Constraint on cosmological parameters by Hubble parameter from
  gravitational wave standard sirens of neutron star binary system
  In this paper, we present a new method of measuring Hubble parameter($H(z)$),
making use of the anisotropy of luminosity distance($d_{L}$), and the analysis
of gravitational wave(GW) of neutron star(NS) binary system. The method has
never been put into practice before due to the lack of the ability of detecting
GW. LIGO's success in detecting GW of black hole(BH) binary system merger
announced the possibility of this new method. We apply this method to several
GW detecting projects, including Advanced LIGO(Adv-LIGO), Einstein
Telescope(ET) and DECIGO, finding that the $H(z)$ by Adv-LIGO and ET is of bad
accuracy, while the $H(z)$ by DECIGO shows a good accuracy. We use the error
information of $H(z)$ by DECIGO to simulate $H(z)$ data at every 0.1 redshift
span, and put the mock data into the forecasting of cosmological parameters.
Compared with the available 38 observed $H(z)$ data(OHD), mock data shows an
obviously tighter constraint on cosmological parameters, and a concomitantly
higher value of Figure of Merit(FoM). For a 3-year-observation by standard
sirens of DECIGO, the FoM value is as high as 834.9. If a 10-year-observation
is launched, the FoM could reach 2783.1. For comparison, the FoM of 38 actual
observed $H(z)$ data is 9.3. These improvement indicates that the new method
has great potential in further cosmological constraints.
