Free Astronomy Magazine May-June 2021

37 MAY-JUNE 2021 ASTRO PUBLISHING the black hole, increasing the rate at which gas falls in. Therefore, study- ing radio-loud quasars can provide important insights into how black holes in the early Universe grew to their supermassive sizes so quickly after the Big Bang. “I find it very ex- citing to discover ‘new’ black holes for the first time, and to provide one more building block to understand the primordial Universe, where we come from, and ultimately our- selves,” says Mazzucchelli. P172+18 was first recognised as a far- away quasar, after having been pre- viously identified as a radio source, at the Magellan Telescope at Las Campanas Observatory in Chile by Bañados and Mazzucchelli. “As soon as we got the data, we inspected it by eye, and we knew immediately that we had discovered the most dis- tant radio-loud quasar known so far,” says Bañados. However, owing to a short observa- tion time, the team did not have enough data to study the object in detail. A flurry of observations with other telescopes followed, including with the X-shooter instrument on ESO’s VLT, which allowed them to dig deeper into the characteristics of this quasar, including determining key properties such as the mass of the black hole and how fast it’s eat- ing up matter from its surroundings. Other telescopes that contributed to the study include the National Radio Astronomy Observatory’s Very Large Array and the Keck Telescope in the US. While the team are excited about their discovery, appeared in The As- trophysical Journal , they believe this radio-loud quasar could be the first of many to be found, perhaps at even larger cosmological distances. “This discovery makes me optimistic and I believe — and hope — that the distance record will be broken soon,” says Bañados. Observations with facilities such as ALMA, in which ESO is a partner, and with ESO’s upcoming Extremely Large Telescope (ELT) could help un- cover and study more of these early- Universe objects in detail. ! T his artist’s impression shows how the distant quasar P172+18 and its radio jets may have looked. To date (early 2021), this is the most distant quasar with radio jets ever found and it was studied with the help of ESO’s Very Large Telescope. It is so distant that light from it has travelled for about 13 billion years to reach us: we see it as it was when the Universe was only about 780 mil- lion years old. [ESO/M. Kornmesser]