New limit on a varying proton-to-electron mass ratio from high-resolution optical quasar spectra

Abstract

Abstract. Molecular transitions recently discovered at redshift z ab s = 2.059 toward the bright background quasar J2123−0050 are analysed to limit cosmological variation in the proton-toelectron mass ratio, μ ≡ mp /me . Observed with the Keck telescope, the optical spectrum has the highest resolving power and largest number (86) of H2 transitions in such analyses so far. Also, (7) 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 ± 5.5 stat ± 2.7sys ) × 10 −6 . This is the first Keck result to complement recent constraints from three systems at z ab s > 2.5 observed with the Very Large Telescope.

Varying Constants, Gravitation and Cosmology

“…Recently discovered molecular transitions at z = 2.059 toward the quasar J2123-0050 observed by the Keck telescope allow to obtain 86 H 2 transitions and 7 HD transitions to conclude [340] ∆µ/µ = (5.6 ± 5.5 stat ± 2.7 syst ) × 10 −6 , z = 2.059.…”

“…Recently discovered molecular transitions at z = 2.059 toward the quasar J2123-0050 observed by the Keck telescope allow to obtain 86 H 2 transitions and 7 HD transitions to conclude [340] ∆µ/µ = (5.6 ± 5.5 stat ± 2.7 syst ) × 10 −6 , z = 2.059. (99) This method is subject to important systematic errors among which (1) the sensitivity to the laboratory wavelengths (since the use of two different catalogs yield different results [425]), (2) the molecular lines are located in the Lyman-α forest where they can be strongly blended with intervening Hi Lyman-α absorption lines which requires a carfull fitting of the lines [289] since it is hard to find lines that are not contaminated.…”