Dark matter information is still in its` early stages. Chandra images have confirmed just recently that dark matter is in fact hydrogen concentration in "stressed gravity". Extremly dense and several times more dense than dark nebula. In fact scientist are still conferring on the subject that dark nebulas and dark matter are almost the same. They did in fact admit that this is not 100% confirmed by all professional scientist in this field. Dark nebulas still need a small amount of light to properly identify, whereas dark matter has the lack thereof.