Arecibo Begins Search for Dark Galaxies

Feb 08, 2005
Arecibo  radio telescope

Fitted with a new compound eye, the Arecibo radio telescope in Puerto Rico last week began a multiyear effort to survey all the galaxies in a large swath of sky out to a distance of 800 million light years—a survey that may well uncover the often-theorized, but never-seen, "dark galaxies."

If they do exist, dark galaxies, would be vast clumps of primordial hydrogen and helium gas that have drifted through the universe for 10 billion years or more, but for some reason have never been able to turn that gas into stars. As such, they would account for at least some of the mysterious cosmic "dark matter," which makes itself known only by its gravitational effects on the ordinary, star-rich galaxies. Certainly the dark galaxies would have been missed by previous astronomical surveys, most of which were restricted to optical and infrared light; the cold hydrogen and helium of a dark galaxy would shine only at radio wavelengths—Arecibo's specialty.

Funded by the National Science Foundation and operated by the the National Astronomy and Ionosphere Center at Cornell University, the 305-meter-wide Arecibo Observatory telescope is the world's largest and most-sensitive single-dish radio telescope. Last year, its sensitivity was further boosted by the Arecibo L-Band Feed Array (ALFA): essentially a seven-pixel camera that will allow astronomers to collect data about seven times faster than before. The the survey project starting today has thus been dubbed ALFALFA, for Arecibo Legacy Fast Alfa Survey.

Explore further: Mercury's magnetic field tells scientists how its interior is different from Earth's

add to favorites email to friend print save as pdf

Related Stories

Microsoft unveils Xbox in China as it faces probe

7 hours ago

Microsoft on Wednesday unveiled its Xbox game console in China, the first to enter the market after an official ban 14 years ago, even as it faces a Chinese government probe over business practices.

Recommended for you

Tidal forces gave moon its shape, according to new analysis

10 hours ago

The shape of the moon deviates from a simple sphere in ways that scientists have struggled to explain. A new study by researchers at UC Santa Cruz shows that most of the moon's overall shape can be explained by taking into ...

Evidence of a local hot bubble carved by a supernova

12 hours ago

I spent this past weekend backpacking in Rocky Mountain National Park, where although the snow-swept peaks and the dangerously close wildlife were staggering, the night sky stood in triumph. Without a fire, ...

User comments : 0