First-year Sloan Digital Sky Survey-II supernova results: consistency and constraints with other intermediate-redshift data sets

We present an analysis of the luminosity distances of Type Ia Supernovae from\nthe Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey in conjunction with\nother intermediate redshift (z<0.4) cosmological measurements including\nredshift-space distortions from the Two-degree Field Galaxy Redshift Survey\n(2dFGRS), the Integrated Sachs-Wolfe (ISW) effect seen by the SDSS, and the\nlatest Baryon Acoustic Oscillation (BAO) distance scale from both the SDSS and\n2dFGRS. We have analysed the SDSS-II SN data alone using a variety of\n"model-independent" methods and find evidence for an accelerating universe at\n>97% level from this single dataset. We find good agreement between the\nsupernova and BAO distance measurements, both consistent with a\nLambda-dominated CDM cosmology, as demonstrated through an analysis of the\ndistance duality relationship between the luminosity (d_L) and angular diameter\n(d_A) distance measures. We then use these data to estimate w within this\nrestricted redshift range (z<0.4). Our most stringent result comes from the\ncombination of all our intermediate-redshift data (SDSS-II SNe, BAO, ISW and\nredshift-space distortions), giving w = -0.81 +0.16 -0.18(stat) +/- 0.15(sys)\nand Omega_M=0.22 +0.09 -0.08 assuming a flat universe. This value of w, and\nassociated errors, only change slightly if curvature is allowed to vary,\nconsistent with constraints from the Cosmic Microwave Background. We also\nconsider more limited combinations of the geometrical (SN, BAO) and dynamical\n(ISW, redshift-space distortions) probes.\n