scholarly journals A combined analysis of the H0 late time direct measurements and the impact on the Dark Energy sector

2021 ◽  
Vol 502 (2) ◽  
pp. 2065-2073
Author(s):  
Eleonora Di Valentino
Keyword(s):  
Dark Energy ◽  
Time Delay ◽  
Surface Brightness ◽  
Hubble Constant ◽  
New Physics ◽  
Late Time ◽  
Direct Measurements ◽  
Phantom Dark Energy ◽  
Surface Brightness Fluctuations ◽  
The Impact

ABSTRACT We combine 23 Hubble constant measurements based on Cepheids-SN Ia, TRGB-SN Ia, Miras-SN Ia, Masers, Tully Fisher, Surface Brightness Fluctuations, SN II, Time-delay Lensing, Standard Sirens and γ-ray Attenuation, obtaining our best optimistic H0 estimate, that is H0 = 72.94 ± 0.75 km s–1 Mpc–1 at 68 per cent CL. This is in 5.9σ tension with the ΛCDM model, therefore we evaluate its impact on the extended Dark Energy cosmological models that can alleviate the tension. We find more than 4.9σ evidence for a phantom Dark Energy equation of state in the wCDM scenario, the cosmological constant ruled out at more than 3σ in a w0waCDM model and more than 5.7σ evidence for a coupling between Dark Matter and Dark Energy in the IDE scenario. Finally, we check the robustness of our results; and we quote two additional combinations of the Hubble constant. The ultra-conservative estimate, H0 = 72.7 ± 1.1 km s–1 Mpc–1 at 68 per cent CL, is obtained removing the Cepheids-SN Ia and the Time-Delay Lensing based measurements, and confirms the evidence for new physics.

scholarly journals Cosmic dissonance: are new physics or systematics behind a short sound horizon?

2020 ◽  
Vol 639 ◽  
pp. A57 ◽  
Author(s):  
Nikki Arendse ◽  
Radosław J. Wojtak ◽  
Adriano Agnello ◽  
Geoff C.-F. Chen ◽  
Christopher D. Fassnacht ◽  
...  
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Background Radiation ◽  
Hubble Constant ◽  
New Physics ◽  
Physical Models ◽  
Late Time ◽  
Absolute Distance ◽  
Acoustic Oscillations ◽  
Distance Indicators

Context. Persistent tension between low-redshift observations and the cosmic microwave background radiation (CMB), in terms of two fundamental distance scales set by the sound horizon rd and the Hubble constant H0, suggests new physics beyond the Standard Model, departures from concordance cosmology, or residual systematics. Aims. The role of different probe combinations must be assessed, as well as of different physical models that can alter the expansion history of the Universe and the inferred cosmological parameters. Methods. We examined recently updated distance calibrations from Cepheids, gravitational lensing time-delay observations, and the tip of the red giant branch. Calibrating the baryon acoustic oscillations and type Ia supernovae with combinations of the distance indicators, we obtained a joint and self-consistent measurement of H0 and rd at low redshift, independent of cosmological models and CMB inference. In an attempt to alleviate the tension between late-time and CMB-based measurements, we considered four extensions of the standard ΛCDM model. Results. The sound horizon from our different measurements is rd = (137 ± 3stat. ± 2syst.) Mpc based on absolute distance calibration from gravitational lensing and the cosmic distance ladder. Depending on the adopted distance indicators, the combined tension in H0 and rd ranges between 2.3 and 5.1 σ, and it is independent of changes to the low-redshift expansion history. We find that modifications of ΛCDM that change the physics after recombination fail to provide a solution to the problem, for the reason that they only resolve the tension in H0, while the tension in rd remains unchanged. Pre-recombination extensions (with early dark energy or the effective number of neutrinos Neff = 3.24 ± 0.16) are allowed by the data, unless the calibration from Cepheids is included. Conclusions. Results from time-delay lenses are consistent with those from distance-ladder calibrations and point to a discrepancy between absolute distance scales measured from the CMB (assuming the standard cosmological model) and late-time observations. New proposals to resolve this tension should be examined with respect to reconciling not only the Hubble constant but also the sound horizon derived from the CMB and other cosmological probes.

scholarly journals Manifestations of dark energy in the dynamics of the Solar system

