The Euclid space telescope has discovered 31 quasars from the early Universe. Two of them are the most ancient ones known so far.
A quasar is a brief phase in a galaxy's life, when large amounts of matter fall onto the supermassive black hole at its centre. This releases enormous energy. The galaxy's nucleus starts to shine brighter than anything around it — sometimes hundreds to thousands of times brighter than the rest of its host galaxy.
The two record-holders, EUCL J172902.75+641018.1 and EUCL J125308.55+705432.3, have redshifts of 7.77 and 7.69 (redshift is a measure of distance and motion tied to how light stretches in the expanding Universe). Both lie just over 13 billion light-years away. They shone when the Universe was only 670 million years old — about 5% of its present age.
Finding quasars from that time is hard. They are rare, because few galaxies had grown large enough. And their faint light is easily confused with that of nearer stars. It took astronomers more than a decade to find the first dozen quasars with a redshift above 7. Euclid found more in a single year.
These quasars belong to the epoch of reionisation — the transition when the cold, dark Universe began to heat up and become "ionised" under the energetic light of the first sources. They act as time machines: they let us look into how the first galaxies and supermassive black holes formed. Euclid surveys only a part of the sky — its full survey will cover more than a third of the whole sky.