The high-Z supernova search: Measuring cosmic deceleration and global curvature of the universe using type Ia supernovae

Brian P. Schmidt, Nicholas B. Suntzeff, M. M. Phillips, Robert A. Schommer, Alejandro Clocchiatti, Robert P. Kirshner, Peter Garnavich, Peter Challis, B. Leibundgut, J. Spyromilio, Adam G. Riess, Alexei V. Filippenko, Mario Hamuy, R. Chris Smith, Craig Hogan, Christopher Stubbs, Alan Diercks, David Reiss, Ron Gilliland, John TonryJosé Maza, A. Dressler, J. Walsh, R. Ciardullo

Research output: Contribution to journalArticlepeer-review

1202 Scopus citations


The High-Z Supernova Search is an international collaboration to discover and monitor Type Ia supernovae (SNe 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 SNe 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 that provide accurate two-color rest frame B and V light curves of SNe 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 (SN), 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 SNe, yields an estimate for the matter density of the universe of ΩM = -0.2-0.8+1.0 if ΩA = 0. For a spatially flat universe composed of normal matter and a cosmological constant, we find ΩM = 0.4-0.4+0.5, ΩA = 0.6-0.5+0.4. 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.

Original languageEnglish (US)
Pages (from-to)46-63
Number of pages18
JournalAstrophysical Journal
Issue number1 PART I
StatePublished - 1998

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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