What can the CMB sll tell us?• Praccally CV limited for determining the integrated reionizaon...
Transcript of What can the CMB sll tell us?• Praccally CV limited for determining the integrated reionizaon...
WhatcantheCMBs-lltellus?
ElenaPierpaoliUniversityofSouthernCalifornia
Summary
– AbroadlookatPlanckparameteres-ma-on
– Reioniza-on– DiffuseForegroundscharacteriza-on– Tensor‐to‐scalar(i.e.res-ma-on)forPlanckandfutureexperiments
From:Colombo&Pierpaoli(arXiv:0804.0278) Colombo,PierpaoliPritchard(arXiv:0811.2622) Betouleetal(arXiv:0901.1056)Macellarietal(tobesubmiZed)
+WhitePapersforCMBPol
I:NearPerspec-ves:thePlancksatellite
• Smallerbeam• Lowernoise• Polariza-on• BeZerfrequencycoverage
COBE WMAP PlanckYear data received 1992 2003 2009Spatial resolution (deg) 7 0.23 0.08Frequencies (GHz) 30-90 22-94 30–857Polarization no yes yesSensitivity (muK/30' pix) 10.5 (8yrs) 1.4
WherePlanckwilldobeZer
• New information coming from: – second and third peak in TT spectrum – greater l range – reionization “bump” in EE and second peak
(L.ColomboE.PierpaoliJ.Pritchard2008)
Comparisonofparameteres-ma-onperformances(WMAPorPlanckonly)
(ColomboPierpaoliPritchard08)
Wheredoestheinforma-oncomesfrom?
• Temperature: 217 GHz and 143GHz playing similar roles at high resolution
• Polarization: CV limited to l= 8-12, possibly sensitive to 3rd peak
Impactonparameters
• Major information coming from 70-143 GHz. Adding 217GHz iproves parameter determination by ~10%.
• Giving up 143Ghz,pol results in a 73% (or factor 2) degradation for r estimate. • LFI useful for improving r estimates.
Frequencycoverageanddegeneracies
• Frequencycoveragehelpssomedegeneracies,notall….
Impactofbeammodeling
• Assumingawrongbeambytheamountconsistentwithcurrentuncertain-esmaybiasimportantparametersby~sigma
Under‐es-ma-ngorover‐es-ma-ngthebeamby0.05%( )or0.2%()
Tensortoscalarra-orfromPlanck
Forr>0.05,halfoftheinforma-oncomesfromtheBBspectrum
Issueswiththetensorspectralindex
• Forr~0.1,Planckwillnotbeabletoconstrainrandn_tsimultaneosly
• EvenforanEPICtypeofexperiment,marginalizingonn_tincreasestheerrorsonrbyafactor3.
Synergieswithothersurveys
Planckonly
BAO~JDEM(z=0.5‐2,10000sqdeg)
(CIP:z=2–6.5,1000sqdeg,2Mgal)
Thelow‐lparameters:Thetensor‐to‐scalarra-orandreioniza-onτ
• Reioniza-onimpactstheCMBtempertatureandpolariza-onspectra.• TheOp-caldepthistheonlyparametercurrentlyconstrainedanditis
determinedbyEEspectra.
Constraints(WMAP3):Alldata:τ = 0.09 +/‐0.03EEonly:τ = 0.1 +/‐0.03(Pageetal2006)(WMAP5:0.087+/‐0.017)
II.REIONIZATION
Lookingmorecarefully….
• Differencesatl<30onEEandBBspectraare~10%‐20%
t=0.0845
(seee.g.HolderHaiman,Kaplinghat,Knox03,Hu&Holder03Colomboetal05)
Ques-ons
• Currentanalysismodelsassume“sharp”reioniza-on(possiblyincorrect).Howmuchthisassump-onaffectsPlanckparameteres-ma-on?
• Canyouavoidmakingthisassump-on?Atwhichcost?Areotherparametersaffectedbythechoice?
