Report confirms criticism of Big Bang finding

Stardust got in their eyes.

In late spring, a group of astronomers who go by the name of BICEP announced they had detected ripples in the sky, gravitational waves that were the opening notes of the Big Bang. The finding was heralded as potentially the greatest discovery of the admittedly young century, but some outside astronomers said the group had underestimated the extent to which interstellar dust could have contaminated the results -- a possibility that the group conceded in its official report in June.

Now, a long-awaited report by astronomers using data from the European Space Agency's Planck satellite has confirmed that criticism, concluding that there was enough dust in BICEP's view of the sky to produce the swirly patterns without recourse to primordial gravitational waves.

"We show that even in the faintest dust-emitting regions there are no 'clean' windows in the sky," the authors, led by Jean-Loup Puget of the Astrophysical Institute in Paris, wrote in a paper submitted to the journal Astronomy & Astrophysics and posted online Monday.

This is not the end of the story, both the Planck scientists and the BICEP group agree. But the original euphoria that the secrets of inflation and quantum gravity might be at hand has evaporated. Planck and BICEP are now collaborating on a detailed comparison of their results, which could tell how much of the signal is dust and how much could still be gravitational waves.

John Kovac of the Harvard-Smithsonian Center for Astrophysics, the lead author of the BICEP paper, said the new report confirmed in greater detail the trend suggested by the first Planck papers in the spring, which indicated there is more dust even in the cleanest parts of the galaxy than anyone had thought.

But Jamie Bock, a Caltech astronomer in the BICEP group, noted that the new data still does not say exactly how much of the BICEP signal was the result of dust.

That leaves an opening for gravitational waves, although they would be weaker than the BICEP analysis indicated, causing theorists to reshuffle their ideas.

The joint comparison and Planck's own polarization maps are due at the end of the year.

In the meantime, said Lyman Page, an astrophysicist at Princeton, "the science is still fantastic and the search is far from over."

If true, BICEP's detection of gravitational waves would confirm a theory that the universe began with a violent outward antigravitational swoosh known as inflation, the mainspring of Big Bang theorizing for the last three decades.

The BICEP observations are the deepest look yet into a thin haze of microwaves, known as the cosmic background radiation, left over from the end of the Big Bang.

According to theory, the onset of inflation, less than a trillionth of a second after time began, should have left ripples in space-time known as gravitational waves. They would manifest as corkscrew patterns in the direction of polarization of the cosmic microwaves.

The BICEP group -- its name is an acronym for Background Imaging of Cosmic Extragalactic Polarization -- is led by Kovac; Bock; Clement Pryke of the University of Minnesota; and Chao-Lin Kuo of Stanford. They have deployed a series of radio telescopes at the South Pole in search of the swirl pattern.

Their most recent, BICEP2, detected a signal in the sweet spot for some of the most popular models of inflation, leading to a splashy news conference and a summer of controversy and gossip.

As the critics pointed out, things besides quantum ripples from the beginning of time could produce those swirls, including light from interstellar dust polarized by magnetic fields in space. The BICEP astronomers had chosen to observe a region of sky thought to be free of dust.

The BICEP astronomers extrapolated from existing data to conclude that there was little dust interfering with their observations.

The new Planck report has knocked the pins out from under that. But there are still uncertainties that leave room for primordial gravitational waves at some level.

A Section on 09/23/2014

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