We examine the impact of baryon acoustic oscillation ( BAO ) scale measurements on the discrepancy between the value of the Hubble constant ( H _ { 0 } ) inferred from the local distance ladder and from Planck cosmic microwave background ( CMB ) data .
While the BAO data alone can not constrain H _ { 0 } , we show that combining the latest BAO results with WMAP , Atacama Cosmology Telescope ( ACT ) , or South Pole Telescope ( SPT ) CMB data produces values of H _ { 0 } that are 2.4 - 3.1 \sigma lower than the distance ladder , independent of Planck , and that this downward pull was less apparent in some earlier analyses that used only angle-averaged BAO scale constraints rather than full anisotropic information .
At the same time , the combination of BAO and CMB data also disfavors the lower values of H _ { 0 } preferred by the Planck high-multipole temperature power spectrum .
Combining galaxy and Lyman- \alpha forest ( Ly \alpha ) BAO with a precise estimate of the primordial deuterium abundance produces H _ { 0 } = 66.98 \pm 1.18 km s ^ { -1 } Mpc ^ { -1 } for the flat \Lambda \mathrm { CDM } model .
This value is completely independent of CMB anisotropy constraints and is 3.0 \sigma lower than the latest distance ladder constraint , although 2.4 \sigma tension also exists between the galaxy BAO and Ly \alpha BAO .
These results show that it is not possible to explain the H _ { 0 } disagreement solely with a systematic error specific to the Planck data .
The fact that tensions remain even after the removal of any single data set makes this intriguing puzzle all the more challenging to resolve .