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                          <header>
                              <identifier>oai:research.chalmers.se:188714</identifier>
                              <datestamp>2018-01-25T20:37:42Z</datestamp>
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                          <metadata>
                              <oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
                                  <dc:title>Robust Constraint on a Drifting Proton-to-Electron Mass Ratio at z=0.89 from Methanol Observation at Three Radio Telescopes</dc:title>
                                  <dc:identifier>https://research.chalmers.se/en/publication/188714</dc:identifier>
                                  <dc:date>2013</dc:date>
                                              <dc:creator>Bagdonaite, Julija</dc:creator>
                                              <dc:creator>Dapra, M.</dc:creator>
                                              <dc:creator>Jansen, P.</dc:creator>
                                              <dc:creator>Bethlem, H. L.</dc:creator>
                                              <dc:creator>Ubachs, Wim</dc:creator>
                                              <dc:creator>Muller, Sebastien</dc:creator>
                                              <dc:creator>Henkel, Christian</dc:creator>
                                              <dc:creator>Menten, K. M.</dc:creator>
                                                  <dc:subject>Physical Sciences</dc:subject>
                                                  <dc:subject>Astronomy, Astrophysics and Cosmology</dc:subject>
                                          <dc:description>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 Kμ 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±0.8stat±1.0sys)×10−7.</dc:description>
                                                                  <dc:relation>info:eu-repo/grantAgreement/EC/FP7/283393//Advanced Radio Astronomy in Europe (RADIONET3)/</dc:relation>
                                                  <dc:relation>info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevLett.111.231101</dc:relation>
                                          <dc:type>info:eu-repo/semantics/article</dc:type>
                                          <dc:source>Physical Review Letters (0031-9007) vol.111(2013)</dc:source>
                                                      <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:language>eng</dc:language>
                                  <dc:audience>Researchers</dc:audience>
                                  <dc:format>application/pdf</dc:format>
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                          </metadata>
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