scholarly journals Constraints on the electron-to-proton mass ratio variation at the epoch of reionization

2020 ◽  
Vol 498 (3) ◽  
pp. 3624-3632
Author(s):  
S A Levshakov ◽  
M G Kozlov ◽  
I I Agafonova
Keyword(s):  
Dark Matter ◽  
Fine Structure ◽  
Dark Energy ◽  
High Redshift ◽  
Far Infrared ◽  
Mass Ratio ◽  
Regression Curve ◽  
Proton Mass ◽  
Ratio Variation ◽  
Dynamical Nature

ABSTRACT Far-infrared fine-structure transitions of [C i] and [C ii] and rotational transitions of CO are used to probe hypothetical variations of the electron-to-proton mass ratio μ = me/mp at the epoch of reionization (z > 6). A constraint on Δμ/μ = (μobs − μlab)/μlab = (0.7 ± 1.2) × 10−5 (1σ) obtained at $\bar{z} = 6.31$ is the most stringent up-to-date limit on the variation of μ at such high redshift. For all available estimates of Δμ/μ ranging between z = 0 and z ∼ 1100, the epoch of recombination, a regression curve Δμ/μ = kμ(1 + z)p, with kμ = (1.6 ± 0.3) × 10−8 and p = 2.00 ± 0.03, is deduced. If confirmed, this would imply a dynamical nature of dark matter/dark energy.

scholarly journals CONSTRAINING TEVES GRAVITY AS EFFECTIVE DARK MATTER AND DARK ENERGY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2055-2063 ◽  
Author(s):  
HONGSHENG ZHAO
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Gravitational Lensing ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Dual Roles ◽  
Acceleration Of The Universe ◽  
The Universe

The phenomena customarily described with the standard ΛCDM model are broadly reproduced by an extremely simple model in TeVeS, Bekenstein's1 modification of general relativity motivated by galaxy phenomenology. Our model can account for the acceleration of the Universe seen at SNeIa distances without a cosmological constant, and the accelerations seen in rotation curves of nearby spiral galaxies and gravitational lensing of high-redshift elliptical galaxies without cold dark matter. The model is consistent with BBN and the neutrino mass between 0.05 eV to 2 eV. The TeVeS scalar field is shown to play the effective dual roles of dark matter and dark energy, with the amplitudes of the effects controlled by a μ function of the scalar field, called the μ essence here. We also discuss outliers to the theory's predictions on multiimaged galaxy lenses and outliers on the subgalaxy scale.

scholarly journals Multiverse Predictions for Habitability: Number of Potentially Habitable Planets

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 157 ◽  
Author(s):  
McCullen Sandora
Keyword(s):  
Fine Structure ◽  
Mass Distribution ◽  
Lower Bounds ◽  
Structure Constant ◽  
Stellar Mass ◽  
Fine Structure Constant ◽  
Mass Ratio ◽  
Habitable Planets ◽  
Hot Jupiters ◽  
Proton Mass

How good is our universe at making habitable planets? The answer to this depends on which factors are important for life: Does a planet need to be Earth mass? Does it need to be inside the temperate zone? are systems with hot Jupiters habitable? Here, we adopt different stances on the importance of each of these criteria to determine their effects on the probabilities of measuring the observed values of several physical constants. We find that the presence of planets is a generic feature throughout the multiverse, and for the most part conditioning on their particular properties does not alter our conclusions much. We find conflict with multiverse expectations if planetary size is important and it is found to be uncorrelated with stellar mass, or the mass distribution is too steep. The existence of a temperate circumstellar zone places tight lower bounds on the fine structure constant and electron to proton mass ratio.

scholarly journals Cosmological Constraints on the Coupling Model from Observational Hubble Parameter and Baryon Acoustic Oscillation Measurements

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 57
Author(s):  
Shulei Cao ◽  
Tong-Jie Zhang ◽  
Xinya Wang ◽  
Tingting Zhang
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Hubble Parameter ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Coupling Model ◽  
Acoustic Oscillation ◽  
Baryon Acoustic Oscillation ◽  
Best Fitting ◽  
Age Of The Universe

In the paper, we consider two models in which dark energy is coupled with either dust matter or dark matter, and discuss the conditions that allow more time for structure formation to take place at high redshifts. These models are expected to have a larger age of the universe than that of ΛCDM [universe consists of cold dark matter (CDM) and dark energy (a cosmological constant, Λ)], so it can explain the formation of high redshift gravitationally bound systems which the ΛCDM model cannot interpret. We use the observational Hubble parameter data (OHD) and Hubble parameter obtained from cosmic chronometers method (H(z)) in combination with baryon acoustic oscillation (BAO) data to constrain these models. With the best-fitting parameters, we discuss how the age, the deceleration parameter, and the energy density parameters evolve in the new universes, and compare them with that of ΛCDM.

