An article by Chris Lee in Ars Technica presents in simple terms the paper for the public.
The paper presents constraints on the self-interactions of dark matter particles based on observations of nearby old neutron stars.
Under certain circumstances self-interactions of dark matter particles can lead to formation of a small black hole made of dark matter inside a neutron star. This black hole could eventually eat up the rest of the star transforming the whole star to a big black hole.The existence of old neutron stars in specific places of the Galaxy, can therefore impose constraints on dark matter self-interactions and other properties.
Kouvaris’s recent paper in Physical Review Letters: Limits on Self-Interacting Dark Matter from Neutron Stars.
The article by Chris Lee can be found on arstechnica.com.