Samplings: July-August 2009

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MG J0414+0534, a distant galaxy, appears four times (with red halos). The image was made possible by a second galaxy (center, white) closer to Earth, which acts as a magnifying and multiplying lens.

John McKean/HST Archive data

Astronomers have reported the oldest and most distant sign of water in the universe: a cloud of water vapor near a supermassive black hole at the center of a faraway galaxy.

A team led by C.M. Violette Impellizzeri, at the time a doctoral student at the Max Planck Institute for Radio Astronomy in Bonn, Germany, first spotted it in 2007—apparently from 11.1 billion light years away.

Molecular signals must be unusually strong to be detected from such a great distance. The astronomers inferred the presence of the water cloud after detecting an unusually powerful water maser—an amplified microwave signal produced by stimulated water molecules. A galaxy between Earth and the maser served as a gravitational lens by bending and further magnifying the microwave rays.

Water masers exist in galaxies close to home, but they are rare. Yet Impellizzeri’s team found one on their first look through a gravitational lens. Powerful water masers must therefore have been much more common in the early universe than they are now.
Were it possible to plan a trip to that wet galaxy (MG J0414+0534, it’s called), remember that the universe has expanded considerably since the signal originated, 11.1 billion years ago. The water maser is now 19.8 billion light years away—so pack a lunch. (Nature)