Everything with a pinch of salt, especially when it comes to space. Scientists always try to sound brainy when they haven't made any new discoveries for some time. Think about all the "New Discoveries" that were later quietly swept under carpet due to their theories being incorrect. Dark matter could exist but until they can physically test it they shouldn't claim that they can see it. There is far too much that is unknown about space to claim that what they see is in fact dark matter and not just some galactic aurora.