Artist's Impression of Lyman-Alpha Halo Around a Distant Milky Way Type Galaxy (IMAGE)
Caption
This artist's impression shows a Milky Way type galaxy in the local Universe, surrounded by a much larger halo of blue, faint light, made of Lyman-alpha photons. While these photons were produced around hot, young stars in much more central regions, they struggle to escape the galaxies, suffering many absorptions and re-emissions as they try to escape, and creating these giant haloes. For typical distant galaxies, only a few per cent actually make it out at all. This is what astronomers have now been able to see for similar galaxies that existed 11 billion years ago, in a very young, active Universe. This has important implications for studying the young Universe, where these photons are remarkably important, but are usually measured over only the very central component of each galaxy.
Credit
ESO/L. Calçada
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