scholarly journals Constraining the magnetic field on white dwarf surfaces; Zeeman effects and fine structure constant variation

2019 ◽  
Vol 485 (4) ◽  
pp. 5050-5058 ◽  
Author(s):  
J Hu ◽  
J K Webb ◽  
T R Ayres ◽  
M B Bainbridge ◽  
J D Barrow ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
White Dwarf ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Line Profiles ◽  
Space Telescope ◽  
Gravitational Fields ◽  
Upper Limit ◽  
The Magnetic Field

ABSTRACT White dwarf (WD) atmospheres are subjected to gravitational potentials around 105 times larger than occur on Earth. They provide a unique environment in which to search for any possible variation in fundamental physics in the presence of strong gravitational fields. However, a sufficiently strong magnetic field will alter absorption line profiles and introduce additional uncertainties in measurements of the fine structure constant. Estimating the magnetic field strength is thus essential in this context. Here, we model the absorption profiles of a large number of atomic transitions in the WD photosphere, including first-order Zeeman effects in the line profiles, varying the magnetic field as a free parameter. We apply the method to a high signal-to-noise, high-resolution, far-ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph spectrum of the WD G191−B2B. The method yields a sensitive upper limit on its magnetic field of B < 2300 G at the 3σ level. Using this upper limit, we find that the potential impact of quadratic Zeeman shifts on measurements of the fine structure constant in G191−B2B is 4 orders of magnitude below laboratory wavelength uncertainties.

scholarly journals Measuring the fine structure constant on a white dwarf surface; a detailed analysis of Fe V absorption in G191-B2B

2020 ◽  
Author(s):  
J Hu ◽  
J K Webb ◽  
T R Ayres ◽  
M B Bainbridge ◽  
J D Barrow ◽  
...  
Keyword(s):  
Fine Structure ◽  
White Dwarf ◽  
Hubble Space Telescope ◽  
Zeeman Effect ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Gravitational Fields ◽  
Systematic Uncertainties ◽  
Isotopic Abundances ◽  
Comprehensive Search

Abstract The gravitational potential φ = GM/Rc2 at the surface of the white dwarf G191-B2B is 10,000 times stronger than that at the Earth’s surface. Numerous photospheric absorption features are detected, making this a suitable environment to test theories in which the fundamental constants depend on gravity. We have measured the fine structure constant, α, at the white dwarf surface, used a newly calibrated Hubble Space Telescope STIS spectrum of G191-B2B, two new independent sets of laboratory Fe V wavelengths, and new atomic calculations of the sensitivity parameters that quantify Fe V wavelength dependency on α. The two results obtained are: Δα/α0 = (6.36 ± 0.35stat ± 1.84sys) × 10−5 and Δα/α0 = (4.21 ± 0.48stat ± 2.25sys) × 10−5. The measurements hint that the fine structure constant increases slightly in the presence of strong gravitational fields. A comprehensive search for systematic errors is summarised, including possible effects from line misidentifications, line blending, stratification of the white dwarf atmosphere, the quadratic Zeeman effect and electric field effects, photospheric velocity flows, long-range wavelength distortions in the HST spectrum, and variations in the relative Fe isotopic abundances. None fully account for the observed deviation but the systematic uncertainties are heavily dominated by laboratory wavelength measurement precision.

scholarly journals Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

2013 ◽  
Vol 111 (1) ◽  
Author(s):  
J. C. Berengut ◽  
V. V. Flambaum ◽  
A. Ong ◽  
J. K. Webb ◽  
John D. Barrow ◽  
...  
Keyword(s):  
Fine Structure ◽  
Gravitational Potential ◽  
White Dwarf ◽  
Structure Constant ◽  
Fine Structure Constant

scholarly journals TIME VARIATION OF THE FINE STRUCTURE CONSTANT IN DECRUMPLING OR TVSD MODEL

2007 ◽  
Vol 16 (05) ◽  
pp. 899-907 ◽  
Author(s):  
FOROUGH NASSERI
Keyword(s):  
Fine Structure ◽  
Time Variation ◽  
Space Dimension ◽  
Structure Constant ◽  
Time Variable ◽  
Fine Structure Constant ◽  
Absolute Value ◽  
Upper Limit ◽  
Spatial Dimensions ◽  
Variable Space

Within the framework of a model universe with time variable space dimension (TVSD), known as decrumpling or TVSD model, we study the time variation of the fine structure constant. Using observational bounds on the present time variation of the fine structure constant, we are able to obtain an upper limit for the absolute value of the present time variation of spatial dimensions.

