A Chemical Evolution Explanation for the Apparent Time-Dependent Fine Structure Constant

Details A Chemical Evolution Explanation for the Apparent Time-Dependent Fine Structure Constant A Chemical Evolution Explanation for the Apparent Time-Dependent Fine Structure Constant

May 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004aps..aprw10002a&link_type=abstract

American Physical Society, April Meeting, 2004, May 1-4, 2004, Denver, Colorado April 2004, MEETING ID: APR04, abstract #W10.002

Physics

Scientific paper

The many-multiplet method applied to high redshift quasar absorption spectra has been interpreted as evidence for a possible time variation of the fine structure constant. However, a constant value of α can be made consistent with the observational analysis if a non-solar isotopic ratio of ^24,25,26Mg occurs at large (0.5 < z < 1.8) redshifts . A higher abundance of the heavier isotopes ^25,26Mg are required to explain the observed multiplet splitting. We show that new stellar evolution calculations enhance the synthesis of ^25,26Mg at the base of the convective envelope in low-metallicity asymptotic giant branch stars. Furthermore, there is evidence for a burst of intermediate-mass AGB stars at low metallicity. Hence, a simple model of galactic chemical evolution can produce the required isotopic ratios. This model is supported both by recent observations of high abundances for neutron-rich Mg isotopes in metal-poor globular-cluster stars and evidence of an enhancement in the population of carbon-enriched stars at low metallicity. We conclude that the present data based on quasar absorption spectra may be providing interesting information on the nucleosynthetic history of such systems rather than a time variation of fundamental constants.

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