Constraints on Changes in Fundamental Constants from a Cosmologically Distant OH Absorber or Emitter
Constraints on Changes in Fundamental Constants from a Cosmologically Distant OH Absorber or Emitter
We have detected the four 18 cm OH lines from the $z\ensuremath{\sim}0.765$ 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 …