The beginning of time
Welcome to the early universe, less than a billion years after the big bang: It's a violent place where the rate of star birth has surged with amazing speed to baby boom proportions.
Rare snapshots of the universe found
Welcome to the early universe, less than a billion years after the big bang: It's a violent place where the rate of star birth has surged with amazing speed to baby boom proportions, but the young stars are clustered in galaxies so small and weak that they may be unable to save their inner monsters - black holes - from starvation.
Five billion years later, the galaxies have grown into hulks by colliding with one another, and they now harbour an impressive population of super-massiveblack holes. But the growth rate is trailing off. The era of major cosmic construction has subsided, and the universe is only about half its present age of 13.7 billion years. These rare snapshots of the growing universe are some of the initial findings, released last week, from the broadest in-depth survey ever conducted of the evolution of the largest cosmic building blocks - galaxies.
Among the survey's intriguing discoveries are seven mystery objects that could be the most distant black holes ever detected. "This is the first time that the cosmic tale of how galaxies build themselves has been traced reliably to such early time,'' said Mauro Giavalisco, leader of the Hubble Space Telescope's part of the survey. The international effort, known as GOODS, for Great Observatories Origins Deep Survey, combines NASA's major observing platforms in space with the world's largest ground telescopes. The effort, Giavalisco said, so far has taken several years, more than 100 scientists and "pretty much the largest mirrors on the planet.'' It has generated at least 15 papers, which are undergoing peer review for a special issue of the Astrophysical Journal Letters.
The survey's two images - of the Northern and Southern skies - show a total of about 50,000 galaxies across a wide range of distances, ages and growth stages. The findings to date come primarily from the Hubble telescope and the Chandra X-ray Observatory. NASA's Space Infrared Telescope Facility (SIRTF) is to join the effort after its launch, scheduled for August.
This combination of instruments enables the astronomers to examine the same patch of sky at different wavelengths and to reveal a variety of properties in sharper detail and with higher sensitivity over greater distances than ever before.
© Los Angeles Times-Washington Post News Service
