At a considerable cosmic distance of approximately 1.2 billion light-years from our planet, a monumental astronomical occurrence is presently unfolding.
Within this celestial expanse, not merely a duo but a trio of galaxies are in the process of an unhurried convergence, engaged in a colossal, tripartite collision designated J1218/1219+1035. While such a confluence is an anomaly in itself, this particular event transcends mere rarity.
Each of the three gargantuan black holes situated at the nuclei of their respective galactic entities is voraciously ingesting surrounding matter, consequently emitting intense radio radiation.
“Galactic systems featuring three active nuclei in such close proximity are exceptionally uncommon, and witnessing one in the midst of a merger provides us with an unparalleled vantage point to observe the co-evolution of massive galaxies and their central black holes,” opined astrophysicist Emma Schwartzman from the United States Naval Research Laboratory.
“Through the observation that all three black holes within this system are radiantly active and are expelling energetic jets, we have transitioned the concept of triple radio active galactic nuclei (AGN) from theoretical postulation to empirical evidence, thereby unveiling a novel perspective on the developmental trajectories of supermassive black holes.”
The amalgamation of galaxies is a commonplace phenomenon across the cosmos; indeed, these events are recognized as primary drivers for the growth of both galaxies and their associated supermassive black holes. Our own Milky Way galaxy bears the imprints of at least three to four major mergers throughout its 13 billion-year history.
While celestial observers have meticulously documented a substantial number of binary galaxy mergers in our galactic vicinity, the occurrence of triple galaxy mergers is considerably more infrequent. These events necessitate the simultaneous interaction of all three galactic bodies, rather than a sequential, hierarchical process.
The presence of active galactic nuclei (AGN) in all three constituent galaxies is an even rarer characteristic; J1218/1219+1035 represents merely the third such system documented in the local universe, and notably, the inaugural instance where all three active galactic nuclei exhibit radio luminosity.
This extraordinary configuration was initially identified within data acquired by the Wide-field Infrared Survey Explorer, which indicated an anomalous signature. At the outset, the observation suggested a merger involving two overlapping galaxies, each possessing its own active galactic nucleus, a scenario already of considerable scientific interest.
Subsequent, more detailed investigations corroborated that these two proximate galaxies indeed host active galactic nuclei, separated by an interval of approximately 74,000 light-years. Astonishingly, the research team identified a third galaxy, also featuring a vigorously active nucleus, situated roughly 316,000 light-years distant and participating in this celestial dance. Evidence of a gaseous filament extending from this more remote galaxy towards the other two serves as conclusive proof of its involvement in this rare triplet.
Given that triple galaxy mergers serve as invaluable cosmic laboratories for dissecting the mechanisms of galactic and black hole evolution, astronomers intend to conduct further observations across a broader spectrum of wavelengths. The objective is twofold: to deepen comprehension of this specific celestial triad and to refine methodologies for identifying similar, potentially concealed systems that await the precise observational conditions to reveal themselves.
“These observations,” the researchers state, “substantiate the triple active galactic nucleus nature of this system and underscore the imperative for employing diverse, multiwavelength selection strategies in the ongoing pursuit of these uncommon configurations.”
The comprehensive findings associated with this remarkable discovery have been formally disseminated in The Astrophysical Journal Letters.
