Exploitation of the gravitational lensing signal Probing the
Exploitation of the gravitational lensing signal: Probing the large scale structures with the CMB Laurence Perotto; LAL Orsay BPol workshop
The CMB lensing effect n z~1 to 3 n + d z~1100 z=0 d = F F: the gravitational potential integrated along the line-of-sight Lensing effect introduces NG in the CMB maps in the form of: mode coupling observable correlation (e. g. EB, TB, etc. ) From CMB maps, gravitational potential can be statistically reconstructed Laurence Perotto Motivations Method Prospects BPol workshop
Probing neutrino masses, dark energy, … An alternative and advantageous measure of the matter density. Free-streaming suppression advantages: • no light-to-mass bias • probing high redshift structures: still in their linear regime • no need to a dedicated experiment With lensing extraction, CMB data alone become sensitive to mν , w. DE , … Laurence Perotto Motivations Method Prospects BPol workshop
Breaking cosmological parameters degeneracy : the Planck example projected 68% and 95% C. L. within an 11 -parameters Λ(H+C)DM model without lensing fn = Ωn /Ωdm 2 s sensitivity to Mv of 1 e. V with lensing 2 s sensitivity to Mv of 0. 3 e. V LP, J. Lesgourgues, S. Hannestadt, H. Tu, Y. Wong [astro-ph/06062271] Laurence Perotto Motivations Method Prospects BPol workshop
Where is the lensing information? correlation length: dd ~ few degrees TT EE r. m. s. of the deflection angle: BB (T/S~0) ~ 1 arcmin both large and small scales are needed Laurence Perotto Motivations Method Prospects BPol workshop
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 Laurence Perotto Motivations Method Prospects BPol workshop
Noise spectra of quadratic estimators « lensing designed » FWHM ~ 4 arcmin P ~ √ 2 K. arcmin aba’b’ Nl dd Cl TTTT EBEB all combined J. Lesgourgues, L. P. , S. Pastor, M. Piat [ Phys. Rev. D (2006)] Laurence Perotto Motivations Method Prospects BPol workshop
Can be calculated for any experiment… aba’b’ Nl EBEB all combined « SAMPAN-like » FWHM ~ 30 arcmin P = 6 K. arcmin J. Lesgourgues, L. P. , S. Pastor, M. Piat [ Phys. Rev. D (2006)] Laurence Perotto Motivations Method Prospects BPol workshop
Lensing extraction with forthcoming experiments « ideal » Y Y = { T, E, d } Laurence Perotto Motivations Method Prospects BPol workshop
Is this feasible in «real world» ? Lots of noises and secondaries could mimic the lensing signature… the systematics: sky cut non-axisymetric beam … generate an E to B leakage 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 Laurence Perotto Motivations Method Prospects BPol workshop
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 Laurence Perotto Motivations Method Prospects BPol workshop
Probing the matter distribution with Planck The expected error on angular power spectra reconstruction: 90° angular scale 0. 2° 2° 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)] Laurence Perotto Motivations Method Prospects BPol workshop
How to probe neutrino mass in Cosmology? The clearer signature of massive neutrinos: the free-streaming effect Gravitationnal collapse in an expanding Universe Neutrinos cannot collapse below a diffusion lenght: l = ∫ v dt baryons+CDM neutrinos For (2 p/k) < l , free-streaming supresses growth of structures. Laurence Perotto Motivations Method Probes Prospects BPol workshop
quadratic estimators sensitivity Nl EBEB TTTT combiné Laurence Perotto Motivations Method dd Cl Prospects BPol workshop
Lensing extraction with up-coming experiments Y Y = { T, E, d } Laurence Perotto Motivations Method Prospects BPol workshop
Is it sufficient? FWHM = 4 arcmin P = √ 2 K. arcmin C. Hirata & U. Seljak [astro-ph/0306354] Laurence Perotto Motivations Method Prospects BPol workshop
Probing neutrino mass with CMB lensing Forecasts on several up-coming exp. sensitivity in e. V d. TT d. EB 0. 06 NH 0. 1 0. 2 0. 3 masse totale (e. V) IH Inflation Probe/ Planck Cosmic Vision SAMPAN Planck Laurence Perotto 1 Motivations Method WMAP+SDSS Prospects BPol workshop
Lensing extraction with up-coming experiments Y Y = { T, E, d } Laurence Perotto Motivations Method Prospects BPol workshop
Laurence Perotto Motivations Method Prospects BPol workshop
Laurence Perotto Motivations Method Prospects BPol workshop
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