paper

Constraining the variation of fundamental constants using 18cm OH lines

arXiv:astro-ph/0310764 · doi:10.1103/PhysRevLett.91.241302

Abstract

We describe a new technique to estimate variations in the fundamental constants using 18cm OH absorption lines. This has the advantage that all lines arise in the same species, allowing a clean comparison between the measured redshifts. In conjunction with one additional transition (for example, an HCO line), it is possible to simultaneously measure changes in , and . At present, only the 1665 MHz and 1667 MHz lines have been detected at cosmological distances; we use these line redshifts in conjunction with those of HI 21cm and mm-wave molecular absorption in a gravitational lens at to constrain changes in the above three parameters over the redshift range . While the constraints are relatively weak ( 1 part in ), this is the first simultaneous constraint on the variation of all three parameters. We also demonstrate that either one (or more) of , and must vary with cosmological time or there must be systematic velocity offsets between the OH, HCO and HI absorbing clouds.

5 pages, no figures. Accepted for publication in Phys. Rev. Lett

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