Miércoles 24 de Julio de 2002, Ip nº 20

Report: cosmos could be much older than thought
Por Richard Stenger

(CNN) --The universe could be much older than previously expected, based on an examination of X-rays from a peculiar body near the edge of the known cosmos, the European Space Agency said this week.

Many astronomers theorize that the universe began with the Big Bang between 13 billion and 14 billion years ago. In large part the estimate comes from measuring the red shift of light and other energy from moving galaxies.

But scientists using ESA's XMM-Newton X-ray satellite observatory found that a quasar about 13.5 billion light-years away offered a serious challenge to the conventional age estimate.

"One distinct possibility to explain these observations is that at the red shift we are looking at, the universe is older than we think," said Fred Jansen, an XMM-Newton project scientist.

Red shifts resemble Doppler sound shifts. For example, sound waves from a train whistle become longer and lower in pitch when a train moves away from an observer.

Likewise, spectral light from galaxies seems to shift lower, observations that astronomers use to estimate the speed and age of galaxies.

Moreover, spectral red shifts provide the scientific foundation for the cosmological model that the universe continues to expand after the primordial Big Bang.

"If you study the evolution the universe, one of the basic rules is that we can tie red shift to age," Jansen said.

Yet the red shift of the quasar, a vibrant galaxy with a bright central region and massive central black hole, revealed that it contained much more iron than it should for its age.

Scientists think that exploding stars release iron and that the metal gradually builds up in the universe. Earlier generation stars should have little iron compared to later generation ones like the sun.

But iron in the quasar, known as APM 8279+5255, was three times more plentiful than in our solar system, which puzzled astronomers.

"The solar system formed just 5 [billion] years ago, so it should contain more iron than the quasar, which formed over 13.5 [billion] years ago," ESA said in a statement.

By looking at distant objects, scientists in a sense look back in time. The light from APM 8279+5255, for example, takes 13.5 billion years to reach Earth, so we see it as looks 13.5 billion years ago.

Presumably, the quasar should look very young in the early cosmic snapshot, but due to its iron-rich content, it looks much more mature.

The team, which includes researchers at the Max-Planck Institute in Germany, said that the most likely explanation for the mystery is that the quasar and hence the universe are older than expected.

They added that perhaps undiscovered "iron factories" are sprinkled through the early universe, spitting out the metal through an unknown physical process.

"This is the less likely solution in my opinion," Jansen said.

The report appeared in the July 10 issue of Astrophysical Journal Letters.


  11/07/2002. CNN.