Below are a few brief excerpts from an article summarizing a new paper (published, where? not sure) on new and surprising astronomical observations. The excerpts are a brief part of the summary, which you should read. Also the following is rearranged a bit.
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ESA's Herschel space observatory has discovered a population of dust-enshrouded galaxies that do not need as much dark matter as previously thought to collect gas and burst into star formation....
The galaxies are far away and each boasts some 300 billion times the mass of the Sun. The size challenges current theory that predicts a galaxy has to be more than ten times larger, 5000 billion solar masses, to be able form large numbers of stars...Most of the mass of any galaxy is expected to be dark matter, a hypothetical substance that has yet to be detected but which astronomers believe must exist to provide sufficient gravity to prevent galaxies ripping themselves apart as they rotate....
Current models of the birth of galaxies start with the accumulation of large amounts of dark matter. Its gravitational attraction drags in ordinary atoms. If enough atoms accumulate, a 'starburst' is ignited, in which stars form at rates 100-1000 times faster than in our own galaxy does today....
Further analysis and simulations have shown that this smaller mass for the galaxies [Herschel's results] is a sweet spot for star formation. Less massive galaxies find it hard to form more than a first generation of stars before fizzling out. At the other end of the scale, more massive galaxies struggle because their gas cools rather slowly, preventing it from collapsing down to the high densities needed to ignite star formation....
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