Six galaxies trapped in the web of an ancient supermassive black hole

Six galaxies trapped in the web of an ancient supermassive black hole

Astronomers have discovered a half-dozen galaxies, which formed within the first billion years of the universe, blockading a supermassive black hole.

Astronomers have long struggled how supermassive black holes may have evolved in the early cosmos. They understand that these cosmic goliaths would have had to expand exceedingly quickly to acquire their supermassive status so quickly (within about 1 billion years of the Big Bang). But it’s unknown where they found such massive amounts of matter to gorge on.

The six newly discovered old-school galaxies reside within a vast web of gas — which spans some 300 times the diameter of the Milky Way — and were observed thanks to extended observations by VLT. After analyzing the data, the researchers determined they were seeing these galaxies as they existed just 900 million years after the Big Bang, when the universe was little more than 6 percent its current age. This is the first time such a close grouping of galaxies has been found within the first billion years of the universe.

In addition, at the heart of the galactic mosh pit is a supermassive black hole 1 billion times the mass of the Sun. “[Supermassive black holes in the early universe] are extreme systems with no good explanation,” said lead author Marco Mignoli in an ESO press release.

Feeding a black hole

Scientists are aware of an upper limit to how quickly a black hole can grow: the Eddington limit. While this plays a role in the creation of supermassive black holes in the early cosmos, the true mystery for scientists is determining where early black holes got their food in the first place.

The key is most likely related to the universe’s huge cosmic network. This (literally) global structure is woven throughout the entire cosmos, connecting distant galaxies, galaxy clusters, and galaxy superclusters via filaments, which are threads of weak gas.

The researchers behind the new study believe that their supermassive black hole and its surrounding galaxies, named SDSS J1030+0524, likely nourished on gas accumulated in a tangled knot of cosmic web filaments.

“The cosmic web filaments are like spider’s web threads,” Mignoli said. “The galaxies stand and grow where the filaments cross, and streams of gas — available to fuel both the galaxies and the central supermassive black hole — can flow along the filaments.”

But that just pushes the question farther back. How did these filaments first get their gas? Astronomers think that answer might be related to another long-standing astronomical mystery: dark matter.

Normal matter was too hot in the early universe to stick together and create gravitationally bound structures like black holes and galaxies. However, experts believe dark matter was much colder than normal stuff. This implies that dark matter clumped together in the early universe, generating massive formations known as dark matter halos. The attraction from these dark objects would have pulled in normal matter, gathering massive amounts of gas, allowing the earliest galaxies and black holes to form.

The galaxies discovered in this new study are also among the weakest ever detected, implying that there could be many more in the neighborhood.

“We believe we have just seen the tip of the iceberg, and that the few galaxies discovered so far around this supermassive black hole are only the brightest ones,” said co-author Barbara Balmaverde.

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