Adam Riess led the 1998 analysis of Type Ia supernovae that provided evidence for accelerating cosmic expansion. His team compared distant and nearby supernovae, using their light curves to estimate distances and their cosmological redshifts to test the expansion history.
The distant events were farther away than expected in the cited low-mass density model without a cosmological constant. Different fitting methods and sample selections favored a positive cosmological constant and present acceleration. The evidence came from a distance–redshift relation interpreted within cosmological models.[ref]
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant by Adam Riess and others. Abstract: nearby and high-redshift samples, distance excess and agreement of independent fits
Portrait of Adam Riess
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