A team of astronomers has made a groundbreaking discovery: a cosmic trio of galaxies, named J1218/1219+1035, is merging. Located 1.2 billion light-years away, this is the first documented case where three galaxies, all hosting active supermassive black holes, are in the process of merging.
This unique formation sheds light on how immense galaxies evolve. High-resolution radio imaging confirmed that these black holes can simultaneously feed and launch jets, a process seen earlier only in one or two other confirmed cases. However, this is the first time we’ve observed clear radio emissions from all three cores in such a system.
The research, led by Dr. Emma Schwartzman at the U.S. Naval Research Laboratory, presents an exciting opportunity for scientists. It offers insights into how massive galaxies and their central black holes grow together through mergers. According to Dr. Schwartzman, this discovery moves the concept of triple radio active galactic nuclei (AGN) from theory to reality, enriching our understanding of supermassive black holes.
How They Discovered It
The journey began with NASA’s Wide-field Infrared Survey Explorer (WISE), which detected peculiar mid-infrared colors indicating two active galactic nuclei in merging galaxies, leaving the third galaxy somewhat of a mystery. Following up with optical measurements confirmed that all three galaxies were interconnected and interacting.
Astronomers used the Very Large Array (VLA) and the Very Long Baseline Array (VLBA) to observe compact radio emissions. These emissions typically suggest the presence of actively feeding supermassive black holes. The steep spectral slopes detected ruled out star formation as the source of energy, solidifying the belief that this system contains three genuine radio AGN.
The Significance of This Find
J1218/1219+1035 is unlike any previous findings. Prior candidates for triple AGN either failed to show radio emissions from all nuclei or were in advanced merger stages. This system is at an intermediate stage, establishing a critical link in understanding galaxy evolution. Observations indicate gravitational interactions, with some galaxies showing signs of tidal features, revealing dynamic interactions.
The rarity of such systems means that confirming their existence can help test established theories around galaxy growth and the merging of black holes. Interestingly, radio interferometry has proven to be a more effective method of detection than traditional optical or infrared approaches, particularly when dust clouds obscure views of galactic centers.
Future Research Directions
The astronomers plan to continue observing J1218/1219+1035 across additional wavelengths, including near-infrared and X-ray. This will help them better understand the structures of the galaxies involved and the energy production of each black hole.
This discovery not only serves as a fascinating example of cosmic interactions but also suggests that active black hole accretion can occur well before galaxies fully merge. As we explore these cosmic wonders, we not only broaden our knowledge of the universe but also our understanding of fundamental processes that shape it.
For more detailed insights, you can check the original study in The Astrophysical Journal Letters here.
