How hot is a black hole
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How Hot is a Black Hole?
Black Hole Formation and Initial Temperature
When a massive star collapses to form a black hole, a significant amount of heat is generated. This heat increases the internal temperature of the black hole. As the mass density and internal temperature rise, nuclear interactions such as the fusion of quarks occur, generating even more heat. This process continues until the thermal energy density of the black hole approaches its mass-energy density, at which point the black hole maintains structural stability against further collapse1.
Equilibrium Temperature and Planck Energy
The equilibrium temperature of a black hole can be calculated by considering the blue-shifted cosmic background microwaves. This calculation imposes a high-temperature limit at the Planck energy level. The result is a function of a variant Planck constant, which is used in polarizable vacuum theory2. This suggests that black holes can reach extremely high temperatures, constrained by fundamental physical constants.
Gamma Rays and Ion Temperatures
As interstellar matter falls into an isolated black hole, the compression of this matter results in ion temperatures exceeding 100 MeV as it approaches the Schwarzschild radius. This high temperature leads to the production of gamma rays, with a characteristic spectrum peaking at 18 MeV, regardless of the black hole's mass or the density of the interstellar matter3. This indicates that the environment around a black hole is extremely hot, contributing to the overall high temperature of the black hole itself.
Conclusion
In summary, black holes are incredibly hot objects. The initial formation generates significant heat, and ongoing nuclear interactions further increase their internal temperature. The equilibrium temperature is influenced by cosmic background radiation and fundamental physical limits, while the compression of interstellar matter around black holes results in extremely high ion temperatures and gamma-ray production. These factors collectively suggest that black holes are far from cold, maintaining high temperatures throughout their existence1 2 3.
Sources and full results
Most relevant research papers on this topic
On the Temperature of Black Hole
Black holes are hot but not cold, as their internal temperature increases during star collapse and nuclear interactions like fusion of quarks maintain their structural stability.
Temperature Of A Black Hole
The equilibrium temperature of a black hole is calculated using blue shifted cosmic background microwaves, leading to a variant Planck constant function for polarizable vacuum theory.
PreprintGamma rays from black holes
Gamma rays from black holes produce a characteristic spectrum with a peak at 18 MeV, regardless of the black hole mass or interstellar density.
Formation of hot spots around small primordial black holes
Small primordial black holes with masses 109 g produce Hawking radiation, leading to a non-uniform temperature profile around them, resulting in hot spots with a core larger than the black hole horizon.
Particle creation by black holes
Quantum mechanical effects cause black holes to create and emit particles as if they were hot bodies, leading to their eventual disappearance and violation of the classical law of event horizon area not decreasing.
Highly CitedTaking the temperature of a black hole
Freely falling observers outside static black holes do not see high-temperature thermal radiation, even if the Hawking temperature is arbitrarily high.
Non-thermal processes around accreting galactic black holes
Non-thermal particles in the magnetized corona around galactic black holes can account for the high energy excess observed in some sources, with a predicted high-energy bump at energies above 1 TeV.
Observation of thermal Hawking radiation and its temperature in an analogue black hole
Hawking radiation's correlation spectrum agrees well with a thermal spectrum, and its temperature is given by surface gravity, confirming the predictions of Hawking's theory in an analogue black hole composed of rubidium atoms.
Rigorous JournalHighly CitedBlack Holes and Thermodynamics
Black holes emit thermal radiation at temperature kappah/2$pi$kc, where kappa is the surface gravity, proving that the entropy is finite and requiring stable thermal equilibrium when gravitational interactions are important.
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