Does the Fine-Structure Constant Vary with Cosmological Epoch?
Abstract
We use the strong nebular emission lines of O III, λλ5007 and 4959, to set a robust upper limit on the time dependence of the fine-structure constant. We find α-1dα(t)/dt<2×10-13 yr-1, corresponding to Δα/α(0)=(0.7+/-1.4)×10-4 for quasars with 0.16<z<0.80 obtained from the SDSS Early Data Release. Using a blind analysis, we show that the upper limit given here is invariant with respect to 17 different ways of selecting the sample and analyzing the data. As a by-product, we show that the ratio of transition probabilities corresponding to the λλ5007 and 4959 lines is 2.99+/-0.02, in good agreement with (but more accurate than) theoretical estimates. We compare and contrast the O III emission line method used here with the many-multiplet method that was used recently to suggest evidence for a time-dependent α. In an appendix we analyze the quasars from the recently available SDSS Data Release One sample and find Δα/α(0)=(1.2+/-0.7)×10-4.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2004
- DOI:
- 10.1086/379971
- arXiv:
- arXiv:astro-ph/0301507
- Bibcode:
- 2004ApJ...600..520B
- Keywords:
-
- Atomic Data;
- Line: Identification;
- Line: Profiles;
- Galaxies: Quasars: Absorption Lines;
- Galaxies: Quasars: Emission Lines;
- Astrophysics;
- General Relativity and Quantum Cosmology;
- High Energy Physics - Experiment;
- High Energy Physics - Phenomenology
- E-Print:
- Added analysis of larger quasar sample from SDSS Data Release One. Accepted for publication ApJ