Alex McColgan

we think newborn black hole stars could form in places like these where enough hydrogen is still present to give us the properties we see in little red dots as for the missing x-rays they're not missing at all they are trapped in a black hole star

The surrounding hydrogen envelope would be so dense that even high-energy X-rays couldn't punch through it.

They would get absorbed by the gas and re-emitted as thermal energy and the red optical light we see instead.

Okay, but what about all the other unanswered questions?

The strange V-shaped spectral energy distributions, all the missing dust, and the black holes too big for their own galaxies?

How does the black hole star tackle these challenges?

Lucky for us, astronomer Rohan Naidoo of MIT and his team have some ideas.

In 2025, they were studying an object they also referred to as a black hole star, and found it to have a thick hydrogen gas envelope about 40 astronomical units wide, plus one of the strongest Balmer breaks ever witnessed at any redshift.

Naidoo argued the black hole star is a two-component object, a black hole star which produces broad emission lines, a strong Balmer break, point-source compactness of light, and strong red emissions, and a star-forming host galaxy that produces narrow emission lines in the UV spectrum.

Taken together, this compact object would produce a V-shaped spectral energy distribution just like what we see from little red dots.

the low-energy red emissions from the black hole star and high-energy UV emissions from the surrounding host galaxy superimpose to create one unusual spectrum.

The object Naidoo and his team were studying wasn't a little red dot itself, but by examining it they concluded that black hole stars, when embedded in brighter host galaxies, produce the little red dot properties we've seen.

The remaining issues of dust and overly massive black holes go hand in hand.

Under the black hole star model, little red dots wouldn't have any dust at all.

They're red due to the opacity and the surrounding dense gas.

Since there's no dust to worry about, there's no shortage to account for.

And the overmassive black hole problem is also connected to this dense cloud.

The standard way to calculate a black hole's mass is to measure how broad its emission lines are.

Broader lines mean faster moving gas, which means a more massive black hole.

But in a black hole star, photons don't travel cleanly outward.