| 摘要: |
We report a tight Hubble constant constraint 67.78(-1.86)(+1.21) km s(-1) Mpc(-1) (2.26 per cent precision) derived from galaxy redshift surveys. We combine the baryon acoustic oscillation (BAO) measurements from 6dFGS, the SDSS DR7 main galaxies, the BOSS DR12 galaxies, and eBOSS DR14 quasars, and also apply the tomographic Alcock-Paczynski (AP) method to the BOSS DR12 galaxies, to place constraints on H-0. Although the AP method alone cannot constrain H-0, it assists the BAO method by tightening the constraint on Omega(m) and breaks the degeneracy between the two parameters. Our result is fully consistent with the cosmic microwave background constraints from Planck, but in 2.58 sigma tension with local measurements. Compared with the BAO-alone constraint, the combined result reduces the error bar by 32 per cent, showing the strong power of the tomographic AP method in extracting cosmological information from galaxy surveys. In the analysis we adopt a prior of Omega(b) h(2) from the Planck experiment constraint and assume that the cosmology is the six-parameter flat lambda cold dark matter (Lambda CDM). We find that the first assumption has little effect on the derived constraints, i.e. the constraint is less affected as long as the Planck Omega(b) h(2) is not deviated from the true value by >4 sigma; the second assumption means that the results may alter in alternatives to Lambda CDM, where the H-0 constraints from different experiments can become more consistent. |
