Spectral distortions of the microwave background radiation resulting from the damping of pressure waves

Daly, Ruth A.

doi:10.1086/169866

Cited by 133 publications

(149 citation statements)

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“…Even if no deviation from a blackbody spectrum -commonly referred to as spectral distortion -was detected, this remarkable observation places very tight constraints on the thermal history of our universe, ruling out cosmologies with extended periods of significant energy release that could have disturbed the equilibrium between matter and radiation in the post-BBN era. One source of energy release is due to the dissipation of small-scale perturbations in the photon-baryon fluid [388][389][390][391]315, 392], as we explain here. Nearly 25 years have passed since the launch of COBE, and from the technological point of view already today it should be possible to improve the absolute spectral sensitivity by more than three orders of magnitude [28,29].…”

Section: Observables: Measuring Cmb Spectral Distortionsmentioning

confidence: 99%

“…Without any more detailed derivations, it is thus already clear that larger smallscale power gives rise to larger distortions [388][389][390]393]. Furthermore, the shape of the small-scale power spectrum will determine the effective heating rate at different times and thus can be probed using spectral distortions [391,315,445,446,395,424,447].…”

Section: Damping Of Small-scale Acoustic Modesmentioning

confidence: 99%

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

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

208

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: Observables: Measuring Cmb Spectral Distortionsmentioning

confidence: 99%

Section: Damping Of Small-scale Acoustic Modesmentioning

confidence: 99%

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

Chluba

Hamann

Patil

2015

Int. J. Mod. Phys. D

208

233

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“…Quite generally, a mixture of Planck functions at slightly different temperatures is indistinguishable from a slightly comptonized spectrum ( [28]). The correspondance in Eq.…”

Section: Spectral Distortions By Diffuse Scatteringmentioning

confidence: 99%

Geocentrism reexamined

1995

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Observations show that the universe is nearly isotropic on very large scales. It is much more difficult to show that the universe is radially homogeneousthat is, independent of distance from us-or equivalently, that the universe is isotropic about distant points. This is usually taken as an axiom, since otherwise we would occupy a special position. Here we consider several empirical arguments for radial homogeneity, all of them based on the cosmic microwave background (CMB). We assume that physical laws are uniform, but we suppose that structure on very large scales may not be. The tightest limits for inhomogeneity on the scale of the horizon appear to be of order ten percent. These involve observations of the Sunyaev-Zel'dovich effect in clusters of galaxies, excitation of low-energy atomic transitions, and the accurately thermal spectrum of the CMB. Weaker limits from primordial nucleosynthesis are discussed briefly.98. 65, 98.80, 95.10, 95.30

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“…The latter are particularly important at z 2 × 10 6 , leading to a strong suppression of the distortion amplitude (e.g., Hu & Silk 1993a). Expected sources of µ-distortions include the Silk damping of smallscale acoustic modes in the early Universe (Sunyaev & Zeldovich 1970a;Daly 1991;Hu et al 1994a;Chluba et al 2012b) and the extraction of energy from the photon bath due to the adiabatic cooling of ordinary matter (Chluba 2005;Chluba & Sunyaev 2012).…”

Section: Introductionmentioning

confidence: 99%

Prospects for measuring cosmic microwave background spectral distortions in the presence of foregrounds

Abitbol

Chluba

Hill

et al. 2017

Monthly Notices of the Royal Astronomical Society

146

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Measurements of cosmic microwave background spectral distortions have profound implications for our understanding of physical processes taking place over a vast window in cosmological history. Foreground contamination is unavoidable in such measurements and detailed signal-foreground separation will be necessary to extract cosmological science. In this paper, we present MCMC-based spectral distortion detection forecasts in the presence of Galactic and extragalactic foregrounds for a range of possible experimental configurations, focusing on the Primordial Inflation Explorer (PIXIE) as a fiducial concept. We consider modifications to the baseline PIXIE mission (operating 12 months in distortion mode), searching for optimal configurations using a Fisher approach. Using only spectral information, we forecast an extended PIXIE mission to detect the expected average non-relativistic and relativistic thermal Sunyaev-Zeldovich distortions at high significance (194σ and 11σ, respectively), even in the presence of foregrounds. The ΛCDM Silk damping µ-type distortion is not detected without additional modifications of the instrument or external data. Galactic synchrotron radiation is the most problematic source of contamination in this respect, an issue that could be mitigated by combining PIXIE data with future ground-based observations at low frequencies (ν 15 − 30 GHz). Assuming moderate external information on the synchrotron spectrum, we project an upper limit of |µ| < 3.6 × 10 −7 (95% c.l.), slightly more than one order of magnitude above the fiducial ΛCDM signal from the damping of small-scale primordial fluctuations, but a factor of 250 improvement over the current upper limit from COBE/FIRAS. This limit could be further reduced to |µ| < 9.4 × 10 −8 (95% c.l.) with more optimistic assumptions about extra low-frequency information and would rule out many alternative inflation models as well as provide new constraints on decaying particle scenarios.

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Spectral distortions of the microwave background radiation resulting from the damping of pressure waves

Cited by 133 publications

References 0 publications

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

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

Geocentrism reexamined

Prospects for measuring cosmic microwave background spectral distortions in the presence of foregrounds

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