ASTRONOMERS believe they have identified six ‘dark galaxies’ with few — if any — stars.

The enigmatic blotches are shown up as shadows some 12 billion light years distant.

We can’t actually see them. Instead, what we have are clues buried in the light of the galaxies around them.

The universe itself is calculated to be 13.8 billion years old. And the oldest known star is 13.2 billion years.

Their existence has been anticipated. But finding a galaxy that emits little or no light is obviously a testing task. Then there’s the added difficulty of proving what it is.

But physicists from ETH Zurich have found six new candidates for what could be immense clouds of primeval gas and rocky debris.

It’s the raw material left over from the dying embers of the Big Bang. Other galaxies have little of this raw ‘stuff’ left. They are constantly recycling — and polluting — the stuff that makes them up through the life cycles of their stars.

The Zurich researchers published the results of their work in The Astrophysical Journal.

GHOST GALAXIES
Dark galaxies are thought to be rare. For some reason, they are ineffective at forming and igniting stars.

Instead, they’re filled with vast quantities of gas and matter not hot enough to emit enough light for our telescopes to see.

Theoretical models of the birth and evolution of our universe suggest they should exist. They could have formed at a time when our universe was too immature for star formation.

But little actual data has been assembled on them.

This is possibly because most of them have been consumed.

Astronomers believe much of their gas and material may have long since been drawn into larger galaxies, fuelling fresh bursts of star formation.

“Despite substantial progress over the past half a century in understanding of how galaxies form, important open questions remain regarding how precisely the diffuse gas known as the intergalactic medium is converted into stars,” the researchers write.

“One possibility, suggested in recent theoretical models, is that the early phase of galaxy formation involves an epoch when galaxies contain a great amount of gas but are still inefficient at forming stars.”

Finding them, however, is a challenge.

SHADOW HUNT
While dark galaxies are dark, they’re not invisible. So it’s possible for them to distort and cast shadows from light glowing beyond them.

Across the gulf of time and space, quasars — the brightest objects in the universe — are proving capable of casting light on the matter.

A quasar is a bright ball of superheated plasma powered by the supermassive black holes in the centre of most visible galaxies. It’s generated by the immense gravitational forces tearing apart and bashing together matter as it falls towards the event horizon.

“They emit intense UV light, which in turn induces fluorescent emission in hydrogen atoms known as the Lyman-alpha line. As a result, the signal from any dark galaxies in the vicinity of the quasar gets a boost, making them visible,” the researchers write.

SHADOW HUNT
While dark galaxies are dark, they’re not invisible. So it’s possible for them to distort and cast shadows from light glowing beyond them.

Across the gulf of time and space, quasars — the brightest objects in the universe — are proving capable of casting light on the matter.

A quasar is a bright ball of superheated plasma powered by the supermassive black holes in the centre of most visible galaxies. It’s generated by the immense gravitational forces tearing apart and bashing together matter as it falls towards the event horizon.

“They emit intense UV light, which in turn induces fluorescent emission in hydrogen atoms known as the Lyman-alpha line. As a result, the signal from any dark galaxies in the vicinity of the quasar gets a boost, making them visible,” the researchers write.