Space-borne atom interferometric gravitational wave detections. Part II.
  Dark sirens and finding the one
  In this paper, we investigate the potential of dark sirens by the space-borne
atom interferometric gravitational-wave detectors to probe the Hubble constant.
In the mid-frequency band, the sources live a long time. The motion of a
detector around the Sun as well as in Earth orbit would induce large Doppler
and reorientation effects, providing a precise angular resolution. Such precise
localization for the GW sources makes it possible to observe the dark sirens
with only one potential host galaxy, which are dubbed "golden dark sirens". We
construct the catalogs of golden dark sirens and estimate that there are around
79 and 35 golden dark sirens of binary neutron stars (BNS) and binary black
holes (BBH) that would be pass the detection threshold of AEDGE in 5 years. Our
results show that with 5, 10, and all 79 golden dark BNS tracked by AEDGE one
can constrain $H_0$ at 5.5\%, 4.1\%, and 1.8\% precision levels. With 5, 10,
and all 35 golden dark BBH one can constrain $H_0$ at 2.2\%, 1.8\%, and 1.5\%
precision levels, respectively. It suggests that only 5-10 golden dark BBH by
AEDGE are sufficient to arbitrate the current tension between local and
high-$z$ measurements of $H_0$.
