Type Ia Supernovae Cosmic Acceleration

摘要

The current application of Type Ia supernovae to the determination of theexpansion history of the universe is discussed. Work by two separate research teams— the Supernova Cosmology Project, and the High-Z Team — has shown that themost straightforward interpretation of observations of Type Ia supernova at (z) ~0.5is that the expansion of the universe is accelerating. The form of this acceleration isconsistent with a positive value of Einstein's "cosmological constant." Various formsof systematic error, both intrinsic and extrinsic to Type Ia supernovae have beenproposed as alternative explanations. I review the constraints on systematic errorsprovided by current observations, and then discuss improvements which will be possiblewith a new sample of nearby supernovae and planned future observations of z > 1supernovae. Assuming that systematic errors are negligible, or can be converted intostatistical errors, large homogeneous samples of very distant Type Ia supernovae holdthe potential to determine several key cosmological parameters to an accuracy rivalingor exceeding that of planned CMB observations. A satellite concept designed to bringthis promise to fruition is outlined.