2008 (IPP)
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Item General relativistic treatment of LISA optical links(2008-05) Dhurandhar, Sanjeev; Vinet, J-Y.; Nayak, K. R.LISA is a joint spae mission of the NASA and the ESA for deteting low frequeny gravitational waves in the band 10−5 − 1 Hz. In order to attain the requisite sensitivity for LISA, the laser frequeny noise must be suppressed below the other seondary noises suh as the optial path noise, a eleration noise et. This is ahieved by ombining time-delayed data for whih preise knowledge of time-delays is required. The gravitational eld, mainly that of the Sun and the motion of LISA a e t the time-delays and the opti al links. Further, the e e t of the gravitational eld of the Earth on the orbits of spaeraft is inluded. This leads to additional exing over and above that of the Sun. We have written anumerial ode whih omputes the optial links, that is, the time-delays with great auray∼ 10−2 metres - more than what is required for time delay interferometry (TDI) - for most of the orbit and with su ient auray within ∼ 10 metres for an integrated time window of about six days, when one of the arms tends to be tangent to the orbit. Our analysis of the optial links is fully general relativisti and the numerial ode takes into aount e ets suh as the Sagna, Shapiro delay, et. We show that with the deemed parameters in the design of LISA, there are symmetries inherent in the on guration of LISA and in the physi s, whih may be used e etively to suppress the residual laser noise in the modi ed rst generation TDI. We demonstrate our results for some important TDI variables.