scholarly journals Does the Hubble constant tension call for new physics?

2018 ◽  
Vol 2018 (09) ◽  
pp. 025-025 ◽  
Author(s):  
Edvard Mörtsell ◽  
Suhail Dhawan
Keyword(s):  
Hubble Constant ◽  
New Physics ◽  
Constant Tension

scholarly journals Generalized emergent dark energy model and the Hubble constant tension

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Weiqiang Yang ◽  
Eleonora Di Valentino ◽  
Supriya Pan ◽  
Arman Shafieloo ◽  
Xiaolei Li
Keyword(s):  
Dark Energy ◽  
Dark Energy Model ◽  
Hubble Constant ◽  
Energy Model ◽  
Constant Tension

scholarly journals How does an incomplete sky coverage affect the Hubble Constant variance?

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Carlos A. P. Bengaly ◽  
Uendert Andrade ◽  
Jailson S. Alcaniz
Keyword(s):  
Hubble Constant ◽  
Real Data ◽  
Data Sets ◽  
Constant Variance ◽  
Uniform Distributions ◽  
Constant Tension ◽  
Type Ia ◽  
Data Points ◽  
Standard Cosmological Model ◽  
Celestial Sphere

Abstract We address the $$\simeq 4.4\sigma $$≃4.4σ tension between local and the CMB measurements of the Hubble Constant using simulated Type Ia Supernova (SN) data-sets. We probe its directional dependence by means of a hemispherical comparison through the entire celestial sphere as an estimator of the $$H_0$$H0 cosmic variance. We perform Monte Carlo simulations assuming isotropic and non-uniform distributions of data points, the latter coinciding with the real data. This allows us to incorporate observational features, such as the sample incompleteness, in our estimation. We obtain that this tension can be alleviated to $$3.4\sigma $$3.4σ for isotropic realizations, and $$2.7\sigma $$2.7σ for non-uniform ones. We also find that the $$H_0$$H0 variance is largely reduced if the data-sets are augmented to 4 and 10 times the current size. Future surveys will be able to tell whether the Hubble Constant tension happens due to unaccounted cosmic variance, or whether it is an actual indication of physics beyond the standard cosmological model.

scholarly journals Tempeature Redshift of Photons

2020 ◽  
Author(s):  
Xiaoping Hu
Keyword(s):  
Dark Matter ◽  
Hubble Constant ◽  
Big Bang ◽  
New Physics ◽  
Current Theory ◽  
Big Bang Theory ◽  
Celestial Bodies ◽  
Expansion Force ◽  
The Big Bang ◽  
The Universe

This article presents a new theory on redshift of light from celestial bodies. Lately it has been found that the Hubble constant calculated from different methods discord so much that calls arise for new physics to explain. Also, in addition to many unsolved puzzles like dark matter and source of expansion force, we shall show in this article that the current theory of redshift implies a few hidden, unreasonale assumptions. By assuming photon has temperature and its thermal energy is fully converted to wave energy, this article shows that photon can have a new redshift called Temperature Redshift, which not only is more significant for remote stars or galaxies, but also better fits the observational data, including those used in Hubble constant calculation. As such, if true, this new theory not only adds to our new understanding of photons, but may totally change our current understanding of the Universe, i.e., the Big Bang theory.

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 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 A fake interacting dark energy detection?

2020 ◽  
Vol 500 (1) ◽  
pp. L22-L26
Author(s):  
Eleonora Di Valentino ◽  
Olga Mena
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Hubble Constant ◽  
Energy Detection ◽  
Microwave Background ◽  
Planck Data ◽  
Cosmological Constraints ◽  
Data Analyses ◽  
Constant Tension

ABSTRACT Models involving an interaction between the dark matter and the dark energy sectors have been proposed to alleviate the long-standing Hubble constant tension. In this paper, we analyse whether the constraints and potential hints obtained for these interacting models remain unchanged when using simulated Planck data. Interestingly, our simulations indicate that a dangerous fake detection for a non-zero interaction among the dark matter and the dark energy fluids could arise when dealing with current cosmic microwave background (CMB) Planck measurements alone. The very same hypothesis is tested against future CMB observations, finding that only cosmic variance limited polarization experiments, such as PICO or PRISM, could be able to break the existing parameter degeneracies and provide reliable cosmological constraints. This paper underlines the extreme importance of confronting the results arising from data analyses with those obtained with simulations when extracting cosmological limits within exotic cosmological scenarios.

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.

scholarly journals A new method to build the (inverse) distance ladder

2020 ◽  
Vol 495 (3) ◽  
pp. 2630-2644 ◽  
Author(s):  
David Camarena ◽  
Valerio Marra
Keyword(s):  
High Redshift ◽  
Photon Number ◽  
Hubble Constant ◽  
New Physics ◽  
New Method ◽  
Luminosity Distance ◽  
Local Measurements ◽  
The Impact ◽  
Distance Relation ◽  
Inverse Distance

ABSTRACT The cosmic distance ladder is the succession of techniques by which it is possible to determine distances to astronomical objects. Here, we present a new method to build the cosmic distance ladder, going from local astrophysical measurements to the CMB. Instead of relying on high-redshift cosmography in order to model the luminosity–distance relation and calibrate supernovae with BAO, we exploit directly the distance–duality relation dL = (1 + z)2dA – valid if photon number is conserved and gravity is described by a metric theory. The advantage is that the results will not depend on the parametrization of the luminosity–distance relation at z > 0.15: no model is adopted in order to calibrate BAO with supernovae. This method yields local measurements of the Hubble constant and deceleration parameter. Furthermore, it can directly assess the impact of BAO observations on the strong 4–5σ tension between local and global H0. Using the latest supernova, BAO and CMB observations, we found a consistently low value of q0 and strong inconsistency between angular-only BAO constraints and anisotropic BAO measurements, which are, or not, in agreement with CMB depending on the kind of analysis (see Table 4). We conclude that, in order to understand the reasons behind the H0 crisis, a first step should be clarifying the tension between angular and perpendicular anisotropic BAO as this will help understanding if new physics is required at the pre-recombination epoch or/and during the dark energy era.

scholarly journals Hubble Constant Tension in Terms of Information Approach

2019 ◽  
pp. 1-15
Author(s):  
Boris Menin
Keyword(s):  
Scientific Literature ◽  
Hubble Constant ◽  
Measurement Model ◽  
Current Situation ◽  
Experimental Results ◽  
Relative Uncertainty ◽  
Information Approach ◽  
Amount Of Information ◽  
Advantages And Disadvantages ◽  
Constant Tension

Aims: The purpose of this work is to formulate the theoretically justified information approach to analyze different methods of measuring Hubble’s constant, and to verify their advantages and disadvantages. Place and Duration of Study: Mechanical & Refrigeration Consultation Expert, between June 2019 and November 2019. Methodology: Due to the fact that any measurement model contains a certain amount of information about the studied object, comparative uncertainty is introduced, by which the least achievable relative uncertainty when measuring the Hubble constant is calculated. Results: The experimental results of measuring the Hubble constant presented in the scientific literature are analyzed using the proposed information approach. Conclusion: The information approach can be considered as an additional look at the Hubble constant tension. Most likely, this will help to understand the current situation and identify possible specific ways to solve it.

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