Observations of high-redshift supernovae indicate that the Universe is accelerating. Here we present a model-independent method for estimating the form of the potential of the scalar field driving this acceleration, and the associated equation of state . Our method is based on a versatile analytical form for the luminosity distance , optimized to fit observed distances to distant supernovae and differentiated to yield and . Our results favor at the present epoch, steadily increasing with redshift. A cosmological constant is consistent with our results.
- Received 12 October 1999
- Revised 13 March 2000
- Published in the issue dated 7 August 2000
© 2000 The American Physical Society