Seeds of the first galaxies glimpsed
Astronomers have seen the seeds of the first galaxies in the cosmic microwave background (CMB), also known as the echo of the Big Bang. The observations could answer the question of how galaxies form in the first place.
The CMB dates to the moment 300,000 years after the Big Bang when the opaque plasma of protons and electrons combined to form atoms that light could pass between, making the Universe transparent.
Since 1992 astronomers have known the microwave background is not uniform across the sky but is broken up into brighter and darker blobs, corresponding to regions of higher and lower density in the original plasma.
Now researchers at California Institute of Technology in Pasadena and the Canadian Institute for Theoretical Astrophysics in Toronto have used the Cosmic Background Imager (CBI), a series of radio antennae in the Atacama Desert, Chile, to map out these blobs more precisely than ever before.
The size of the largest blobs confirms previous results that the Universe is mainly repulsive dark energy, which blows the blobs apart, only five per cent normal and dark matter whose gravity holds them together. But the resolution of the CBI is good enough to see an even smaller population of blobs.
“The CBI is seeing the seeds of galaxy clusters” says Anthony Readhead of Caltech. The seeds are a tenth the diameter of the full moon.
But to the surprise of researchers, the experiment has seen many more tiny blobs than was expected. Most likely, say the researchers, some of the darker blobs are caused by photons of the CMB being deflected by hot gas in galactic clusters between their origin and us.
If this is true, then the pattern of the blobs is telling astronomers about clusters of galaxies too far away to be seen directly. “This is a very promising but tentative detection,” says Tim Pearson, Readhead’s colleague.
But Rafael Rebolo of the Astrophysical Institute of the Canaries in Spain, who with groups at Cambridge and Manchester Universities in the UK announced similar but lower resolution measurements of the CMB on Thursday, says he will be looking carefully at the competing group’s results.
“We are mapping all the radio sources in the sky which could be confused with the microwave background at this resolution,” he says. “They haven’t done this as carefully.”
The highest resolution scan yet of the microwave "echo" of the Big Bang, reveals details of the early Universe
Big Bang or Big Goof? Astronomer Challenges ‘Seeds’ Proof
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Nobel Prize-winning research claimed this picture showed the birth of the universe. But new research claims that data is wrong. NASA
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Most astronomers say that world-famous images from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite show structures of the early universe. But a lone radio astronomer is claiming that the pictures depict nearby hydrogen gas clouds in our own galaxy, calling a key theory into question.
Astronomers are abuzz because if Gerrit Verschuur of the University of Memphis is right, one of the most important theories developed in the past 15 years — one that won a Nobel Prize — would be toppled. The world’s top astronomical publication, Astrophysical Journal, will publish Verschuur’s research December 10.
“If I’m right, this is a paradigm shift,” said Verschuur, who is 70 and a well-known author of numerous books on astronomy.
It would mean our understanding of how the cosmos was born 14 billion years ago is seriously flawed. Astronomers would have redder faces than they’ve had since the beginning of the 20th century, when some scientists claimed they saw “canals” built by Martians on the red planet.
NASA scientists led by George Smoot of the Lawrence Berkeley National Laboratory announced in 1992 that their Cosmic Background Explorer satellite had imaged the ultimate baby pictures of the universe, revealing the seeds. Like acorns growing into oak trees, they theorized, those seeds grew into galaxies like the star-packed Milky Way, our own spiral-shaped celestial home.
Stephen Hawking called it the greatest discovery of all time. Smoot compared it to seeing the face of God. In 2003, higher-resolution images of the seeds were taken by another satellite, the Wilkinson Microwave Anisotropy Probe, known as WMAP, showing numerous fine seeds or “ripples” that resemble a serious case of acne.
Verschuur’s research asserts that the seeds are not located on the edge of the universe at all. Rather, he says, the so-called seeds are very nearby: They’re just previously unmapped clouds of “neutral hydrogen” gas located inside the Milky Way. In other words, astronomers who mistook the “seeds” for objects on the edge of the universe are like someone who looks outdoors through a window and mistakes smudges on the glass for clouds in the sky.
“Smoot said he saw the face of God. All I can say is, God lives in our neighborhood,” Verschuur joked.
He said he’s found at least 200 instances where the so-called cosmic seeds lie suspiciously close to known hydrogen clouds inside our galaxy.
There’s a long history of astronomical debates over whether celestial objects are close or distant. For example, the former Mt. Palomar and Mt. Wilson astronomer Halton Arp has argued that super-bright objects in the heavens, quasars, are located much closer to Earth than is generally believed, and that they’re ejected from galaxies like pinballs from pinball machines. But virtually all astronomers reject Arp’s claims on the grounds that they’re based on an unconvincing statistical analysis of the comparative locations of quasars and galaxies.
This week, a similar critique is being lobbed against Verschuur. But, surprisingly, the most cautious reaction came from Smoot.
“One would have to do a very careful (statistical) study to see if this (correlation between hydrogen filaments and cosmic seeds) could happen by simple chance or is truly convincing,” Smoot said in an e-mail.
Within the astronomical community, he noted, experts are quick to fault Verschuur’s correlations between hydrogen and cosmic seeds as statistically unsound. “That might be the correct conclusion,” Smoot said, “but seems a little fast to me.”
At Oxford University in England, astrophysicists Kate Land and Anze Slosar have conducted a statistical analysis of Verschuur’s work.
“It does not hold water at all,” Land told Wired News by e-mail. In other words, she believes Verschuur’s correlations between the WMAP seeds and galactic hydrogen filaments are just coincidences. If that’s true, then Verschuur’s claim is an astronomical version of those Bible evangelists who think they see Jesus’ face in a burrito.
“Notoriously, by eye, one can often think they see correlations between patterns,” Land said. “But one doesn’t really see the anti-correlations. So two maps (of the sky) that just fluctuate randomly can appear correlated.”
A leading cosmologist with the WMAP project, David Spergel of Princeton, agreed. Verschuur’s “is basically a wrong article,” he said.
NASA scientist Gary F. Hinshaw concurred: “I am quite confident that the … correlations claimed in the Verschuur paper are not (statistically) significant.”
Ultimatelly, Verschuur’s claim will stand or fall upon the treacherous terrain of statistics, which means it likely won’t be settled anytime soon. History shows that debates over statistical interpretations can go on forever. The defenders of orthodox cosmology claim Verschuur’s analysis of celestial images is statistically too fragile to take seriously. He counters that his data is too convincing to be deflated by fancy-pants statistical manipulations.
Astronomers regale their students with cautionary tales of stargazers who embarrassed themselves when they reported seeing celestial sights that weren’t really there. Besides the Martian “canals,” some of the funnier examples include the astronomer who, in the 1920s, claimed he saw swarms of insects on the Moon. In the 19th century, astronomers reported — incorrectly — that they saw a planet inside Mercury’s orbit, which they dubbed “Vulcan.” Now all that remains of Vulcan is its most famous fictional inhabitant, Mr. Spock of Star Trek. Like the rest of us, astronomers sometimes see what they expect to see.
For astronomers, the problem now is to decide who’s “seeing” things — Verschuur? Or themselves? Verschuur said he felt “terror” when he published his article, because he’s just one guy at a campus living in a small Tennessee town outside of Memphis, and he’s taking on the whole astronomical world. But he consoles himself with his wife’s advice: “Gerrit, remember that you’re just communicating what the data show.”
Oops! A University of Memphis radio astronomer publishes a paper in a leading journal saying one of the most spectacular discoveries in astronomical history is nothing more than a big mistake.