Reconstruction of the primordial power spectrum using temperature and polarisation data from multiple experiments

Nicholson, Gavin; Contaldi, C. R.

doi:10.1088/1475-7516/2009/07/011

Cited by 82 publications

(72 citation statements)

References 71 publications

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“…There is no fundamental limit to how densely P R (k) can be sampled though; the number of samples in k can even exceed the number of data points (e.g., the C s) if one is willing to forgo the possibility of an analysis based on exploring the likelihood/posterior and treat the issue as a deconvolution problem (i.e., an inversion of Equation 128) instead. Deconvolution techniques have been applied by several groups to CMB temperature data [492][493][494][495][496][497], CMB temperature+polarisation data [498][499][500] and combinations of CMB data with large scale structure data [501]. In order to get rid of spurious high-frequency spikes that are likely to occur for noisy data when the primordial spectrum is oversampled, these methods typically involve a smoothing procedure.…”

Section: Bottom-up: Reconstruction Of the Primordial Power Spectrummentioning

confidence: 99%

Features and new physical scales in primordial observables: Theory and observation

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

212

233

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June 22, 20152 All cosmological observations to date are consistent with adiabatic, Gaussian and nearly scale invariant initial conditions. These findings provide strong evidence for a particular symmetry breaking pattern in the very early universe (with a close to vanishing order parameter, ), widely accepted as conforming to the predictions of the simplest realizations of the inflationary paradigm. However, given that our observations are only privy to perturbations, in inferring something about the background that gave rise to them, it should be clear that many different underlying constructions project onto the same set of cosmological observables. Features in the primordial correlation functions, if present, would offer a unique and discriminating window onto the parent theory in which the mechanism that generated the initial conditions is embedded. In certain contexts, simple linear response theory allows us to infer new characteristic scales from the presence of features that can break the aforementioned degeneracies among different background models, and in some cases can even offer a limited spectroscopy of the heavier degrees of freedom that couple to the inflaton. In this review, we offer a pedagogical survey of the diverse, theoretically well grounded mechanisms which can imprint features into primordial correlation functions in addition to reviewing the techniques one can employ to probe observations. These observations include cosmic microwave background anisotropies and spectral distortions as well as the matter two and three point functions as inferred from large-scale structure and potentially, 21 cm surveys.

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Section: Bottom-up: Reconstruction Of the Primordial Power Spectrummentioning

confidence: 99%

Features and new physical scales in primordial observables: Theory and observation

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

212

233

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“…However, there is no independent evidence for this form of the primordial power, and as the observed anisotropies arise as a convolution of the assumed primordial spectrum with the transfer function of the assumed cosmological model, it is clear that we cannot determine one without making assumptions about the other. (In fact, there are indications that the primordial spectrum is not scale-free, even when a ÃCDM cosmology is assumed [74][75][76][77][78][79][80][81][82][83]. )…”

Section: Primordial Power Spectramentioning

confidence: 99%

Reconciling the local void with the CMB

Nadathur

Sarkar

2011

Phys. Rev. D

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In the standard cosmological model, the dimming of distant Type Ia supernovae is explained by invoking the existence of repulsive `dark energy' which is causing the Hubble expansion to accelerate. However this may be an artifact of interpreting the data in an (oversimplified) homogeneous model universe. In the simplest inhomogeneous model which fits the SNe Ia Hubble diagram without dark energy, we are located close to the centre of a void modelled by a Lema\'itre-Tolman-Bondi metric. It has been claimed that such models cannot fit the CMB and other cosmological data. This is however based on the assumption of a scale-free spectrum for the primordial density perturbation. An alternative physically motivated form for the spectrum enables a good fit to both SNe Ia (Constitution/Union2) and CMB (WMAP 7-yr) data, and to the locally measured Hubble parameter. Constraints from baryon acoustic oscillations and primordial nucleosynthesis are also satisfied.Comment: 13 pages, 4 figures. Typos corrected and missing references added. Matches the published version in PR

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“…These include the "cosmic inversion" method [9][10][11][12][13], regularization methods like truncated singular value decomposition [14] and Richardson-Lucy iteration [3,15,16], and maximum entropy deconvolution [17]. Recently the authors of [18] carried out a reconstruction of the PPS employing Tikhonov regularization using multiple data sets and detected several features in the PPS at a 2σ level of significance (also compare [3]).…”

Section: Introductionmentioning

confidence: 99%

Inflationary freedom and cosmological neutrino constraints

2014

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The most stringent bounds on the absolute neutrino mass scale come from cosmological data. These bounds are made possible because massive relic neutrinos affect the expansion history of the universe and lead to a suppression of matter clustering on scales smaller than the associated free streaming length. However, the resulting effect on cosmological perturbations is relative to the primordial power spectrum of density perturbations from inflation, so freedom in the primordial power spectrum affects neutrino mass constraints. Using measurements of the cosmic microwave background (CMB), the galaxy power spectrum and the Hubble constant, we constrain neutrino mass and number of species for a modelindependent primordial power spectrum. Describing the primordial power spectrum by a 20-node spline, we find that the neutrino mass upper limit is a factor 3 weaker than when a power law form is imposed, if only CMB data are used. The primordial power spectrum itself is constrained to better than 10% in the wave vector range k ≈ 0.01 − 0.25 Mpc −1 . Galaxy clustering data and a determination of the Hubble constant play a key role in reining in the effects of inflationary freedom on neutrino constraints. The inclusion of both eliminates the inflationary freedom degradation of the neutrino mass bound, giving for the sum of neutrino masses Σm ν < 0.18 eV (at 95% confidence level, Planck þ BOSS þ H 0 ), approximately independent of the assumed primordial power spectrum model. When allowing for a free effective number of species, N eff , the joint constraints on Σm ν and N eff are loosened by a factor 1.7 when the power law form of the primordial power spectrum is abandoned in favor of the spline parametrization.

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Reconstruction of the primordial power spectrum using temperature and polarisation data from multiple experiments

Cited by 82 publications

References 71 publications

Features and new physical scales in primordial observables: Theory and observation

Features and new physical scales in primordial observables: Theory and observation

Reconciling the local void with the CMB

Inflationary freedom and cosmological neutrino constraints

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