title: Constraint on a varying proton-electron mass ratio 1.5 billion years after the big bang.
abstract: A molecular hydrogen absorber at a lookback time of 12.4 billion years, corresponding to 10% of the age of the Universe today, is analyzed to put a constraint on a varying proton-electron mass ratio, μ. A high resolution spectrum of the J1443+2724 quasar, which was observed with the Very Large Telescope, is used to create an accurate model of 89 Lyman and Werner band transitions whose relative frequencies are sensitive to μ, yielding a limit on the relative deviation from the current laboratory value of Δμ/μ=(-9.5 ± 5.4(stat)± 5.3(syst))×10(-6).
authors.affiliation: Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Bagdonaite
authors.affiliation: Department of Physics and Astronomy, and LaserLaB, VU University, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: Ubachs
authors.affiliation: Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
authors.forename: M T
authors.initials: MT
authors.lastname: Murphy
authors.affiliation: Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
authors.forename: J B
authors.initials: JB
authors.lastname: Whitmore