Keck telescope constraint on cosmological variation of the proton-to-electron mass ratio

Abstract

Molecular transitions recently discovered at redshift zabs= 2.059 towards the bright background quasar J2123−0050 are analysed to limit cosmological variation in the proton‐to‐electron mass ratio, μ≡mp/me. Observed with the Keck telescope, the optical echelle spectrum has the highest resolving power and largest number (86) of H2 transitions in such analyses so far. Also, (seven) HD transitions are used for the first time to constrain μ‐variation. These factors, and an analysis employing the fewest possible free parameters, strongly constrain μ's relative deviation from the current laboratory value: Δμ/μ= (+5.6 ± 5.5stat± 2.9sys) × 10−6, indicating an insignificantly larger μ in the absorber. This is the first Keck result to complement recent null constraints from three systems at zabs > 2.5 observed with the Very Large Telescope. The main possible systematic errors stem from wavelength calibration uncertainties. In particular, distortions in the wavelength solution on echelle order scales are estimated to contribute approximately half the total systematic error component, but our estimate is model dependent and may therefore under or overestimate the real effect, if present. To assist future μ‐variation analyses of this kind, and other astrophysical studies of H2 in general, we provide a compilation of the most precise laboratory wavelengths and calculated parameters important for absorption‐line work with H2 transitions redwards of the hydrogen Lyman limit.

Galaxy counterparts of metal-rich damped Lyα absorbers: the case of J205922.4−052842★

“…Column densities are on a log scale in cm −2 . like HD Malec et al 2010) and CO ) have so far been detected in only one or two high-redshift systems.…”

The UVES Large Program for testing fundamental physics – III. Constraints on the fine-structure constant from three telescopes

“…We followed the same procedure as Malec et al (2010) in our HIRES extraction. HIRES_REDUX performs an optimal extraction of the flux and produces a robust, formal statistical error spectrum.…”

Searching for spatial variations ofα2/μin the Milky Way

“…Non-zero values of Δμ/μ = −30.5 ± 7.5 ppm, Δμ/μ = −16.5 ± 7.4 ppm (Ivanchik et al 2005), and Δμ/μ = −24 ± 6 ppm (Reinhold et al 2006) found at z = 2.595 (Q 0405-443) and z = 3.025 (Q 0347-383) from the Werner and Lyman bands of H 2 were later refuted by Wendt & Reimers (2008), King et al (2008) and Thompson et al (2009), who used the same optical absorption-line spectra of quasars and restricted changes in μ at the level of |Δμ/μ| < 6 ppm. The third H 2 system at z = 2.059 towards the quasar J2123-0050 also does not show any evidence of cosmological variation in μ: Δμ/μ = −5.6 ± 5.5 stat ± 2.9 sys ppm (Malec et al 2010). More stringent constraints have been obtained at lower redshifts from radio observations of the absorption lines of NH 3 and other molecules: |Δμ/μ| < 1.8 ppm at z = 0.68 , A&A 516, A113 (2010) and |Δμ/μ| < 0.6 ppm at z = 0.89 (Henkel et al 2009).…”