Astronomers stumble upon a monstrous surprise in one of the most studied pieces of the night sky

Researchers have discovered a supermassive precursor to a black hole that existed when the universe was just a toddler. And possibly this object is the missing link that has been sought for so long.

Using the Hubble Space Telescope, astronomers have discovered a unique object in the distant early Universe. It is a special find. Because this object could be a crucial link between star-forming galaxies and the emergence of the first supermassive black holes. Remarkably, this object has been hiding undetected all along in one of the most studied pieces of the night sky.

Mystery

One of the greatest mysteries in astronomy is how supermassive black holes, millions to billions of times the mass of the Sun, could grow so large so quickly. Prevailing theories are that supermassive black holes begin life in the dust-shrouded cores of powerful star-forming galaxies. They then expel the surrounding gas and dust, appearing as extremely luminous quasars. Although extremely rare, such dusty star-forming galaxies and luminous quasars have been discovered in the early Universe. But a fast-growing black hole that resides in such a dusty, early star-forming galaxy had not yet been found.

Until now. Remarkably enough, researchers have stumbled upon a monstrous surprise in one of the best-studied pieces of the night sky. In collected data from the Hubble Space Telescope, astronomers have found a special object they call GNz7q. GNz7q existed when the universe was just a toddler, just 750 million years after the Big Bang. And after further analysis, it appears that for the first time a fast-growing black hole residing in a dusty, early star-forming galaxy has been found.

Missing link

The researchers suspect this, because the mixture of radiation cannot be attributed solely to star formation. The best explanation is that it is a growing black hole, shrouded in dust. Over time, the black hole will emerge from its dusty ‘cocoon’ as a brilliant quasar. So, according to the team, GNz7q could be the missing link between dusty, star-forming galaxies and luminous quasars. “GNz7q provides a direct link between these two rare populations,” said study researcher Seiji Fujimoto. “It offers a new way of understanding the rapid growth of supermassive black holes in the early days of the Universe. Our discovery is a precursor to the supermassive black holes we observe in later eras.”

Characteristics

Although other interpretations of the data cannot be completely ruled out, the observed properties of GNz7q are very much in line with theoretical predictions. GNz7q’s host galaxy forms stars at a rate of 1,600 solar masses per year. In addition, the object is bright at UV wavelengths, but very dim at X-ray wavelengths. And that’s strange. In general, the accretion disk of a massive black hole should be very bright in both UV and X-ray light. That this is not the case now suggests that the core of the accretion disk – where X-rays come from – is still obscured, while the outer part of the accretion disk – where UV light comes from – is unobstructed. And this suggests that GNz7q is a fast-growing black hole still obscured by the dusty core of its star-forming host galaxy.

Hubble Ultra Deep Field

Besides the importance of GNz7q to our understanding of the origin of supermassive black holes, the place where the object was discovered is remarkable. For example, astronomers found GNz7q in the so-called Hubble Ultra Deep Field† It Hubble Ultra Deep Field is a shot of a small portion of the sky, found in the southern constellation Oven. According to ESO, it is one of the most well-explored pieces of space that has already been studied at X-ray to radio wavelengths with thirteen instruments from eight different telescopes.

The red dot is GNz7q, found in the Hubble Ultra Deep Field. Image: NASA, ESA, G. Illingworth (University of California, Santa Cruz), P. Oesch (University of California, Santa Cruz; Yale University), R. Bouwens and I. Labbé (Leiden University), and the Science Team, S. Fujimoto et al. (Cosmic Dawn Center [DAWN] and University of Copenhagen)

“GNz7q is a unique discovery found in the midst of a famous, well-studied sky region,” said study researcher Gabriel Brammer. “This shows that great discoveries can be hidden right in front of you. Incidentally, it is unlikely that the discovery of GNz7q in the relatively small research area studied was ‘lucky luck’. Rather, it means that there are many more similar objects than previously thought.”