2004 (IPP)

Permanent URI for this collectionhttp://localhost:4000/handle/11007/625

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Data analysis techniques for gravitational wave observations
(2011-07-06) Dhurandhar, Sanjeev
Astrophysical sources of gravitational waves fall broadly into three categories: (i) transient and bursts, (ii) periodic or continuous wave and (iii) stochastic. Each type of source requires a di®erent type of data analysis strategy. In this talk various data analysis strategies will be reviewed. Optimal ¯ltering is used for extracting binary inspirals; Fourier transforms over Doppler shifted time intervals are computed for long duration periodic sources; optimally weighted cross-correlations for stochastic background. Some recent schemes which e±ciently search for inspirals will be described. The performance of some of these techniques on real data obtained will be discussed. Finally, some results on cancellation of systematic noises in laser interferometric space antenna (LISA) will be presented and future directions indicated.
Fundamentals of the LISA Stable Flight Formation
(2011-07-06) Dhurandhar, Sanjeev; Nayak, K. R.; Koshti, S.
Time-Delay Interferometry
(2011-07-06) Tinto, Massimo; Dhurandhar, Sanjeev
Equal-arm interferometric detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is diﬀerenced at the photo detector. In this situation, much lower level secondary noises then set overall performance. If, however, the two arms have diﬀerent lengths (as will necessarily be the case with space-borne interferometers), the laser noise experiences diﬀerent delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-diﬀerence readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called Time- Delay Interferometry (or TDI). This article provides an overview of the theory and mathematical foundations of TDI as it will be implemented by the forthcoming space-based interferometers such as the Laser Interferometer Space Antenna (LISA) mission. We have purposely left out from this ﬁrst version of our “Living Review” article on TDI all the results of more practical and experimental nature, as well as all the aspects of TDI that the data analysts will need to account for when analyzing the LISA TDI data combinations. Our forthcoming “second edition” of this review paper will include these topics.