Title: Latest Cosmological Measurements from the SCP: 11 New High-Redshift Supernovae Observed with the Hubble Space Telescope

Abstract: The Supernova Cosmology Project has reported the first complete set of high-redshift supernovae all of which have lightcurves measured with the HST. The precision afforded by the Space Telescope allows excellent determinations of the lightcurves. This new set of high-redshift supernovae confirm the accelerating Universe results, yielding a flat-universe mass density of , or equivalently a cosmological constant of . When the supernova results are combined with independent flat-universe measurements of from CMB and galaxy redshift distortion data, they provide a measurement of the dark energy equation of state parameter . In addition to high-precision lightcurve measurements, the new data offer greatly improved color measurements, and hence much better direct limits on host galaxy extinction than was possible with previous high-redshift supernovae. While previous host-galaxy extinction estimates relied on assumptions about the intrinsic extinction distribution, a full extinction correction with the current data confirms that dark energy required, with a greater than 99% probability for a positive dark energy density.