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arXiv · 2001.04581

The Megamaser Cosmology Project. XI. A geometric distance to CGCG 074-064

D. W. Pesce·J. A. Braatz·M. J. Reid·J. J. Condon·F. Gao·C. Henkel·C. Y. Kuo·K. Y. Lo·W. Zhao
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Abstract

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 GBT and the VLA, 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 HSA to make a high-sensitivity VLBI 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 $2.42^{+0.22}_{-0.20} \times 10^7$ M$_{\odot}$ and a geometric distance to the system of $87.6^{+7.9}_{-7.2}$ Mpc. Assuming a CMB-frame recession velocity of $7308 \pm 150$ km s$^{-1}$, we constrain the Hubble constant to $H_0 = 81.0^{+7.4}_{-6.9}$ (stat.) $\pm 1.4$ (sys.) km s$^{-1}$ Mpc$^{-1}$.

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D. W. Pesce, J. A. Braatz, M. J. Reid, J. J. Condon, F. Gao, C. Henkel, C. Y. Kuo, K. Y. Lo, W. Zhao. 2020-01-14. The Megamaser Cosmology Project. XI. A geometric distance to CGCG 074-064. https://doi.org/10.3847/1538-4357%2Fab6bcd

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