In a groundbreaking discovery, NASA’s Hubble Space Telescope and the Chandra X-ray Observatory have captured the closest known pair of supermassive black holes in the local universe. This remarkable find, located in the galaxy MCG-03-34-64, reveals two supermassive black holes about 300 light-years apart, orbiting within the heart of their colliding host galaxies.
Despite the vast distances between individual stars, collisions between galaxies are not uncommon. Our own Milky Way is on a collision course with the Andromeda galaxy, a cosmic event that will culminate in a merger of these two galactic giants. When such galactic collisions occur, their supermassive black holes typically merge into a single, enormous black hole.
The newly discovered AGN (Active Galactic Nucleus) pair stands out due to its proximity and brightness in visible and X-ray wavelengths. Previous discoveries of dual black holes often showed them at much greater distances. The observation team, led by Anna Trindade Falcão from the Center for Astrophysics | Harvard & Smithsonian, stumbled upon this rare sight when Hubble’s high-resolution imaging detected unusual diffraction spikes, hinting at a dense concentration of glowing oxygen gas.
To confirm their findings, the team analyzed X-ray data from Chandra, revealing two powerful sources of high-energy emission. Supporting evidence came from radio observations using the Karl G. Jansky Very Large Array, which showed that the AGN pair also emits strong radio waves.
The merging black holes, which were once at the centers of separate galaxies, will continue to spiral closer together over the next 100 million years until they eventually merge, producing significant gravitational waves. While LIGO has detected such waves from stellar-mass black hole mergers, the longer wavelengths from supermassive black hole mergers require the future LISA (Laser Interferometer Space Antenna) mission for detection. Scheduled for launch in the mid-2030s, LISA will be a collaborative effort between NASA and ESA.
This discovery not only enhances our understanding of galaxy mergers but also underscores the invaluable contributions of Hubble and Chandra in exploring the cosmos. Hubble, operational for over three decades, and Chandra, managed by NASA’s Marshall Space Flight Center and the Smithsonian Astrophysical Observatory, continue to deliver insights that shape our knowledge of the universe.