• Canweconstrainsomethingmorethanjustτ?• Ifyoudogiveupthatassump-on,whichisthebeststrategytoincorporateamoregeneralreioniza-onhistory?
Colombo&Pierpaoli08
• GetCl'sformodelswithdifferentxe(z)butsame t andothercosmologicalparameters• BuildsimplePlancksimulateddatafor143GHzwithfsky=80%skycoverage
• MCMCanalysisofsimulateddataassumingasharpreioniza-on
Howbigistheproblem?
fiducialmodels:sharp,extended,two‐step,doublewitht=.0845
t=.0845modelmean sbiasSR .0844.0045 ‐.02ER .0850.0044 .112R .0895.0046 1.09DR .0861.0046 .35log[1010As]=3.135modelmeansbiasSR 3.1349.0092 ‐.01ER 3.1356.0092 .072R 3.1452.0094 1.09DR 3.1382.0093 .34r=0.1modelmeansbiasSR .104.029 .14LR .096.029 ‐.142R .088.028 ‐.43DR .092 .030 ‐.26
“Agnos-c”approachestoreioniza-on• Binnedreioniza-on(Lewis,Weller,BaZye06)
• PrincipalComponentofreioniza-onhistory(Mortonson&Hu07)
– Assumeafiducialbinnedreioniza-onhistoryxe
fid(zi),i=1,2,...,Nzzmin≤zi≤zmax– EvaluatetheFisherMatrixfortheEEmodes
– TheprincipalcomponentsSn(zi)aretheeigenvectorsoftheFishermatrix
– Agenericreioniza-onhistoriycanbespecifiedonthisbasisbyasetofcoefficientsµnas:
– Evaluateasubsetofthesefromthedata
xe(z) = xfid + ∑ µnSn(z)
Xefid=1,z<60.15,6<z<30
Reconstruc-ngreioniza-on• Underlyingmodel:sharpreioniza-on(i.e.:wewanttobenasty)• Analyzedwith6binsbetweenz=6andz=30(Δz=4)
Black:binnedreioniza-onRed:5Eigenmodes
• Samebiasinrobservedinthetwomethods(otherparametersarerecoveredequallywell)
• Binnedspectralesswellreconstructed(alotofcorrela-onbetweenbins)
• Computa-onally:4-mesmoreexpensive
• BinnedmodelingmaybebeZersuitedtointroduceexternalconstraintsonreioniza-on
Colombo&Pierpaoli08
EPIC,PlanckandWMAPreioniza-on
WMAP5PlanckEPIC
Zaldarriagaetal2008
PlanckwillgreatlyimproveonWMAPonhighredshi{reioniza-on.
“Experimental”Heliumcontribu-ontothemeasurementofreioniza-onhistory
BeingabletousemorecoolingheliumwouldresultinbeZerconstraintsonthereioniza-onhistoryathighredshi{s.
Howwellwillafutureexperimentperform?
• Prac-callyCVlimitedfordeterminingtheintegratedreioniza-onsignal• Notverygoodindeterminingtheextentofreioniza-on• WillhelpinrelievingsomemilddegeneraciesPlanckmayhave.
Zaldarriagaetal08
III:Whatwewantandwhatweget:foregroundsissues
=+
CMB
Foregrounds
ObservaPons(realWMAPmaps!)
Galaxyclusters
GalacPcdust
Synchrotronemission
Thesearchforr
• B‐modepolariza-onwouldbeasmokinggunforinfla-onbutpolarizedforegroundsmaybealimi-ngfactor.
Pageetal07• Howmuchdoweknowaboutpolarizedforegrounds
• Howwellcanwehandlethem
• Ul-mately,howlowofanrcanwemeasure,givenourcurrentknowledgeofforegrounds
Characterizingdiffuseforegrounds:Cross‐correla-onmethod
• Idea:assessforegroundcontribu-ontoWMAP5mapandtheirproper-esviacross‐correla-onswithdifferenttemplates(seeDaviesetal06)
• Objec-ves:performananalysisatdifferentla-tudes,alsoincludingpolariza-on
• Advantages:non‐parametric• Disadvantages:notlocalized,dependentontherepresenta-onoftheforegroundbythetemplate.
