Published: Thu, December 07, 2017
Science | By Hubert Green

Massive black hole reveals when the first stars blinked on

Massive black hole reveals when the first stars blinked on

The oldest and most distant black hole ever observed - a celestial brute 800 million times more massive than the sun - is providing scientists some surprises about the nature of the universe when, on a cosmic scale, it was a mere toddler.

Boffins believe that the central mass of the black hole existed when our universe was only 5% of its current age.

The most interesting aspect of this supermassive black hole is its age - it's 13 billion light years away, which scientists determined via redshift. But the new observations have revealed the hydrogen in the early universe was far different from most of the hydrogen in outer space today. "Only one quasar was known to exist at a redshift greater than seven before now, despite extensive searching", said Xiaohui Fan of the University of Arizona's Steward Observatory. As the gas falls into the black hole, it speeds up, heats up and brightens, which allows astronomers to see them from across the universe.

This behemoth black hole formed when stars were beginning to alter the cosmic universe by exposing objects to light. This shift from neutral to ionized hydrogen represented a fundamental change in the universe that has persisted to this day.

As often happens in astronomy, this new discovery has left astronomers perplexed.

"What we have found is that the universe was about 50/50 - it's a moment when the first galaxies emerged from their cocoons of neutral gas and started to shine their way out", Simcoe says. He was joined by another researcher from MIT and researchers from several other institutions. "Gathering all this mass in fewer than 690 million years is an enormous challenge for theories of supermassive black hole growth", said Eduardo Bañados, the Carnegie scientist who spotted it. Bañados was looking in particular for quasars - some of the brightest objects in the universe, that consist of a supermassive black hole surrounded by swirling, accreting disks of matter. FIRE is a spectrometer that classifies objects based on their infrared spectra. It took more than 13 billion years for the light from the quasar to reach us.

The astronomer who found the odd black hole said that there's no way of explaining how a black hole would be able to pick up such mass, and that it might challenge out current understandings of how black holes form.

The newly-discovered black hole is part of a quasar, meaning it sits at the center of a cloud of gas that it's slowly swallowing.

The Big Bang started the universe as a hot, murky soup of extremely energetic particles that was rapidly expanding. Eventually gravity condensed matter and the first few stars and galaxies were born. About half the hydrogen atoms near this quasar, however, are neutral, which means they're still holding onto their electrons.

"This adds to our understanding of our universe at large because we've identified that moment of time when the universe is in the middle of this very rapid transition from neutral to ionized", said Professor Simcoe. "We now have the most accurate measurements to date of when the first stars were turning on".

An artist's impression of the supermassive black hole.

Like this: