parameters. We show that for optimal detection of the amplitude modulated signal we need four linear filters instead of one linear filter needed for a constant amplitude signal. Searching for the doubled frequency signal increases further the number of linear filters by a factor of 2. We indicate how the fast Fourier transform algorithm and resampling methods commonly proposed in the analysis of periodic signals can be used to calculate the detection statistics for our signal. We find that the probability density function of the detection statistics is determined by one parameter: the optimal signal-to-noise ratio. We study the signal-to-noise ratio by means of the Monte Carlo method for all long-arm interferometers that are currently under construction. We show how our analysis can be extended to perform a joint search for periodic signals by a network of detectors and we perform a Monte Carlo study of the signal-to-noise ratio for a network of detectors.

Data analysis of gravitational-wave signals from spinning neutron stars. IV. An all-sky search

We discuss several aspects of cosmic censorship hypothesis. There is evidence both in favor of and against the hypothesis. On one hand one can prove that cosmic censorship holds in several special cases and on the other hand there are a number of special solutions of Einstein equations in which it is violated. One way to resolve cosmic censorship problem is to test it observationally. We point out several possibilities of such tests using present and future instruments.

Naked strong curvature singularities in Szekeres spacetimes

The Mock LISA Data Challenges are a programme to demonstrate and encourage the development of LISA data-analysis capabilities, tools and techniques. At the time of this workshop, three rounds of challenges had been completed, and the next was about to start. In this paper we provide a critical analysis of the entries to the latest completed round, Challenge 1B. The entries confirm the consolidation of a range of data-analysis techniques for galactic and massive-black-hole binaries, and they include the first convincing examples of detection and parameter estimation of extreme-mass-ratio inspiral sources. In this paper we also introduce the next round, Challenge 3. Its data sets feature more realistic waveform models (e.g., galactic binaries may now chirp, and massive-black-hole binaries may precess due to spin interactions), as well as new source classes (bursts from cosmic strings, isotropic stochastic backgrounds) and more complicated nonsymmetric instrument noise.

Estimation of the post-Newtonian parameters in the gravitational-wave emission of a coalescing binary.

We develop a set of data analysis tools for a realistic all-sky search for continuous gravitational-wave signals and we test our tools against simulated data. The aim of the paper is to prepare for an analysis of the real data from the EXPLORER bar detector; however, the methods that we present apply both to data from the resonant bar detectors that are currently in operation and the laser interferometric detectors that are in the final stages of construction and commissioning. With our techniques we shall be able to perform an all-sky coherent search of 2 days of data from the EXPLORER detector for a frequency bandwidth of 0.76 Hz in one month with 250 Mflops computing power. This search will detect all the continuous gravitational-wave signals with the dimensionless amplitude larger than

Data analysis of gravitational-wave signals from spinning neutron stars. III. Detection statistics and computational requirements

2.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}23}

Detectability of the gravitational wave signal from a close neutron star binary with mass transfer

with 99% confidence, assuming that the noise in the detector is Gaussian.

A proof of the cosmic censorship hypothesis

We investigate the occurrence and nature of naked singularities in the Szekeres spacetimes. These spacetimes represent irrotational dust. They do not have any Killing vectors and they are generalizations of the Tolman - Bondi - Lemaitre spacetimes. It is shown that in these spacetimes there exist naked singularities that satisfy both the limiting focusing condition and the strong limiting focusing condition. The implications of this result for the cosmic censorship hypothesis are discussed.

Searching for gravitational waves from known pulsars using the {\cal F} and {\cal G} statistics

The effect of the recently calculated second post-Newtonian correction on the accuracy of the estimation of the parameters of the gravitational-wave signal from a coalescing binary is investigated. It is shown that the addition of this correction degrades considerably the accuracy of the determination of the individual masses of the members of the binary. However the chirp mass and the time parameter in the signal are still determined to a very good accuracy. The possibility of estimating the effects of other theories of gravity is investigated. The performance of the Newtonian filter is investigated and it is compared with the performance of post-Newtonian search templates introduced recently. It is shown that both search templates can extract accurately useful information about the binary.