A Neutron Star Inside a Black Hole: A Theoretical Research

• Chen Tan and Yong-Qiang Wang from Lanzhou University have proposed a theoretical model where a neutron star exists intact inside a black hole.
• The model relies on a specific configuration of dark matter that creates a 'regular black hole' without a central singularity.
• In this scenario, the black hole's event horizon forms around the star, leaving the neutron star structured and non-singular inside.

Core Theoretical Mechanism

• Standard black hole theory posits a singularity of infinite density, which creates a limit for current physics.
• By using exotic dark matter halos with specific pressure-density relationships, the researchers show that stable configurations exist where space geometry flips outside the neutron star.
• In one model, the neutron star surface sits at 8.5 kilometers while the event horizon forms at 10 kilometers, effectively enclosing the star without causing collapse.

Caveats and Scientific Context

• The dark matter density levels required for this solution are significantly higher than anything currently expected by astronomers.
• The research serves as a thought experiment demonstrating that the interior of a black hole does not necessarily represent the end of physics.
• The paper does not claim such objects have been detected, but rather identifies a mathematical possibility that suggests black holes could be places containing structure.