Measurements of Ω and Λ from 42 High‐Redshift Supernovae

Journal Article · Tue Jun 01 00:00:00 EDT 1999 · The Astrophysical Journal

DOI:https://doi.org/10.1086/307221· OSTI ID:840560

Perlmutter, S. ^[1]; Aldering, G. ^[2]; Goldhaber, G. ^[1]; Knop, R. A. ^[2]; Nugent, P. ^[2]; Castro, P. G. ^[3]; Deustua, S. ^[2]; Fabbro, S. ^[4]; Goobar, A. ^[5]; Groom, D. E. ^[2]; Hook, I. M. ^[6]; Kim, A. G. ^[7]; Kim, M. Y. ^[2]; Lee, J. C. ^[8]; Nunes, N. J. ^[3]; Pain, R. ^[4]; Pennypacker, C. R. ^[1]; Quimby, R. ^[2]; Lidman, C. ^[9]; Ellis, R. S. ^[10] ; Irwin, M. ^[10]; McMahon, R. G. ^[10]; Ruiz‐Lapuente, P. ^[11]; Walton, N. ^[12]; Schaefer, B. ^[13]; Boyle, B. J. ^[14]; Filippenko, A. V. ^[15]; Matheson, T. ^[15]; Fruchter, A. S. ^[16]; Panagia, N. ^[17]; Newberg, H. M. ^[18]; Couch, W. J. ^[19]

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1. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)
2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
3. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Institute of Superior Tecnico (IST), Lisbon (Portugal)
4. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of Paris VI and VII, Paris (France)
5. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Stockholm University (Sweden)
6. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); European Southern Observatory, Munich (Germany)
7. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States); Collège de France, Paris (France)
8. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Institute of Astronomy, Cambridge (United Kingdom)
9. European Southern Observatory, La Silla (Chile)
10. Institute of Astronomy, Cambridge (United Kingdom)
11. University of Barcelona (Spain)
12. Isaac Newton Group, La Palma (Spain)
13. Yale University, New Haven, CT (United States)
14. Anglo-Australian Observatory, Sydney (Australia)
15. University of California, Berkeley, CA (United States)
16. Space Telescope Science Institute, Baltimore, MD (United States)
17. Space Telescope Science Institute, Baltimore, MD (United States); European Space Agency, Paris (France)
18. Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
19. University of New South Wales, Sydney, NSW (Australia)

Here we report measurements of the mass density, Ω_M, and cosmological-constant energy density, Ω_Λ, of the universe based on the analysis of 42 type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fitted jointly with a set of supernovae from the Calán/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. All supernova peak magnitudes are standardized using a SN Ia light-curve width-luminosity relation. The measurement yields a joint probability distribution of the cosmological parameters that is approximated by the relation 0.8Ω_M-0.6Ω_Λ≈-0.2±0.1 in the region of interest (Ω_M≲1.5). For a flat (Ω_M+Ω_Λ=1) cosmology we find Ω$$_{M}^{flat}$$=0.28$$^{+0.09}_{-0.08}$$ (1 σ statistical) $$^{+0.05}_{-0.04}$$ (identified systematics). The data are strongly inconsistent with a Λ=0 flat cosmology, the simplest inflationary universe model. An open, Λ=0 cosmology also does not fit the data well: the data indicate that the cosmological constant is nonzero and positive, with a confidence of P(Λ>0)=99%, including the identified systematic uncertainties. The best-fit age of the universe relative to the Hubble time is t$$_{0}^{flat}$$=14.9$$^{+1.4}_{-1.1}$$(0.63/h) Gyr for a flat cosmology. The size of our sample allows us to perform a variety of statistical tests to check for possible systematic errors and biases. We find no significant differences in either the host reddening distribution or Malmquist bias between the low-redshift Calán/Tololo sample and our high-redshift sample. Excluding those few supernovae that are outliers in color excess or fit residual does not significantly change the results. The conclusions are also robust whether or not a width-luminosity relation is used to standardize the supernova peak magnitudes. We discuss and constrain, where possible, hypothetical alternatives to a cosmological constant.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Director, Office of Science (US); National Science Foundation (NSF); Swedish Natural Science Research Council; France-Berkeley Fund; Stockholm-Berkeley Fund
• Grant/Contract Number: AC03-76SF00098; ADT-88909616; AST 94-17213
• OSTI ID: 840560
• Report Number(s): LBNL-41801; TRN: US200512%%101
• Journal Information: The Astrophysical Journal, Vol. 517, Issue 2; Other Information: Journal Publication Date: 06/01/1999; PBD: 3 Sep 1998; ISSN 0004-637X
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
cosmology
observations
distance scale
supernovae