1. GWDAW9 - 2004/12/161 Activities of the LIGO Scientific Collaboration’s Continuous Wave Group Xavier Siemens for the LSC University of Wisconsin -- Milwaukee

2. GWDAW9 - 2004/12/162 The CW Group http://www.lsc-group.phys.uwm.edu/pulgroup/ http://www.lsc-group.phys.uwm.edu/pulgroup/ For the first science run (S1): set upper limit on a single known pulsar (J1939+2134) using two independent methods (Frequency domain, optimal for large parameter space searches, and Time domain, optimal for targeted searches).For the first science run (S1): set upper limit on a single known pulsar (J1939+2134) using two independent methods (Frequency domain, optimal for large parameter space searches, and Time domain, optimal for targeted searches). For the second and third science runs (S2, S3) the group has been involved in a variety of activities, which include the coherent methods used for S1 as well as incoherent methods…For the second and third science runs (S2, S3) the group has been involved in a variety of activities, which include the coherent methods used for S1 as well as incoherent methods… (NASA/CXC/SAO)

3. GWDAW9 - 2004/12/163 The Signal We search for gravitational waves generated by neutron star with deviations from axisymmetry.We search for gravitational waves generated by neutron star with deviations from axisymmetry. For example, isolated neutron star parameters: Frequency f of source in Solar System Barycenter (SSB) Rate of change of frequency df/dt in SSB Sky coordinates ( ,  ) of source Strain amplitude h 0 Spin-axis inclination  Phase, Polarization ,  Phase evolution Amplitude modulation

4. GWDAW9 - 2004/12/164 The Searches Coherent searches: Incoherent searches: - Time-domain: - Targeted - Markov Chain Monte Carlo - Frequency-domain: - Isolated - Binary, Sco X-1 - Hough transform - Stack-Slide - Powerflux Searches over narrow parameter space Searches over wide parameter space Excess power searches Ultimately, would like to combine these two in a hierarchical scheme

5. GWDAW9 - 2004/12/165 Time domain searches Targeted search: Targeting radio pulsars with rotational frequencies > 25 Hz at known locations with phase inferred from radio dataTargeting radio pulsars with rotational frequencies > 25 Hz at known locations with phase inferred from radio data Upper limits defined in terms of Bayesian posterior probability distributions for the pulsar parametersUpper limits defined in terms of Bayesian posterior probability distributions for the pulsar parameters For S2 looked at 28 known isolated pulsars (gr-qc/0410007) ; best strain upper limits were at the level of a few x 10^-24For S2 looked at 28 known isolated pulsars (gr-qc/0410007) ; best strain upper limits were at the level of a few x 10^-24 For S3 will soon extend search to known neutron stars in binaries and will benefit from much improved sensitivity.For S3 will soon extend search to known neutron stars in binaries and will benefit from much improved sensitivity. TALK: Matt Pitkin TALK: Matt Pitkin Computational Bayesian techniqueComputational Bayesian technique MCMC can both estimate parameters and generate summary statistics (pdfs, cross- correlations, etc)MCMC can both estimate parameters and generate summary statistics (pdfs, cross- correlations, etc) Initial Applications: searches in restricted parameter space and SN1987a (location known but other parameters not known)Initial Applications: searches in restricted parameter space and SN1987a (location known but other parameters not known) POSTER: John Veitch POSTER: John Veitch Markov Chain Monte Carlo:

6. GWDAW9 - 2004/12/166 Isolated Search The detection statistic is the so-called F-Statistic, which is the log of the likelihood maximized over the unknown parameters [Jaranowski, Krolak and Schutz, PRD58 063001; Jaranowski and Krolak, PRD59 063003]The detection statistic is the so-called F-Statistic, which is the log of the likelihood maximized over the unknown parameters [Jaranowski, Krolak and Schutz, PRD58 063001; Jaranowski and Krolak, PRD59 063003] For S2 we are doing a wide band (160 Hz-460 Hz) all-sky search for the 10 most sensitive hours of data for both the Livingston and the Hanford (4km) interferometers.For S2 we are doing a wide band (160 Hz-460 Hz) all-sky search for the 10 most sensitive hours of data for both the Livingston and the Hanford (4km) interferometers. We are combining the results of the two searches incoherently using a coincidence scheme and setting upper limits on 1Hz bands using a frequentist scheme based on the loudest coincident event.We are combining the results of the two searches incoherently using a coincidence scheme and setting upper limits on 1Hz bands using a frequentist scheme based on the loudest coincident event. For S2 we expect upper limits in the strain to be in the range of several x 10^-23 for quiet bands and around 10^-22 for noisy bandsFor S2 we expect upper limits in the strain to be in the range of several x 10^-23 for quiet bands and around 10^-22 for noisy bands TALK: Yousuke Itoh

