How dense is black hole
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Understanding Black Hole Density
Introduction to Black Hole Density
Black holes are often perceived as incredibly dense objects, a notion reinforced by their comparison to white dwarfs and neutron stars. However, the density of black holes varies significantly depending on their mass. While smaller black holes are indeed extremely dense, supermassive black holes can have surprisingly low densities .
Density of Stellar-Mass Black Holes
Stellar-mass black holes, which form from the gravitational collapse of massive stars, are incredibly dense. These black holes have densities that can exceed a trillion times that of water, creating immense gravitational and tidal forces at their boundaries . This extreme density is a result of the compact nature of the stellar remnants from which they form.
Density of Supermassive Black Holes
In contrast, supermassive black holes, such as those found at the centers of galaxies, can have much lower densities. For instance, a black hole with a mass of 387 million solar masses would have an average density comparable to that of water, while one with 11 billion solar masses would have a density similar to that of air . This dramatic decrease in density with increasing mass is due to the volume of a black hole growing faster than its mass.
Local Black Hole Mass Density
Recent studies have revised the local mass density of black holes, suggesting it is five times higher than previously estimated. This increase has implications for our understanding of black hole growth and the radiative efficiency of accretion processes in Active Galactic Nuclei (AGN) . The local mass density is crucial for understanding the overall distribution and growth of black holes in the universe.
Primordial Black Holes and Density Constraints
Primordial black holes, which may have formed in the early universe, also contribute to the overall black hole density. X-ray data has been used to set upper limits on the abundance of these primordial black holes, particularly in the mass range detectable by LIGO . These constraints help refine our understanding of the early universe and the formation of black holes.
Conclusion
The density of black holes varies widely depending on their mass. While stellar-mass black holes are extremely dense, supermassive black holes can have much lower densities. Recent revisions in the local black hole mass density and constraints on primordial black holes further enhance our understanding of these enigmatic objects. Understanding black hole density is essential for comprehending their formation, growth, and the role they play in the cosmos.
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