Astronomers, using three telescopes based in the US State of Hawaii, have discovered the second-oldest, or second most distant, quasar so far found in the universe. Quasars are the most energetic objects known in the universe and are powered by supermassive black holes in their centres. And the supermassive black hole in the centre of the newly discovered quasar is twice the size of the one in the most distant (or oldest) quasar yet found, which is the only other one currently known in that era.
The quasar has been given a Hawaiian name, Poniua’ena, which means “unseen spinning source of creation, surrounded in brilliance”. It has been calculated to have a cosmological redshift of more than 7.5. This indicates that the light from Poniua’ena left the quasar only 700-million years after the Big Bang, and took more than 13-billion years to reach us.
(Redshift is the lengthening of the wavelengths of radiation, including visible light, emitted by a body. Cosmological redshift is not the same as doppler redshift. Doppler redshift depends on the motion of the body emitting the radiation. Cosmological redshift happens because of the ongoing expansion of the the universe or, to phrase it differently, the expansion of space itself; it has nothing to do with the motion of the body emitting the radiation.)
Poniua’ena’s supermassive black hole is 1.5-billion times more massive than our Sun. “Poniua’ena is the most distant object known in the universe hosting a black hole exceeding one-billion solar masses,” pointed out University of Arizona Steward Observatory postdoctoral research associated Jinyi Yang.
To be so big, so early in the history of the universe, this black hole would have needed to start out with a mass of about 10 000 of our Suns, and at about 100-million years after the Big Bang. It could not have grown from a small black hole created by the collapse of a single star.
The current theory holds that the stars and galaxies with which we are familiar were first born during the Epoch of Reionisation, which started about 400-million years after the Big Bang. The first big black holes were also thought to have first emerged in this era.
“How can the universe produce such a massive black hole so early in its history?” queried University of Arizona Astronomy Department associate head and Regents’ professor Xiaohui Fan. “This discovery presents the biggest challenge yet for the theory of black hole formation and growth in the early universe.”
Poniua’ena is also designated J1007+2115. The oldest (or most distant) known quasar was found in 2018 and is designated J1342+0928.