Improvement of cosmological constraints with the cross correlation
  between line-of-sight optical galaxy and FRB dispersion measure
  Fast Radio Bursts (hereafter FRBs) can be used in cosmology by studying the
Dispersion Measure (hereafter DM) as a function of redshift. The large scale
structure of matter distribution is regarded as a major error budget for such
application. Using optical galaxy and dispersion measure mocks built from
N-body simulations, we have shown that the galaxy number density can be used as
a tracer for large scale electron density and help improve the measurement of
DM as a function of redshift. We have shown that, using the line-of-sight
galaxy number counts within 1' around the given localized FRB source can help
improve the cosmological parameter constraints by more than 20%.
