A primordial, starless cloud of gas and dark matter has been confirmed for the first time, offering astronomers a direct look at a “failed galaxy” from the Universe’s infancy.
Using the NASA/ESA Hubble Space Telescope, researchers have identified a unique object nicknamed ‘Cloud-9,’ officially known as a Reionization-Limited H I Cloud (RELHIC). This relic, a dark matter cloud rich in neutral hydrogen, failed to form stars and remains a pristine building block of galaxy formation.
“This is a tale of a failed galaxy,” said principal investigator Alejandro Benitez-Llambay. “Seeing no stars is what proves the theory right. We have found a primordial building block that hasn’t formed.”
The discovery confirms a long-theorized class of objects. Hubble’s sensitive cameras ruled out the presence of any faint stars, confirming it is truly starless. “With Hubble, we’re able to nail down that there’s nothing there,” explained lead author Gagandeep Anand.
Cloud-9 is remarkably compact and spherical. While its hydrogen gas equals about one million solar masses, the cloud must contain roughly 5 billion solar masses of material to hold itself together. This indicates it is overwhelmingly dominated by dark matter.
“This cloud is a window into the dark Universe,” said team member Andrew Fox. “Cloud-9 gives us a rare look at a dark-matter-dominated cloud.”
Originally detected by China’s FAST radio telescope and confirmed by other observatories, Cloud-9 resides near the spiral galaxy Messier 94. Its pristine state is fragile; slightly more massive, it would have collapsed to form stars, and slightly less massive, its gas would have dispersed.
The discovery suggests the Universe may harbor many such dark, ghostly relics. Studying them provides crucial insights into dark matter and the earliest stages of how galaxies assemble, focusing on the unseen components that dominate the cosmos’s mass.
