  We present cosmological constraints arising from the first measurement of the
radial (line-of-sight) baryon acoustic oscillations (BAO) scale in the large
scale structure traced by the galaxy distribution. Here we use these radial BAO
measurements at z = 0.24 and z = 0.43 to derive new constraints on dark energy
and its equation of state for a flat universe, without any other assumptions on
the cosmological model: w = -1.14 +/- 0.39 (assumed constant), Omega_m =
0.24+0.06-0.05. If we drop the assumption of flatness and include previous
cosmic microwave background and supernova measurements, we find w = -0.974 +/-
0.058, Omega_m = 0.271 +/- 0.015, and Omega_k = -0.002 +/- 0.006, in good
agreement with a flat cold dark matter cosmology with a cosmological constant.
To our knowledge, these are the most stringent constraints on these parameters
to date under our stated assumptions.
