American astronomers, utilizing archival data from the Gemini North Telescope in the constellation of Gemini, have uncovered the heaviest supermassive black hole known to date. The combined "weight" of these black holes is estimated to be 28 billion times that of the Sun. This groundbreaking discovery contributes significantly to resolving a longstanding mystery among scientists regarding the highly improbable occurrence of supermassive black hole mergers in the universe. The findings of this research have been published in the latest issue of the Astrophysical Journal.
Scientists have long predicted the merger of two supermassive black holes, but direct observation of this phenomenon has eluded them.
Image Source: National Science Foundation
A research team analyzed a pair of supermassive black holes located within the elliptical galaxy B2 0402+379. This is the only pair of supermassive black holes analyzed in sufficient detail, with a mere 24 light-years separating them. Such close proximity between the two black holes suggests a strong likelihood of eventual merger. However, further study revealed that these black holes have remained at this distance for over 3 billion years.
According to Roger Romani, a co-author of the latest paper and a physics professor at Stanford University, to better understand the dynamics of this system and why they haven't merged, they delved into archival data from the Gemini Observatory in the Northern Hemisphere to determine the velocities of stars near the black holes. From this, they inferred that the total "weight" of this black hole pair is 28 billion times that of the Sun, making it the heaviest pair of black holes ever measured.
The research team notes that this measurement not only provides valuable insight into the formation of binary black hole systems and the history of their host galaxies but also supports a long-standing theory that the mass of supermassive black hole pairs is a key factor preventing their merger.
Typically, galaxies with lighter black hole pairs seem to have enough stars and mass to facilitate their merger. For example, in 2015, scientists detected the merger of stellar-mass black holes through gravitational waves. However, due to the extreme mass of this black hole pair, a substantial amount of stars and gas would be needed to accomplish this task. Given the lack of sufficient material within the B2 0402+379 galaxy, the merger of this black hole pair remains stalled.
Romani points out that it remains uncertain whether these black holes will eventually merge on a scale of millions of years. If they do, the intensity of the gravitational waves produced would be a hundred million times greater than those generated by the merger of stellar-mass black holes.
