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Observational Constraints on the Nature of Dark Energy: First Cosmological Results from the ESSENCE Supernova Survey

W. M. Wood‐VaseyHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138G. MiknaitisFermilab, Batavia, IL 60510-0500C. W. StubbsDepartment of Physics, Harvard University, Cambridge, MA 02138Saurabh W. JhaDepartment of Astronomy, University of California, Berkeley, CA 94720-3411Adam G. RiessJohns Hopkins University, Baltimore, MD 21218P. GarnavichDepartment of Physics, University of Notre Dame, Notre Dame, IN 46556-5670R. KirshnerHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138C. AguileraCerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, ChileA. BeckerDepartment of Astronomy, University of Washington, Seattle, WA 98195-1580Joshua W. BlackmanResearch School of Astronomy and Astrophysics, Australian National University, Mount Stromlo and Siding Spring Observatories, Weston Creek PO 2611, AustraliaS. BlondinHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138Peter ChallisHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138A. ClocchiattiPontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Casilla 306, Santiago 22, ChileA. ConleyDepartment of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4, CanadaR. CovarrubiasDepartment of Astronomy, University of Washington, Seattle, WA 98195-1580T. M. DavisDark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, DenmarkA. V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA 94720-3411R. J. FoleyDepartment of Astronomy, University of California, Berkeley, CA 94720-3411Arti GargDepartment of Physics, Harvard University, Cambridge, MA 02138M. HickenDepartment of Physics, Harvard University, Cambridge, MA 02138K. KrisciunasDepartment of Physics, Texas A&M University, College Station, TX 77843-4242B. LeibundgutEuropean Southern Observatory, D-85748 Garching, GermanyWenyu LiDepartment of Astronomy, University of California, Berkeley, CA 94720-3411T. MathesonNational Optical Astronomy Observatory, Tucson, AZ 85719-4933A. MiceliDepartment of Astronomy, University of Washington, Seattle, WA 98195-1580Gautham NarayanDepartment of Physics, Harvard University, Cambridge, MA 02138G. PignataPontificia Universidad Católica de Chile, Departamento de Astronomía y Astrofísica, Casilla 306, Santiago 22, ChileJ. L. PrietoDepartment of Astronomy, Ohio State University, Columbus, OH 43210A. RestCerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, ChileM. SalvoResearch School of Astronomy and Astrophysics, Australian National University, Mount Stromlo and Siding Spring Observatories, Weston Creek PO 2611, AustraliaB. SchmidtResearch School of Astronomy and Astrophysics, Australian National University, Mount Stromlo and Siding Spring Observatories, Weston Creek PO 2611, AustraliaR. C. SmithCerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, ChileJ. SollermanDark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, DenmarkJ. SpyromilioEuropean Southern Observatory, D-85748 Garching, GermanyJ. TonryInstitute for Astronomy, University of Hawaii, Honolulu, HI 96822N. B. SuntzeffCerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, ChileA. ZentenoCerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena, Chile

2007en

ABI

Annotatsiya

We present constraints on the dark energy equation-of-state parameter, w = P/(ρc2), using 60 SNe Ia from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (ΩM, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05img1.gif (stat 1 σ) ± 0.13 (sys) and ΩM = 0.274img2.gif (stat 1 σ) with a best-fit χ2/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1.07img3.gif (stat 1 σ) ± 0.13 (sys), ΩM = 0.267img4.gif (stat 1 σ) with a best-fit χ2/dof of 0.91. The current global SN Ia data alone rule out empty (ΩM = 0), matter-only ΩM = 0.3, and ΩM = 1 universes at >4.5 σ. The current SN Ia data are fully consistent with a cosmological constant.

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DOI: 10.1086/518642

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