Development of NIR detectors and science requirements for SNAP.

Abstract

The SuperNova Acceleration Probe (SNAP) is an optical and near infrared space telescope designed to study the properties of dark energy with multiple techniques. One of SNAP's primary science goals is to constrain the dark energy equation of state using observations of thousands of type Ia supernovae from a redshift of 0.1--1.7. The highest redshift supernovae provide the most leverage on cosmology measurements since dark energy models, especially those with a time dependent equation of state, begin to diverge at redshifts greater than 1. For objects beyond a redshift of 1, the restframe optical light is shifted to the near infrared (NIR). The SNAP focal plane uses 36 visible CCD detectors and 36 hybridized HgCdTe detectors to achieve accurate measurements of both nearby and high redshift objects over a large field of view. The SNAP NIR detector development effort has succeeded in producing low noise, high quantum efficiency HgCdTe detectors. This work focuses on the characterization and simulation of NIB detectors properties; and the ability of SNAP to constrain the nature of dark energy. Simulations show that recently achieved increases in quantum efficiency lead to the largest gains in accuracy for supernova photometry. The best R&D detectors are approaching the performance of ideal (no noise, QE = 100%) NIR detectors for supernovae observations. Simulated uncertainties for type Ia supernovae are combined with results from cosmic microwave background observations and the SNAP weak lensing survey to constrain the dark energy equation of state. Supernovae alone cannot constrain the nature of dark energy with high accuracy. Independent measurements that have different systematic uncertainties and are sensitive to different combinations of cosmological parameters are needed to achieve the desired precision. With the currently achieved detector technology, the SNAP supernova and weak lensing surveys will constrain sw0 = 0.04 and swa = 0.14.