Robust constraint on a drifting proton-to-electron mass ratio at z=0.89 from methanol observation at three radio telescopes

J Bagdonaite; M Daprà; P Jansen; H L Bethlem; W Ubachs; S Muller; C Henkel; K M Menten

doi:10.1103/PhysRevLett.111.231101

Robust constraint on a drifting proton-to-electron mass ratio at z=0.89 from methanol observation at three radio telescopes

Phys Rev Lett. 2013 Dec 6;111(23):231101. doi: 10.1103/PhysRevLett.111.231101. Epub 2013 Dec 4.

Authors

J Bagdonaite¹, M Daprà¹, P Jansen¹, H L Bethlem¹, W Ubachs¹, S Muller², C Henkel³, K M Menten⁴

Affiliations

¹ Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands.
² Onsala Space Observatory, Chalmers University of Technology, SE 439-92 Onsala, Sweden.
³ 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.
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany.

PMID: 24476248
DOI: 10.1103/PhysRevLett.111.231101

Abstract

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).