SPECTRA AND HUBBLE SPACE TELESCOPE LIGHT CURVES OF SIX TYPE Ia SUPERNOVAE AT 0.511 < z < 1.12 AND THE UNION2 COMPILATION
- Department of Physics, Stockholm University, Albanova University Center, SE-106 91 Stockholm (Sweden)
- The Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, AlbaNova, Stockholm University, SE-106 91 Stockholm (Sweden)
- E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
- LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, 75005 Paris (France)
- Colorado College, 14 East Cache La Poudre Street, Colorado Springs, CO 80903 (United States)
- Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo, 181-0015 (Japan)
- Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)
- Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 9110 (United States)
- National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
We report on work to increase the number of well-measured Type Ia supernovae (SNe Ia) at high redshifts. Light curves, including high signal-to-noise Hubble Space Telescope data, and spectra of six SNe Ia that were discovered during 2001, are presented. Additionally, for the two SNe with z > 1, we present ground-based J-band photometry from Gemini and the Very Large Telescope. These are among the most distant SNe Ia for which ground-based near-IR observations have been obtained. We add these six SNe Ia together with other data sets that have recently become available in the literature to the Union compilation. We have made a number of refinements to the Union analysis chain, the most important ones being the refitting of all light curves with the SALT2 fitter and an improved handling of systematic errors. We call this new compilation, consisting of 557 SNe, the Union2 compilation. The flat concordance {Lambda}CDM model remains an excellent fit to the Union2 data with the best-fit constant equation-of-state parameter w = -0.997{sup +0.050} {sub -0.054}(stat){sup +0.077} {sub -0.082}(stat + sys together) for a flat universe, or w = -1.038{sup +0.056} {sub -0.059}(stat){sup +0.093} {sub -0.097}(stat + sys together) with curvature. We also present improved constraints on w(z). While no significant change in w with redshift is detected, there is still considerable room for evolution in w. The strength of the constraints depends strongly on redshift. In particular, at z {approx_gt} 1, the existence and nature of dark energy are only weakly constrained by the data.
- OSTI ID:
- 21451103
- Journal Information:
- Astrophysical Journal, Vol. 716, Issue 1; Other Information: DOI: 10.1088/0004-637X/716/1/712; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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