Unlocking the Mystery: Astronomers Reveal Secrets Behind the Enigmatic ‘Little Red Dots’

When the James Webb Space Telescope launched in 2022, it discovered something surprising: tiny red dots scattered across deep space, dating back to when the universe was just a billion years old. These faint signals puzzled scientists. The leading theory suggests they might be compact galaxies. But there’s a catch—these galaxies would need a star density that challenges what we believe about physics.

Interestingly, these dots are too faint to be from quasars, which are supermassive black holes that glow brightly while consuming matter. This challenges the theory that starts with large black holes being at the center of these mini-galaxies.

Harvard astronomer Avi Loeb and his colleague, Fabio Pacucci, have proposed a new explanation. Their recent study in the Astrophysical Journal Letters suggests these red dots are indeed galaxies, but they are unusually small because they haven’t yet started to spin fast enough.

Their theory builds on how galaxies form in dark matter halos, which are invisible structures that influence gravity. Dark matter makes up about 85% of the universe’s mass, even though we can’t see it. Loeb points out that these tiny galaxies likely formed in halos that aren’t rotating quickly—99% of halos spin faster. Their study uses a simple analogy: think about holding a piece of rope. If you spin, the rope stretches. If you slow down, it droops. The slower spin explains why these dots appear so early in cosmic time. Over time, the halos will speed up, and the galaxies will grow.

However, not everyone is convinced. Other astronomers are exploring a different idea—that these red dots could be part of a new class of cosmic objects called “black hole stars.” In this scenario, a supermassive black hole could be surrounded by a thick shell of gas. The intense heat from the black hole would make this shell glow, but its brightness might be dampened for outside viewers.

Loeb and Pacucci’s model leaves open the possibility that these small galaxies could give rise to black holes over time. Pacucci notes that low-spin halos can gather more mass at their centers, which might aid in black hole formation.

This ongoing debate highlights how much is still unknown about our universe, especially the early stages of galaxy and black hole formation. It not only fractures our understanding of cosmic history but also beckons further exploration into the secrets these “little red dots” might hold.

For further reading, you can find more on how dark matter shapes our universe here.

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