A 3% SOLUTION: DETERMINATION OF THE HUBBLE CONSTANT WITH THE HUBBLE SPACE TELESCOPE AND WIDE FIELD CAMERA 3
A 3% SOLUTION: DETERMINATION OF THE HUBBLE CONSTANT WITH THE HUBBLE SPACE TELESCOPE AND WIDE FIELD CAMERA 3
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DOI：
10.1088/0004-637x/730/2/119
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发表时间：
2011-03
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影响因子：
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通讯作者：
A. Riess;L. Macri;S. Casertano;H. Lampeitl;H. Ferguson;A. Filippenko;S. Jha;Weidong Li;R. Cho
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作者：
A. Riess;L. Macri;S. Casertano;H. Lampeitl;H. Ferguson;A. Filippenko;S. Jha;Weidong Li;R. Cho
我们利用哈勃太空望远镜(HST)上的广视场3号相机(WFC3)，从光学和红外观测中测定了8个新近Ia型超新星(SNE Ia)的宿主星系中600多个造父变星的哈勃常数，为基于253个SNE Ia的星等红移关系提供了定标。对过去哈勃常数测量的精度提高来自五个改进：(1)将附近SN主机中造父变星的红外观测次数增加一倍以上；(2)将理想的SN Ia校准器的样本量从6个增加到8个；(3)将在超级激光主机NGC4258中进行红外观测的造父变星数量增加20%；(4)将NGC4258和SN主机之间造父变星比较样本的平均金属丰度差异从Δlog[O/H]=0.08缩小到0.05；以及(5)用单个相机WFC3校准所有光学造父变星的颜色，以消除交叉仪器的零点误差。结果是，由于超出距离阶梯的第一级，H0中的不确定度从3.5%减少到2.3%。通过到NGC4258的几何距离测量的H0为74.8±3.1千米S−1MPC−1，包括系统不确定度的4.1%的测量。与距离NGC4258的距离无关的更高精度是由于使用了两个替代的造父变星绝对定标：(1)13个银河系造父变星，使用HST/精细制导传感器和依巴谷测量到的三角视差；(2)大麦哲伦星云中的92个造父变星，有多个精确的日食双星距离可用，产生74.4±2.5千米S−1 MPC−1，包括系统学在内的3.4%不确定度。我们的最佳估计使用了所有三个校准，但任何两个校准都提供了更大的不确定度：H0=73.8士2.4kM S−1 Mpc−1，包括系统误差，对应于3.3%的不确定度。改进的H0测量，当结合威尔金森微波各向异性探测器7年的数据时，导致对暗能量的状态方程参数w=−1.08±0.10有更严格的约束。它还排除了最适合千兆秒尺度的空洞模型，该模型被认为是暗能量的替代品。H0+WMAP的组合结果给出了早期宇宙中相对论粒子物种数量的NEff=4.2±0.7，对于已知的三种中微子类型的预期值来说，这是一个较低的显著超量。
We use the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) to determine the Hubble constant from optical and infrared observations of over 600 Cepheid variables in the host galaxies of eight recent Type Ia supernovae (SNe Ia), providing the calibration for a magnitude–redshift relation based on 253 SNe Ia. Increased precision over past measurements of the Hubble constant comes from five improvements: (1) more than doubling the number of infrared observations of Cepheids in the nearby SN hosts; (2) increasing the sample size of ideal SN Ia calibrators from six to eight; (3) increasing by 20% the number of Cepheids with infrared observations in the megamaser host NGC 4258; (4) reducing the difference in the mean metallicity of the Cepheid comparison samples between NGC 4258 and the SN hosts from Δlog [O/H] = 0.08 to 0.05; and (5) calibrating all optical Cepheid colors with a single camera, WFC3, to remove cross-instrument zero-point errors. The result is a reduction in the uncertainty in H0 due to steps beyond the first rung of the distance ladder from 3.5% to 2.3%. The measurement of H0 via the geometric distance to NGC 4258 is 74.8 ± 3.1 km s−1 Mpc−1, a 4.1% measurement including systematic uncertainties. Better precision independent of the distance to NGC 4258 comes from the use of two alternative Cepheid absolute calibrations: (1) 13 Milky Way Cepheids with trigonometric parallaxes measured with HST/fine guidance sensor and Hipparcos and (2) 92 Cepheids in the Large Magellanic Cloud for which multiple accurate and precise eclipsing binary distances are available, yielding 74.4 ± 2.5 km s−1 Mpc−1, a 3.4% uncertainty including systematics. Our best estimate uses all three calibrations but a larger uncertainty afforded from any two: H0 = 73.8 ± 2.4 km s−1 Mpc−1 including systematic errors, corresponding to a 3.3% uncertainty. The improved measurement of H0, when combined with the Wilkinson Microwave Anisotropy Probe (WMAP) 7 year data, results in a tighter constraint on the equation-of-state parameter of dark energy of w = −1.08 ± 0.10. It also rules out the best-fitting gigaparsec-scale void models, posited as an alternative to dark energy. The combined H0 + WMAP results yield Neff = 4.2 ± 0.7 for the number of relativistic particle species in the early universe, a low-significance excess for the value expected from the three known neutrino flavors.