Alleviating the H0 and σ8 anomalies with a decaying dark matter model

Pandey, Kanhaiya L.; Karwal, Tanvi; Das, Subinoy

doi:10.1088/1475-7516/2020/07/026

Cited by 129 publications

(84 citation statements)

References 71 publications

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“…Early-time solutions aim to reduce r with essentially two possibilities: (i) a coincidental increase of the Hubble expansion around recombination or (ii) new physics that alters the rate of recombination. Proposals in class (i) include the presence of early dark energy [13][14][15][16][17][18] , extra radiation in either neutrinos [19][20][21][22] or some other dark sector [23][24][25][26][27][28] , and dark energy-dark matter interactions 29 . Proposals in class (ii) include primordial magnetic fields 30 , non-standard recombination 31 , or varying fundamental constants 32,33 .…”

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confidence: 99%

“…3 shows the best fit values of r d h, H 0 and S 8 in models from Refs. 14,15,19,24,25,[29][30][31]33 . One can see that, except for the model represented by the red dot at the very right of the plot, corresponding to the strongly interacting neutrino model of 19 , solutions which operate at low Ω m h 2 are in tension with BAO, whereas solutions operating at higher Ω m h 2 are in tension with DES and KiDS.…”

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confidence: 99%

“…Model 3 has Ω m h 2 = 0.167 and corresponds to the overlap region between the θ (3) line and the BAO and SH0ES bands in Figure 1. 14,15,15,19,24,25,[29][30][31]33 , along with the 68% CL bands from BAO 39 , SH0ES, DES 34 and the combination of DES with KiDS (KV450) 40 .…”

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confidence: 99%

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Why reducing the cosmic sound horizon can not fully resolve the Hubble tension

Jedamzik

Pogosian

Zhao

2020

Preprint

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The mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by Planck in the context of the standard ΛCDM, known as the Hubble tension, has become one of the most pressing problems in cosmology. A large number of amendments to the ΛCDM model have been proposed in order to solve this tension. Many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing the sound horizon at recombination r*. We demonstrate here that any model which only reduces r* can never fully resolve the Hubble tension while remaining consistent with other cosmological datasets. We show explicitly that models which operate at lower matter density Ωmh2 run into tension with the observations of baryon acoustic oscillations, while models operating at higher Ωmh2 develop tension with galaxy weak lensing data.

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Why reducing the cosmic sound horizon can not fully resolve the Hubble tension

Jedamzik

Pogosian

Zhao

2020

Preprint

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“…Many scenarios to resolve the Hubble tension have been proposed, including modified dark energy [19][20][21] and decaying dark matter particles [22][23][24][25][26][27][28]. In this note, we argue that Hubble tension may be a result of extrapolating the CMB data from the time of recombination (z = 1089) to the present time (z = 0) using the CDM cosmology, which assumes pressureless dark matter.…”

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confidence: 90%

Non-particle dark matter from Hubble parameter

Popławski

2019

Eur. Phys. J. C

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The measurements of the Hubble parameter using the cosmic microwave background radiation appear to be inconsistent with the measurements of this parameter using Cepheid variable stars. This inconsistency may be a result of using the CDM cosmology, which assumes pressureless dark matter, in extrapolating the data from the recombination time to the present time. We show that both measurements are consistent if dark matter satisfies an equation of state in which the pressure p and the energy density are related by p = w with a negative value of w. The data give w ≈ −0.01. The negative value of w indicates that dark matter would not be formed by particles, which is consistent with the lack of experimental evidence for them.The observations of the temperature angular power spectrum of the cosmic microwave background (CMB) radiation provide the information about the composition of the universe [1]. The measurements of the position of the first acoustic peak show that the universe is nearly flat, with the density parameter ≈ 1. The measurements of the amplitudes of the peaks determine the values of b h 2 and c h 2 , where b is the density parameter for baryonic matter, c is the density parameter for dark matter, and the present-day Hubble parameter H 0 = 100h km/s/Mpc. Combining these values with the measured h = 0.674 ± 0.005 gives (omitting errors) b = 0.049 and c = 0.265, as obtained by the Planck satellite [2,3]. Consequently, the density parameter for total matter is m = 0.314.Before the Planck measurements, most measured values of h also clustered around 0.68, including the data from high-redshift type Ia supernovae (SN Ia) [4,5], Wilkinson Microwave Anisotropy Probe CMB data [6], baryon acoustic oscillations (BAO) [7], SN Ia and BAO data [8], measurements of the Hubble parameter at intermediate redshifts [9], and large-scale-structure data [10]. Assuming a flat universe, = 1 − m = 0.686 for dark energy (cosmological constant). The resulting age of the universe is t univ = a e-mail: NPoplawski@newhaven.edu da/(a H) =

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“…Accordingly, a profound adjustment of the ΛCDM model or new physics are now growing due to this new evidence underlying the model assumptions [23]. On the other hand, several alternative theories which encounter the assumptions of the ΛCDM model are under consideration, such as modified gravity, entropic gravity, bimetric gravity, modified Newtonian dynamics, scale invariance of empty-space, large-scale variations in the matter density of the universe and the decaying dark matter [30]- [33].…”

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confidence: 99%

Astromechanics of Dual Universe: A New Possible Explanation for the Universe Unsolved Problems

Al-Fadhli¹

2020

Preprint

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The necessity of the dark energy and dark matter in the present universe could be a consequence of the antimatter elimination assumption in the early universe. Current cosmological models that rely on the dark side have left many unsolved mysteries, remarkably: tension in Hubble parameter measurements, the accelerated expansion, the fast orbital speed of stars, the dark flow observations, cosmic horizon, space flatness, absent of the antimatter, etc. On the other hand, General Relativity (GR) has relied on the spacetime to demonstrate the movement of matter due to a local curvature caused by the presence of matter. Founded on this, I trace the evolution of the spacetime worldlines based on the evolution of the universe spatial scale factor and its evolution time in polar coordinates in order to construct a potential spatial curvature over the temporal dimension or a global spacetime curvature. The mathematical derivations of a positively curved universe governed by only gravity revealed two opposite solutions of the worldline evolution. This possibly implies that the matter and antimatter could be evolving in opposite directions as distinct sides of the universe. By implementing the derived model, we find a decelerated phase of spatial expansion during the first 10 Gyr, that is followed by a second phase of an accelerated expansion; potentially matching the tension in Hubble parameter measurements. In addition, the model predicts a final time-reversal phase of spatial contraction, due to rapid surge in density i.e. reversal entropy, leading to a Big Crunch of a cyclic universe. The predicted density is 1.14. Other predictions are (1) an evolvable curved spacetime at the decelerated phase that is transformed to flatness at the accelerated phase with internal voids which could continuously increase the matter and antimatter densities elsewhere in both sides. (2) the spatial curvature through time dimension along spacetime worldlines was found to increase galaxy orbital speed and (3) a calculable flow rate of the matter side towards the antimatter side at the accelerated phase; conceivably explaining the dark flow observation. These findings may indicate the existence of the antimatter as a distinct side, which influences the evolution of the universe instead of the dark energy or dark matter. These theoretical outcomes and predictions are promising, which can be verified, fine-tuned or disproved using astrometric data in future works.

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Alleviating the H₀ and σ₈ anomalies with a decaying dark matter model

Cited by 129 publications

References 71 publications

Why reducing the cosmic sound horizon can not fully resolve the Hubble tension

Why reducing the cosmic sound horizon can not fully resolve the Hubble tension

Non-particle dark matter from Hubble parameter

Astromechanics of Dual Universe: A New Possible Explanation for the Universe Unsolved Problems

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