Has Hawking radiation and black hole evaporation been observed by astronomers?

Question

Has Hawking radiation ever been observed or has there been any attempt of observing them? Do we have any evidence that black holes can evaporate?

I wonder how would one distinguish between Hawking radiation from some other radiation. Moreover, Hawking radiation causes a black hole to evaporate. Is there any hint in astronomy for the occurrence of such events? Are there chances of observing them in future in the sense that are there people/collaborations who dedicatedly looking for Hawking radiation?

Answer 1

Has Hawking radiation ever been observed or has there been any attempt of observing them?

No, it has never been detected. The Hawking radiation from a stellar-mass black hole is so weak that it can never be detected by any foreseeable technology.

Moreover, Hawking radiation causes a black hole to evaporate. Is there any hint in astronomy for the occurrence of such events?

No. Any stellar-mass black hole that has existed in the universe so far will have been absorbing mass-energy faster than it lost it through Hawking radiation, even if the only infalling energy was from the cosmic microwave background.

Are there chances of observing them in future in the sense that are there people/collaborations who dedicatedly looking for Hawking radiation?

The only realistic possibility I've seen suggested was that in some scenarios involving large extra dimensions, the LHC could have produced microscopic black holes. Microscopic black holes could evaporate relatively quickly, and the radiation might be detectable. However, they don't seem to have been produced at the LHC.

Answer 2

You might find the following physicisworld article somewhat interesting (though it does not talk about the detection of Hawking radiation from actual black holes):

Physicists stimulate Hawking radiation from the optical analogue of a black hole

As explained in the other answer, the article re-confirms

Direct astronomical observations are very challenging because the radiation is too feeble; the X-rays streaming from suspected black holes are instead emitted by incredibly hot gas as it spirals inwards.

However, it says that

... equivalent of Hawking radiation might be seen emerging from laboratory experiments that mimic black holes in other media, such as light, acoustic or water waves.

According to this article, certain non-gravitational systems, in some sense, can mimic black holes and event horizons in a wave medium, and their mathematical equations are equivalent to those of general relativity describing black holes. Such a connection was first shown by Unruh: Experimental Black-Hole Evaporation?

Unruh showed, can have an equivalent of Hawking radiation, in this case corresponding to a particular spectrum of sound waves emitted from a "sonic horizon". Optical physicist Ulf Leonhardt, who led the new study, comments: "Hawking radiation is a much more general phenomenon than originally thought. It can happen whenever event horizons are made, be it in astrophysics or for light in optical materials, water waves or ultracold atoms."

Some interesting points from the article are:

Jeff Steinhauer ... reported an experiment on a cloud of ultracold atoms held in a collective quantum state called a Bose-Einstein condensate (BEC), in which he claimed that a black-hole analogue showed self-amplifying Hawking radiation: a kind of lasing. But this experiment too has drawn criticism, although Steinhauer stands by his claim.

... in 2016 Steinhauer claimed to have observed Hawking radiation and the entanglement between the Hawking partners in the same BEC system. Another preprint by Steinhauer and his co-authors "looks much better – this is the first one I would begin to believe".

"Unruh comments: "There is now a competition between BECs and optical systems for the first unarguable sighting of spontaneous emission of Hawking radiation by an event horizon."