# What is the experimental evidence - direct or indirect - for Hawking or Unruh radiation?

I'm wondering what evidence exists, direct or indirect, for Hawking or Unruh radiation.

I believe one of the initial goals for the Fermi LAT mission was to look for evaporating microscopic black holes, which would be direct observation of Hawking radiation, but that this has not been observed by that mission - is that correct?

For the indirect evidence, I'm wondering if there is anything analogous to how the Hulse-Taylor binary was indirect evidence for gravity waves - is there some analogous measured effect of energy loss or change in other physical property that we attribute to Hawking/Unruh radiation?

I'm aware of a similar question "Is Hawking radiation a theory or a hypothesis?" but that question could be construed as more concerned with the semantics of the words theory and hypothesis, so I created this new question.

• Even indirect evidence of Hawking radiation is tricky, unless it's coming from tiny primordial black holes. According to vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator the radiation of a 3 solar mass BH is only $10^{-29}$ watts, at a temperature of 20 nanokelvins; it absorbs far more energy from stray atoms and the CMB. Jan 28, 2020 at 11:55