The galaxy power spectrum take on spatial curvature and cosmic concordance

Vagnozzi, Sunny; Valentino, Eleonora Di; Gariazzo, Stefano; Melchiorri, A.; Mena, Olga; Silk, Joseph

doi:10.1016/j.dark.2021.100851

Cited by 113 publications

(48 citation statements)

References 221 publications

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“…We have found some deviations from spatial flatness and only upper bounds on anisotropic expansion, which also affect the predicted Hubble constant and present-day density parameter of the pressureless fluid, at various significance lev-els depending on the data set used. However, when the data sets relevant to the low-and high-redshifts are simultaneously employed, all the extended models are predicted to be indistinguishable from the Planck 2018 ΛCDM model [3], though we emphasize that when the spatial curvature is free to vary, some tensions appear between the data [17,18,20]. In particular, with regard to the expansion anisotropy, from the low redshift data, viz., the CC and/or Pan data, we have found Ω σ0 10 −2 (about one order of magnitude looser than the model independent estimations [70][71][72][73][74][75][76]), while it considerably tightens to Ω σ0 10 −14 with the addition of the BAO data.…”

Section: Discussionmentioning

confidence: 99%

“…where m = 0 is a non-zero real constant. It can be observed that Bianchi type V metric (20) reduces to the Bianchi type I metric (8) when m = 0. EFE (2) for the Bianchi type V metric (20) lead to the following set of differential equations:…”

Section: Spatially Homogeneous Open and Anisotropic Universementioning

confidence: 99%

“…Moreover, spatially closed models are in agreement with not only the low CMB anisotropy quadrupole of Planck, but also the WMAP CMB data [15,16]. However, the drastic exacerbation of the H 0 tension in this case, and the favoring of spatial flatness with extremely high precision by the Planck CMB data in combination with the baryon acoustic oscillations (BAO) data, and the astrophysical data such as type Ia Supernovae (SNIa) and cosmic chronometers (CC), have stimulated the debate on the spatial flatness assumption [3,[17][18][19][20][21][22][23]; particularly, given that it is in line with the canonical inflationary paradigm-yet, note that inflation is not necessarily in conflict with a non-flat space [16,[24][25][26], but spatially closed inflationary models are significantly fine-tuned [16]. On the other hand, the canonical inflationary paradigm makes sense if the observable universe exhibits isotropic expansion (ignoring the possibility of being broken by, for instance, anisotropic dark energy in the late universe).…”

Section: Introductionmentioning

confidence: 99%

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Testing spatial curvature and anisotropic expansion on top of the $Λ$CDM model

Akarsu¹,

Valentino²,

Kumar³

et al. 2021

Preprint

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We explore the possible advantages of extending the standard ΛCDM model by more realistic backgrounds compared to its spatially flat Robertson-Walker spacetime assumption, while preserving the underpinning physics; in particular, by simultaneously allowing non-zero spatial curvature and anisotropic expansion on top of ΛCDM, viz., the An-oΛCDM model. This is to test whether the latest observational data still support spatial flatness and/or isotropic expansion in this case, and, if not, to explore the roles of spatial curvature and expansion anisotropy (due to its stiff fluid-like behavior) in addressing some of the current cosmological tensions associated with ΛCDM. We first present the theoretical background and explicit mathematical construction of An-oΛCDM. Then we constrain the parameters of this model and its particular cases, namely, An-ΛCDM, oΛCDM, and ΛCDM, by using the data sets from different observational probes, viz., Planck CMB(+Lens), BAO, SnIa Pantheon, and CC data, and discuss the results in detail. Ultimately, we conclude that (i) the observational data confirm the spatial flatness and isotropic expansion assumptions of ΛCDM, though a very small amount of expansion anisotropy cannot be excluded, e.g., Ωσ0 10 −18 (95% C.L.) for An-ΛCDM from CMB+Lens data, (ii) the introduction of spatial curvature or anisotropic expansion, or both, on top ΛCDM does not offer a possible relaxation to the H0 tension, and (iii) the introduction of anisotropic expansion neither affects the closed space prediction from the CMB(+Lens) data nor does it improve the drastically reduced value of H0 led by the closed space.

