We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration. Joint constraints on both the recent equation of state of dark energy, w 0, and its time evolution, dw/dz, are a factor of ∼ 8 more precise than its first estimate and twice as precise as those without the SNe Ia discovered with HST. Our constraints are consistent with the static nature of and value of w expected for a cosmological constant (i.e., w 0 = −1.0, dw/dz = 0), and are inconsistent with very rapid evolution of dark energy.
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© 2004 American Institute of Physics.
2004
American Institute of Physics
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