A remarkable cadre of three coalescing galaxies, designated J1218/1219+1035, harbors not one, but three supermassive black holes actively engaged in accretion and emitting strong radio signals, as reported by an assembly of American astrophysicists.
An artist’s impression of a rare trio of merging galaxies, J121/1219+1035, which host three actively feeding, radio-bright supermassive black holes and whose jets light up the surrounding gas. Image credit: NSF / AUI / NRAO / P. Vosteen.
The celestial arrangement known as J1218/1219+1035 is situated at an approximate extraterrestrial remove of 1.2 billion light-years.
This cosmic entity encompasses three galaxies in the process of interaction, wherein their central supermassive black holes are all actively assimilating matter and exhibiting luminosity in the radio spectrum.
“Systems presenting three active galaxies, such as this one, are exceedingly uncommon, and observing such a phenomenon amidst a merger provides us with an unparalleled vantage point to comprehend the co-evolution of colossal galaxies and their associated black holes,” stated Dr. Emma Schwartzman, a researcher affiliated with the U.S. Naval Research Laboratory.
“By verifying that all three black holes within this configuration are radio- luminous and actively expelling jets, we have transitioned the concept of triple radio active galactic nuclei (AGN) from hypothetical to observable reality, thereby unveiling a novel avenue for studying the life cycle of supermassive black holes.”
Dr. Schwartzman and her research associates employed the National Science Foundation’s Very Large Array (VLA) and Very Long Baseline Array (VLBA) observational instruments to scrutinize J1218/1219+1035.
The resultant data indicated the presence of compact, synchrotron-emitting radio cores within each galaxy, corroborating the existence of AGNs in all three, fueled by burgeoning black holes.
This discovery establishes J1218/1219+1035 as the inaugural confirmed triple radio AGN and positions it as merely the third identified triple AGN system in our proximate cosmic neighborhood.
“The three galaxies comprising J1218/1219+1035 were observed in the act of merging, with their central regions separated by approximately 22,000 and 97,000 light-years, forming a gravitationally bound consortium whose tidal signatures vividly illustrate their mutual interactions,” commented the astronomers.
“Such quintuple configurations represent a pivotal, albeit infrequently documented, consequence of hierarchical galaxy evolution, a paradigm wherein substantial galaxies akin to the Milky Way achieve growth through recurrent collisions and mergers with less massive celestial bodies.”
“By capturing three concurrently feeding black holes within a single merging assemblage, the recent observations furnish an exceptional laboratory for validating the mechanisms by which galactic encounters propel gas towards galactic centers and initiate black hole accretion.”
J1218/1219+1035 was initially identified as an anomalous system through mid-infrared data acquired by NASA’s Wide-field Infrared Survey Explorer (WISE), which suggested the presence of at least two obscured AGNs within an interacting pair of galaxies.
Subsequent optical spectroscopic analysis confirmed an AGN in one nucleus and revealed a composite spectral signature in another, but left the precise nature of the third galaxy indeterminate, as its emission could potentially be attributed to stellar formation or shockwaves.
“It was only through the acquisition of novel, exceptionally high-resolution radio imagery from the VLA—at frequencies of 3, 10, and 15 GHz – that we were able to detect compact radio cores precisely aligned with all three optical galaxies, thereby demonstrating that each harbors an AGN that is conspicuous in its radio emissions and likely responsible for generating diminutive jets or outflows,” the research team reported.
“The radio spectra of the three cores exhibit characteristics congruent with non-thermal synchrotron radiation originating from AGNs, including two sources displaying typical steep spectral indices and a third with an even more pronounced steepness, potentially indicative of unresolved jet activity.”