7. GWDAW9 - 2004/12/167 Binary Search S2 analysis: upper-limit on Sco X-1 using aS2 analysis: upper-limit on Sco X-1 using a one-stage coherent search over short integration one-stage coherent search over short integration time (Tobs = 6 hr). time (Tobs = 6 hr). Also uses the F-statistic and a coincidence scheme,Also uses the F-statistic and a coincidence scheme, and sets a frequentist upper limit based on the loudest coincident event TALK: Chris Messenger TALK: Chris Messenger In the future: search Sco X-1 and other known LMXBs (~20 targets) with a hierarchical scheme:In the future: search Sco X-1 and other known LMXBs (~20 targets) with a hierarchical scheme: –Coherent analysis over short data chunks –Add incoherently (stack-slide) chunks POSTER: Virginia Re POSTER: Virginia Re (Artist’s impression: NASA)

8. GWDAW9 - 2004/12/168 Stack-Slide An incoherent search method that stacks and slides normalised power to search for periodic sources.An incoherent search method that stacks and slides normalised power to search for periodic sources. Starting point is a set of Short Fourier Transforms (SFTs). Then we:Starting point is a set of Short Fourier Transforms (SFTs). Then we: Stack the (normalised) powerStack the (normalised) power Slide to correct for Doppler shifts and spin-downSlide to correct for Doppler shifts and spin-down Sum and search for significant peaksSum and search for significant peaks Can be used as part of a hierarchical search with coherent & incoherent stagesCan be used as part of a hierarchical search with coherent & incoherent stages

9. GWDAW9 - 2004/12/169 Hough transform An incoherent search method conceptually similar to stack-slideAn incoherent search method conceptually similar to stack-slide Select a threshold for the normalised power and label frequency bins with a 1 if the threshold is exceeded or 0 otherwiseSelect a threshold for the normalised power and label frequency bins with a 1 if the threshold is exceeded or 0 otherwise Slide to correct for Doppler shifts and spin-downSlide to correct for Doppler shifts and spin-down Compute the number count for a given frequency bin by summing the 0’s and 1’sCompute the number count for a given frequency bin by summing the 0’s and 1’s For S2: All-sky search using entire data set with one spin-down parameter for the Livingston and Hanford 4km interferometers. Set an frequentist upper limit using software injectionsFor S2: All-sky search using entire data set with one spin-down parameter for the Livingston and Hanford 4km interferometers. Set an frequentist upper limit using software injections Can be used as part of a hierarchical search with coherent & incoherent stagesCan be used as part of a hierarchical search with coherent & incoherent stages TALK: Badri Krishnan TALK: Badri Krishnan

10. GWDAW9 - 2004/12/1610 Powerflux An incoherent search method, similar to stack-slide and HoughAn incoherent search method, similar to stack-slide and Hough The main differences are that for this search the sum of the power for each frequency bin isThe main differences are that for this search the sum of the power for each frequency bin is weighted with the antenna pattern functions of the interferometer, and,weighted with the antenna pattern functions of the interferometer, and, weighted by the noise, which is estimated from neighboring frequency bins. The weighting scheme is chosen to minimize the variance for the estimator of the gravitational wave amplitudeweighted by the noise, which is estimated from neighboring frequency bins. The weighting scheme is chosen to minimize the variance for the estimator of the gravitational wave amplitude Can be used as part of a hierarchical search with coherent & incoherent stagesCan be used as part of a hierarchical search with coherent & incoherent stages

11. GWDAW9 - 2004/12/1611 Einstein@home Like SETI@home, but for LIGO/GEO data. When computer idle, screensaver does ‘real work’.Like SETI@home, but for LIGO/GEO data. When computer idle, screensaver does ‘real work’. American Physical Society (APS) will publicize as part of World Year of Physics (WYP) 2005 activities, and will help with web site & graphics.American Physical Society (APS) will publicize as part of World Year of Physics (WYP) 2005 activities, and will help with web site & graphics. Use infrastructure/help from SETI@home developers for the distributed computing parts.Use infrastructure/help from SETI@home developers for the distributed computing parts. Goal: pulsar searches using ~1 million clients. Support for Windows, Mac OSX, Linux clients.Goal: pulsar searches using ~1 million clients. Support for Windows, Mac OSX, Linux clients. Why?Why? –From our own clusters we can get ~ thousands of CPUs. From Einstein@home hope to get order(s) of magnitude more at low cost. –Great outreach and science education tool. It runs the coherent isolated F-statistic code. Still testing but… Read all about it and sign up at : Still testing but… Read all about it and sign up at :http://einstein.phys.uwm.edu

12. GWDAW9 - 2004/12/1612 Upcoming talks/posters Talks: 10:18 Badri Krishnan: The Hough transform search for gravitational waves from pulsars 10:55 Chris Messenger: Bounding the strength of gravitational radiation from SCO-X1 11:13 Mathew Pitkin: Searching for gravitational waves from known milisecond pulsars 11:31 Yousuke Itoh: All-sky broad band search for continuous waves using LIGO Posters: Reinhard Prix: Matched filtering properties of all-sky searches for continuous gravitational waves Virginia Re: Stack-slide hierarchical searches for gravitational waves from accreting neutron stars John Veitch: A time-domain MCMC search technique for gravitational radiation of uncertain frequency from a targeted neutron star.