scholarly journals Cosmology with weak lensing surveys

2005 ◽  
Vol 363 (1837) ◽  
pp. 2675-2691 ◽  
Author(s):  
Dipak Munshi ◽  
Patrick Valageas
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Lensing ◽  
Large Scale ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
Weak Lensing ◽  
Satellite Mission ◽  
The Universe

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bispectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

scholarly journals Spectra of Distant Quasars and Verification of Possible Variation of Fundamental Constants over Cosmological Time-Scales

1994 ◽  
Vol 159 ◽  
pp. 361-362
Author(s):  
D.A. Varshalovich ◽  
A.Y. Potekhin
Keyword(s):  
Fine Structure ◽  
Time Scales ◽  
Spectroscopic Data ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Cosmological Time ◽  
Proton Mass ◽  
Variation Rate

Constraints on possible variation rate of the fine-structure constant, , and the electron-proton mass ratio , over cosmological time scales are obtained from analyses of quasar spectroscopic data.

scholarly journals Search for variation of the fundamental constants in atomic, molecular, and nuclear spectra

2009 ◽  
Vol 87 (1) ◽  
pp. 25-33 ◽  
Author(s):  
V V Flambaum ◽  
V A Dzuba
Keyword(s):  
Fine Structure ◽  
Absorption Spectra ◽  
Atomic Clock ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Frequency Change ◽  
Fundamental Constants ◽  
Mass Ratio ◽  
Proton Mass ◽  
Nuclear Transitions

The search for variation of the fundamental constants such as the fine-structure constant α (α = e2/hc) and the ratios of fundamental masses (for example, electron-to-proton mass ratio μ = me/mp) is reviewed. Strong emphasis is given to establishing the relationships between the change in the measured frequencies of atomic, molecular, or nuclear transitions and the corresponding change of the fundamental constants. Transitions in which the sensitivity of the frequency change to the variation of the fine-structure constant is strongly enhanced are discussed and most recent experimental results are presented. Most attention is given to the use of atomic, molecular, and nuclear transitions in the study of quasar absorption spectra and in atomic clock experiments.PACS Nos.: 31.25.Eb, 31.25.Jf

STRUCTURE FORMATION IN DARK MATTER/DARK ENERGY DOMINATED UNIVERSES

2007 ◽  
Vol 16 (02n03) ◽  
pp. 453-461
Author(s):  
NILZA PIRES ◽  
HIDALYN T. C. M. DE SOUZA
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Structure Formation ◽  
General Result ◽  
High Redshift ◽  
Matter Density ◽  
Density Perturbations ◽  
Hydrodynamic Code ◽  
Baryonic Dark Matter ◽  
Very High

In this work we present preliminary results of an analysis on the evolution of primordial baryonic and dark matter density perturbations. A top-hat hydrodynamic code has been utilized to analyze the evolution of these primordial perturbations, from the beginning of the recombination era until the redshift when the collapse occurs. All the relevant processes are included in the calculations, which includes the effect of a dark energy in the expanding universe. In particular, we find that the perturbations with dark matter collapse at very high redshift, which could explain the existence of old galaxies at high redshift. As a general result we find that the distribution of the non-baryonic dark matter is more concentrated than the baryonic one.

scholarly journals Multiverse Predictions for Habitability: The Number of Stars and Their Properties

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 149 ◽  
Author(s):  
McCullen Sandora
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Mass Ratio ◽  
High Significance ◽  
Proton Mass

In a multiverse setting, we expect to be situated in a universe that is exceptionally good at producing life. Though the conditions for what life needs to arise and thrive are currently unknown, many will be tested in the coming decades. Here we investigate several different habitability criteria, and their influence on multiverse expectations: Does complex life need photosynthesis? Is there a minimum timescale necessary for development? Can life arise on tidally locked planets? Are convective stars habitable? Variously adopting different stances on each of these criteria can alter whether our observed values of the fine structure constant, the electron to proton mass ratio, and the strength of gravity are typical to high significance. This serves as a way of generating predictions for the requirements of life that can be tested with future observations, any of which could falsify the multiverse scenario.

Sign in / Sign up

Export Citation Format

Share Document