We estimate cosmological parameters using data obtained by the Very Small Array ( VSA ) in its extended configuration , in conjunction with a variety of other CMB data and external priors .
Within the flat \Lambda CDM model , we find that the inclusion of high resolution data from the VSA modifies the limits on the cosmological parameters as compared to those suggested by WMAP alone , while still remaining compatible with their estimates .
We find that \Omega _ { b } h ^ { 2 } = 0.0234 ^ { +0.0012 } _ { -0.0014 } , \Omega _ { dm } h ^ { 2 } = 0.111 ^ { +0.014 } _ { -0.016 } , h = 0.73 ^ { +0.09 } _ { -0.05 } , n _ { S } = 0.97 ^ { +0.06 } _ { -0.03 } , 10 ^ { 10 } A _ { S } = 23 ^ { +7 } _ { -3 } and \tau = 0.14 ^ { +0.14 } _ { -0.07 } for WMAP and VSA when no external prior is included.On extending the model to include a running spectral index of density fluctuations , we find that the inclusion of VSA data leads to a negative running at a level of more than 95 \% confidence ( n _ { run } = -0.069 \pm 0.032 ) , something which is not significantly changed by the inclusion of a stringent prior on the Hubble constant .
Inclusion of prior information from the 2dF galaxy redshift survey reduces the significance of the result by constraining the value of \Omega _ { m } .
We discuss the veracity of this result in the context of various systematic effects and also a broken spectral index model .
We also constrain the fraction of neutrinos and find that f _ { \nu } < 0.087 at 95 \% confidence which corresponds to m _ { \nu } < 0.32 { eV } when all neutrino masses are the equal .
Finally , we consider the global best fit within a general cosmological model with 12 parameters and find consistency with other analyses available in the literature .
The evidence for n _ { run } < 0 is only marginal within this model .