2009 ◽  
Vol 5 (S264) ◽  
pp. 410-412
Author(s):  
Michal Křížek ◽  
Jan Brandts
Keyword(s):  
Dark Energy ◽  
Solar System ◽  
Hubble Constant ◽  
The Sun ◽  
Expansion Speed ◽  
Current Value ◽  
The Impact ◽  
The Universe

AbstractThe expansion speed of the Universe is increasing (Glanz 1998). This acceleration is attributed to dark energy which acts almost uniformly everywhere (including the Solar system) and thus essentially influences the Hubble constant. Its current value on a distance of 1 AU is H0 = 10 m/(yr AU). This is quite a large number and thus, the impact of dark energy should be detectable in the Solar system. We will illustrate it by several examples. Dark energy may partially be caused by gravitational aberration of the Sun, planets and other bodies.

scholarly journals Dark energy at early times and ACT data: A larger Hubble constant without late-time priors

2021 ◽  
Vol 104 (12) ◽  
Author(s):  
Vivian Poulin ◽  
Tristan L. Smith ◽  
Alexa Bartlett
Keyword(s):  
Dark Energy ◽  
Hubble Constant ◽  
Late Time

scholarly journals Interplay between Swampland and Bayesian Machine Learning in constraining cosmological models

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Emilio Elizalde ◽  
Martiros Khurshudyan
Keyword(s):  
Machine Learning ◽  
Dark Energy ◽  
High Redshift ◽  
Hubble Constant ◽  
State Parameter ◽  
Energy Models ◽  
Important Message ◽  
Phantom Dark Energy ◽  
Probabilistic Machine Learning ◽  
Bayesian Machine Learning

AbstractConstraints on a dark energy dominated Universe are obtained from an interplay Bayesian (Probabilistic) Machine Learning and string Swampland criteria. Unlike in previous studies, here, the field traverse itself has been used to constraint the theory and reveal its connection to the Swampland approach. The field traverse based Bayesian (Probabilistic) Learning approach is applied to two toy models. A parametrization of the Hubble constant is used for the first model, while a parametrization of the deceleration parameter is considered for the second one. The results obtained here allow to estimate how the high-redshift behavior of the Universe will affect the low-redshift one. Moreover, the adopted approach may highlight, in the future, the borders of the Swampland for the low-redshift Universe and help to develop new string-theory motivated dark energy models. The most important message from our study is a hint that the string Swampland criteria might be in tension with recent observations indicating that phantom dark energy cannot be in the Swampland. Finally, another interesting result obtained in our study is a spontaneous sign switch in the dark energy equation of state parameter when the field traverses are in the $$z\in [0,5]$$ z ∈ [ 0 , 5 ] redshift range, a remarkable phenomenon requiring further analysis.

scholarly journals A new measurement of the Hubble constant using Type Ia supernovae calibrated with surface brightness fluctuations

2021 ◽  
Vol 647 ◽  
pp. A72 ◽  
Author(s):  
Nandita Khetan ◽  
Luca Izzo ◽  
Marica Branchesi ◽  
Radosław Wojtak ◽  
Michele Cantiello ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Hubble Constant ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Type Ia Supernovae ◽  
Distance Measurements ◽  
Surface Brightness Fluctuations ◽  
Type Ia ◽  
Red Giant ◽  
Ia Supernovae

We present a new calibration of the peak absolute magnitude of Type Ia supernovae (SNe Ia) based on the surface brightness fluctuations (SBF) method, aimed at measuring the value of the Hubble constant. We build a sample of calibrating anchors consisting of 24 SNe hosted in galaxies that have SBF distance measurements. Applying a hierarchical Bayesian approach, we calibrate the SN Ia peak luminosity and extend the Hubble diagram into the Hubble flow by using a sample of 96 SNe Ia in the redshift range 0.02 < z < 0.075, which was extracted from the Combined Pantheon Sample. We estimate a value of H0 = 70.50 ± 2.37 (stat.) ± 3.38 (sys.) km s−1 Mpc−1 (i.e., 3.4% stat., 4.8% sys.), which is in agreement with the value obtained using the tip of the red giant branch calibration. It is also consistent, within errors, with the value obtained from SNe Ia calibrated with Cepheids or the value inferred from the analysis of the cosmic microwave background. We find that the SNe Ia distance moduli calibrated with SBF are on average larger by 0.07 mag than those calibrated with Cepheids. Our results point to possible differences among SNe in different types of galaxies, which could originate from different local environments and/or progenitor properties of SNe Ia. Sampling different host galaxy types, SBF offers a complementary approach to using Cepheids, which is important in addressing possible systematics. As the SBF method has the ability to reach larger distances than Cepheids, the impending entry of the Vera C. Rubin Observatory and JWST into operation will increase the number of SNe Ia hosted in galaxies where SBF distances can be measured, making SBF measurements attractive for improving the calibration of SNe Ia, as well as in the estimation of H0.

scholarly journals Concordance cosmology?

