Milky Way Quasars Infinity Galaxy MCG-03-34-64 Star Formation Supermassive Black Holes Supermassive Black Hole Mergers Stellar Collisions Elliptical Galaxies NGC5713 and NGC5719 IC 2163 and NGC 2207 Gravitational Wave Background Black Holes Ancient Galaxy Discoveries OJ 287 Abell 402-BCG Arp 122 Andromeda Galaxy Fossil Galaxies Supermassive Black Hole Merger Milky Way Mergers Machine Learning Binary Supermassive Black Holes Arp 107 Supermassive Black Hole Binaries Triple Galaxy Mergers Host Galaxy Properties Gravitational Lensing Black Hole Formation Markarian 501 Milky Way and Andromeda Colliding Galaxies Perseus Cluster Early Universe Active Galactic Nuclei Black Hole Growth Andromeda and Milky Way Merger Arp 105 NGC 2207 and IC 2163
Targeted spectroscopy, X‑ray and radio observations will test whether the pairs are merging accreting black holes.