WASHINGTON, July 8 : A quasar — among the universe's most luminous and energetic objects — is a supermassive black hole caught in the act of guzzling matter at the heart of a galaxy. Scientists have now found quasars dating to so early in cosmic history that they are baffled as to how they already existed at that primordial time.

Using the European Space Agency's Euclid space telescope, researchers said they have identified 31 ancient quasars, observations that add to the mystery of how the universe was far more advanced in its earliest stages than previously believed.

These included the two earliest quasars known, dating to a bit more than 13.1 billion years ago when the universe was 5 per cent of its current age, about 670 million years after the inceptive Big Bang event. They both shine with a brightness about a trillion times greater than the sun's.

Quasars like these are powered by black holes hundreds of millions to billions of times the sun's mass, though the masses of these two have yet to be precisely measured.

"A quasar is the blazing core of a galaxy," said Daming Yang, a doctoral student in astrophysics at Leiden University's Leiden Observatory in the Netherlands and lead author of the study published in the journal Astronomy & Astrophysics.

"At the center sits a giant black hole. Black holes themselves are dark, but the black hole's gravity pulls in gas and dust, which spiral toward it like water going down a drain. As this happens, the gas gets incredibly hot and shines brighter than the entire galaxy around it," Yang said.

The two earliest ones described in the study date to a chapter in the universe's history that scientists call the "epoch of reionization," or cosmic dawn.

"The universe back then was much smaller and denser, and filled with a fog of neutral hydrogen. It was also a time of rapid change: the first stars, galaxies and black holes were lighting up and burning away that fog, transforming the universe into the transparent one we see today," Yang said.

During this time, hydrogen atoms were stripped of their electrons and put into the state in which most hydrogen in intergalactic space remains today.

A DEEPENING MYSTERY

Scientists in recent years, through observations by the James Webb Space Telescope and Euclid among others, have gained a greater understanding of the universe's earliest stages. It possessed mature galaxies and, as the new study illustrates, hungr...