A milestone in cosmic history

The second most ancient quasar found by Daming and colleagues was recently studied in more detail by Silvia Belladitta and collaborators. These observations showed that the quasar is embedded in a dusty, gas-filled galaxy that is furiously forming new stars, hinting at what the host galaxy of an early supermassive black hole may be like.

The quasars hark back to a fascinating period in cosmic history known as the ‘epoch of reionisation’: when everything shifted from being cold and dark (the ‘dark ages’) to hot and ‘ionised’ (split apart by energetic light). This transitional epoch was a crucial era that set the stage for everything we see today.

“Ancient quasars are rare discoveries. They're interesting in themselves, but also time machines that enable us to explore the early Universe and understand how the first generation of galaxies came to be,” says ESA Euclid Project Scientist Valeria Pettorino.

“Euclid’s capabilities are unrivalled. The telescope combines a large area, depth, sharp imaging, and unique space-based infrared vision in a way that lets us pick out rare, extremely distant objects far more efficiently than before.

And it’s not just the telescope: the data processing is only possible thanks to thousands of Euclid Consortium scientists and engineers working together to deliver scientific discoveries, sifting through enormous datasets to identify rare, distant quasars that we can study further using telescopes on the ground.”

The 31 quasars reported here were discovered in data from the Euclid Wide Survey, which will cover more than one-third of the total sky once complete. Euclid will reveal the secrets of the dark Universe; the telescope is exploring its composition, history, evolution, and mapping out its large-scale structure, observing billions of galaxies – and revealing many quasars – as it does so.