Hubble's Constant with GW170817 Standard Siren and GW190814 Dark Siren

The local universe expansion rate is one of the most fundamental and essential cosmological parameters. This value which is known by the name of Hubble’s Constant is scientifically measured by electromagnetic sources called distance ladder. Surprisingly, using Gravitational Wave (GW) analysis this value can be measured making GW sources another significant method to act as standard sirens with their electromagnetic counterparts from their host galaxy. The gravitational wave event GW 170817 was the outcome of the merger of two different neutron stars. The electromagnetic event was recorded from the host galaxy NGC4993. The GW170817 has been a considerable success in this direction measuring the value of universe acceleration H0 = 70.0+12.0 −8.0 kms−1 Mpc−1. Another event in this series GW190817 is Compact Binary Coalescence involving a 22.2 – 24.3 The EM counterpart of this event is unknown so far and hence the event is named Dark Siren.The Hubble’s value proposed with this even is close to H0 = 75+59 −13 km s−1Mpc−1 .The source GW190814 which involves a massive black hole and the other compact object as the lightest black hole or the heaviest neutron star was localized to 18.5 deg2 at a distance of Mpc.