2020 ◽  
Vol 499 (4) ◽  
pp. 4638-4645
Author(s):  
Youngsoo Park ◽  
Eduardo Rozo
Keyword(s):  
Cold Dark Matter ◽  
Hubble Constant ◽  
Big Bang ◽  
New Physics ◽  
Current Data ◽  
Data Sets ◽  
Late Time ◽  
Acoustic Oscillations ◽  
Dark Energy Survey ◽  
The Difference

ABSTRACT We propose a new intuitive metric for evaluating the tension between two experiments, and apply it to several data sets. While our metric is non-optimal, if evidence of tension is detected, this evidence is robust and easy to interpret. Assuming a flat Lambda cold dark matter (ΛCDM) cosmological model, we find that there is a modest 2.2σ tension between the Dark Energy Survey (DES) Year 1 results and the Planck measurements of the cosmic microwave background. This tension is driven by the difference between the amount of structure observed in the late-time Universe and that predicted from fitting the Planck data, and appears to be unrelated to the tension between Planck and local estimates of the Hubble rate. In particular, combining DES, baryon acoustic oscillations, big bang nucleosynthesis, and supernovae measurements recover a Hubble constant and sound horizon consistent with Planck, and in tension with local distance–ladder measurements. If the tension between these various data sets persists, it is likely that reconciling all current data will require breaking the flat ΛCDM model in at least two different ways: one involving new physics in the early Universe, and one involving new late-time Universe physics.

scholarly journals Interacting dark side of universe through generalized uncertainty principle

2019 ◽  
Vol 28 (06) ◽  
pp. 1950081
Author(s):  
M. Rashki ◽  
M. Fathi ◽  
B. Mostaghel ◽  
S. Jalalzadeh
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Uncertainty Principle ◽  
Generalized Uncertainty Principle ◽  
Cosmological Parameters ◽  
State Parameter ◽  
Dark Side ◽  
Late Time ◽  
Doubly Special Relativity ◽  
The Impact

We investigate the impact of the generalized uncertainty principle proposed by some approaches to quantum gravity such as string theory and doubly special relativity on the cosmology. Using generalized Poisson brackets, we obtain the modified Friedmann and Raychaudhuri equations and suggest a dynamical dark energy to explain the late-time acceleration of the universe. After considering the interaction between dark matter and dark energy, originated from the minimal length, we obtain the effective cosmological parameters and equation of state parameter for dark matter and dark energy. Finally, we show that the resulting model is equivalent to the Phantom and Tachyon fields.

scholarly journals Resolving Hubble tension with the Milne model

2020 ◽  
Vol 29 (14) ◽  
pp. 2043025
Author(s):  
Ram Gopal Vishwakarma
Keyword(s):  
Hubble Constant ◽  
Big Bang ◽  
New Physics ◽  
Late Time ◽  
Standard Cosmology ◽  
Evolution Dynamics ◽  
Age Of The Universe ◽  
The Big Bang ◽  
The Universe ◽  
Big Bang Singularity

The recent measurements of the Hubble constant based on the standard [Formula: see text]CDM cosmology reveal an underlying disagreement between the early-Universe estimates and the late-time measurements. Moreover, as these measurements improve, the discrepancy not only persists but becomes even more significant and harder to ignore. The present situation places the standard cosmology in jeopardy and provides a tantalizing hint that the problem results from some new physics beyond the [Formula: see text]CDM model. It is shown that a nonconventional theory — the Milne model — which introduces a different evolution dynamics for the Universe, alleviates the Hubble tension significantly. Moreover, the model also averts some long-standing problems of the standard cosmology, for instance, the problems related with the cosmological constant, the horizon, the flatness, the Big Bang singularity, the age of the Universe and the nonconservation of energy.

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