天体物理宇宙学及物理学电子书合辑cosmicmicrowavebackgroundobservabl.pptx

Cosmic Microwave BackgroundCarlo Baccigalupi,SISSACarlo Baccigalupi,SISSACMB lectures at TRR33,see the complete program at CMB lectures at TRR33,see the complete program at darkuniverse.uni-hd.de/view/Main/WinterSchoolLecture5darkuniverse.uni-hd.de/view/Main/WinterSchoolLecture5These lectures are available in pdf format at These lectures are available in pdf format at people.sissa.it/bacci/work/lectures people.sissa.it/bacci/work/lectures 第1页CMB observables第2页Outline Generalities and historical remarksCosmological fossilsTotal intensity and polarization:T,E,BAngular power spectraStatus of the CMB observationsSuggested lectures第3页Generalities and historical remarks第4页Expanding universe CMBcompression compression in in the the early early stages stages of of an an expanding expanding universe universe causes causes lots lots of of radiation radiation arising arising from from thermonuclear explosionsthermonuclear explosionsReactions Reactions are are rapid rapid enough enough to to achieve achieve thermalization thermalization and and a a black body spectrumblack body spectrumIt It is is possible possible to to compute compute the the rarefaction rarefaction caused caused by by the the expansion since that epochexpansion since that epochThe The relic relic radiation radiation is is predicted predicted to to peak peak in in microwaves,microwaves,temperature temperature of of a a few few Kelvin,Kelvin,known known today today as as the the Cosmic Cosmic Microwave Microwave Background Background(CMB,(CMB,Gamow et al.1948)Gamow et al.1948)George Gamow,three years old in Odessa,Ukraine,1907第5页Discovery 第6页CMB:where and when?Opacity:Opacity:=(n(ne e T T)-1-1 horizonhorizonDecoupling:Decoupling:horizon horizonFree Free streaming:streaming:horizonhorizonCosmological Cosmological expansion,expansion,Thomson Thomson cross cross section section and and electron electron abundance abundance conspire conspire to to activate activate decoupling decoupling about about 300000 300000 years years after after the the Big Big Bang,Bang,at at about about 3000 3000 K K CMB CMB photon temperaturephoton temperature第7页A postcard from the big bangFrom From the the Stephan Stephan Boltzmann Boltzmann law,law,regions regions at at high high temperature temperature should should carry high densitycarry high densityThe The latter latter is is activated activated by by perturbations perturbations which which are are intrinsic intrinsic of of the the fluid fluid as as well as of spacetimewell as of spacetimeThus,Thus,the the maps maps of of the the CMB CMB temperature temperature is is a a kind kind of of snapshot snapshot of of primordial primordial cosmological cosmological perturbationsperturbationsAnimation from the NASA WMAP team第8页COsmic Background Explorer第9页From COBE to the Wilkinson Microwave Anisotropy ProbeAbout About 20 20 years years of of insight insight into into one one of of the the most most important important observables observables in in physicsphysicsLots Lots of of experiments,experiments,from from ground ground as as well well as as the stratospherethe stratosphereA A fantastic fantastic technological technological and and data data analysis analysis progress,progress,in in parallel parallel to to theorytheorylambda.gfsc.nasa.govlambda.gfsc.nasa.govAnimation from the NASA WMAP team第10页Cosmological fossils第11页CMB physics:Boltzmann equation d photons =metric+Compton scattering dtd baryons+leptons =metric+Compton scattering dt第12页CMB physics:Boltzmann equation d neutrinos =metric+weak interaction dt d dark matter =metric+weak interaction(?)dtmetric=photons+neutrinos+baryons+leptons+dark matter第13页CMB physics:metric第14页CMB Physics:Compton scatteringCompton Compton scattering scattering is is anisotropicanisotropicAn An anisotropic anisotropic incident incident intensity intensity determines determines a a linear linear polarization polarization in in the the outgoing radiationoutgoing radiationAt At decoupling decoupling that that happens happens due due to to the the finite finite width width of of last last scattering scattering and and the the cosmological cosmological local quadrupolelocal quadrupole第15页CMB anisotropy:total intensity+第16页CMB anisotropy:polarization+Gradient(E):Curl(B):第17页CMB anisotropy:reionizatione-e-e-第18页CMB anisotropy:lensing第19页Last scatteringForming structures-lensesEBCMB anisotropy:lensingSeljak&Zaldarriaga 1998第20页Forming structures-lensesEBCMB anisotropy:lensingaccelerationLast scattering第21页Anisotropies T(,),Q(,),U(,),V(,)X=T,E,BX(,)=lm almX Yslm(,)spherical harmonicss=0 for T,2 for Q and UE and B modes have opposite parity第22页Angular power spectrumT(,),Q(,),U(,),V(,)aXlm,X=T,E,BCl=m(almX)(almY)*/(2l+1)spherical harmonicsinformationcompression第23页Status of the CMB observations and future experimental probes第24页CMB angular power spectrumAngle 200/l degrees第25页CMB angular power spectrumAngle 200/l degreesPrimordial powerGravity wavesAcoustic oscillationsReionization Lensing 第26页WMAP first yearAngle 200/l degrees第27页WMAP third yearAngle 200/l degrees第28页CMB angular power spectrumboomerangdasiWMAP第29页Cosmological concordance model第30页Cosmological concordance model第31页Cosmological concordance model第32页CMB anisotropy statistics:unknown,probably still hidden by systematicsEvidence Evidence for for North North south south asymmetry asymmetry(Hansen(Hansen et et al.al.)Evidence Evidence for for Bianchi Bianchi models(Jaffe et al.)models(Jaffe et al.)Poor Poor constraints constraints on on inflation,inflation,the the error error is is about about 100 100 times times the the predicted predicted deviations deviations from from Gaussianity Gaussianity(Komatsu(Komatsu et et al.)al.)Lensing Lensing detection detection out out of of reachreach第33页Other cosmological backgrounds?Neutrinos:abundance comparable to photons,decoupling at MeV,cold as photons,weak interaction Gravity waves:decoupling at Planck energy,abundance unknown,gravitational interaction Morale:insist with the CMB,still for many yearsthats the best we have for longSee lambda.gfsc.nasa.gov第34页Suggested readingModern Cosmology textbook from Scott DodelsonMy lecture notes from the course at SISSA,people.sissa.it/bacci/lectures/Cosmological inflation and large scale structure,textbook from Andrew R.Liddle and David H.LythThese lectures are available in pdf format at people.sissa.it/bacci/work/lectures/第35页