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Section: Discussionmentioning

confidence: 99%

Section: Spatially Homogeneous Open and Anisotropic Universementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Testing spatial curvature and anisotropic expansion on top of the $Λ$CDM model

Akarsu¹,

Valentino²,

Kumar³

et al. 2021

Preprint

Self Cite

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show abstract

“…Much previous work has investigated how exploiting information contained in the turnover and the full-shape power spectrum on larger scales can break certain degeneracies (Ivanov et al 2020a;Philcox et al 2020;Philcox et al 2021;D'Amico et al 2021), reveal information about curvature (Vagnozzi et al 2021) and also sharpen constraints on beyond ΛCDM models (Chudaykin et al 2021). We refer the reader to these investigations for a more comprehensive analysis of this topic in general.…”

Section: Cosmology From Turnover Scalesmentioning

confidence: 99%

Detecting the power spectrum turnover with HI intensity mapping

Cunnington

2022

Preprint

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A goal for pathfinder intensity mapping (IM) surveys will be detecting features in the neutral hydrogen (H ) power spectrum, which serve as conclusive evidence of cosmological signals. Observing such features at the expected scales in H IM auto-correlations, where contribution from systematics is uncertain, will provide a more convincing cosmological detection. We demonstrate how the turnover, i.e. the peak of the power spectrum at ultra-large scales, can be detected with H IM. We find that a MeerKAT 4,000 deg 2 survey using the UHF-band is capable of a 3.1𝜎 detection of the turnover, relative to a null model power spectrum with no turnover. This should exceed that capable from current galaxy surveys in optical and near-infrared. The detection significance falls to ∼1𝜎 in MeerKAT's L-band but can reach ∼13𝜎 with the SKAO, which should easily surpass the constraint capable from future Stage-IV-like spectroscopic galaxy surveys. We also propose a new model-independent methodology for constraining the precise turnover scale (𝑘 0 ) and our tests on UHF-band simulated data achieved a precision of 10%. This improved to 2.4% when using the full SKAO. We demonstrate how the results are robust to foreground contamination by using transfer functions, even when an incorrect cosmology has been assumed in their construction. Given that the turnover is related to the horizon scale at matter-radiation equality, a sufficiently precise constraint of 𝑘 0 presents the possibility for a novel probe of cosmology. We therefore present a potential methodology for constructing a standard-ruler-based distance measurement, independent of the sound horizon, using the turnover location in the H power spectrum.

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“…From the previous studies of the exponential f (R) gravity model, the model and spatial curvature density parameters are constrained to be 0.392 < λ −1 < 0.851 [23] and −0.0011 < Ω 0 K < 0.0027 at 68% C.L. [24], respectively. In this work, we choose λ −1 = 0.5 and Ω 0 K = ±0.001 to see the behavior of exponential f (R) gravity.…”

Section: Numerical Calculationsmentioning

confidence: 99%

Cosmological Constraints on Non-flat Exponential $f(R)$ Gravity

Geng,

Hsu,

2021

Preprint

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We explore the viable f (R) gravity models in FLRW backgrounds with a free spatial curvature parameter Ω K . In our numerical calculation, we concentrate on the exponential f (R) model of, where R ch is the characteristic curvature scale, which is independent of Ω K , and λ corresponds to the model parameter, while R ch λ = 2Λ with Λ the cosmological constant. In particular, we study the evolutions of the dark energy density and equation of state for exponential f (R) gravity in open, flat and closed universe, and compare with those for ΛCDM. From the current observational data, we find that λ −1 = 0.42927 +0.39921 −0.32927 at 68% C.L and Ω K = −0.00050 +0.00420 −0.00414 at 95% C.L. in the exponential f (R) model. By using Akaike information criterion (AIC), Bayesian information criterion (BIC) and Deviance Information Criterion (DIC), we conclude that there is no strong preference between the exponential f (R) gravity and ΛCDM models in the non-flat universe.

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The galaxy power spectrum take on spatial curvature and cosmic concordance

Cited by 113 publications

References 221 publications

Testing spatial curvature and anisotropic expansion on top of the $Λ$CDM model

Testing spatial curvature and anisotropic expansion on top of the $Λ$CDM model

Detecting the power spectrum turnover with HI intensity mapping

Cosmological Constraints on Non-flat Exponential $f(R)$ Gravity

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