=== Duncan Brown - first NINJA project === - numerical injection analysis: study response of GW pipelines to waveforms to foster collaborations between NR and data-analysis communities - start in spring 2008, developed format, waveforms freely submitted - vacuum spacetime only - up to two waveforms per code - equal and few:one masses, spinning and nonspinning, few to several cycles - waveforms added to simulated colored Gaussian noise - initial LIGO and Virgo - generate random distances, locations, orientations, masses - constraints: starting frequency below 30 Hz, SNR > 5 - nine groups analyzed data with a variety of algorithms - signal parameters published - different data-analysis algorithms - methods applied - CBC matched-filter pipeline (SPA, extended SPA, EOB-IMR, phenom-IMR) - CBC pipeline with Neyman-Pearson detection - LSC-Virgo ringdown - Q pipeline - Bayesian inference pipelines - ... - conclusions - success, but hard to draw conclusions - follow-on - broader parameter space - PN-NR stitching - non-Gaussian noise transients - questions - possible avenues of collaboration: eased providing NR waveforms to LVC; may imagine requests of real data from NINJA - how can LVC improve pipelines with these results? 3.5PN EOB with ringdown cutoff would improve sensitivity === Arun - burst search for BBH mergers in Virgo C7 data === === Laura Cadonati - systematics of NR waveform accuracy and burst searches for binary black hole mergers === - uses of NR in GW data analysis - template banks - injections - NR questions: resolution, extraction radius, starting frequency, harmonics, hybrids - DA questions: parameter space to explore, changes in reach, parameter estimation - more questions: choice of NR parameters - MayaKranc PSU/Gatech code - burst search yardsticks: radius of sphere at which uniformly distributed population has 50% detection probability - ... === Jon Gair - seed black holes with ET === - galactic black holes grow by accretion and mergers - first generation of black holes probably created by collapse of massive, zero-metallicity pop-III stars - seed BH parameters poorly constrained - Einstein telescope - x10 over advanced LIGO, 1-10 Hz sensitivity - two colocated detectors at 45 deg, but triangular topology reaches same sensitivity - estimate ET event rate using galaxy merger trees: four different models for mass distribution and accretion history - SNR with Ajith et al. waveforms (somewhat simple piece-wise amplitude expressions) - several high-redshifts (> 7) events -> indicates pop-III star mergers - no events seen indicates seed BHs not from pop-III - events at z < 5 may come from IMBHs in clusters - LISA will see similar numbers anyway - parameter estimation: good masses, 15-30% luminosity distance === Lisa Goggin - possibility of inspiral-ringdown test? === - NR gives information about mergers, but searches can only afford analytic waveforms based on NR results - investigation: inject EOBNR waveforms, compare recovered inspiral and ringdown parameters - test is viable === Ruslan Vaulin - in search for the CBC optimal statistic === - question: does data contain signal? - formal optimal strategy: compute likelihood function, announce detection if larger than threshold - Neyman-Pearson optimization: maximize detection probability at false-alarm probability - goal is to move the detection statistic closer to the optimal decision curve with real data - SNR is only zeroth-order approximation to the true likelihood - other parameters (chi2, e-thinca radius) can supplement it - estimate p(data|signal) and p(data|noise) by injections and time slides - search pipeline maps signal parameters to detection parameters - brute force approach - p(data|signal) = number of found injections near candidate / injections - p(data|noise) = noise trials with triggers near candidate / noise trials - "near" -> same parameters with epsilon fractional error - multidimensional visualization: injections need to make it through "gates" of epsilon fractional width in each parameter - get few injection "hits", expensive computationally - less restrictive: fixed gates in chirp mass and mu, semi-open neighborhood for effective SNR - ranking based on marginalized likelihood - evaluate efficiency of likelihood statistics in one month of data (w/same false alarm) - BNS: 11% -> 16% (rho-eff) -> 19% (epsilon box) - NSBH: 10% -> 14% - BBH: 7% -> 8% === Walter del Pozzo - Bayesian model selection and tests of general relativity === - tests of GR with GWs: coalescing binaries with advanced ground-based, EMRIs, etc. - search for no-GR signature in GW signal - use a Bayesian model selection approach - GR vs. massive graviton as test case - model selection: look at Bayes factor---ratios of marginal likelihoods (integrated over all model parameters) - graviton mass adds phasing term - actually compute P(d|H_MG)/P(d|n) vs. P(d|H_GR)/P(d|n) and take ratio - find little discrimination === Jessica Clayton - joint-LV CBC lowmass search === - data between May and October 2007; five one-month periods - 3 detectors allow source localization - Mtot in [1,35] Msun; Virgo templates cover only BNS chirp-mass region (DQ vetoes not fully studied in high-mass region) - range limited for Virgo data - tune parameters by monitoring detection probability while restricting the cuts - investigating new "bank" chi2 test, more computationally efficient, of comparable utility === Reinhard Prix - is the F-statistic optimal? === - parametrized CW signal family - amplitude parameters (h0,cos i,psi,phi0) - Doppler parameters - strain at detector: F+(t,psi,n) A+ cos phi(t,lambda,phi0) + Fx(t,psi,n) Ax sin phi(t,lambda,phi0) - with A+x(h0,cos i) - JKS 1998: factorize signal parameters s = sum_mu A^mu h_mu - classical hypothesis testing: point hypothesis - Neyman-Pearson: likelihood ratio is "most powerful" test - plot ROC - for F-statistic, hypothesis is not point-wise - Neyman-Pearson lemma does not apply - we're looking at maximum likelihood detection - F-statistic has nice properties, but is less powerful than the likelihood ratio - can it be improved? - the F-statistic is equivalent to the Bayes factor (Bayesian detection statistic, integrated over A) with a flat prior in Amu coordinates - redo with ignorance priors on Amu' = phi0, psi, cos i, h0 (= 1/h0) - in this coordinates the F-statistic prior is biased towards edge-on systems and large h0 - define new detection statistic integrated over the Amu' priors - ROC curve can be above or below F-stat for specific sources: neither is uniformly more powerful - over isotropic random angles, B statistic is more powerful - but difference in sensitivity is not big, and has comparable sensitivity to B-statistic - extend to better hypothesis-setup + priors to use odds ratio directly - extend to marginalization over Doppler space, to eliminate problem of number of independent trials