The most relevant evidence for the existence of dark energy comes from supernovae that are moving away at an accelerating rate.
In the late 1990s, observations of distant type Ia supernovae revealed that they were dimmer than expected under the assumption of a constant rate of cosmic expansion. This indicated that the expansion of the universe is accelerating rather than slowing down, suggesting the influence of an unseen force, which is termed dark energy.
The other options you listed do not provide strong evidence for dark energy:
- Black holes that are expanding at a constant rate: The behavior of black holes does not directly relate to the expansion of the universe.
- Galaxies that are rotating at a constant rate: This is more related to the concept of dark matter rather than dark energy.
- Pulsars that seem to be moving closer at an accelerating rate: This statement is not a commonly recognized phenomenon in the context of cosmology and does not support the evidence for dark energy.
Therefore, the accelerating movement of supernovae is the key evidence supporting the concept of dark energy.