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Paper: Probing Acceleration Now with Supernovae: The PANS Higher-z Supernova Survey
Volume: 342, 1604-2004: Supernovae as Cosmological Lighthouses
Page: 471
Authors: Strolger, L.-G.; Riess, A.G.; Dahlen, T.
Abstract: The Hubble Space Telescope (HST) has become a very effective instrument in the study of supernovae (SNe) at high redshift and the dark energy. Programs which aim to study the evolution of galaxies have been cooperatively adapted to accommodate what has become the Probing Acceleration Now with Supernovae (PANS) project, an ongoing survey for SNe at z > 1. The principle campaigns of this survey, conducted in cooperation with the Great Observatories Origins Deep Survey (GOODS), have yielded 42 SNe in the range 0.2 < z < 1.6. Through detailed target of opportunity observations with HST (+ACS and NICMOS), we have collected 16 SNe Ia with well-sampled multi-wavelength light curves primarily spanning the rest-frame U and B passbands. The addition of this dataset to extensive ground based data at lower redshifts results in much improved constraints on cosmological parameters, specifically the equation of state (w) and its time evolution (w′). We find constraints on w′w have improved by a factor of ∼ 8, producing w0 = −1.3 ± 0.3 and w0 = 1.5 ± 0.9.

The GOODS/PANS SN data has also been used to compare the event rate histories of Type Ia and core-collapse SNe to recent determinations of the star formation rate history [SFR(z)]. The core-collapse SN rate history has provided an independent measure of the SFR(z) in the z < 1 universe, which is shown to be consistent with standard SFR(z) s. The Type Ia SN rate history is considerably offset from the SFR(z) by a range in delay times which stem primarily from the lifetimes of the progentior systems. We show that the delay times of SNe Ia must be generally greater than 2 Gyr (to 95% confidence), and are likely characterized by a mean delay of ∼ 4 Gyr, with a narrow dispersion of < 1 Gyr. This may suggest that SNe Ia are ted by a single-degenerate mechanism with some scatter in the conditions of the channel.

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