Quasars are one of the brightest objects in the sky. These are the most distant galaxies with supermassive black holes in their centers, surrounded by large amounts of gas that is heated by the rapid rotation around the black hole. From time to time, large amounts of radiation and gas are ejected, perpendicular to the disk around the black hole, in powerful jets that can be observed at different wavelengths of light like x-rays, visible, and radio. Because this powerful activity is concentrated in their nucleus, these are also known as AGNs or “Active Galactic Nuclei” galaxies.
The term Quasar stands for “Quasi-stellar objects,” because when observed there are dim points of light resembling stars. What we are seeing, in reality, are the jets generated by the powerful black holes that coincidentally are pointed toward us. In this image of Hubble, we don’t see one but two quasars in what seems to be a binary system. Each of these bright sources is a supermassive black hole embedded inside a pair of colliding galaxies and blasting an enormous amount of energy from its center.
The discovery resulted from a study looking for evidence of merging galaxies that give place to the larger systems we see now. These two quasars are distant objects that existed when the universe was just 3 billion years old. The supermassive black holes powering these bright jets, each in the core of their host galaxy, are quite close and will eventually merge. An artistic conception provides an idea of how chaotic the process the host galaxies are going through might be. The interaction of the gas due to the tug of this binary system must be powering intense star formation, creating a system even more complex than usually observed in AGNs. In a few tens of millions of years, the black holes powering the quasar pair will merge, forming an even more massive black hole.
To find these kinds of objects, astronomers required observations from many telescopes: the W.M. Keck Observatories and the International Gemini Observatory in Hawaii, National Science Foundation's Karl G. Jansky Very Large Array in New Mexico, NASA's Chandra X-ray Observatory, and the European Space Agency's ESA/Gaia space observatory. The Hubble Space Telescope with its great sensitivity and resolution, showed unequivocally that this was indeed a genuine pair of supermassive black holes.
Finding double quasars this early in the universe is not common and hence an exciting discovery by the team leader of this project Yu-Ching Chen of the Universidad de Illinois - Urbana-Champaign.
For more information refer to:
https://www.nasa.gov/feature/goddard/2023/hubble-unexpectedly-finds-double-quasar-in-distant-universe
https://hubblesite.org/contents/news-releases/2023/news-2023-002
Credits: Yu-Ching Chen and Xin Liu - University of Illinois Urbana-Champaign, Champaign, Illinois
Artwork: NASA, ESA, Joseph Olmsted (STScI)