1998/05/15 by Brian P. Schmidt, Nicholas B. Suntzeff, M. M. Phillips +21 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/306308
published as Astrophys.J. 507 (1998) 46-63 · 51 pages, 14 figures, To Appear in the Astrophysical Journal
arxiv created 1998/05/15 · arxiv updated 2009/12/01
The High-Z Supernova Search is an international collaboration to discover and monitor type Ia supernovae (SN Ia) at z > 0.2 with the aim of measuring cosmic deceleration and global curvature. Our collaboration has pursued a basic understanding of supernovae in the nearby Universe, discovering and observing a large sample of objects, and developing methods to measure accurate distances with SN Ia. This paper describes the extension of this program to z ≥ 0.2, outlining our search techniques and follow-up program. We have devised high-throughput filters which provide accurate two-color restframe B and V light curves of SN Ia, enabling us to produce precise, extinction-corrected luminosity distances in the range 0.25 < z < 0.55. Sources of systematic error from K-corrections, extinction, selection effects, and evolution are investigated, and their effects estimated. We present photometric and spectral observations of SN 1995K, our program's first supernova, and use the data to obtain a precise measurement of the luminosity distance to the z=0.479 host galaxy. This object, when combined with a nearby sample of SN, yields an estimate for the matter density of the Universe of ΩM = -0.2+1.0-0.8 if ΩΛ= 0. For a spatially flat universe composed of normal matter and a cosmological constant, we find ΩM = 0.4+0.5-0.4, ΩΛ= 0.6+0.4-0.5. We demonstrate that with a sample of ∼ 30 objects, we should be able to determine relative luminosity distances over the range 0 < z< 0.5 with sufficient precision to measure ΩM with an uncertainty of ± 0.2.