Technical University of Denmark: Scientists discover the precursor to a supermassive black hole

A special type of cosmic object from the early epochs after the Big Bang have been discovered by an international research team led by scientists from DTU Space at the Technical University of Denmark and The Niels Bohr Institute at the University of Copenhagen. They have, for they first time, identified a distant object with properties that lie in-between those of a galaxy and those of a so-called quasar.

“The object can be seen as the ancestor of a supermassive black hole, and it was born relatively soon after the Big Bang. Simulations had indicated that such objects would exist, but this is the first actual finding,” says associate professor at DTU Space Georgios Magdis, who has contributed to the scientific work behind the discovery.

The newly found object named GNz7q by the research team was born about 750 million years after the Big Bang occurred about 13.8 billion years ago which is generally accepted as the beginning of the universe as we know it.

The new discovery has now been published in the scientific journal Nature with Magdis as one of the authors.

“The discovered object connects two rare populations of celestial objects, namely dusty starbursts and luminous quasars, and thereby provides a new avenue toward understanding the rapid growth of supermassive black holes in the early universe,” says Seiji Fujimoto, a postdoctoral fellow based at the Niels Bohr Institute, who led the study and is the main author of the article in Nature.

Discovered with data from the Hubble Space Telescope
The discovery can be attributed to the Hubble Space Telescope operated jointly by ESA and NASA.

With its location in space – undisturbed by for example weather changes and pollution – the telescope can gaze further into the depths of the universe than would have been the case on the ground.

And in astronomy, looking further equals being able to observe phenomena which took place at earlier cosmic periods – since light and other types of radiation will have traveled longer to reach us and be registered by telescopes.

How supermassive black holes form is a challenging question
The discovery is linked to a specific type of quasars. Quasars, also known as quasi-stellar objects, are extremely luminous objects. Images from Hubble and other advanced telescopes have revealed that quasars occur in the centers of galaxies.

The stars, in turn, create and heat cosmic dust, making it glow in infrared to the extent that GNz7q’s host is more luminous in dust emission than any other known object at this period of the Cosmic Dawn.

In the most recent years it has transpired, that luminous quasars are powered by supermassive black holes surrounded by vast amounts of gas. As the gas falls towards the black hole, it will heat up due to friction which provides the enormous luminous effect.

Scientists are working on understanding how supermassive black holes form and grow in the early universe. Theorists have predicted that these black holes undergo an early phase of rapid growth: a dust-reddened compact object emerges from a heavily dust-obscured starburst galaxy, then transitions to an unobscured luminous compact object by expelling the surrounding gas and dust.

Although luminous quasars had already been found even at the earliest epochs of the universe, the transition phase of rapid growth of both the black hole and its star-bursting host had not been found at similar epochs. Moreover, the observed properties are in excellent agreement with the theoretical simulations and suggest that GNz7q is the first example of the transitioning, rapid growth phase of black holes at the dusty star core, a precursor of the later supermassive black hole.

A discovery hiding in plain sight
Curiously, GNz7q was found at the center of an intensely studied sky field known as the Hubble GOODS North field.

The team now hopes to systematically search for similar objects using dedicated high-resolution surveys and to take advantage of the new James Webb Space Telescope which ESA, NASA and the Canadian space agency CSA are behind.

“Fully characterizing these objects and probing their evolution and underlying physics in much greater detail will become possible with the James Webb Telescope. Webb will have the power to decisively determine how common these rapidly growing black holes truly are,” says Seiji Fujimoto.

Georgios Magdis and Seiji Fujimoto both contribute to the Cosmic Dawn Center (DAWN), which is a collaboration between the Niels Bohr Institute and DTU Space. DAWN scientists will also use data from James Webb when this telescope is soon ready to be put into use in space.

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