Constraints on compact dark matter with fast radio burst observations
  Fast Radio Bursts (FRBs) are bright radio transients with millisecond
duration at cosmological distances. Since compact dark matter/objects (COs)
could act as lenses and cause split of this kind of very short duration
signals, Mu$\rm{\tilde{n}}$oz et al. (2016) has proposed a novel method to
probe COs with lensing of FRBs. In this Letter, we for the first time apply
this method to real data and give constraints of the nature of COs with
currently available FRB observations. We emphasize the information from dynamic
spectra of FRBs is quite necessary for identifying any lensed signals and find
no echoes in the existing data. The null search gives a constraint comparable
to that from galactic wide binaries, though the methods of redshift inference
from dispersion measure would impact a little. Furthermore, we make an improved
forecast basing on the distributions of real data for the ongoing and upcoming
telescopes. Finally, we discuss the situation where one or more lensed signals
will be detected. In such a case, the parameter space of COs can be pinned down
very well since the lens mass can be directly determined through the observed
flux ratio and time delay between split images.
