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PhD student Leo Kim, postdoctorate Melissa Diamond, and professor Joe Bramante have their research published in the prestigious . The letter, , is also the Editor's Suggestion.

They 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.

Abstract

We demonstrate a new technique to search for dark compact objects. When dark matter comprising a dark compact object interacts with photons, the compact object can disperse light traveling though it. As these objects pass between the Earth and a distant star, they act as "lampshades’’ that dim the star. We examine how dimming effects from clumps of dark matter in the galaxy could be searched for in microlensing surveys, which measure the brightness of stars as a function of time. Using the EROS-2 and OGLE surveys, we show that a dimming analysis of existing data can be used to constrain dark sectors, and could be used to discover dark matter in compact objects.