Paper

Spectroscopic Needs for Imaging Dark Energy Experiments: Photometric Redshift Training and Calibration

de la Macorra, A, Frye, B, Newman, J, Hirata, C, Brodwin, M, Moos, W, Comparat, J, Hall, P, Miquel, R, Schmidt, S, Brunner, R, Grady, K, Marshall, J, Abate, A, Barkhouse, W, von der Linden, A, Ménard, B, Colless, M, Matthews, D, Cervantes-Cota, J, Moustakas, J, Honscheid, K, S Ho, Blanton, M, Tyson, T, Stern, D, Huterer, D, Wechsler, R, Abdalla, F, Hildebrandt, H, Zentner, A, Moniez, M, Rhodes, J, Hagen, A, Cheu, E, Ivezic, Z, Kruk, J, Ansari, R, Carrasco-Kind, M, Peacock, J, Mandelbaum, R, Cunha, C, Gawiser, E, Bailey, S, Dell'Antonio, I, Chisari, E, Coupon, J, Slozar, A, Brownstein, J, Gehrels, N, Lahav, O, Beers, T, Papovich, C, J -P Kneib, J-S Ricol, Allen, S, Hearin, A, Allam, S, Wood-Vasey, W, Park, C, Sadeh, I

2013

Overview

Large sets of objects with spectroscopic redshift measurements will be needed for imaging dark energy experiments to achieve their full potential, serving two goals:_training_, i.e., the use of objects with known redshift to develop and optimize photometric redshift algorithms; and_calibration_, i.e., the characterization of moments of redshift (or photo-z error) distributions. Better training makes cosmological constraints from a given experiment stronger, while highly-accurate calibration is needed for photo-z systematics not to dominate errors. In this white paper, we investigate the required scope of spectroscopic datasets which can serve both these purposes for ongoing and next-generation dark energy experiments, as well as the time required to obtain such data with instruments available in the next decade. Large time allocations on kilo-object spectrographs will be necessary, ideally augmented by infrared spectroscopy from space. Alternatively, precision calibrations could be obtained by measuring cross-correlation statistics using samples of bright objects from a large baryon acoustic oscillation experiment such as DESI. We also summarize the additional work on photometric redshift methods needed to prepare for ongoing and future dark energy experiments.

• Publisher: Cornell University Library, arXiv.org
• Subject: Algorithms / Allocations / Calibration / Correlation analysis / Dark energy / Experiments / Measuring instruments / Photometry / Red shift / Spectrographs / Statistical analysis / Statistical methods / Training