Dim, pint-sized galaxies are likely to point to a more complete understanding of a key characteristic of matter in the universe, according to Dawn Erb, associate professor of physics at the University of Wisconsin-Milwaukee.
Writing in the journal Nature, Erb points out that a few hundred million years after the Big Bang, the universe became cool and dense enough for galaxies to form, but the resulting burst of star formation bombarded interstellar – and intergalactic – space with radiation, separating the electrons of hydrogen gas from their protons and reionizing most of the matter in the universe.
However, we don’t see enough massive, bright galaxies to supply the amount of energy thought to be needed for this “reionization” of the universe.
Low-mass galaxies are “probably the key” to understanding the universe’s reionization, according to Erb. But these galaxies, while probably very numerous, are inherently faint. This makes it difficult for astronomers to detect them, and also to confidently assess both their numbers and the amount of radiation they might have contributed to the reionization of interstellar gas.
A better understanding of these phenomena awaits the arrival of an upcoming generation of 30-meter class telescopes that will provide high-resolution views of the faint galaxies that Erb and her colleagues are studying, she says.
Erb’s paper, “Feedback in low-mass galaxies in the early Universe,” was published in the July 9 issue of Nature.
