What To Know
- A system of black holes in an active galaxy brightened dramatically when one of the two cosmic ogres passed through the accretion disk of the other, briefly creating a double quasar.
- Binary black holes often arise from the chaotic merger of galaxies, a tumultuous process where the central black holes of the galaxies parents slowly approach each other over time.
- Astronomers use a variety of methods to study them, including observation of X-ray emissions emanating from the accretion disks surrounding these black holes, as well as the detection of emitted gravitational waves during their tight orbits and eventual merger.
Astronomers recently observed a remarkable phenomenon four billion light-years from Earth. A system of black holes in an active galaxy brightened dramatically when one of the two cosmic ogres passed through the accretion disk of the other, briefly creating a double quasar.
The Foundations of Binary Black Holes
Binary black holes often arise from the chaotic merger of galaxies, a tumultuous process where the central black holes of the galaxies parents slowly approach each other over time. This epic encounter sets off a gravitational dance that can last millions or even billions of years. Understanding this process is essential for exploring the evolution of galaxies and the growth of supermassive black holes. Modern observatories, both ground-based and space-based, have paved the way for the direct and indirect detection of these binary black holes throughout the Universe. Astronomers use a variety of methods to study them, including observation of X-ray emissions emanating from the accretion disks surrounding these black holes, as well as the detection of emitted gravitational waves during their tight orbits and eventual merger. These techniques reveal unique characteristics of binaries, such as their orbital periods, masses and distances.
Illustration of a black hole at the center of a galaxy. Credits: ClaudioVentrella/istock
The case of OJ 287
A fascinating example of a binary black hole is the system OJ 287located approximately four billion light years from Earth. This system has captured the attention of astronomers due to its unique characteristics and observed phenomena. It consists of a primary supermassive black hole, estimated to be about 18.35 billion solar massesand a smaller companion with a mass of about 150 million solar masses. Long-term observations of OJ 287 have revealed periodic eruptions intriguing, interpreted as manifestations of dynamic interactions between these two black holes. According to current models, the smaller companion orbits the primary black hole in an elongated orbit, periodically approaching approximately every twelve years. At each close passage, the companion disrupts the accretion disk surrounding the primary black hole, triggering spectacular events. Recent observations by NASA’s Transiting Exoplanet Survey Satellite (TESS) have confirmed these models with unprecedented precision. In November 2021, TESS captured a bright flare from OJ 287, characterized by a significant increase in brightness over a period of about twelve hours. This intense emission has been interpreted as the manifestation of a quasar jet generated by the interaction between the two black holes. These observations have allowed scientists to better understand the mechanisms underlying the complex dynamics of binary black holes like OJ 287. By scrutinizing these phenomena, they also hope to obtain crucial clues about the formation and evolution of galaxies, as well as about the extreme physical processes at work in the Universe. Details of the study are published in The Astrophysical Journal.
