* Astronomy

New discovery sheds light on the ecosystem of young galaxies

A team of scientists, led by Michael Rauch from the Carnegie Observatories, has discovered a distant galaxy that may help elucidate two fundamental questions of galaxy formation: How galaxies take in matter and how they give off energetic radiation. Their work will be published in the Monthly Notices of the Royal Astronomical Society.
During the epoch when the first galaxies formed, it is believed that they radiated energy, which hit surrounding neutral hydrogen atoms and excited them to the point where they were stripped of electrons. This produced the ionised plasma that today fills the universe. But little is known about how this high-energy light was able to escape from the immediate surroundings of a galaxy, known as the galactic halo. The galaxies we observe today tend to be completely surrounded by gaseous halos of neutral hydrogen, which absorb all light capable of ionising hydrogen before it has a chance to escape.
Rauch and his team, using the Magellan Telescopes at Las Campanas Observatory and archival images from the Hubble Space Telescope, discovered a galaxy with an extended patch of light surrounding it. The objects appearance means that roughly half of the galaxy's radiation must be escaping and exciting hydrogen atoms outside of its halo.
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