Observation of stationary spontaneous Hawking radiation and the time evolution of an analogue black hole

Understand

The emission of Hawking radiation from a black hole was predicted to be stationary, which is necessary for the correspondence between Hawking radiation and black-body radiation.

• Spontaneous Hawking radiation was observed in analogue black holes in atomic Bose-Einstein condensates, although the stationarity was not probed.
• Here, we confirm that the spontaneous Hawking radiation is stationary, by observing such a system at six different times.
• Furthermore, we follow the time evolution of Hawking radiation and compare and contrast it with predictions for real black holes.