Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
Abstract
We present a new compilation of Type Ia supernovae (SNe Ia), a new dataset of low-redshift nearby-Hubble-flow SNe and new analysis procedures to work with these heterogeneous compilations. This ``Union'' compilation of 414 SN Ia, which reduces to 307 SNe after selection cuts, includes the recent large samples of SNe Ia from the Supernova Legacy Survey and ESSENCE Survey, the older datasets, as well as the recently extended dataset of distant supernovae observed with HST. A single, consistent and blind analysis procedure is used for all the various SN Ia subsamples, and a new procedure is implemented that consistently weights the heterogeneous data sets and rejects outliers. We present the latest results from this Union compilation and discuss the cosmological constraints from this new compilation and its combination with other cosmological measurements (CMB and BAO). The constraint we obtain from supernovae on the dark energy density is \Omega_\Lambda= 0.713^{+0.027}_{-0.029} (stat)}^{+0.036}_{-0.039} (sys)}, for a flat, LCDM Universe. Assuming a constant equation of state parameter, , the combined constraints from SNe, BAO and CMB give . While our results are consistent with a cosmological constant, we obtain only relatively weak constraints on a that varies with redshift. In particular, the current SN data do not yet significantly constrain at . With the addition of our new nearby Hubble-flow SNe Ia, these resulting cosmological constraints are currently the tightest available.
Cite
@article{arxiv.0804.4142,
title = {Improved Cosmological Constraints from New, Old and Combined Supernova Datasets},
author = {M. Kowalski and D. Rubin and G. Aldering and R. J. Agostinho and A. Amadon and R. Amanullah and C. Balland and K. Barbary and G. Blanc and P. J. Challis and A. Conley and N. V. Connolly and R. Covarrubias and K. S. Dawson and S. E. Deustua and R. Ellis and S. Fabbro and V. Fadeyev and X. Fan and B. Farris and G. Folatelli and B. L. Frye and G. Garavini and E. L. Gates and L. Germany and G. Goldhaber and B. Goldman and A. Goobar and D. E. Groom and J. Haissinski and D. Hardin and I. Hook and S. Kent and A. G. Kim and R. A. Knop and C. Lidman and E. V. Linder and J. Mendez and J. Meyers and G. J. Miller and M. Moniez and A. M. Mourao and H. Newberg and S. Nobili and P. E. Nugent and R. Pain and O. Perdereau and S. Perlmutter and M. M. Phillips and V. Prasad and R. Quimby and N. Regnault and J. Rich and E. P. Rubenstein and P. Ruiz-Lapuente and F. D. Santos and B. E. Schaefer and R. A. Schommer and R. C. Smith and A. M. Soderberg and A. L. Spadafora and L. -G. Strolger and M. Strovink and N. B. Suntzeff and N. Suzuki and R. C. Thomas and N. A. Walton and L. Wang and W. M. Wood-Vasey and J. L. Yun},
journal= {arXiv preprint arXiv:0804.4142},
year = {2008}
}
Comments
49 pages, 17 figures; accepted for publication in Astrophysical Journal. For data tables, code for cosmological analysis and full-resolution figures, see http://supernova.lbl.gov/Union