GNz7q, a black hole that formed 750 million years after the Big Bang, was discovered by astronomers using the Hubble Space Telescope in the Great Observatories Origins Deep Survey-North (GOODS-North) field.
Simulations had indicated that such objects would exist, but experts say this is the first actual finding.
“Our analysis suggests that GNz7q is the first example of a rapidly growing black hole in the dusty core of a starburst galaxy at an epoch close to the earliest supermassive black hole known in the Universe,” said Dr Seiji Fujimoto, an astronomer with the Niels Bohr Institute at the University of Copenhagen.
“The object’s properties across the electromagnetic spectrum are in excellent agreement with predictions from theoretical simulations.”
The study was carried out by an international team of experts led by astrophysicists from the Niels Bohr Institute, the University of Copenhagen, and the Technical University of Denmark.
According to current theories, supermassive black holes begin their existence in the dust-shrouded cores of starburst galaxies before expelling the surrounding gas and dust and emerging as bright quasars. While exceedingly rare, dusty starburst galaxies and luminous quasars were discovered in the early Universe.
Dr Fujimoto suggests that GNz7q could be the missing link between these two types of objects. GNz7q has both the dusty starburst galaxy and the quasar, with the quasar light revealing the dust’s reddish colour.
Furthermore, GNz7q lacks several features typically observed in typical, very luminous quasars, which is most likely explained by the fact that the central black hole in GN7q is still in a young and less massive phase.
These characteristics are identical to those predicted in a young transition phase quasar models. Still, they have never been observed in the same high-redshift Universe as the exceedingly brilliant quasars identified up to a redshift of 7.6.
“GNz7q provides a direct connection between these two rare populations and provides a new avenue toward understanding the rapid growth of supermassive black holes in the Universe’s early days,” Dr Fujimoto said.
“Our discovery provides an example of precursors to the supermassive black holes we observe at later epochs.”
While other analyses of the team’s data cannot be excluded completely, the observed features of GNz7q are in fair agreement with theoretical predictions. For example, the host galaxy of GNz7q is producing stars at a rate of 1,600 solar masses per year, and GNz7q itself is bright in UV wavelengths but weak in X-ray wavelengths.
A big black hole’s accretion disc should be extraordinarily luminous in UV and X-ray photons. However, while the team identified UV light with Hubble, X-ray radiation was undetected.
These findings suggest that the accretion disc’s core, where X-rays originate, remains shrouded, but the outer section, where UV light originates, is unblurred. Hence, GNz7q is a rapidly-developing black hole hidden by the dusty core of its star-forming host galaxy.
“GNz7q is a unique discovery that was found just at the centre of a famous, well-studied sky field — it shows that big discoveries can often be hidden just in front of you,” said Dr Gabriel Brammer, also from the Niels Bohr Institute at the University of Copenhagen.
“It’s unlikely that discovering GNz7q within the relatively small GOODS-North survey area was just ‘dumb luck,’ but rather that the prevalence of such sources may, in fact, be significantly higher than previously thought.”
The findings were published in the journal Nature.