The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z a?? 1.4

摘要

Wemeasuretheredshift-spacecorrelationfunctionfromaspectroscopicsampleof2783emissionlinegalaxiesfromtheFastSoundsurvey.Thesurvey,whichusestheSubaruTelescopeandcoversaredshiftrangeof1.19z1.55,isthefirstcosmologicalstudyatsuchhighredshifts.Wedetectclearanisotropyduetoredshift-spacedistortions(RSD)bothinthecorrelationfunctionasafunctionofseparationsparallelandperpendiculartothelineofsightanditsquadrupolemoment.RSDhasbeenextensivelyusedtotestgeneralrelativityoncosmologicalscalesatz1.Adoptinga??CDMcosmologywiththefixedexpansionhistoryandnovelocitydispersion(??v=0),andusingtheRSDmeasurementsonscalesabove8a€‰ha?’1a€‰Mpc,weobtainthefirstconstraintonthegrowthrateattheredshift,fa€‰(z)??8(z)=0.482?±0.116atza??1.4aftermarginalizingoverthegalaxybiasparameterb(z)??8(z).Thiscorrespondsto4.2a€‰??detectionofRSD.Ourconstraintisconsistentwiththepredictionofgeneralrelativityf??8a??0.392withinthe1a€‰??confidencelevel.Whenweallow??vtovaryandmarginalizeoverit,thegrowthrateconstraintbecomes$$fsigma_8=0.494^{+0.126}_{-0.120}$$.Wealsodemonstratethatbycombiningwiththelow-zconstraintsonf??8,high-zgalaxysurveysliketheFastSoundcanbeusefultodistinguishmodifiedgravitymodelswithoutrelyingonCMBanisotropyexperiments.