We illustrate how recently improved low-redshift cosmological measurements can tighten constraints on neutrino properties .
In particular we examine the impact of the assumed cosmological model on the constraints .
We first consider the new HST H _ { 0 } = 74.2 \pm 3.6 measurement by Riess et al .
( 2009 ) and the \sigma _ { 8 } ( \Omega _ { m } / 0.25 ) ^ { 0.41 } = 0.832 \pm 0.033 constraint from Rozo et al .
( 2009 ) derived from the SDSS maxBCG Cluster Catalog .
In a \Lambda CDM model and when combined with WMAP5 constraints , these low-redshift measurements constrain \sum m _ { \nu } < 0.4 eV at the 95 % confidence level .
This bound does not relax when allowing for the running of the spectral index or for primordial tensor perturbations .
When adding also Supernovae and BAO constraints , we obtain a 95 % upper limit of \sum m _ { \nu } < 0.3 eV .
We test the sensitivity of the neutrino mass constraint to the assumed expansion history by both allowing a dark energy equation of state parameter w \neq - 1 and by studying a model with coupling between dark energy and dark matter , which allows for variation in w , \Omega _ { k } , and dark coupling strength \xi .
When combining CMB , H _ { 0 } and the SDSS LRG halo power spectrum from Reid et al .
2009 , we find that in this very general model , \sum m _ { \nu } < 0.51 eV with 95 % confidence .
If we allow the number of relativistic species N _ { rel } to vary in a \Lambda CDM model with \sum m _ { \nu } = 0 , we find N _ { rel } = 3.76 ^ { +0.63 } _ { -0.68 } ( ^ { +1.38 } _ { -1.21 } ) for the 68 % and 95 % confidence intervals .
We also report prior-independent constraints , which are in excellent agreement with the Bayesian constraints .