scholarly journals Quantum Electrodynamics in Strong Magnetic Fields. IV. Electron Self-energy

1987 ◽  
Vol 40 (1) ◽  
pp. 1 ◽  
Author(s):  
AJ Parle
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
Quantum Electrodynamics ◽  
Mass Shell ◽  
Mass Operator ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Strong Magnetic Fields ◽  
Self Energy ◽  
Cyclotron Emission

The electron self-energy in a magnetic field is calculated with the effect of the field included exactly. A new representation of the wavefunctions and other quantities is defined, in which the mass operator has a particularly simple form. After renormalisation, the form of the mass operator allows corrections to the Dirac equation, wavefunctions, vertex function and the electron propagator close to the mass shell to be calculated to lowest order in the fine structure constant. The probability for an electron to change spin while remaining in the same Landau level is calculated, and is found to be much less than the probability of cyclotron emission.

Implications of quasar spectroscopy for constancy of constants

1983 ◽  
Vol 310 (1512) ◽  
pp. 245-247 ◽  
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
De Sitter ◽  
Upper Limit ◽  
Upper Limits ◽  
Look Back ◽  
Universal Expansion ◽  
De Sitter Universe ◽  
Hubble Time

Given that the redshifts of quasars are due to the universal expansion, the details of their spectra can be used to check the constancy of certain dimensionless ratios of physics over look-back times comparable with the Hubble time and distances exceeding that of the particle horizon in the Einstein-de Sitter universe. With a,g p , g e , m p , m e denoting the fine structure constant, and the gyromagnetic ratios and masses of protons and electrons respectively, the following upper limits to variability over such times and distances have been derived in this way: approximate 3tr upper limit to effect optical doublet splittings comparison of optical and 21 cm redshifts comparison of hydrogen and metal redshifts quantity CL ot?gvm J mv (or <**(&/&) (me/mp)) m e/ m p variation 3% io- 3 50%

scholarly journals The Theoretical Value of the Hubble Constant Ho and Unification of the Fundamental Forces of Nature

2021 ◽  
Vol 3 (4) ◽  
pp. 17-24
Author(s):  
Paul Cadelina Rivera
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Hubble Constant ◽  
High Energy ◽  
Theoretical Explanation ◽  
Fine Structure Constant ◽  
Fundamental Relation ◽  
Gravitational Fields ◽  
Cosmological Observations ◽  
Fundamental Forces

The Hubble constant Ho represents the speed of expansion of the universe and various cosmological observations and modeling methods were utilized by astronomers for a century to pin down its exact value. Determining Ho from cosmological observations is a long and tedious process requiring highly accurate datasets. To circumvent this need, a simple theoretical approach is introduced in this study which uses the concept of gravitational weakening and seismic-induced recession. As tremors occur among celestial objects, their gravitational fields would also change. This resulted in a fundamental relation of Ho and the computed rate of recession that gives a theoretical value for Ho=69.921 Km/s/Mpc. Using the newly discovered seismic-induced gravitational weakening and time dilation, it is possible that various astrophysical methods using different measurement methods would converge to this theoretical Ho value when cosmological distances and time delay measurements are corrected with the simple formulas we derived. The new model assumes that, as quakes occur in celestial objects, luminosity-induced acceleration and high-energy collision of protons and electrons may produce a massive number of neutrinos, quarks and other subatomic particles. Furthermore, the fine structure constant was found to be inversely proportional to Ho-squared and that the fine-structure constant obtained in this study gives a new physical interpretation of α. New relations for the speed of light, orbital velocity, gravitational force and the Hubble constant were further derived from the new recession constant using approximate relations for the Newtonian and electric force constant. This resulted in a modified gravitational law that is both repulsive and attractive and a theoretical explanation of the phenomenon of light-induced gravitation analogous to the electromagnetic force where photon is the force-carrier. Finally, the fundamental forces of gravitation, electromagnetism and strong nuclear force are now unified.

scholarly journals Updated Constraints on the Variations of the Fine-Structure Constant from an Analysis of White-Dwarf Spectra

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 936
Author(s):  
Le
Keyword(s):  
Fine Structure ◽  
Temporal Variation ◽  
White Dwarf ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Spatial And Temporal Variation ◽  
Dwarf Star

I used observed spectra from the white-dwarf star G191-B2B to constrain the spatial and temporal variation of the fine-structure constant,[...]

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