Space-time variation of the fine-structure constant and evolution of isotope abundances

Kozlov, M. G.; Korol, Vasili; Berengut, J. C.; Dzuba, V. A.; Flambaum, V. V.

doi:10.1103/physreva.70.062108

Cited by 59 publications

(63 citation statements)

References 24 publications

(56 reference statements)

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“…Accounting for a systematic such as this is difficult, especially since the isotope shift is unknown for many of the lines used in the analysis. The transition with the largest known shift used in the analysis are the λλ2796 and 2803 lines in Mg ii, and calculations suggest that the unknown isotope shifts are smaller and less important (Kozlov et al 2004).…”

Section: Robustness Of the Dipole Modelmentioning

confidence: 99%

Is there a spatial gradient in values of the fine-structure constant? A reanalysis of the results

Berengut

Kava

Flambaum

2012

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We statistically analyse a recent sample of data points measuring the fine-structure constant α (relative to the terrestrial value) in quasar absorption systems, where a spatial gradient in α was recently reported. We find agreement with previous authors that the dipole model is a robust, well-justified fit to the data. Using a simple analysis we find that the monopole term (the constant offset in Δα/α) may be caused by non-terrestrial magnesium isotope abundances in the absorbers. Finally we test the domain-wall model against the data.Key words. cosmology: theory -methods: statistical -large-scale structure of Universe -cosmology: miscellaneous Optical quasar absorption spectra provide a probe of variations in the fine-structure constant, α = e 2 / c, along a past-light cone centred on present-day telescopes. In this paper we analyse the results of a large sample of quasar absorption systems where values of Δα/α have been measured using the many-multiplet method (Dzuba et al. 1999a,b). Here Δα/α = (α(r) − α 0 )/α 0 is the relative variation in α at a particular position r in the Universe where the absorption occurs.The data used in this paper are taken from Murphy et al. (2003 and King et al. (2012, Very Large Telescope), kindly supplied by the King in a usable text format including the location of each absorber and its measured value of Δα/α. In total there are 293 points in our data file including 140 from Keck and 153 from VLT of which seven absorbers are seen in both the Keck and VLT samples. The data is described fully in King et al. (2012) (see Berengut et al. 2012 for a discussion pertinent to the current analysis). In Webb et al. (2011), the combined data sample is interpreted as providing evidence for variation in α throughout the Universe with an angular-dependence. This "dipole" model is found to be preferred to a monopole (constant offset) model of the variation at the 4.1σ level.Note that both the Keck and VLT samples account for unknown sources of scatter in the data by including extra systematic errors, σ rand , that are added in quadrature with the underlying statistical error. The data we use includes a conservative (large) value which will tend to reduce the significance of the dipole relative to a monopole model. In practice the results of this paper are relatively insensitive to the exact σ rand used.The In this paper we test the dipole interpretation B(z) ∼ r. In this form (1) represents a gradient in the value α throughout the Universe, and r cos θ is the distance to a quasar absorption system along that gradient. Of course, r itself is model dependent at large redshifts. In this work we use the standard Λ CDM cosmology parametrized by WMAP5 (Hinshaw et al. 2009) to determine r = ct (t is lookback time) from the redshift z:Again, this reflects the fact that we are taking measurements along a past light cone centred on present-day Earth. An alternative approach is to use the comoving distance:In this case the dipole model (1) is modified to use B(z) = B d(z). This parameterisatio...

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Section: Robustness Of the Dipole Modelmentioning

confidence: 99%

Is there a spatial gradient in values of the fine-structure constant? A reanalysis of the results

Berengut

Kava

Flambaum

2012

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“…Using the mass shift constants k MS calculated by Kozlov et al (2004) which was not included in the fitting of this line. Since both the λ2382 and λ2600 lines are considered as having the same radial velocity and the line λ2382 is clean, this contamination of λ2600 does not influence the final value of ∆α/α.…”

Section: Possible Systematicsmentioning

confidence: 99%

A new measure of $\mathsf{\Delta\alpha/\alpha}$ at redshift $\mathsf{z = 1.84}$ from very high resolution spectra of Q 1101–264

Levshakov¹,

Molaro

López

et al. 2007

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“…This problem can be resolved if both the relativistic shift and isotope shift of each transition is known, by using particular combinations of the transition frequencies as probes which are insensitive to either α-variation or isotopic abundances [9]. Changes in the isotope abundances and the fine-structure constant can then be measured directly.…”

Section: Introductionmentioning

confidence: 99%

Calculation of isotope shifts and relativistic shifts in C I, C II, C III, and C IV

2006

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We present an accurate ab initio method of calculating isotope shifts and relativistic shifts in atomic spectra. We test the method on neutral carbon and three carbon ions. The relativistic shift of carbon lines may allow them to be included in analyses of quasar absorption spectra that seek to measure possible variations in the fine structure constant α over the lifetime of the Universe. Carbon isotope shifts can be used to measure isotope abundances in gas clouds: isotope abundances are potentially an important source of systematic error in the α-variation studies. These abundances are also needed to study nuclear reactions in stars and supernovae, and test models of chemical evolution of the Universe.

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Space-time variation of the fine-structure constant and evolution of isotope abundances

Cited by 59 publications

References 24 publications

Is there a spatial gradient in values of the fine-structure constant? A reanalysis of the results

Is there a spatial gradient in values of the fine-structure constant? A reanalysis of the results

A new measure of $\mathsf{\Delta\alpha/\alpha}$ at redshift $\mathsf{z = 1.84}$ from very high resolution spectra of Q 1101–264

Calculation of isotope shifts and relativistic shifts in C I, C II, C III, and C IV

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