We constrain cosmological parameters using combined measurements of the baryon acoustic oscillation ( BAO ) feature in the correlation function of galaxies and Ly- \alpha absorbers that together cover 0.1 < z < 2.4 .
The BAO position measurements alone – without fixing the absolute sound horizon ‘ standard ruler ’ length with cosmic microwave background ( CMB ) data – constrain \Omega _ { m } = 0.303 \pm 0.040 ( 68 per cent confidence ) for a flat \Lambda CDM model , and w = -1.06 ^ { +0.33 } _ { -0.32 } , \Omega _ { m } = 0.292 ^ { +0.045 } _ { -0.040 } for a flat w CDM model .
Adding other large-scale structure ( LSS ) clustering constraints – correlation function shape , the Alcock-Paczynski test and growth rate information – to the BAO considerably tightens constraints ( \Omega _ { m } = 0.290 \pm 0.019 , H _ { 0 } = 67.5 \pm 2.8 ~ { } km ~ { } s ^ { -1 } ~ { } Mpc ^ { -1 } , \sigma _ { 8 } = 0.80 \pm 0.05 for \Lambda CDM , and w = -1.14 \pm 0.19 for w CDM ) .
The LSS data mildly prefer a lower value of H _ { 0 } , and a higher value of \Omega _ { m } , than local distance ladder and type IA supernovae ( SNe ) measurements , respectively .
While tension in the combined CMB , SNe and distance ladder data appears to be relieved by allowing w < -1 , this freedom introduces tension with the LSS \sigma _ { 8 } constraint from the growth rate of matter fluctuations .
The combined constraint on w from CMB , BAO and LSS clustering for a flat w CDM model is w = -1.03 \pm 0.06 .