Can dark matter be a lampshade for stars?

Physicists at Queen’s have found a new way to search for puffed-up clouds of dark matter by looking to see if stars "wink" in the night sky. Despite making up 85% of the matter content in the Universe, the true nature of dark matter remains a mystery. In some models, the dark matter particles can form large clumps. A prominent way to look for them is through microlensing, an effect where a dark clump can gravitationally bend the light from a star it passes in front of, briefly increasing the starlight received at a telescope. However, this phenomenon no longer works if the dark matter clump is too large. In this letter, the authors showed that for these "puffy" dark matter clouds, they can instead dim starlight, similar to how a regular lampshade dims a lightbulb. These "lampshade" dark matter clumps can be searched for in the already-existing microlensing data sets, and can be used to constrain and differentiate between candidates for dark matter.