Hubble telescope discovers double quasar from ten billion years ago
NASA probably discovered a double quasar via the Hubble telescope. It concerns a pair that caught fire ten billion years ago. Quasars are rays of very intense light produced by huge black holes located at the center of galaxies.
According to NASA, the Hubble Space Telescope has discovered a pair of quasars so close together that they can be seen as a single object by terrestrial telescopes. The research team also found a second quasar pair. These are quasar pair J0749+2255 and quasar pair J0841+4825. These quasar pairs emit a lot of light because in both cases they are galaxies that are on the verge of merging into each other. Such a collision will one day also happen with our Milky Way Galaxy and the Andromeda Galaxy.
In both pairs, the quasars are 10,000 light-years apart. Relatively speaking, that’s very close. By comparison, our sun is about 26,000 light-years from the massive black hole at the center of the Milky Way. Once the galaxies merge, the quasars also merge, creating an even larger, single black hole.
Each of the four visible quasars belongs to its own galaxy. Those galaxies themselves cannot be seen by Hubble because they emit too little light. The image on the left was taken on January 5, 2020 and the other on November 30, 2019.
The search was not easy, because Hubble’s resolution is not high enough to discover these quasar pairs on its own. Researchers needed to know roughly where Hubble should be aimed. The tricky part is that ten billion years ago there were many quasars that ignited, only a fraction of which were a few.
To discover the quasar pairs, ESA’s Gaia satellite and the Sloan Digital Sky Survey survey were used to create a pool of potential candidates. The Sloan Telescope in New Mexico makes three-dimensional maps of objects in the sky. Gaia was then called in as she accurately maps the positions, distances and movements of nearby objects.
Gaia’s database was searched, looking for quasars that mimic the motion of nearby stars. In the Gaia data they appear to be single objects, but Gaia was able to detect subtle fluctuations in their positions. Those fluctuations could be evidence of random fluctuations in the light, which is because each quasar of a pair varies in brightness, which in turn is caused by the amount of matter the black holes ingest. This is then emitted again as very bright radiation along the poles; that is the light that is perceived.
This is mainly a proof-of-concept, a new research method that could lead to the discovery of double quasars at much greater distances from Earth. This method would also be a lot more efficient than the previously used methods. The research team is still skeptical about the discovery of the quasar pairs, because in theory they could be duplicate images. It would then be an illusion caused by the effect of a gravitational lens. However, the researchers consider that scenario unlikely, because Hubble has not seen any star systems in the foreground.
The researchers have published their findings in the scientific journal Nature Astronomy, under the title A hidden population of high-redshift double quasars unveiled by astrometry.