IUCAA Preprints
Permanent URI for this communityhttp://localhost:4000/handle/11007/149
Browse
10 results
Search Results
Item Morphology of clusters and superclusters in N-body simulations of cosmological gravitational clustering(2015-03-13) Sathyaprakash, B.S.; Sahni, Varun; Shandarian, SergeiItem Filaments and pancakes in the IRAS 1.2 jy redshift catalogue(2015-03-13) Sathyaprakash, B.S.; Sahni, Varun; Shandarian, Sergei; Fisher, K.B.Item Shapefinders: a new shape diagnostic for large scale structure(2015-03-11) Sahni, Varun; Sathyaprakash, B.S.; Shandarian, SergeiItem Evidence for filamentarity in the las campanas redshift survey(2015-03-01) Bharadwaj, Somanath; Sahni, Varun; Sathyaprakash, B.S.; Shandarin, S.F.; Yess, CappItem Gravitational instability in the strongly nonlinear regime: A study of various approximations(2015-02-18) Sathyaprakash, B.S.; Sahni, Varun; Munshi, Dipak; Pogosysn, D.; Melott, A.L.Item The thermo-optical coupling in optical resonators(2015-02-07) Dhurandhar, S.V.; Hello, P.; Sathyaprakash, B.S.Interferometric detectors of gravitational waves employ long baseline FabryPerot cavities with stored power of the order of 10 kW. The mirrors have a high reflectivity with absorption coefficient of a few parts in a million. The laser beam therefore acts as a source of heat creating a thermal gradient in the substrate and the consequent deformation in the mirror which in turn modifies the intra-cavity light field. The problem is thus coupled and nonlinear. Though the effect is expected to be negligible in the case of initial interferometers future interferometers are expected to employ much higher powers and it is necessary to ascertain thermo-elastic deformations and their effect on the stability of the laser field in the cavity. In this paper, which is first in a series to study instabilities in giant high power laser cavities, we have analytically solved the coupled problem of thermo-elastic deformations and their effect on the laser field, perturbatively and we show that within the realm of our (physically reasonable) assumptions there are no instabilities in the frequency range of 1 Hz-1 kHz.Item Estimation of parameters of gravitational waves from coalescing binaries(2015-01-25) Balasubramanian, R.; Sathyaprakash, B.S.; Dhurandhar, S.V.Item The evolution voids in the adhesion approximation(2015-01-17) Sahni, Varun; Sathyaprakash, B.S.; Shandarin, S.F.Item Choice of filters for the detection of gravitational waves from coalescing binaries II: detection in coloured noise(2014-11-25) Dhurandhar, S.V.; Sathyaprakash, B.S.We discuss the problem of detecting gravitational waves signals embedded in coloured noise from coalescing binary systems. The signal is assumed to be Newtonian and matched filtering techniques are employed to filter out the signal. The problem is discussed at first for a general power spectral density of the noise and then specific numerical results are obtained for the standard recycling case. Since the signal parameters are unknown, a bank of filters is needed to carry out the signal detection. The number of filters in a bank , the spacing between filter etc. is obainted for different values of minimum strength of the signal relative to the threshold. We also present an approximate analytical formula which relates the spacing between filter to the minimum strength. Finally we discuss the problem of detection probabilities given a data train.Item A parallel algorithm for filtering gravitational waves from coalescing binaries(2014-11-23) Sathyaprakash, B.S.; Dhurandhar, S.V.Coalescing binary stars are perhaps the most promising sources for the observation of gravitational waves with laser interferometric gravity wave detectors. The waveform from these sources can be predicted with sufficient accuracy for matched filtering techniques to be applied. In this paper we present a parallel algorithm for detecting signals from coalescing compact binaries by the method of matched filtering. We also report the details of its implementation on a 256-node connection machine consisting of a network of transputers. The results of our analysis indicate that parallel processing is a promising approach to on-line analysis of data from gravitational wave detectors to filter out coalescing binary signals. The algorithm described is quite general in that the kernel of the algorithm is applicable to any set of matched filters.