Syhchrotron:HaslamDust:FDS8Free‐free:Hα(Dickinsonetal03)
Macellarietal,inprep.
Templates:
Intensityresults
• Evidenceforanomalousdustemissionplusthermaldust,Free‐freeandsynchrotronspectralindexwithnosurprises.
CfrDaviesetal06
Intensityresultsbyla-tude
• Dustcorrelatedcomponentdominantonsynchrotronatlowandintermediatela-tudes
Polariza-onemissivity
• Synchrotrondominantatlowfrequencies,dustat94GHz.
• Totaldustfrac-onalpolariza-onbelow5%.• Trendinla-tudeandfrequency.
Synchrotronspectralindex
• Consistentresultsintemperatureandpolariza-on,flaZeningathigherla-tudes
• Synchrotronfrac-onalpolariza-onsmallonthegalac-cplane,reaching40‐50%atintermediate/highgalac-cla-tudes
IV:Impactofforegroundsonrdetermina-on
• Methodforcomponentsepara-on:SMICA(Cardosoetal2008)
• Maps:implemen-ngBforthethePlanckSkyModel• Advantages:“bestpowerspectrumreconstruc-on”• Disadvantages:noforegroundreconstruc-on.• Foregroundconsidered:
– Synchrotron(withrunning)– Thermaldust(differentamplitedes/powerspectra)– (extra‐galac-csources)– (Lensing)
X=vectorinfrequencyofobserva-ons:
Thelikelihood
• Insteadoftheusual:Thelikelihoodisgivenby:
WhereKisthesprectralmismatchbetweenthematrices:
Wemaximizethelikelihoodwithrespectto
PreviousaZempts:
• Verdeetal06:Fishermatrixapproachwithinstrumentalnoiseand~10%foregroundresiduals
• Amblardetal07:Wienerfilteredmapsandes-mateoferrorsincludingforegroundresiduals(needtoknowcovariancesofyourforegrounds!)
Foregroundlevelsandmodeling
ForegroundmodeledoutofthePSM
Forecastsforfutureexperiments
VariantstothemainmodelPointsources(EPIC‐CS)
Lensing(r=0.001)
Varia-onsinthesynchrotronspectralindex
Varia-onsinthedust
Conclusions• WMAPnaïveparameteres-matesabout30%lowerthanrealones.
Planckmayimprovebyseveralfactors,especiallyonr(with1/2oftheinforma-oncomingfromtheBBpowerspectrum).Es-matesconsideringforegroundsuggestthatatr~0.1foregroundsshouldnotdegradethesignificanceofthedetec-on.Planckwillcomplementfuturesurveysin…….
• Allowingforageneralreioniza-onmodelwithinPlanckparameteres-ma-onisnecessarynottobiasrandpowerspectrumamplitude.Theimplementa-onisprac-callydoable.Bothprincipalcomponentorredshi{binsmaybeused.FutureCMBpolariza-onmissionsallperformwellNogoodreconstruc-onofreioniza-onhistoryistobeexpected,apartfromdiscrimina-ngbroadlybetweenearlyandlatecontribu-ontotheop-caldepth.
• WMAP5Cross‐correla-onanalysis:dustpolariza-onbelow6%,dependentonfrequencyandla-tude.Synchrotronpolariza-onincreasingwithla-tudeupto40‐50%.Synchrotronspectralindexconsistentintemperatureandpolariza-on,flaZeningathigherla-tudes.
• AsforfutureCMBpolariza-onmissions,foregroundshouldnotlimitdetec-onifr~0.001,withactualperformancesdependingonconfigura-on.Varia-onsinthediffusecomponentsisirrelevantfortheresults.Pointsources,ifneglected,biastheresults.