Theoretical priors in scalar-tensor cosmologies: Thawing quintessence

García-García, Carlos; Bellini, Emilio; Ferreira, Pedro G.; Traykova, Dina; Zumalacárregui, Miguel

doi:10.1103/physrevd.101.063508

Cited by 12 publications

(10 citation statements)

References 62 publications

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“…On the theoretical side, it would be interesting to study the feasibility of geometry vs growth splits beyond ΛCDM. It is clear that the distinction proposed in this work can be extrapolated straightforwardly to modified models that only introduce changes to the background cosmology, such as non-flat ΛCDM models or dark energy models with an effective equation of state, which have proven to be successful at encapsulating a wide variety of models (Traykova et al 2021;García-García et al 2020). Another type of modification that is compatible with this framework is an effective Newton's constant for gravity because it does not change the shape of the Jeans equation (Baker et al 2014).…”

Section: Discussionmentioning

confidence: 98%

Geometry vs growth: Internal consistency of the flat ΛCDM model with KiDS-1000

Ruiz-Zapatero,

Stölzner,

Joachimi

et al. 2021

Preprint

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We carry out a multi-probe self-consistency test of the flat ΛCDM model with the aim of exploring potential causes of the reported tensions between high-and low-redshift cosmological observations. We divide the model into two theory regimes determined by the smooth background (geometry) and the evolution of matter density fluctuations (growth), each governed by an independent set of ΛCDM cosmological parameters. This extended model is constrained by a combination of weak gravitational lensing measurements from the the Kilo-Degree Survey, galaxy clustering signatures extracted from Sloan Digital Sky Survey campaigns and the Six-Degree Field Galaxy Survey, as well as the angular baryon acoustic scale and the primordial scalar fluctuation power spectrum measured in Planck cosmic microwave background (CMB) data. For both the weak lensing data set individually and the combined probes, we find strong consistency between the geometry and growth parameters, and with the posterior of standard ΛCDM analysis. Tension in the amplitude of matter density fluctuations as measured by the parameter S 8 persists at around 3σ, with a 1.5 % constraint of S 8 = 0.776 +0.016 −0.008 for the combined probes. We also observe less significant trends (at least 2σ) towards higher values of the Hubble constant H 0 = 70.5 +0.7 −1.5 km s −1 Mpc −1 and towards lower values of the total matter density parameter Ω m = 0.289 +0.007 −0.005 compared to the full Planck analysis. Including the subset of the CMB information in the probe combination enhances these differences rather than alleviate them, which we link to the discrepancy between low and high multipoles in Planck data. Our analysis does not yet yield clear signs whether the origin of discrepancies lies in ΛCDM structure growth or expansion history, but holds promise as an insightful test for forthcoming more powerful data.

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Section: Discussionmentioning

confidence: 98%

Geometry vs growth: Internal consistency of the flat ΛCDM model with KiDS-1000

Ruiz-Zapatero,

Stölzner,

Joachimi

et al. 2021

Preprint

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show abstract

“…On the theoretical side, it would be interesting to study the feasibility of geometry versus growth splits beyond ΛCDM. It is clear that the distinction proposed in this work can be extrapolated straightforwardly to modified models that only introduce changes to the background cosmology, such as non-flat ΛCDM models or dark energy models with an effective equation of state, which have proven to be successful at encapsulating a wide variety of models (Traykova et al 2021, García-García et al 2020. Another type of modification that is compatible with this framework is a time-varying Newton's constant for gravity because it does not change the shape of the Jeans equation (Baker et al 2014).…”

