Quasar transmits from the early days of the universe
In the 1950s, astronomers discovered radio sources to which point-like, i.e. star-like objects could be assigned in the visible light range. Until then, whole galaxies had been identified as radio sources. The findings were called «quasi-stellar objects», or quasars for short. Later, however, researchers realized that quasars are embedded in galaxies after all, and in fact constitute their active nuclei radiating in many wavelength ranges. That they had been seen only as point sources was simply because they are very, very distant.
In fact, they are the most distant objects in the universe that we can observe. This is not because there is nothing else at that distance. But only quasars are bright enough to be seen from this distance. Their light needs about 13 billion years to reach us. Since the Big Bang happened only 13.8 billion years ago, quasars, as we see them, are also very young objects.
Contrary to what astronomers assumed in the 1950s, not all quasars radiate particularly loudly at radio frequencies. That’s why researchers are even more pleased to have now found an object that is particularly «radioloud» in the form of P172+18 (their discovery was published in The Astrophysical Journal). The newly discovered quasar is so distant that we see it as it was when the universe was just about 780 million years old. Although more distant quasars have been discovered before, this is the first time astronomers have been able to identify the telltale signatures of radio jets in a quasar so early in the history of the universe. Only about 10% of quasars classified by astronomers as «radiolucent» have jets that glow brightly at radio frequencies.
P172+18 is powered by a black hole that is about 300 million times heavier than our Sun and is consuming gas at a breathtaking rate. «The black hole is absorbing matter very rapidly and growing in mass at one of the highest rates ever observed,» explains astronomer Chiara Mazzucchelli, a fellow at ESO in Chile who studied P172+18 with Eduardo Bañados of the Max Planck Institute for Astronomy in Germany.
The astronomers suspect there is a connection between the rapid growth of supermassive black holes and the powerful radio jets detected in quasars like P172+18. The jets are thought to be able to disrupt the gas around the black hole, increasing the speed at which the gas falls in. Therefore, the study of radiolucent quasars may provide important insights into how black holes in the early universe grew so rapidly to their supermassive dimensions after the Big Bang.