A 2.4% DETERMINATION OF THE LOCAL VALUE OF THE HUBBLE CONSTANT
A 2.4% DETERMINATION OF THE LOCAL VALUE OF THE HUBBLE CONSTANT
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DOI：
10.3847/0004-637x/826/1/56
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发表时间：
2016-04
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通讯作者：
A. Riess;L. Macri;S. Hoffmann;D. Scolnic;S. Casertano;A. Filippenko;B. Tucker;M. Reid;David O
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作者：
A. Riess;L. Macri;S. Hoffmann;D. Scolnic;S. Casertano;A. Filippenko;B. Tucker;M. Reid;David O
我们使用哈勃太空望远镜（HST）上的宽视场相机3（WFC 3）将哈勃常数的局部值的不确定性从3.3%降低到2.4%。这一改进的大部分来自于对11个最近Ia型超新星（SNe Ia）的宿主星系中的造父变星的近红外（NIR）观测，将具有造父变星校准距离的可靠SNe Ia的样本增加了一倍以上，达到19个;这些反过来又利用了基于Z <0.15的SNe Ia 300的星等-红移关系。所有19个宿主以及超脉泽系统NGC 4258都已经用光学和近红外的WFC 3观测到，从而消除了造父变星相对距离估计中的跨仪器零点误差。其他值得注意的改进包括：到NGC 4258的脉泽距离的系统不确定性降低了33%，大麦哲伦云（LMC）中造父变星的更大样本，基于晚型分离食双星（DEBs）的到LMC的更鲁棒的距离，M31中造父变星的HST观测，以及银河系（MW）造父变星的新的HST三角测量。我们考虑了造父变星的四种几何距离校准：（i）NGC 4258中的超脉泽，（ii）LMC中的8个DEB，（iii）用HST/FGS，HST/WFC 3空间扫描和/或依巴谷测量的15 MW造父变星，以及（iv）M31中的2个DEB。哈勃常数分别为72.25 ± 2.51、72.04 ± 2.67、76.18 ± 2.37和74.50 ± 3.27 km s − 1 Mpc − 1。我们对H0 = 73.24 ± 1.74 km s − 1 Mpc − 1的最佳估计结合了NGC 4258、MW和LMC的锚点，得出了2.4%的确定性（所有引用的不确定性包括完全传播的统计和系统分量）。这个值比Λ CDM预测的66.93 ± 0.62 km s − 1 Mpc − 1高出3.4 σ，其中3种中微子的质量为0.06 eV，新的普朗克数据，但相对于基于WMAP + ACT + SPT + BAO观测的精确组合预测的69.3 ± 0.7 km s − 1 Mpc − 1，差异减小到2.1 σ，这表明CMB辐射测量的系统不确定性可能在紧张局势中发挥作用。如果我们把普朗克高红移测量和我们对H0的局部测定之间的冲突放在表面上，一个合理的解释可能涉及早期宇宙中Δ Neff = 0.4 - 1范围内的另一个暗辐射源。我们预计，从即将到来的视差测量长周期MW造父变星H0进一步显着改善。
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to reduce the uncertainty in the local value of the Hubble constant from 3.3% to 2.4%. The bulk of this improvement comes from new near-infrared (NIR) observations of Cepheid variables in 11 host galaxies of recent type Ia supernovae (SNe Ia), more than doubling the sample of reliable SNe Ia having a Cepheid-calibrated distance to a total of 19; these in turn leverage the magnitude-redshift relation based on ∼300 SNe Ia at z < 0.15. All 19 hosts as well as the megamaser system NGC 4258 have been observed with WFC3 in the optical and NIR, thus nullifying cross-instrument zeropoint errors in the relative distance estimates from Cepheids. Other noteworthy improvements include a 33% reduction in the systematic uncertainty in the maser distance to NGC 4258, a larger sample of Cepheids in the Large Magellanic Cloud (LMC), a more robust distance to the LMC based on late-type detached eclipsing binaries (DEBs), HST observations of Cepheids in M31, and new HST-based trigonometric parallaxes for Milky Way (MW) Cepheids. We consider four geometric distance calibrations of Cepheids: (i) megamasers in NGC 4258, (ii) 8 DEBs in the LMC, (iii) 15 MW Cepheids with parallaxes measured with HST/FGS, HST/WFC3 spatial scanning and/or Hipparcos, and (iv) 2 DEBs in M31. The Hubble constant from each is 72.25 ± 2.51, 72.04 ± 2.67, 76.18 ± 2.37, and 74.50 ± 3.27 km s−1 Mpc−1, respectively. Our best estimate of H0 = 73.24 ± 1.74 km s−1 Mpc−1 combines the anchors NGC 4258, MW, and LMC, yielding a 2.4% determination (all quoted uncertainties include fully propagated statistical and systematic components). This value is 3.4σ higher than 66.93 ± 0.62 km s−1 Mpc−1 predicted by ΛCDM with 3 neutrino flavors having a mass of 0.06 eV and the new Planck data, but the discrepancy reduces to 2.1σ relative to the prediction of 69.3 ± 0.7 km s−1 Mpc−1 based on the comparably precise combination of WMAP+ACT+SPT+BAO observations, suggesting that systematic uncertainties in CMB radiation measurements may play a role in the tension. If we take the conflict between Planck high-redshift measurements and our local determination of H0 at face value, one plausible explanation could involve an additional source of dark radiation in the early universe in the range of ΔNeff ≈ 0.4–1. We anticipate further significant improvements in H0 from upcoming parallax measurements of long-period MW Cepheids.