Section: Discussionmentioning

confidence: 99%

Geometry versus growth

Ruiz-Zapatero

Stölzner

Joachimi

et al. 2021

A&A

View full text Add to dashboard Cite

We carry out a multi-probe self-consistency test of the flat ΛCDM model with the aim of exploring potential causes of the reported tensions between high-and low-redshift cosmological observations. We divide the model into two theory regimes determined by the smooth background (geometry) and the evolution of matter density fluctuations (growth), each governed by an independent set of Lambda Cold Dark Matter (ΛCDM) cosmological parameters. This extended model is constrained by a combination of weak gravitational lensing measurements from the Kilo-Degree Survey, galaxy clustering signatures extracted from Sloan Digital Sky Survey campaigns and the Six-Degree Field Galaxy Survey, and the angular baryon acoustic scale and the primordial scalar fluctuation power spectrum measured in Planck cosmic microwave background (CMB) data. For both the weak lensing data set individually and the combined probes, we find strong consistency between the geometry and growth parameters, as well as with the posterior of standard ΛCDM analysis. In the non-split analysis, for which one single set of parameters was used, tension in the amplitude of matter density fluctuations as measured by the parameter S 8 persists at around 3σ, with a 1.5 % constraint of S 8 = 0.776 +0.016 −0.008 for the combined probes. We also observe a less significant preference (at least 2σ) for higher values of the Hubble constant, H 0 = 70.5 +0.7 −1.5 km s −1 Mpc −1 , as well as for lower values of the total matter density parameter Ω m = 0.289 +0.007 −0.005 compared to the full Planck analysis. Including the subset of the CMB information in the probe combination enhances these differences rather than alleviate them, which we link to the discrepancy between low and high multipoles in Planck data. Our geometry versus growth analysis does not yet yield clear signs regarding whether the origin of the discrepancies lies in ΛCDM structure growth or expansion history but holds promise as an insightful test for forthcoming, more powerful data.

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“…No.. In the spirit of [65], we now want to find the set of parameters {w 0 , w a , αB , m} that reproduce the Hubble rate (H), the angular diameter distance (D A ) and the growth factor…”

Section: Yesmentioning

confidence: 99%

“…There have been a number of studies where the evolution of the DE equation of state has been reconstructed nonparametricaly (in redshift bins) using data [55][56][57][58][59], as well as ones where the impact of theoretical priors on the parameters of quintessence and more general scalar-tensor theories was considered and used to introduce correlations and minimise the number of these parameters [60][61][62][63][64]. Using a different and complementary approach, we have tackled this problem of physical priors in the case of thawing quintessence where, remarkably, we could construct an analytic prior for w(a) [65]. By parametrising it as…”

Section: Introductionmentioning

confidence: 99%

Theoretical priors in scalar-tensor cosmologies: Shift-symmetric Horndeski models

Traykova,

Bellini,

Ferreira

et al. 2021

Preprint

Self Cite

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Attempts at constraining theories of late time accelerated expansion often assume broad priors for the parameters in their phenomenological description. Focusing on shift-symmetric scalar-tensor theories with standard gravitational wave speed, we show how a more careful analysis of their dynamical evolution leads to much narrower priors. In doing so, we propose a simple and accurate parametrisation of these theories, capturing the redshift dependence of the equation of state, w(z), and the kinetic braiding parameter, α B (z), with only two parameters each, and derive their statistical distribution (a.k.a. theoretical priors) that fit the cosmology of the underlying model. We have considered two versions of the shift-symmetric model, one where the energy density of dark energy is given solely by the scalar field, and another where it also has a contribution from the cosmological constant. By including current data, we show how theoretical priors can be used to improve constraints by up to an order of magnitude. Moreover, we show that shift-symmetric theories without a cosmological constant are observationally viable. We work up to quartic order in first derivatives of the scalar in the action and our results suggest this truncation is a good approximation to more general shift-symmetric theories. This work establishes an actionable link between phenomenological parameterisations and Lagrangian-based theories, the two main approaches to test cosmological gravity and cosmic acceleration.

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Theoretical priors in scalar-tensor cosmologies: Thawing quintessence

Cited by 12 publications

References 62 publications

Geometry vs growth: Internal consistency of the flat ΛCDM model with KiDS-1000

Geometry vs growth: Internal consistency of the flat ΛCDM model with KiDS-1000

Geometry versus growth

Theoretical priors in scalar-tensor cosmologies: Shift-symmetric Horndeski models

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