Determining the Hubble Constant with AGN-assisted Black Hole Mergers

Understand

Gravitational waves from neutron star mergers have long been considered a promising way to measure the Hubble constant, $H_0$, which describes the local expansion rate of the universe.

• While black hole mergers are more abundantly observed, their expected lack of electromagnetic emission and poor gravitational-wave localization make them less well suited for measuring $H_0$.
• Black hole mergers within the disks of Active Galactic Nuclei (AGN) could be an exception.
• Accretion from the AGN disk may produce an electromagnetic signal, pointing observers to the host galaxy.