Developing a unified pipeline for large-scale structure data analysis with angular power spectra – I. The importance of redshift-space distortions for galaxy number counts

Tanidis, Konstantinos; Camera, Stefano

doi:10.1093/mnras/stz2366

Cited by 22 publications

(15 citation statements)

References 70 publications

(69 reference statements)

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“…In angular space, the nonlinear modelling of redshift space distortions is more complex and depends on the redshift binning under consideration [236]. The treatment of RSDs in the Limber approximation on linear scales has recently been developed [237], while N-body and hydrodynamical simulations [91,93] have also been used to model the effect of redshift space distortions on HI intensity maps. Just as in the case of galaxy RSDs, the HI RSDs can potentially constrain several interesting effects and break degeneracies.…”

Section: Extensions To the Halo Model Frameworkmentioning

confidence: 99%

A Multi-messenger view of Cosmic Dawn: Conquering the Final Frontier

Padmanabhan

2021

Preprint

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The epoch of Cosmic Dawn, when the first stars and galaxies were born, is widely considered the final frontier of observational cosmology today. Mapping the period between Cosmic Dawn and the present-day provides access to more than 90% of the baryonic (normal) matter in the Universe, and unlocks several thousand times more Fourier modes of information than available in today's cosmological surveys. We review the progress in modelling baryonic gas observations as tracers of the cosmological large-scale structure from Cosmic Dawn to the present day. We illustrate how the description of dark matter haloes can be extended to describe baryonic gas abundances and clustering. This innovative approach allows us to fully utilize our current knowledge of astrophysics to constrain cosmological parameters from future observations. Combined with the information content of multi-messenger probes, this will also elucidate the properties of the first supermassive black holes at Cosmic Dawn. We present a host of fascinating implications for constraining physics beyond the ΛCDM model, including tests of the theories of inflation and the cosmological principle, the effects of non-standard dark matter, and possible deviations from Einstein's general relativity on the largest scales.

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Section: Extensions To the Halo Model Frameworkmentioning

confidence: 99%

A Multi-messenger view of Cosmic Dawn: Conquering the Final Frontier

Padmanabhan

2021

Preprint

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“…Failing to include them in the theoretical modelling will bias the estimate of primordial non-Gaussianity, f NL , and lead to an incorrect estimate of the parameter errors. A correct implementation of the velocity terms has been shown to be crucial not to bias parameter estimation [120][121][122].…”

Section: Effects Of Cosmic Magnificationmentioning

confidence: 99%

Beware of commonly used approximations I: errors in forecasts

Bellomo,

Bernal,

Scelfo

et al. 2020

Preprint

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In the era of precision cosmology, establishing the correct magnitude of statistical errors in cosmological parameters is of crucial importance. However, widely used approximations in galaxy surveys analyses can lead to parameter uncertainties that are grossly mis-estimated. These approximations can be introduced at three different levels: in the form of the likelihood, in the theoretical modelling of the observable and in the numerical computation of the observable. Their consequences are important both in data analysis through e.g., Markov Chain Monte Carlo parameter inference, and when survey instrument and strategy are designed and their constraining power on cosmological parameters is forecasted, for instance using Fisher matrix analyses. In this work, considering the galaxy angular power spectrum as the target observable, we report one example for each of such three categories and derive their impact on the estimated parameters uncertainties and degeneracies. We show that there are cases where these commonly used approximations lead, perhaps counterintuitively, to unacceptably large mis-estimates of parameters errors and correlations. Furthermore, we stress how these approximations might even spoil the benefits of the nascent multi-tracer and multi-messenger cosmology. Hence we recommend that the type of analysis presented here should be repeated for every approximation adopted in survey design or data analysis, to quantify how it may affect the results. To this aim, we have developed Multi CLASS, a new extension of CLASS that includes the angular power spectrum for multiple (galaxy and other tracers such as gravitational waves) populations. The public release of Multi CLASS is associated with this paper.

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“…• SKA1: z ∈ [0.4, 0.6], with shot-noise = 1/n g ≈ 1.45 × 10 −5 sr and linear galaxy bias b 1 ≈ 1.02 consistent with SKA1 Medium-Deep Band 2 Survey (5σ detection threshold) [18,41]. We use again Equation 4.4 and Equation 4.5 as galaxy bias prescription.…”

Section: Spectroscopic Surveysmentioning

confidence: 99%

Speeding up the detectability of the harmonic-space galaxy bispectrum

Montanari,

Camera

2020

Preprint

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For the first time we estimate the signal-to-noise ratio (SNR) of the harmonic-space galaxy bispectrum induced by gravity, a complementary probe to Fourier-space clustering analyses. We show how to do it considering only ∼ 1000 triangle configurations in multipole space, corresponding to a computational speedup of a factor O(10 2 ) − O(10 3 ), depending on the redshift bin, when including mildly nonlinear scales. Assuming observational specifications consistent with Euclid -like and SKA1-like spectroscopic and photometric galaxy surveys, we show: that given a single redshift bin, spectroscopic surveys outperform photometric surveys by almost an order of magnitude; and that-due to shot-noise and redshift bin width balance-bins at redshifts z ∼ 1 bring higher cumulative SNR than bins at lower redshifts z ∼ 0.5. Our results for the cumulative SNR 0.5 exclude detection of the harmonic-space bispectrum within the single redshift bins here considered and suggest that tomographic studies with upcoming galaxy surveys will be necessary to enhance the detectability. We further discuss how, using the Karhunen-Loève transform, a detection analysis only requires a 1 × 1 covariance matrix for a single redshift bin.

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Developing a unified pipeline for large-scale structure data analysis with angular power spectra – I. The importance of redshift-space distortions for galaxy number counts

Cited by 22 publications

References 70 publications

A Multi-messenger view of Cosmic Dawn: Conquering the Final Frontier

A Multi-messenger view of Cosmic Dawn: Conquering the Final Frontier

Beware of commonly used approximations I: errors in forecasts

Speeding up the detectability of the harmonic-space galaxy bispectrum

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