What To Know
- This is the most distant and oldest pair of interacting quasars ever found, marking a first for this time in the history of the Universe.
- This period, which extends from fifty million to one billion years after the Big Bang, was marked by the formation of the first stars and galaxies and the reionization of neutral hydrogen in the Universe.
- The two quasars observed are each about a hundred million times more massive than the Sunmore than twenty times the mass of Sagittarius A*, the supermassive black hole at the center of our galaxy.
Astronomers have recently made a remarkable discovery: a pair of merging quasars dating from the late Cosmic Dawn, about 900 million years after the Big Bang. This is the most distant and oldest pair of interacting quasars ever found, marking a first for this time in the history of the Universe. The discovery offers a fascinating window into the early stages of cosmic evolution and raises new questions about the formation of supermassive black holes and galaxies.
What is a quasar?
Quasars, or quasi-stellar objects, are among the brightest and most energetic objects in the Universe. They are powered by supermassive black holes located at the centers of galaxies. These black holes attract huge amounts of matter and then form an accretion disk around themselves. The matter in this disk is heated to extremely high temperatures, releasing a huge amount of energy in the form of radiation. It is this intense emission that makes quasars so luminous that they can be observed at cosmological distances. A quasar merger occurs when two galaxies, each with a supermassive black hole at their center, collide and eventually merge. This process is spectacular and complex. As the galaxies move closer together, their black holes begin to gravitationally interact, causing major disturbances in their accretion disks and generating huge jets of matter. Eventually, the black holes themselves merge, creating an even more massive black hole. These quasar mergers are particularly interesting because they can teach us a lot about the evolution of galaxies and supermassive black holes. They are also natural laboratories for studying the effects of extreme gravitational forces and the mechanisms of rapid growth of black holes, hence the interest of this new observation.
A remarkable discovery at the cosmic dawn
We owe this observation to the Subaru and Gemini North telescopes. The two interacting quasars were observed approximately 900 million years after the Big Bang, which brings us back to the time of the Cosmic Dawn. This period, which extends from fifty million to one billion years after the Big Bang, was marked by the formation of the first stars and galaxies and the reionization of neutral hydrogen in the Universe. Discovering quasars in fusion at this time is therefore extraordinary. The two quasars observed are each about a hundred million times more massive than the Sunmore than twenty times the mass of Sagittarius A*, the supermassive black hole at the center of our galaxy. Observations revealed a gas bridge extending between the two quasars, indicating that their interaction affects their host galaxies on a much larger scale. Note that the existence of merging quasars at this time has long been anticipated. However, this is indeed a first direct observationThe chance discovery of these two red dots in the Subaru images, confirmed by follow-up observations, illustrates how much we still have to learn about the early phases of the Universe.
Image of the quasar pair. Credits: NOIRLab/NSF/AURA/TA Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin (NSF NOIRLab) and M. Zamani (NSF NOIRLab) This discovery This spectacular discovery therefore marks a significant advance in our understanding of quasars, supermassive black holes and cosmic evolution. The statistical properties of these objects will soon tell us about the conditions and processes that shaped the early Universe.
