Multipolar expansion profile of Hawking radiation on Kerr black holes

I would be very curious if Kerr black holes emit Hawking radiation at the same temperature in the equatorial bulges and in their polar regions. I've been looking some reference for this for a couple of months now but i haven't been successful yet.According to this answer, Too great Hawking radiation could thwart mass from being feed into a black hole, so this begs the question: Could possibly a (very small) Kerr black hole be able to accept infalling matter if it falls along the rotational axis? Possibly, since 4D Kerr black holes angular momen...Read more

hawking radiation - If virtual particles do not exist, how do they come to life at the event horizon?

Most of you (not me) know that virtual particles are only a nickname for some perturbation terms. So my question is how these perturbations become particles at the edge of an event horizon to create Hawking's radiation. Is there some mechanism that we know from current theories (other than "the energy has to somehow come from the gravitational field") or we will have to wait for a full understanding of quantum gravity? What has to specifically change in that perturbation to change its status from virtual to real? How do they get the energy?...Read more

Where does the time asymmetry come from in Hawking Radiation?

Taking General Relativity and Quantum Field Theory, Hawking predicts radiation emitted from a black hole.Both GR and QFT are time CPT symmetric.Taking just GR by itself, a black hole will stay the same forever.Taking QFT by itself a vacuum will stay the same forver (on average).So why, when combining the two do we get something time asymmetric: small black holes evaporating?Or equally a very large black hole will increase in size due to in coming radiation from the background.I mean, in classical mechanics I can see how a clump of atoms will ge...Read more

hawking radiation - micro black hole forces

A black hole would radiate mass optimally for interstellar-travel applications in the range between $10^7$ and $10^8$ kilograms. Assuming a light-only radiation emission spectrum, with a parabolic reflector with efficiency $f$, this would create an acceleration$$ a = \frac{f P}{mc}$$$$ a = \frac{ f \hbar c^5 }{ 15360 \pi G^2 M^3}$$$$ a = \frac{ f 10^{24} m \times sec^{-2}}{M^3} $$The problem is that the schwarzschild radius at this mass is a few attometers, which creates a host of problems:1) the rate at which it can feed from normal matter is ...Read more

Hawking Radiation: Attraction of negative mass particles?

My understanding of Hawking Radiation is this:All the time, small amounts of matter and antimatter pop into existence, find each other, and annihilate. When this happens near/on the edge of a black hole, the matter particle slips out into space, while the antimatter particle falls into the black hole and reduces it's mass.That's fine. My question is; How is the thing with negative mass being pulled in by gravity, while the thing with positive mass is escaping? shouldn't it be opposite of that?...Read more

Do apparent event horizons have Hawking radiation?

As I understand it, black holes have an absolute event horizon and an apparent horizon specific an observer. In addition to black holes, an apparent horizon can come from any sustained acceleration. Firstly, there is the "particle horizon" of the universe, which is the furthest co-moving distance from which light can reach us before the acceleration of the expansion of the universe prohibits it, then there is the case of a constantly accelerating observer in just regular flat space.My zeroth question is if the Hawking radiation from a black h...Read more

Does A Collapsing Star Emit Hawking Radiation?

So I've seen a number of answers/questions pointing out that massive objects which aren't black holes don't emit Hawking radiation. This certainly seems right for the steady state case with a time invariant gravitational field.However, what happens as a star starts collapsing into a black-hold before any actual event horizon is realized? Does the changing gravitational field somehow create a net flow of radiation out of the collapsing region?Or to put the point differently is gravitational collapse (whether or not into a blackhole) slowed eve...Read more

Does Hawking radiation or something similar occur inside the event horizon?

The question Why is a black hole black? states that stuff can't escape the event horizon and must ceaselessly pull inwards towards the singularity. At the singularity the forces become infinite. However, I heard that Hawking radiation (but not information) can escape the event horizon. Can something similar to Hawking radiation escape the inside of the event horizon and the singularity? Would a person inside the event horizon see Hawking radiation emitted from the singularity?It is hard for me to understand this because I think as soon as one p...Read more

hawking radiation - Mass Loss per Unit of Time of a Black Hole of a Given Size

What is the equation which gives us the mass loss per unit of time, of a black hole (non-rotating) of a given mass? What does a graph of a range of [BH masses/(mass loss/t)^-1] (?) look like? Is there a startling relation such as S~A/4 (entropy of a BH is proportional to (or equal to, in Planck units) a quarter of the BH area), which inspired the holographic conjecture?...Read more