Hawking radiation from not-a-black-hole?

[nikkkom]

Since Schwarzschild solution describes exterior not only of black holes, but of any spherically symmetric non-rotating objects, then any such object should emit Hawking radiation, no?

Then how exactly is that working?

Let's set up a thought experiment. Say, we construct a spherically symmetric non-rotating object from ordinary atoms (say, a sphere of pure silicon). We know exactly how many atoms is there. We cool it to zero K (IOW: it has no thermal energy to create any particles) and position it in an empty space, devoid of any matter and radiation.

Now we observe it. When we detect a quantum of "Hawking-radiated" emission, where did the object get energy to create it? Is there one less Si atom in the object?

 

[mfb]

Objects with a finite radius have a different metric inside. In particular, you are missing the event horizon that is crucial for Hawking radiation.

You don't need a black hole for a horizon, however. You can create horizons for quasiparticles in matter (example) or with accelerations (Unruh effect).