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Baryon Acoustic Oscillation Intensity Mapping of Dark Energy

TL;DR: Here it is shown how the study of acoustic oscillation in the 21 cm brightness can be accomplished by economical three-dimensional intensity mapping, and may be the starting point for a new class of dark energy experiments dedicated to large angular scale mapping of the radio sky, shedding light on dark energy.
Abstract: The expansion of the universe appears to be accelerating, and the mysterious anti-gravity agent of this acceleration has been called ``dark energy''. To measure the dynamics of dark energy, Baryon Acoustic Oscillations (BAO) can be used. Previous discussions of the BAO dark energy test have focused on direct measurements of redshifts of as many as $10^9$ individual galaxies, by observing the 21cm line or by detecting optical emission. Here we show how the study of acoustic oscillation in the 21 cm brightness can be accomplished by economical three dimensional intensity mapping. If our estimates gain acceptance they may be the starting point for a new class of dark energy experiments dedicated to large angular scale mapping of the radio sky, shedding light on dark energy.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data.

1,253 citations

Journal ArticleDOI
TL;DR: This review detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations, and generalize the discussion to intensity mapping of other atomic and molecular lines.
Abstract: Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window into this epoch. This will transform our understanding of the formation of the first stars and galaxies and of the thermal history of the Universe. A new generation of radio telescopes is being constructed for this purpose with the first results starting to trickle in. In this review, we detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations. We also generalize our discussion to intensity mapping of other atomic and molecular lines.

720 citations


Cites background from "Baryon Acoustic Oscillation Intensi..."

  • ...The notion of intensity mapping of 21 cm bright galaxies was introduced in several papers [159, 160, 161], and similar ideas were discussed by [162]....

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  • ...The horizontal lines indicate the scale of the first three BAO wiggles, and the dashed lines show contours of constant spherical harmonic order ` [161]....

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Journal ArticleDOI
TL;DR: In this article, the authors discuss recent advances in theoretical understanding of the epoch of reionization (EoR), the application of 21-cm tomography to cosmology and measurements of the dark energy equation of state after reionisation, and the instrumentation and observational techniques shared by 21cm EoR and postreionization cosmology machines.
Abstract: Measurement of the spatial distribution of neutral hydrogen via the redshifted 21-cm line promises to revolutionize our knowledge of the epoch of reionization and the first galaxies, and may provide a powerful new tool for observational cosmology from redshifts 1

449 citations


Cites background from "Baryon Acoustic Oscillation Intensi..."

  • ...Chang et al. (2008) argued that a radio telescope with a diameter of ∼ 200 wavelengths would provide an efficient method for surveying huge volumes, and so provide constraints on dark energy parameters that would be competitive with planned galaxy redshift surveys....

    [...]

  • ...Wyithe, Loeb & Geil (2008), Chang et al. (2008) and Peterson, Bandura & Pen (2006) realized that compact interferometers with wide fields-of-view might be able to perform cosmological measurements, particularly those associated with the BAO scale, at a fraction of the SKA’s cost....

    [...]

  • ...…Universe was discussed by Wyithe, Loeb & Geil (2008) who focused on redshifts z > 3 where telescopes of the design of MWA could operate, and by Chang et al. (2008) who looked at measurement of the oscillations in the redshift range z < 2 where measurements best constrain conventional dark…...

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Journal ArticleDOI
TL;DR: In this paper, the power spectrum and bispectrum up to 4th order in the initial density perturbations were modeled as a Taylor series in the local mass density, with the unknown coefficients in the series treated as free bias parameters.
Abstract: On very large scales, density fluctuations in the Universe are small, suggesting a perturbative model for large-scale clustering of galaxies (or other dark matter tracers), in which the galaxy density is written as a Taylor series in the local mass density, δ, with the unknown coefficients in the series treated as free ``bias'' parameters. We extend this model to include dependence of the galaxy density on the local values of ∇i∇j and ∇ivj, where is the potential and v is the peculiar velocity. We show that only two new free parameters are needed to model the power spectrum and bispectrum up to 4th order in the initial density perturbations, once symmetry considerations and equivalences between possible terms are accounted for. One of the new parameters is a bias multiplying sijsji, where sij = [∇i∇j∇−2−(1/3)δKij]δ. The other multiplies sijtji, where tij = [∇i∇j∇−2−(1/3)δKij](θ−δ), with θ = −(a H dln D/dln a)−1∇v. (There are other, observationally equivalent, ways to write the two terms, e.g., using θ−δ instead of sijsji.) We show how short-range (non-gravitational) non-locality can be included through a controlled series of higher derivative terms, starting with R2∇2δ, where R is the scale of non-locality (this term will be a small correction as long as k2R2 is small, where k is the observed wavenumber). We suggest that there will be much more information in future huge redshift surveys in the range of scales where beyond-linear perturbation theory is both necessary and sufficient than in the fully linear regime.

