Astronomers Spot a Gravitationally Bound Pair of Quasars in Merging Galaxies
Researchers at NASA’s Goddard Space Flight Center report the discovery of a gravitationally bound duo of quasars nestled in galaxies that are in the process of merging. This finding adds a new chapter to our understanding of how massive black holes and their host galaxies grow together over cosmic time.
Quasars are among the most energetic objects in the universe. They shine brilliantly because material spiraling into supermassive black holes heats up to extreme temperatures in the surrounding accretion disks, emitting intense radiation across the electromagnetic spectrum. These cosmic beacons sit at the centers of most large galaxies, including our Milky Way, yet not every galaxy with a black hole becomes a quasar. The difference lies in the availability of fueling material and the dynamics of the central engine.
In a milestone observation, astronomers succeeded in capturing an image of the distant double quasar with the Hubble Space Telescope. The achievement followed a targeted search aimed at unraveling how galaxy mergers play out in the early universe. The two quasars are observed as they existed roughly three billion years after the Big Bang, a time when the universe was still relatively young and galaxies were actively colliding and coalescing.
Over the span of more than ten billion years, the galaxies hosting these quasars are thought to have evolved into a large elliptical system. The paired quasars themselves likely feed a single, enormous supermassive black hole at their shared center, reflecting the deep connection between galaxy mergers and black hole growth. As a point of context, the nearby elliptical galaxy M87 harbors a colossal black hole with a mass around 6.5 billion solar masses. That monster provides a tangible example of how repeated galactic interactions can build up extraordinarily massive central objects over cosmic time.
These discoveries contribute to a broader narrative about the coevolution of galaxies and their central black holes. The gravitational dance of merging galaxies not only reshapes the stellar distribution but also delivers fresh streams of gas and dust toward the central regions. That material powers radiative output that we recognize as a quasar, while also feeding the growth of the black hole itself. The result is a complex, interconnected evolution where the fate of huge galactic structures is tied to the fate of their most energetic cores. In this sense, the double quasar serves as a natural laboratory for studying how interactions between galaxies stimulate black hole feeding and quasar activity in the early universe.
As observational capabilities improve, astronomers expect to map more detailed structures in these systems, including how star formation, gas dynamics, and gravitational interactions unfold during mergers. The Hubble observation confirms that tightly bound quasar pairs can exist within merging galaxies, offering a window into the stages of galaxy assembly that shaped the cosmos we see today. The ongoing effort combines deep imaging with careful spectroscopy to discern how the light from these distant engines travels through intergalactic space and what it reveals about their masses, distances, and environmental context. In the broader scientific landscape, such findings help refine models of galaxy growth and the role of black holes in regulating star formation and galactic evolution. [Source: NASA Goddard Space Flight Center]