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Analysis and Results of Known Isolated Pulsars in S2 Preliminary Phase

This study presents the preliminary results of analyzing known isolated pulsars in the S2 phase, including a quick review of TDS (time domain stitching) and validation of injections. The joint posterior distribution of unknown parameters is determined using a Bayesian approach. The noise estimates and signal extraction were successful for all injected signals. Further plans include analyzing binary pulsars and implementing directed searches using MCMC approach.

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Analysis and Results of Known Isolated Pulsars in S2 Preliminary Phase

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  1. Known Isolated PulsarsPreliminary S2 Results Réjean Dupuis, Matt Pitkin, Graham Woan LIGO-G030584-00-Z

  2. Quick review of TDS E2E Validation of TDS – S2 injections Preliminary S2 results Promises and future plans Outline

  3. For known pulsars phase evolution is removed by heterodyning to dc. A Bayesian approach is used to determine the joint posterior distribution of the probability of the unknown parameters noise estimate Bk’s are processed data model prior likelihood posterior Quick review of TDS = {h0, i, y, f0}

  4. All the parameters of the injected signals were successfully extracted from the noise.http://www.astro.gla.ac.uk/users/rejean/lsc/S2injections Multi-detector analysis successfully increased confidence. Signal P1 all IFOs individual IFOs E2E validation – S2 injections e.g. p(h0,cos | Bk)

  5. Analyzed the 38 known isolated pulsars with 2frot > 50 Hz. Using same procedure as S1 directly gives reasonable results for about 28 pulsars. For 10 of the pulsars we had to remove lines in order to correctly estimate the noise. Now have noise modelled within factor of 2 for all pulsars (in at least 1-2 IFOs). Crab pulsar heterodyned to take timing noise into account. S2 known pulsar analysis

  6. H1 Spectra of tricky pulsars • We use a 4 Hz band around the signal frequency to estimate the noise in our Bk’s. • Lines in this band generally made us overestimate the noise. • Noise estimates were improved by removing lines.

  7. Changes from S1: IIR cutoff frequencies Removed lines in band Estimating noise ~360 Hz ~60 Hz

  8. Preliminary multi-detector upper limits 95% upper limits • Performed joint coherent analysis for all 38 pulsars using data from all IFOs. • The variance is off by less than a factor of 2 for most pulsars. Upper limits should not change much when we improve the noise estimation. 10-24

  9. Upper limits on ellipticity S2 upper limits Equatorial ellipticity: Spindown-based upper limits 10-5 equatorial ellipticity

  10. Wrap up S2 analysis for isolated pulsars by the end of January, 2004. Implement similar search for known binary pulsars with fGW > 50 Hz. Implement directed searches using MCMC approach (e.g., SN87A, Cas A). Future plans for TDS GWDAW – Presentation on hardware signal injections?

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