Effects of observer peculiar motion on the isotropic background frequency spectrum: From the monopole to higher multipoles

Trombetti, T.; Burigana, C.; Chierici, F.

doi:10.1051/0004-6361/202038845

Cited by 4 publications

(1 citation statement)

References 116 publications

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“…The CMB dipole spectrum is furthermore distorted due to our motion with respect to the CMB restframe [48][49][50]. Additional distortions due to the observer's motion also appear in the higher multipoles [51]. Line and resonance scattering effects also leave anisotropic imprints (Sections 3.8 and 3.9).…”

Section: Cmb Spectral Distortion Signals Across the Skymentioning

confidence: 99%

New horizons in cosmology with spectral distortions of the cosmic microwave background

et al. 2021

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This Voyage 2050 paper highlights the unique science opportunities using spectral distortions of the cosmic microwave background (CMB). CMB spectral distortions probe many processes throughout the history of the Universe, delivering novel information that complements past, present and future efforts with CMB anisotropy and large-scale structure studies. Precision spectroscopy, possible with existing technology, would not only provide key tests for processes expected within the cosmological standard model but also open an enormous discovery space to new physics. This offers unique scientific opportunities for furthering our understanding of inflation, recombination, reionization and structure formation as well as dark matter and particle physics. A dedicated experimental approach could open this new window to the early Universe in the decades to come, allowing us to turn the long-standing upper distortion limits obtained with COBE/FIRAS some 25 years ago into clear detections of the expected standard distortion signals and also challenge our current understanding of the laws of nature.

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Section: Cmb Spectral Distortion Signals Across the Skymentioning

confidence: 99%

New horizons in cosmology with spectral distortions of the cosmic microwave background

et al. 2021

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Fast computation of the observer motion effects induced on monopole frequency spectra for tabulated functions

Trombetti,

Burigana,

Tucci

et al. 2024

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Various methods have been studied to compute the boosting effects produced by the observer peculiar motion, which modifies and transfers the isotropic monopole frequency spectrum of the cosmic background radiation to higher multipoles. Explicit analytical solutions for the spherical harmonic expansion coefficients were already presented and applied to different types of background spectrum, strongly alleviating the computational effort needed for accurate theoretical predictions. The frequency spectra at higher multipoles are inherently led by higher-order derivatives of the monopole spectrum. Provided that it can be well described by analytic or semi-analytic functions, the computation of its transfer is not affected by numerical instabilities when evaluated at the required level of numerical accuracy. Instead, monopole frequency spectra described by tabulated functions are computed with a relatively poor frequency resolution in comparison with the Doppler shift, which necessitates interpolation of the tabular representation. The spectra are also affected by uncertainties related to intrinsic inaccuracies in the modelling or in the related observational data as well as to limited accuracy in their numerical computation. These uncertainties propagate and increase with the derivative order, possibly preventing the trustworthy computation of the transfer to higher multipoles and of the observed monopole. We study methods to filter the original function or its derivatives and the multipole spectra, to mitigate numerical instabilities, and to derive reliable predictions of the harmonic coefficients for different cosmic background models. From the analytical solutions, and assuming that the monopole spectrum can be expanded in Taylor's series, we derive explicit expressions for the harmonic coefficients up to the multipole $ max = 6$ in terms of monopole spectrum derivatives. We then consider different low-pass filters: prefiltering in Fourier space of the tabular representation; filtering in both real and Fourier space of the numerical derivatives; interpolation approaches; and a dedicated method based on amplification and deamplification of the boosted signal. We study the quality of these methods when applied to suitable analytical approximations of the tabulated functions, possibly polluted with simulated noise. These methods are then applied to the tabulations. We consider two very different types of monopole spectra superimposed to the cosmic microwave background: the (smooth) extragalactic source microwave background signal from radio-loud active galactic nuclei and the (feature-rich) redshifted 21cm line, and present our results in terms of spherical harmonic coefficients. The direct prediction of these coefficients can be noisy at $ > 1$ or, depending on the uncertainty level, even at $ 1$. Without assuming a functional form for the extragalactic background spectrum, the Gaussian prefiltering coupled to the sequential real-space filtering of derivatives allows us to derive accurate predictions up to $ 6$, while a log--log polynomial representation, which is appropriate over several decades, gives accurate solutions at any ell . Instead, it is difficult to characterise the 21 cm line model variety, and so it is relevant to work without assumptions about the underlying function. Typically, the prefiltering provides accurate predictions up to $ 3$ or $4$, while the further sequential filtering of the derivatives or the boosting amplification and deamplification method improves the results up to $ = 4$, while also allowing reasonable estimations of the spectrum at higher ell . The proposed methods can significantly extend the range of realistic cosmic background models manageable with a fast computation, beyond the cases characterised a priori by analytical or semi-analytical functions. These methods require only an affordable increase in computation time compared to the direct calculation via simple interpolation.

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Cosmic backgrounds from the radio to the far-infrared: Recent results and perspectives from cosmological and astrophysical surveys

Burigana

Battistelli

Bonavera

et al. 2022

Int. J. Mod. Phys. D

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Cosmological and astrophysical surveys in various wavebands, in particular from the radio to the far-infrared, offer a unique view of the universe’s properties and the formation and evolution of its structures. After a preamble on the so-called tension problem, which occurs when different types of data are used to determine cosmological parameters, we discuss the role of fast radio bursts in cosmology, in particular for the missing baryon problem, and the perspectives from the analysis of the 21 cm redshifted line from neutral hydrogen. We then describe the Planck Legacy Archive, its wealth of scientific information and next developments, and the promising perspectives expected from higher resolution observations, in particular for the analysis of the thermal Sunyaev–Zel’dovich effect. Three cosmological results of the Planck mission are presented next: the implications of the map of Comptonization fluctuations, the dipole analysis from cross-correlating cosmic microwave background anisotropy and Comptonization fluctuation maps, and the constraints on the primordial tensor-to-scalar perturbation ratio. Finally, we discuss some future perspectives and alternative scenarios in cosmology, such as the study of the Lorentz invariance violation with the cosmic microwave background polarization, the introduction of new gravitational degrees of freedom to solve the dark matter problem, and the exploitation of the magnification bias with high-redshift sub-millimeter galaxies to constrain cosmological parameters.

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Effects of observer peculiar motion on the isotropic background frequency spectrum: From the monopole to higher multipoles

Cited by 4 publications

References 116 publications

New horizons in cosmology with spectral distortions of the cosmic microwave background

New horizons in cosmology with spectral distortions of the cosmic microwave background

Fast computation of the observer motion effects induced on monopole frequency spectra for tabulated functions

Cosmic backgrounds from the radio to the far-infrared: Recent results and perspectives from cosmological and astrophysical surveys

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