An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe

Details An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe

2009-07-24

arxiv.org/abs/0907.4392v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

Accepted for publication in the Astrophysical Journal

Scientific paper

In an effort to resolve the discrepancy between two measurements of the fundamental constant mu, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the molecular hydrogen absorption lines in archival VLT/UVES spectra of the damped Lyman alpha systems in the QSOs Q0347-383 and Q0405-443 yields a combined measurement of a (Delta mu)/mu value of (-7 +/- 8) x 10^{-6}, consistent with no change in the value of mu over a time span of 11.5 gigayears. Here we define (Delta mu) as (mu_z - mu_0) where mu_z is the value of mu at a redshift of z and mu_0 is the present day value. Our null result is consistent with the recent measurements of King et al. 2009, (Delta mu)/u = (2.6 +/- 3.0) x 10^{-6}, and inconsistent with the positive detection of a change in mu by Reinhold et al. 2006. Both of the previous studies and this study are based on the same data but with differing analysis methods. Improvements in the wavelength calibration over the UVES pipeline calibration is a key element in both of the null results. This leads to the conclusion that the fundamental constant mu is unchanged to an accuracy of 10^{-5} over the last 80% of the age of the universe, well into the matter dominated epoch. This limit provides constraints on models of dark energy that invoke rolling scalar fields and also limits the parameter space of Super Symmetric or string theory models of physics. New instruments, both planned and under construction, will provide opportunities to greatly improve the accuracy of these measurements.

Affiliated with

Also associated with

No associations

Rating

An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-639366