I. Yakushin

Localization of gravitational wave sources with networks of advanced detectors

Coincident observations with gravitational wave (GW) detectors and other astronomical instruments are among the main objectives of the experiments with the network of LIGO, Virgo, and GEO detectors. They will become a necessary part of the future GW astronomy as the next generation of advanced detectors comes online. The success of such joint observations directly depends on the source localization capabilities of the GW detectors. In this paper we present studies of the sky localization of transient GW sources with the future advanced detector networks and describe their fundamental properties. By reconstructing sky coordinates of ad hoc signals injected into simulated detector noise, we study the accuracy of the source localization and its dependence on the strength of injected signals, waveforms, and network configurations.

Detailed comparison of LIGO and Virgo inspiral pipelines in preparation for a joint search

Presented in this paper is a detailed and direct comparison of the detection pipelines used by LIGO and Virgo in their attempt to observe gravitational waves from binary neutron star systems. In order to test the search programs, numerous inspiral signals were added to 24 h of simulated detector data. The efficiencies of the different pipelines were tested, and found to be very similar. Parameter estimation routines were also tested. We demonstrate that there are definite benefits if LIGO and Virgo conduct a joint coincident analysis; these advantages include increased detection efficiency and information on source sky location.

A comparison of methods for gravitational wave burst searches from LIGO and Virgo

The search procedure for burst gravitational waves has been studied using 24 h of simulated data in a network of three interferometers (Hanford 4 km, Livingston 4 km and Virgo 3 km are the example interferometers). Several methods to detect burst events developed in the LIGO Scientific Collaboration (LSC) and Virgo Collaboration have been studied and compared. We have performed coincidence analysis of the triggers obtained in the different interferometers with and without simulated signals added to the data. The benefits of having multiple interferometers of similar sensitivity are demonstrated by comparing the detection performance of the joint coincidence analysis with LSC and Virgo only burst searches. Adding Virgo to the LIGO detector network can increase by 50% the detection efficiency for this search. Another advantage of a joint LIGO–Virgo network is the ability to reconstruct the source sky position. The reconstruction accuracy depends on the timing measurement accuracy of the events in each interferometer, and is displayed in this paper with a fixed source position example.

Performance of the waveburst algorithm on LIGO data

In this paper we describe the performance of the WaveBurst algorithm which was designed for detection of gravitational wave bursts in interferometric data. The performance of the algorithm was evaluated on the test dataset collected during the second LIGO Scientific run. We have measured the false alarm rate of the algorithm as a function of the threshold and estimated its detection efficiency for simulated burst waveforms.

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarization for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated binary black hole waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.

Regression of Environmental Noise in LIGO Data

We address the problem of noise regression in the output of gravitational-wave (GW) interferometers, using data from the physical environmental monitors (PEM). The objective of the regression analysis is to predict environmental noise in the gravitational-wave channel from the PEM measurements. One of the most promising regression method is based on the construction of Wiener-Kolmogorov filters. Using this method, the seismic noise cancellation from the LIGO GW channel has already been performed. In the presented approach the Wiener-Kolmogorov method has been extended, incorporating banks of Wiener filters in the time-frequency domain, multi-channel analysis and regulation schemes, which greatly enhance the versatility of the regression analysis. Also we presents the first results on regression of the bi-coherent noise in the LIGO data.

Prospects for intermediate mass black hole binary searches with advanced gravitational-wave detectors

We estimated the sensitivity of the upcoming advanced ground-based gravitational-wave observatories (the LIGO, Virgo, and KAGRA interferometers) to coalescing intermediate mass black hole binaries (IMBHB). We added waveforms modeling the gravitational radiation emitted by IMBHBs to simulated data from detectors and searched for the injected signals with the coherent WaveBurst algorithm. The tested parameter space of the binaries covers nonspinning IMBHBs with source-frame total masses between 50 and 1050M⊙ and mass ratios between 1=6 and 1. We found that advanced detectors could be sensitive to these systems up to a range of a few Gpc. A theoretical model was adopted to estimate the expected observation rates, yielding up to a few tens of events per year. Thus, our results indicate that advanced detectors will have a reasonable chance to collect the first direct evidence for intermediate mass black holes and to open a new, intriguing channel for probing the Universe over cosmological scales.