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This paper draws a lot of inferences. But there's just one factual discovery: galaxies that stopped star forming 6 billion years ago have more dark matter at 150 parsecs from the centre than those where star formation is ongoing today. This conclusion is based on examining 8 dwarf irregular and 8 dwarf spherical galaxies, and then throwing in some maths (but I don't think there's any obvious reason to doubt it for the 16 galaxies they examined).