A black hole as light as 40 tons can exist inside a star if dark matter helps

# Black Holes Lighter Than Mountains Could Hide Inside Stars With Dark Matter's Help

Stephen Hawking's 1974 discovery that black holes emit radiation fundamentally changed physics. He proved that black holes gradually lose energy through quantum processes now called Hawking radiation. The lighter a black hole becomes, the faster it disappears.

This radiation constraint creates a puzzle for physicists studying primordial black holes, the tiny objects theorized to form in the early universe's extreme conditions. Traditional calculations suggest that black holes lighter than about one trillion tons would have already evaporated since the Big Bang. Yet researchers now propose a solution: dark matter could extend the survival time of exceptionally lightweight black holes.

A research team exploring this possibility found that a black hole as light as 40 tons, roughly equivalent to a small mountain, could theoretically exist inside a star if surrounded by enough dark matter. The dark matter acts as a shield, slowing Hawking radiation and preventing complete evaporation over cosmic timescales.

The mechanism works through gravitational capture. Dark matter particles accumulate around the black hole's event horizon, creating a buffer zone. This dense envelope absorbs and redirects some of the quantum radiation that would normally escape into space. The effect is not absolute but considerable enough that previously impossible black holes become viable candidates in certain stellar environments.

This proposal opens new avenues for hunting primordial black holes. Astronomers could search for unusual stellar behavior or energy signatures that hint at hidden black holes within stars. If such objects exist, their presence would create detectable gravitational anomalies or alter how stars age and burn fuel.

The findings also carry implications for dark matter detection. If dark matter genuinely accumulates around black holes in this manner, it might be possible to infer dark matter properties by studying black hole evaporation rates or searching for the telltale radiation patterns these interactions produce.

However, the proposal faces real challenges. Most stellar interiors lack sufficient dark matter density to produce the shielding effect at full strength. The researchers acknowledge that only specific stellar environments near the galactic center or within dense dark matter halos would support such conditions. Additionally, observational confirmation remains difficult. No confirmed detections of primordial black holes of any mass exist yet.

The work builds on decades of theoretical investigation into primordial black holes as dark matter candidates. If dark matter particles constitute the universe's missing mass, and if they concentrate around gravitational wells like black holes, then stellar cores could represent hidden laboratories for fundamental physics.

Further observations from gravitational wave detectors like LIGO and space-based instruments may eventually settle whether such lightweight black holes actually populate the cosmos. Until then, the hypothesis adds another layer to the puzzle of dark matter's nature and its intimate connection to black hole physics.