All-sky search for periodic gravitational waves in the full S5 LIGO data

Abstract

Wereportonanall-skysearchforperiodicgravitationalwavesinthefrequencyband50-800Hzandwiththefrequencytimederivativeintherangeof0through-6e-9Hz/s.Suchasignalcouldbeproducedbyanearbyspinningandslightlynon-axisymmetricisolatedneutronstarinourgalaxy.Afterrecentimprovementsinthesearchprogramthatyieldeda10xincreaseincomputationalefficiency,wehavesearchedintwoyearsofdatacollectedduringLIGOsfifthsciencerunandhaveobtainedthemostsensitiveall-skyupperlimitsongravitationalwavestraintodate.Near150Hzourupperlimitonworst-caselinearlypolarizedstrainamplitudeh0is1e-24,whileatthehighendofourfrequencyrangeweachieveaworst-caseupperlimitof3.8e-24forallpolarizationsandskylocations.Theseresultsconstituteafactoroftwoimprovementuponpreviouslypublisheddata.AnewdetectionpipelineutilizingaLooselyCoherentalgorithmwasabletofollowupweakeroutliers,increasingthevolumeofspacewheresignalscanbedetectedbyafactorof10,buthasnotrevealedanygravitationalwavesignals.Thepipelinehasbeentestedforrobustnesswithrespecttodeviationsfromthemodelofanisolatedneutronstar,suchascausedbyalow-massorlong-periodbinarycompanion.