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Exploitation of the gravitational lensing signal: Probing the large scale structures with the CMB

Exploitation of the gravitational lensing signal: Probing the large scale structures with the CMB. Laurence Perotto; LAL Orsay. BPol workshop. n. n. + d. From CMB maps, gravitational potential can be statistically reconstructed. The CMB lensing effect. z~1 to 3. z=0. d =  F

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Exploitation of the gravitational lensing signal: Probing the large scale structures with the CMB

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  1. Exploitation of the gravitational lensing signal: Probing the large scale structures with the CMB Laurence Perotto; LAL Orsay BPol workshop

  2. n n + d From CMB maps, gravitational potential can be statistically reconstructed The CMB lensing effect z~1 to 3 z=0 d = F F: the gravitational potential integrated along the line-of-sight z~1100 Lensing effect introduces NG in the CMB maps in the form of: mode coupling observable correlation (e. g. EB, TB, etc. ) Motivations

  3. With lensing extraction, CMB data alone become sensitive to m , w , … Probing neutrino masses, dark energy, … Free-streaming suppression An alternative and advantageous measure of the matter density. advantages: • no light-to-mass bias • probing high redshift structures: still in their linear regime • no need to a dedicated experiment ν DE Motivations

  4. Breaking cosmological parameters degeneracy : the Planck example projected 68% and 95% C. L. within an 11-parameters Λ(H+C)DM model without lensing 2s sensitivity to Mv of 1 eV with lensing fn= Ωn /Ωdm 2s sensitivity to Mv of 0.3 eV LP, J. Lesgourgues, S. Hannestadt, H. Tu, Y. Wong [astro-ph/06062271] Motivations

  5. dd TT EE BB (T/S~0) both large and small scales are needed Where is the lensing information? correlation length: ~ few degrees r.m.s. of the deflection angle: ~ 1 arcmin Method

  6. Full sky quadratic estimators method W. Hu et T. Okamoto (2002) a , b = { T, E, B } geometrical coefficients How to construct an estimator for the deflection? ^ weighted sum over multipole pairs of observed modes (ab) = TT, TE, TB, EE, EB A 4-points estimator of the deflection field APS: cosmic variance + instrumental noise Method

  7. « lensing designed » FWHM ~ 4 arcmin P ~ √2 K.arcmin dd aba’b’ C N l l Noise spectra of quadratic estimators TTTT EBEB all combined J. Lesgourgues, L. P., S. Pastor, M. Piat [ Phys. Rev. D (2006)] Prospects

  8. aba’b’ N l « SAMPAN-like » FWHM ~ 30 arcmin P = 6 K.arcmin Can be calculated for any experiment… EBEB all combined J. Lesgourgues, L. P., S. Pastor, M. Piat [ Phys. Rev. D (2006)] Prospects

  9. Y Y Y Y Y Y Y = { T, E, d } Y = { T, E, d } Lensing extraction with forthcoming experiments « ideal » Prospects

  10. Is this feasible in «real world»? Lots of noises and secondaries could mimic the lensing signature… the systematics: sky cut generate an E to B leakage non-axisymetric beam … the foregrounds: kinetic SZ effect ( A. Amblard et al. [astro-ph/06062271] ) point sources ( LP thesis [tel-00011916] ) polarized dust … tests of the robustness of the estimator against foregrounds and systematics residuals are needed Prospects

  11. Exploiting CMB lensing A powerfull tool to probe LSS constraining m_nu, w_de, … breaking parameters degeneracy Lensing extraction requires both small and large angular scales ideal CMB lensing experiment should provide high quality full sky E and B-mode maps with ~arcmin resolution. However, lensing extraction on a low-resolution SAMPAN-like experiment in combination to Planck would provide high added value A quadratic estimator method should be sufficient but tests of the robustess against foregrounds and systematics residuals are needed

  12. Probing the matter distribution with Planck The expected error on angular power spectra reconstruction: angular scale 0.2° 2° 90° dd deflection angles field TT Temperature E-mode (curl-free) EE BB B-mode (gradient-free) multipole l J. Lesgourgues, L. P., S. Pastor, M. Piat [ Phys. Rev. D (2006)] Prospects

  13. Neutrinos cannot collapse below a diffusion lenght: l= ∫ v dt baryons+CDM neutrinos How to probe neutrino mass in Cosmology? The clearer signature of massive neutrinos: the free-streaming effect Gravitationnal collapse in an expanding Universe • For (2p/k) < l , • free-streaming supresses growth of structures. Probes

  14. EBEB TTTT combiné  dd C N l l quadratic estimators sensitivity

  15. Y Y Y Y = { T, E, d } Lensing extraction with up-coming experiments

  16. FWHM = 4 arcmin P = √2 K.arcmin Is it sufficient? C. Hirata & U. Seljak [astro-ph/0306354]

  17. TT d EB d 0.1 0.06 1 0.2 0.3 masse totale (eV) NH IH Inflation Probe/ Cosmic Vision Planck SAMPAN Planck WMAP+SDSS Probing neutrino mass with CMB lensing Forecasts on several up-coming exp. sensitivity in eV

  18. Y Y Y Y = { T, E, d } Lensing extraction with up-coming experiments

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