Can blackholes at the center of galaxies be the source of the dark energy that we have been detecting?
That seems to be the conclusion based on two recently published papers [1,2]. Both of these are open access papers, so the full papers are available to everyone.
You may read an explanation and review of the papers at the AAS news website. The implication here is that if this is true, then dark energy is not something exotic or new since it can already be explained with General Relativity.
Now, if only we can find those pesky dark matter.... if they exist.