PRIMORDIAL MAGNETIC FIELDS WITH BPOL

Transcription

1 PRIMORDIAL MAGNETIC FIELDS WITH BPOL DANIELA PAOLETTI 1,2,3 & FABIO FINELLI 1,4 1 INAF/IASFBO Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna 2 Dipartimento di Fisica, Università degli Studi di Ferrara 3 INFN sezione di Ferrara 4 INFN sezione di Bologna BPOL Workshop, 28 july 2010, virtually at IAP, Paris 1 1

2 SCIENTIFIC CASE WHY PRIMORDIAL MAGNETIC FIELDS? LARGE SCALE MAGNETIC FIELDS OBSERVED BOTH IN GALAXIES AND GALAXY CLUSTERS REQUIRE PRE EXISTENT FIELDS TO BE GENERATED MANY COSMOLOGICAL MODELS PREDICT THE GENERATION OF PMF IN EARLY EPOCHS PMF CAN BE GENERATED AND CAN REPRESENT THE SEEDS FOR THE OBSERVED LARGE SCALE MAGNETIC FIELDS PMF LEAVE AN IMPRINT ON CMB ANISOTROPIES IN TEMPERATURE AND POLARIZATION AND THEY INDUCE NON GAUSSIANITIES HIGH PRECISION CMB DATA IN TEMPERATURE AND POLARIZATION ARE THE MOST POWERFUL TOOL TO INVESTIGATE PMF PROPERTIES 2 2

3 REFERENCES Finelli, Paci & Paoletti 2008, for a study of the magnetic scalar contribution; Paoletti, Finelli & Paci 2009, for a study of magnetic vector and tensor contributions; Paoletti & Finelli 2010 for the constraints on PMF from present CMB data; Caprini, Finelli, Paoletti & Riotto 2009, for a study on large scales of the NG induced by PMF OTHER REFERENCES IMPACT ON CMB ANISOTROPIES: Bonvin & Caprini 2010; Giovannini 2008 & 2009; Mack Kahniashvili & Kosowsky 2002; Shaw & Lewis 2009 & 2010 NG INDUCED BY PMF Brown & Crittenden 2008; Seshadri & Subramanian

4 MAGNETIC PERTURBATIONS SIMPLEST MODEL OF PMF SUPPORTED IN FRW IS A STOCHASTIC BACKGROUND OF PMF WITH POWER LAW POWER SPECTRA PMF GENERATES SCALAR VECTOR AND TENSOR MODES. MAGNETIC SCALAR MODE IS SOURCED BY MAGNETIC ENERGY DENSITY AND SCALAR ANISOTROPIC STRESS MAGNETIC VECTOR AND TENSOR MODES ARE SOURCED BY MAGNETIC VECTOR AND TENSOR ANISOTROPIC STRESSES PMF INDUCE A LORENTZ FORCE ON BARYONS WHICH AFFECTS BOTH SCALAR AND VECTOR PERTURBATIONS THE DOMINANT CONTRIBUTIONS TO CMB ANISOTROPIES IS REPRESENTED BY SCALAR PERTURBATIONS ON LARGE SCALES AND BY VECTOR PERTURBATIONS ON SMALL SCALES. THE TENSOR CONTRIBUTION REMAINS SUBDOMINANT 4 4

5 NOTE HOW THE DOMINANT CONTRIBUTION IS THE VECTOR ONE AND THAT THE TENSOR MODE ALWAYS REMAINS SUBDOMINANT WITH RESPECT TO THE OTHER TWO. 5 5

6 Dotted: lensing THE VECTOR MAGNETIC MODE GENERATES A B MODE POLARIZATION SIGNAL STRONGER THAN LENSING!!!!! 6 6

7 PMF AND BPOL I Solid: Adiabatic; Dotted: Scalar; Dot Dashed:Vector; Red:Scalar+Vector+Adiabatic; Blue: Noise level for 20 resolution; Green Noise 7 level for 5 resolution. 7

8 PMF AND BPOL I Solid: Primordial Tensor; Dotted: Lensing; Dot Dashed:Vector; Red:Vector+Primordial; Blue: Noise level for 20 resolution; Green Noise level 8 for 5 resolution. 8

9 COSMOLOGICAL PARAMETERS AND PMF I MODIFIED VERSION OF COSMOMC WHICH INCLUDES OUR TREATMENT OF PMF ALREADY REALIZED AND TESTED FOR PLANCK MOCK DATA GENERATED WITHOUT PMF COMPARISON BETWEEN: BPOL 5 RESOLUTION IN BLACK BPOL 20 RESOLUTION IN RED 9 9

10 COSMOLOGICAL PARAMETERS AND PMF II COMPARISON WITH PLANCK COMPARISON BETWEEN: PLANCK EXTENDED MISSION IN RED BPOL 5 RESOLUTION IN BLACK BPOL 20 RESOLUTION IN BLUE PLANCK BPOL 5 BPOL 20 B λ <2.49 ngauss n B < 0.21 B λ <0.91 ngauss n B < 0.3 B λ <2.86 ngauss n B < At the 95% confidence level 10 10

11 MAGNETIC NON GAUSSIANITIES A STOCHASTIC BACKGROUND OF PMF HAS A FULLY NON GAUSSIAN CONTRIBUTION TO CMB. IT IS POSSIBLE TO EVALUATE THE CMB BISPECTRUM INDUCED BY PMF AND DERIVE AND EFFECTIVE f NL WHICH CAN BE USED TO CONSTRAIN PMF FROM NG DATA CMB MAGNETIC BISPECTRUM ALREADY ESTIMATED FOR LARGE SCALES (Caprini, Finelli, Paoletti & Riotto 2009) THE PRESENT AND FUTURE DEVELOPMENTS CONCERN THE CALCULATION OF THE MAGNETIC BISPECTRUM ON INTERMEDIATE AND SMALL SCALES. SINCE THE IMPACT OF PMF ON CMB IS STRONGER ON SMALL SCALES THESE SCALES SHOULD PROVIDE STRONGER CONSTRAINTS THAN THE ONES OBTAINED ON LARGE SCALES Caprini, Finelli, Paoletti & Riotto

12 FARADAY ROTATION PMF INDUCE FARADAY ROTATION ON CMB POLARIZATION E MODE POLARIZATION IS ROTATED INTO B MODE AND VICE VERSA THE SIGNAL HAS A STRONG DEPENDENCE ON THE FREQUENCY OF OBSERVATIONS AND SCALES AS THE INVERSE OF THE FREQUENCY TO THE FOURTH POWER. HENCE WITH MULTIFREQUENCY DATA IS POSSIBLE TO DISTINGUISH FARADAY ROTATION FROM OTHER POLARIZATION SIGNALS ANALITYCAL TOOLS TO ESTIMATE THE SIGNAL ALREADY AVAILABLE FROM KOSOWSKY, KAHNIASHVILI AND LAVRELASHVILI 2005 THE CODE TO ESTIMATE THE POLARIZATION SIGNAL INDUCED BY FARADAY ROTATION IS IN DEVELOPMENT 12 12