Rare twin quasars caught merging in early universe—they are connected by a cosmic gas bridge

Astronomers have identified a rare cosmic event in a recent study. A team led by Minghao Yue submitted their observations on the arXiv of Cornell University. The team studied how two quasars shine side by side as their host galaxies merge in the early universe. Quasars are extremely bright cores of galaxies that belong to the family of active galactic nuclei (AGN). These quasars mainly receive energy from supermassive black holes. 

The team used ALMA observations [Atacama Large Millimeter/submillimeter Array] to confirm that J2037–4537 is a genuine and closer quasar pair, which in all probability originated back when the universe was less than a billion years old. One of the primary catalysts behind the process of quasar formation is galaxy mergers, as those collisions funnel gas towards galactic centers. Quasars form from black holes, but they become active when large amounts of gas fall into them, releasing energy. However, it is extremely rare to spot two blazing quasars together in a single merging system. J2037–4537 are simultaneously active within a single merging system. 

Back in 2021, J2037-4537 was flagged as a closer quasar pair. They were recognized as two objects with a redshift of z = 5.7. But the system’s true nature remained uncertain due to the possibility of gravitational lensing, where one quasar appears as two images. Now, new studies have confirmed that both sources are distinct.

Minghao Yue of the University of Arizona and team resorted to ALMA, studied high-resolution observations, and confirmed the new update about them being distinct sources, although they are physically connected. When the researchers mapped the ionized carbon emission lines, they found traces of cold star-forming gas extending between two objects around J2037-4537. The gas formed a bridge of gravitational pull between the two. That pull, in turn, dragged materials out of each other, stabilizing the bridge. This bridge-like structure further confirmed that they are two different quasars.

In the paper, the team reflected on their study and stated, "The dust continuum and [CII] line emissions clearly reveal the tidal bridge between the two quasars.” Following such a revelation, J2037–4537 is now one of only two confirmed quasar pairs at z > 5 ever found. Scientists have also found that the galaxies that host the quasars are huge star-forming galaxies with a dynamical mass of at least 10 billion solar masses. Researchers have also predicted that J2037–4537 would take about 2.1 billion years to transition into a supermassive black hole from quasars.

The Quasars are powered by huge black holes, so when two such galaxies merge, their black holes slowly spiral toward each other, creating low-frequency gravitational waves in space. These waves are detected by scientists using Pulsar Timing Arrays (PTAs). In recent studies, a stronger background “hum” of gravitational waves has been found by PTAs. This hints that there might be more merging black hole pairs than previously thought. And studies about systems like J2037–4537 could help scientists explore this phenomenon in a better way.

More on Starlust

Accidental double zooming pinpoints unexpected millimeter waves near supermassive black hole's core

Solving the mystery of 'little red dots' in early universe, scientists discover a new class of black hole stars

JWST observes distant galaxy revealing evidence of first stars forged after the Big Bang