Beyondyand μ: the shape of the CMB spectral distortions in the intermediate epoch, 1.5 × 104≲z≲2 × 105

Khatri, Rishi; Sunyaev, R.

doi:10.1088/1475-7516/2012/09/016

Cited by 110 publications

(128 citation statements)

References 73 publications

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“…r-distortions are the residual distortions that encode the information on the transition between the µ-era (when distortions are of the µ-type) and the y-era (when the CMB is not in kinetic equilibrium and energy injections result in distortions of the y-type). We refer to [46,47] for a study of these residual distortions, and to [31,45] for a study of their constraining power on cosmological parameters. 7 We did not investigate, in this work, whether it could be possible to have models of multi-field inflation (or models where the slowroll assumption is relaxed [48]) that can predict such values for the µ-distortion amplitude.…”

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confidence: 99%

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

et al. 2016

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We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running αs = dns/d log k and the running of the running βs = dαs/d log k of the spectral index ns of primordial scalar fluctuations. We find αs = 0.011 ± 0.010 and βs = 0.027 ± 0.013 at 68% CL, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between βs and foregrounds parameters, with the exception of the point sources amplitude at 143 GHz, A P S 143 , which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of such preference for αs, βs ∼ 0.01 by including in the analysis the lensing amplitude AL, the curvature parameter Ω k , and the sum of neutrino masses mν . We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of AL = 1 and Ω k = 0 but still hint at possible deviations. The indication for βs > 0 survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at ∼ 1.7 standard deviations when CMB lensing is considered. We discuss the possibility of constraining βs with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on αs and βs.

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confidence: 99%

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

et al. 2016

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“…Deviations from the Planck spectrum induced by non-linear dynamics [35,36] are negligible as recalled in Eq. (7); see also [19][20][21].…”

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confidence: 99%

Blackness of the cosmic microwave background spectrum as a probe of the distance-duality relation

et al. 2013

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A violation of the reciprocity relation, which induces a violation of the distance duality relation, reflects itself in a change in the normalisation of the cosmic microwave spectrum in such a way that its spectrum is grey. We show that existing observational constraints imply that the reciprocity relation cannot be violated by more than 0.01% between decoupling and today. We compare this effect to other sources of violation of the distance duality relations which induce spectral distortion of the cosmic microwave background spectrum.PACS numbers: 98.80. Cq, 04.80.Cc In the standard cosmological model [1,2], in which the universe is described by a spatially homogeneous and isotropic geometry of the Friedmann-Lemaître family, the luminosity distance D L and angular diameter distance D A are related by the distance duality relation,where z is the redshift. This relation is actually far more general [3,4]. It can be shown (see Ref.[5] for a demonstration) that it holds in any spacetime in which (1) the reciprocity relation holds and (2) the number of photons is conserved. The reciprocity relation connects the area distances up and down the past lightcone and is a relation between the source angular distance, r s , and the observer area distance, r o . The former is defined by considering a bundle of null geodesics diverging from the source and which subtends a solid angle dΩ 2 s at the source. This bundle has a cross section d 2 S o at the observer and the source angular distance is defined by the relationSimilarly, the observer area distance is defined by considering a reciprocal null geodesic bundle converging at the observer byAs long as photons propagate along null geodesics and the geodesic deviation equation holds then these two distances are related by the reciprocity relation [5] regardless of the metric and matter content of the spacetime. While r o is related to the angular distance, the solid angle dΩ 2 s cannot be measured so that r s is not an observable quantity. If one further assumes that the number of photons is conserved, the source angular distance is related to the luminosity distance, by D L = (1 + z)r s , which leads to the distance duality relation (1), whereVarying the distance-duality relation: Violations of the distance duality relation (1) can arise from a violation of the reciprocity relation, which can occur in the case where photons do not follow (unique) null geodesics (e.g. in theories involving torsion and/or non-metricity or birefringence [6]) or (2) from the non-conservation of photons, which occur e.g. when photons are coupled to axions [7] or to gravitons in an external magnetic field [8], to Kaluza-Klein modes associated with extra-dimensions [9], or to a chameleon field [10][11][12]. The fact that such a violation of the distance duality relation can account for a dimming of the supernovae luminosity [13,14], since e.g. in the case of photon-axion mixing the luminosity distance has to be rescaled as D L / 1 − P γ−a (r) with P γ−a being the probability for a photon to oscill...

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“…Although such a deviation can be characterized by several types of distortions such as y-and i-types [30,31], here we focus on the µ-type distortion.…”

Section: Cmb µ Distortionmentioning

confidence: 99%

Mixed inflaton and spectator field models: CMB constraints and μ distortion

Enqvist

Sekiguchi

Takahashi

2016

J. Cosmol. Astropart. Phys.

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We discuss mixed inflaton and spectator field models where both the fields are responsible for the observed density fluctuations. We use the current CMB data to constrain both the general mixed model as well as some specific representative scenarios, and collate the results with the model predictions for the CMB spectral µ distortion. We find the posterior distribution of µ using MCMC chains and demonstrate that the standard single-field inflaton model typically predicts µ ∼ 10 −8 with a relatively narrow distribution, whereas for the mixed models, the distribution turns out to be much broader, and µ could be larger by almost an order of magnitude. Hence future experiments of µ distortion could provide a tool for the critical testing of the mixed source models of the primordial perturbation.

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Beyondyand μ: the shape of the CMB spectral distortions in the intermediate epoch, 1.5 × 10⁴≲z≲2 × 10⁵

Cited by 110 publications

References 73 publications

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

Blackness of the cosmic microwave background spectrum as a probe of the distance-duality relation

Mixed inflaton and spectator field models: CMB constraints and μ distortion

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