Primordial Power Spectrum reconstruction from CMB Weak Lensing Power Spectrum

Sushovan, Chandra, Rajorshi; Souradeep, T.

doi:10.1088/1475-7516/2021/10/081

Cited by 5 publications

(6 citation statements)

References 46 publications

(53 reference statements)

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“…Finally, the CMB lensing power spectrum is not very sensitive to this class of primordial features with high frequencies [40]. The power spectrum of the lensing potential is an integrated quantity where a large range of wavenumbers contribute to each multipole; as a result, high frequency oscillations as those considered here are efficiently smoothed in CMB lensing compared to CMB temperature and polarization spectra.…”

Section: Jcap10(2022)083 2 Primordial Oscillatory Features With a Gau...mentioning

confidence: 76%

On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data

Ballardini¹,

Finelli⋆²

2022

J. Cosmol. Astropart. Phys.

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The Planck DR3 measurements of the temperature and polarization anisotropies power spectra of the cosmic microwave background (CMB) show an excess of smoothing of the acoustic peaks with respect to ΛCDM, often quantified by a phenomenological parameter A L. A specific feature superimposed to the primordial power spectrum has been suggested as a physical solution for this smoothing excess. Here, we investigate the impact of this specific localized oscillation with a frequency linear in the wavenumber, designed to mimic the smoothing of CMB temperature spectrum corresponding to A L ≃ 1.1–1.2 on the matter power spectrum. We verify the goodness of the predictions in perturbation theory at next-to-leading order with a set of N-body simulations, a necessary step to study the non-linear damping of these primordial oscillations. We show that for a large portion of the parameter space, the amplitude of this primordial oscillation can be strongly damped on the observed nonlinear matter power spectrum at z = 0, but a larger signal is still persistent at z ≲ 2 and is therefore a target for future galaxy surveys at high redshifts. From an analysis of the BOSS DR12 two-point correlation function, we find 𝒜lin < 0.26 at 95% CL by keeping the frequency fixed to the best-fit of Planck data.

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Section: Jcap10(2022)083 2 Primordial Oscillatory Features With a Gau...mentioning

confidence: 76%

On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data

Ballardini¹,

Finelli⋆²

2022

J. Cosmol. Astropart. Phys.

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“…We expect to further optimize the algorithm by implementing the sparsity algorithm developed in our previous work [18], as well as carry out a full covariance matrix calculation for the reconstructed P R (k) as well as test existing C T T data for features of interest given the newfound accuracy of the NIRL estimator and it's ability to discriminate finely from features vs lensing artefacts without any prior assumptions.…”

Section: Discussionmentioning

confidence: 99%

“…While practical and efficient with respect to computing resources, the issue with this approach is that the template based delensing process inherently assumes a fiducial C φφ L weak lensing power spectrum. It has been demonstrated earlier that the weak lensing power spectrum C φφ L can be expressed as a convolution of the primordial power spectrum P R (k) with the transport kernel G φφ L (k) and the RL estimator has been successfully employed in deconvolution with relevant statistical analyses and optimization algorithms [18]. This naturally poses a circular problem of having to assume a form of C φφ L , based on a Power Law P R (k), when we are trying to reconstruct the P R (k) itself.…”

Section: Temperature Power Spectrum C T T Weak Lensing Correctionmentioning

confidence: 99%

“…A broad body of work has been performed on the Richardson-Lucy (RL) deconvolution in existing literature [7-10, 12, 13, 15, 16, 19-21, 41, 42]. We will follow the notation, formalism and groundwork laid out in [18] in this work. We recall that the MRL algorithm, which is the RL algorithm modified to incorporate observed covariance matrix information, is based upon certain premises, of which the positive definite nature of the power spectra and radiative transport kernel [22,23], as well as the linear convolution form is primary, given by…”

Section: Temperature Power Spectrum C T T Weak Lensing Correctionmentioning

confidence: 99%

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Primordial Power Spectrum from Lensed CMB Temperature Spectrum using Iterative Delensing

Sushovan¹,

Souradeep²

2021

Preprint

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We address a current caveat in the deconvolution of the Primordial Power Spectrum (PPS), from observed Cosmic Microwave Background (CMB) temperature anisotropy, in the presence of weak lensing of the CMB by the large scale structure (LSS) in the Universe. We propose a modification to the popular Richardson-Lucy (RL) deconvolution algorithm used in the context of reconstructing a free-form PPS, P R (k) from observed lensed CMB temperature anisotropy power spectrum C T T . We show that the modified RL algorithm works in the context of a non-linear convolution problem, such as in the case of weak lensing. The Non-Linear Iterative Richardson-Lucy (NIRL) algorithm is successful at both convergence, as well as fidelity, in reconstructing features in some underlying PPS. This makes PPS reconstruction efforts more robust in the context of lensed CMB temperature observations. No prior assumptions on the PPS are involved during the iterative delensing process, and distinct improvement is noted over a power-law template based delensing approach used earlier, at the cost of moderately increased computational cost due to the NIRL reconstruction.

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“…Localised features have been studied using wavelet basis functions [52,53]. A direct inversion using Singular Value Decomposition on the transfer kernel [54] and Modified Richardson-Lucy algorithm (MRL) [55][56][57][58][59][60][61][62][63][64] can also be grouped into this category.…”

Section: Jcap03(2024)056mentioning

confidence: 99%

Deblurring the early Universe: reconstruction of primordial power spectrum from Planck CMB using image analysis techniques

Sohn,

Shafieloo,

Hazra

2024

J. Cosmol. Astropart. Phys.

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While the simplest inflationary models predict the primordial perturbations to be near scale-invariant, the primordial power spectrum (PPS) can exhibit oscillatory features in many physically well-motivated models. We search for hints of such features via free-form reconstructions of the PPS based on Planck 2018 CMB temperature and polarization anisotropies. In order to robustly invert the oscillatory integrals and handle noisy unbinned data, we draw inspiration from image analysis techniques. In previous works, the Richardson-Lucy deconvolution algorithm for deblurring images has been modified for reconstructing PPS from the CMB temperature angular power spectrum. We extensively develop the methodology by including CMB polarization and introducing two new regularization techniques, also inspired by image analysis and adapted for our cosmological context. Regularization is essential for improving the fit to the temperature and polarization channels (TT, TE and EE) simultaneously without sacrificing one for another. The reconstructions we obtain are consistent with previous findings from temperature-only analyses. We evaluate the statistical significance of the oscillatory features in our reconstructions using mock data and find the observations to be consistent with having a featureless PPS. The machinery developed here will be a complimentary tool in the search for features with upcoming CMB surveys. Our methodology also shows competitive performance in image deconvolution tasks, which have various applications from microscopy to medical imaging.

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Primordial Power Spectrum reconstruction from CMB Weak Lensing Power Spectrum

Cited by 5 publications

References 46 publications

On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data

On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data

Primordial Power Spectrum from Lensed CMB Temperature Spectrum using Iterative Delensing

Deblurring the early Universe: reconstruction of primordial power spectrum from Planck CMB using image analysis techniques

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