Evidence
from Type 1a Supernovae for an
Accelerating
Universe and Dark Energy
The measured distances
of type Ia (white dwarf) supernovae as a function of redshift (z) have shown
that the expansion of the Universe is currently accelerating, probably due to
the presence of dark energy (X) having a negative pressure. Combining all of the data with existing
results from large-scale structure surveys, we find a best fit for Omega M and
Omega X of 0.28 and 0.72 (respectively), in excellent agreement with the values
derived independently from WMAP measurements of the cosmic microwave background
radiation. Thus far, the best-fit value for the dark energy equation-of-state
parameter is -1, and its first derivative is consistent with zero, suggesting
that the dark energy may indeed be Einstein's cosmological constant.