383 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts, and establish a simple way of comparing such surveys with optical galaxy redshift surveys.
Abstract: We present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts. In the process, we establish a simple way of comparing such surveys with optical galaxy redshift surveys. We explore a wide range of experimental configurations and assess how well a number of cosmological observables (the expansion rate, growth rate, and angular diameter distance) and parameters (the densities of dark energy and dark matter, spatial curvature, the dark energy equation of state, etc.) will be measured by an extensive roster of upcoming experiments. A number of potential contaminants and systematic effects are also studied in detail. The overall picture is encouraging?if autocorrelation calibration can be controlled to a sufficient level, Phase I of the Square Kilometre Array should be able to constrain the dark energy equation of state about as well as a DETF Stage IV galaxy redshift survey like Euclid, in roughly the same time frame.

347 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, the authors present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data.

1,253 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss recent advances in theoretical understanding of the epoch of reionization (EoR), the application of 21-cm tomography to cosmology and measurements of the dark energy equation of state after reionisation, and the instrumentation and observational techniques shared by 21cm EoR and postreionization cosmology machines.
Abstract: Measurement of the spatial distribution of neutral hydrogen via the redshifted 21-cm line promises to revolutionize our knowledge of the epoch of reionization and the first galaxies, and may provide a powerful new tool for observational cosmology from redshifts 1

449 citations

Journal ArticleDOI
TL;DR: In this paper, the power spectrum and bispectrum up to 4th order in the initial density perturbations were modeled as a Taylor series in the local mass density, with the unknown coefficients in the series treated as free bias parameters.
Abstract: On very large scales, density fluctuations in the Universe are small, suggesting a perturbative model for large-scale clustering of galaxies (or other dark matter tracers), in which the galaxy density is written as a Taylor series in the local mass density, δ, with the unknown coefficients in the series treated as free ``bias'' parameters. We extend this model to include dependence of the galaxy density on the local values of ∇i∇j and ∇ivj, where is the potential and v is the peculiar velocity. We show that only two new free parameters are needed to model the power spectrum and bispectrum up to 4th order in the initial density perturbations, once symmetry considerations and equivalences between possible terms are accounted for. One of the new parameters is a bias multiplying sijsji, where sij = [∇i∇j∇−2−(1/3)δKij]δ. The other multiplies sijtji, where tij = [∇i∇j∇−2−(1/3)δKij](θ−δ), with θ = −(a H dln D/dln a)−1∇v. (There are other, observationally equivalent, ways to write the two terms, e.g., using θ−δ instead of sijsji.) We show how short-range (non-gravitational) non-locality can be included through a controlled series of higher derivative terms, starting with R2∇2δ, where R is the scale of non-locality (this term will be a small correction as long as k2R2 is small, where k is the observed wavenumber). We suggest that there will be much more information in future huge redshift surveys in the range of scales where beyond-linear perturbation theory is both necessary and sufficient than in the fully linear regime.

383 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts, and establish a simple way of comparing such surveys with optical galaxy redshift surveys.
Abstract: We present a framework for forecasting cosmological constraints from future neutral hydrogen intensity mapping experiments at low to intermediate redshifts. In the process, we establish a simple way of comparing such surveys with optical galaxy redshift surveys. We explore a wide range of experimental configurations and assess how well a number of cosmological observables (the expansion rate, growth rate, and angular diameter distance) and parameters (the densities of dark energy and dark matter, spatial curvature, the dark energy equation of state, etc.) will be measured by an extensive roster of upcoming experiments. A number of potential contaminants and systematic effects are also studied in detail. The overall picture is encouraging?if autocorrelation calibration can be controlled to a sufficient level, Phase I of the Square Kilometre Array should be able to constrain the dark energy equation of state about as well as a DETF Stage IV galaxy redshift survey like Euclid, in roughly the same time frame.

347 citations

Journal ArticleDOI
TL;DR: In this article, the authors used multiple tracers of large-scale density with different biases to measure the redshift-space distortion parameter β ≡ b −1f ≡ b−1d−ln D/d −ln a (where D is the growth factor and a the expansion factor).
Abstract: We show how to use multiple tracers of large-scale density with different biases to measure the redshift-space distortion parameter β ≡ b−1f ≡ b−1d ln D/d ln a (where D is the growth factor and a the expansion factor), to, as the signal-to-noise (S/N) of a survey increases, much better precision than one could achieve with a single tracer (to arbitrary precision in the low noise limit). In combination with the power spectrum of the tracers this would allow a more precise measurement of the bias-free velocity divergence power spectrum, f2Pm, with the ultimate, zero noise limit, being that f2Pm can be measured as well as would be possible if velocity divergence was observed directly, with maximum rms improvement factor ~ [5.2(β2+2β+2)/β2]1/2 (e.g., 10 times better than a single tracer with β = 0.4). This would allow a determination of fD as a function of redshift with an error as low as ~ 0.1% (again, in the idealized case of the zero noise limit). The ratio b2/b1 can be determined with an even greater precision than β, potentially producing, when measured as a function of scale, an exquisitely sensitive probe of the onset of non-linear bias. We also extend in more detail previous work on the use of the same technique to measure non-Gaussianity. Currently planned redshift surveys are typically designed with S/N ~ 1 on scales of interest, which severely limits the usefulness of our method. Our results suggest that there are potentially large gains to be achieved from technological or theoretical developments that allow higher S/N, or, in the long term, surveys that simply observe a higher number density of galaxies.

259 citations