The Megamaser Cosmology Project. XI. A Geometric Distance to CGCG 074-064
The Megamaser Cosmology Project. XI. A Geometric Distance to CGCG 074-064
复制标题
Megamaser 宇宙学项目。
作者：
D. Pesce;D. Pesce;J. Braatz;M. Reid;James J. Condon;F. Gao;F. Gao;C. Henkel;C. Henkel;C. Kuo;K. Lo;W. Zhao
作为Megamaser宇宙学项目的一部分，我们在星系CGCG074-064中发现了一个盘状Megamaser系统。利用绿岸望远镜和甚大天线阵，我们在两年的时间里以每月的节奏获得了对这个脉泽系统的光谱监测观测。我们发现，系统脉泽特征显示∼4.4kmS−1yr−1的视线加速度与速度几乎不变，而高速脉泽特征显示的加速度与速度一致。我们还使用高灵敏度阵列制作了CGCG074-064中脉泽系统的高灵敏度超长基线干涉图，显示脉泽驻留在一个直径为∼1.5mA(0.6pC)的薄片上。用一个三维翘曲圆盘模型来拟合数据，我们测量了黑洞的质量和到MPC系统的几何距离。假定宇宙微波背景帧的后退速度为7308±150千米S−1，我们将哈勃常数约束为(STAT.)±1.4Sys.KM S−1 MPC−1.
As part of the survey component of the Megamaser Cosmology Project, we have discovered a disk megamaser system in the galaxy CGCG 074-064. Using the Green Bank Telescope and the Very Large Array, we have obtained spectral monitoring observations of this maser system at a monthly cadence over the course of two years. We find that the systemic maser features display line-of-sight accelerations of ∼4.4 km s−1 yr−1 that are nearly constant with velocity, while the high-velocity maser features show accelerations that are consistent with zero. We have also used the High-Sensitivity Array to make a high-sensitivity very long baseline interferometric map of the maser system in CGCG 074-064, which reveals that the masers reside in a thin, edge-on disk with a diameter of ∼1.5 mas (0.6 pc). Fitting a three-dimensional warped disk model to the data, we measure a black hole mass of and a geometric distance to the system of Mpc. Assuming a cosmic microwave background-frame recession velocity of 7308 ± 150 km s−1, we constrain the Hubble constant to (stat.) ± 1.4 (sys.) km s−1 Mpc−1.