Constraints on scalar-field dark energy from galaxy cluster gas mass fraction versus redshift data

We use the Allen et al. Chandra measurements of the X-ray gas mass fraction of 26 rich clusters to place constraints on the scalar-field dark energy model with an inverse power-law potential energy density. The constraints are consistent with, and typically more constraining than, those from other cosmological tests, and they mildly favor the Einstein cosmological constant limit of the dark energy model.