Robust constraint on a drifting proton-to-electron mass ratio at z=0.89 from methanol observation at three radio telescopes.
A limit on a possible cosmological variation of the proton-to-electron mass ratio μ is derived from methanol (CH3OH) absorption lines in the benchmark PKS1830-211 lensing galaxy at redshift z=0.89 observed with the Effelsberg 100-m radio telescope, the Institute de Radio Astronomie Millimétrique 30-m telescope, and the Atacama Large Millimeter/submillimeter Array. Ten different absorption lines of CH3OH covering a wide range of sensitivity coefficients K(μ) are used to derive a purely statistical 1σ constraint of Δμ/μ=(1.5±1.5)×10(-7) for a lookback time of 7.5 billion years. Systematic effects of chemical segregation, excitation temperature, frequency dependence, and time variability of the background source are quantified. A multidimensional linear regression analysis leads to a robust constraint of Δμ/μ=(-1.0±0.8(stat)±1.0(sys))×10(-7).
Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
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Bagdonaite
Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
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Daprà
Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
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Jansen
Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
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Bethlem
Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
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Ubachs
Onsala Space Observatory, Chalmers University of Technology, SE 439-92 Onsala, Sweden.
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S
Muller
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany and Astronony Department, King Abdulaziz University, Post Office Box 80203, Jeddah 21589, Saudi Arabia.
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Henkel
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany.
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KM
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