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1、暗能量、残余引力波、暗能量、残余引力波、CMB极化极化Darkenergy,relicGWandCMBpolarization 张杨(YangZhang)中国科学技术大学(USTC)天体物理中心(CFA)8/15/20241OutlineOfTopics一、一、 Cosmic Dark Energy二、二、 Relic Gravitational Waves三、三、 CMB Polarizations by RGW8/15/20242一、一、 Cosmic Dark Energy- the effective YM condensate model8/15/20243Observational
2、 Evidence for Accelerating ExpansionSNIa型超新星Riess(1998)Permutter(1999)Tonry(2003),z=0.31.3,8newKnop(2003),z=0.36-0.86,11newCMBanisotropies(WMAP)Largescalestructureetc.8/15/20244Models for Dark Energy:1. Cosmologicalconstant:2.Effectivegravity:L=R+bRlnR+3.scalarfield：quintessence,k-essence,etc4. Bag-
3、Model(T.D.Lee)=const.5. EffectiveYang-Millscondensate8/15/20245Coincidence Problem：8/15/20246strategy:constructatrackingsolution,thepresentstateisinsensitivetotheinitialconditions.8/15/20247 EffectiveYang-Millscondensate:Idea:WhatiftheUniverseisfilledwithquantumeffectiveYMcondensateasthegroundstate?
4、TheuniverseisquitesimilartotheQCDvacuuminhadrons,towhichthequantumeffectiveYang-Millscondensatecontributes.8/15/20248Recall:MITBagConstant:Idea:Quarksinsidehadronsfeelavacuumwith=B, p= -B, whereBisMITBagconstant.QCDvacuuminhadronscanbephenomenologicallydescribedbytheB,towhichthegluoncondensatecontri
5、butes.8/15/202498/15/202410Interestingfeatures:quantumeffective1-loopcontribution;gaugeinvariance;Lorentzinvariance;correcttraceanomaly;8/15/2024118/15/202412Observethat:theeffectiveYMcondensatebehavesasathighenergies,pyy/3,radiationatlowenergies,py-y,darkenergyThiswillleadtothescalingbehavior,andth
6、etracksolution.8/15/202413Friedmannequation:8/15/2024148/15/202415Non-interaction:8/15/202416Interactionwithmatter:8/15/202417Themodel1:i.e.theYMcondensatedecaysintomatterattherate.8/15/2024188/15/2024198/15/2024208/15/202421Remark:AtrackersolutionexistsforawiderangeoftheinitialYMenergydensity;Thepr
7、esentstate0.73,m0.27isrealizednaturallyasaresultofevolution;8/15/202422wy=y/py goesfrom1/3crossesover-1,andsettlesdowntow-1;Otherchoicesof/H also yield similar evolution behavior; m levels off; 8/15/202423Theasymptoticbehaviorofthetrackersolutionwithy0.73,m0.27,astItisafixedpoint,anditisstable.8/15/
8、202424Phasegraphfortrajectories:8/15/202425Themodel2:i.e.thematterdecaysintotheYMcondensateatarate.8/15/2024268/15/2024278/15/2024288/15/202429Remark:similartothemodel1wy=y/py also goesfrom1/3,andapproachesto-1,butdoesnotgotow-1.8 is ruled out by LIGO; 8/15/202462Nucleosynthesis bound puts =-1.9 in
9、danger;The model =-2.0 is still robust.Reheating enhances the high frequency amplitude, which may be detectable.8/15/202463三、三、CMB Polarizations induced by RGW8/15/202464MagnetictypeofCMBpolarizationcanonlybeproducedbyGW.-ThisgivesawaytodetectGWonlargescales.Wehaveobtainedtheanalyticexpressionsforth
10、eCMBpolarizationspectra.8/15/202465Sachs-Wolfeterm:8/15/2024668/15/202467InPolnarevsmethodtheBolzmannsequationreducesto:8/15/2024688/15/202469ThepolarizationspectraofCMB:8/15/202470Asasource,GWisgivenby:8/15/2024718/15/2024728/15/202473PolarizationsaregeneratedviaThompsonScatteringduringthedecouplin
11、g.Itisdescribedbytheopticaldepth,ormoreconveniently,bythevisibilityfunctionV(t).8/15/202474ThevisibilityfunctionisusallymodeledbyaGaussianfunction,butwemodelitbytwopiecesofhalf-Gaussiancurves:8/15/2024758/15/202476V(t)dependsonthebaryonverysensitively:8/15/202477Integrationtoyield:8/15/202478whereTh
12、isisbecausewehavemodeledthevisibilityfunctionVasconsistingoftwohalf-gaussianpieces:8/15/202479Theresultinganalyticspectra:8/15/202480Theelectricpolarizationspectrum:8/15/202481Themagneticpolarizationspectrum:8/15/202482Dependenceonbaryondensityb:8/15/202483Dependenceondarkenergy:8/15/202484Dependenc
13、eonprimordialindexnT:8/15/202485Tobedetected:8/15/202486 works on the topics Gen.Rel.Grav.34,2155(2002)Gen.Rel.Grav.35;689(2003)Chin.Phys.Lett.20,1899(2003)Chin.Phys.Lett.21,1183（2004）Class.Quant.Grav.22,1383（2005）Chin.Phys.Lett.22,1817（2005）ChineseAstronandAstrophys29,250（2005）Class.Quant.Grav.23,3783（2006）Class.Quant.Grav.23,3405（2006）PRD.73,123509(2006)PRD.74,043503(2006)Phys.Lett.B64,69(2006).8/15/202487谢谢!Merci!8/15/202488
