Constraints on changes in fundamental constants from a cosmologically distant OH absorber/emitter

Abstract

We have detected the four 18cm OH lines from the $z\sim 0.765$ gravitational lens toward PMN J0134-0931. The 1612 and 1720 MHz lines are in conjugate absorption and emission, providing a laboratory to test the evolution of fundamental constants over a large lookback time. We compare the HI and OH main line absorption redshifts of the different components in the $z\sim 0.765$ absorber and the $z\sim 0.685$ lens toward B0218+357 to place stringent constraints on changes in $F\equiv g_p[\hat{I}{\pm }^2/\hat{I}¼{]}^{1.57}$. We obtain $[\hat{I}”F/F]=(0.44\pm 0.36^{\mathrm{stat}}\pm 1.0^{\mathrm{syst}})\times 10^{-5}$, consistent with no evolution over the redshift range $0<z<0.7$. The measurements have a $2\ddot{I}ƒ$ sensitivity of $[\hat{I}”\hat{I}\pm /\hat{I}\pm ]<6.7\times 10^{-6}$ or $[\hat{I}”\hat{I}¼/\hat{I}¼]<1.4\times 10^{-5}$ to fractional changes in $\hat{I}\pm$ and $\hat{I}¼$ over a period of $\sim 6.5$ Gyr, half the age of the Universe. These are among the most sensitive current constraints on changes in $\hat{I}¼$.

4 pages, 3 figures. Final version, with minor changes to match the version in print in Phys. Rev. Lett