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Supernovae and Dark Energy

Dark Energy and Evolution Sensitivity -- Three models consistent with current data are shown: w0 = −0.9; wa = 0 (black), w0 = −1; wa = 0.8 (red), and w0 = −1; wa = 0 with SN Ia evolving as the model of Dominguez et al. (2001), where the peak luminosity changes 3% per solar mass change in the donor star (blue). At z < 1, SN Ia measurements of distance are most sensitive to the static component of dark energy, w0 , at 1 < z < 1.5 the measurements are most sensitive to the dynamic component, wa . By 1.5 < z , the measurements are most sensitive to evolution if present (e.g., the changing C/O ratio of the donor star), providing the means to diagnose and calibrate the degree of SN Ia in dark energy measurements. The errorbars show the constraints at present, as proposed, and if HST continues to collect SNe Ia at the present rate for 7 years. The inset shows the redshift distribution in supernova per unit z per GOODS field per search epoch.