We present an analysis of the luminosity distances of Type Ia Supernovae from the Sloan Digital Sky Survey-II ( SDSS-II ) Supernova Survey in conjunction with other intermediate redshift ( z < 0.4 ) cosmological measurements including redshift-space distortions from the Two-degree Field Galaxy Redshift Survey ( 2dFGRS ) , the Integrated Sachs-Wolfe ( ISW ) effect seen by the SDSS , and the latest Baryon Acoustic Oscillation ( BAO ) distance scale from both the SDSS and 2dFGRS .
We have analysed the SDSS-II SN data alone using a variety of “ model-independent ” methods and find evidence for an accelerating universe at > 97 % level from this single dataset .
We find good agreement between the supernova and BAO distance measurements , both consistent with a \Lambda –dominated CDM cosmology , as demonstrated through an analysis of the distance duality relationship between the luminosity ( d _ { L } ) and angular diameter ( d _ { A } ) distance measures .
We then use these data to estimate w within this restricted redshift range ( z < 0.4 ) .
Our most stringent result comes from the combination of all our intermediate–redshift data ( SDSS-II SNe , BAO , ISW and redshift–space distortions ) , giving w = -0.81 ^ { +0.16 } _ { -0.18 } ( \mathrm { stat } ) { \pm 0.15 } ( \mathrm { sys } ) and \Omega _ { M } = 0.22 ^ { +0.09 } _ { -0.08 } assuming a flat universe .
This value of w , and associated errors , only change slightly if curvature is allowed to vary , consistent with constraints from the Cosmic Microwave Background .
We also consider more limited combinations of the geometrical ( SN , BAO ) and dynamical ( ISW , redshift-space distortions ) probes .