LIGO ends run amidst rumor of gravitational wave detection

Results are being analyzed after the initial run of a gravitational-wave observatory near Richland following a major upgrade and revamp of the scientific facility and its twin in Louisiana.

The run, which started in September, was completed Tuesday.

The Laser Interferometer Gravitational-wave Observatory, or LIGO, located on Hanford land, operated from 2002-10 without detecting a gravitational wave from outer space. But extensive improvements to the scientific facility before a restart in 2015 increased the sensitivity of detection instruments by a factor of 10.

The day before the latest run ended, a rumor circulated on Twitter, started by theoretical physicist Lawrence Krauss of Arizona State University, that the improved scientific facilities may have detected a gravitational wave.

Science Magazine reacted with skepticism, saying there are reasons to doubt the rumor will hold up. False signals are injected into data to test sensitivity of analysis techniques, it said.

“We are really not going to say much,” said Fred Raab, head of the Hanford LIGO.

Scientists still are vetting the early data from the run produced by complicated instruments with hundreds of thousands of data chains, he said.

Results will be announced in papers published in scientific journals, as is done after each LIGO run. Publication is likely at least a month away.

However, some data that could indicate events of note are shared with astronomy groups, Raab said. Until data is analyzed, it is unknown whether the data represents real events.

At the Hanford LIGO, end-of-run measurements were taken this past week, and tests were conducted to assess environmental influences, like noise, on the delicate equipment of the detector.

LIGO is designed to detect the barest movements of mirrors suspended at the end of 2.5 mile-long tubes extending across the shrub-steppe landscape at Hanford. If a gravitational wave is detected, similar results at the Louisiana LIGO would help verify the discovery.

Albert Einstein predicted the existence of gravitational waves in his 1916 general theory of relativity. Violent events in space, such as two neutron stars that orbit each other until gravity pulls them into a collision, send a ripple though space and time. The force is so great that it could be felt on Earth.

As a wave passes through Earth, it would stretch objects lengthwise and compress them sideways. But the change in shape would be exceedingly small.

LIGO is trying to detect a movement about one thousandth of the diameter of a proton, which is the nucleus of a hydrogen atom.

Before improvements, LIGO had the sensitivity to detect gravitational waves from 100 galaxies, said officials at the dedication of Advanced Hanford LIGO in May.

Odds were not great. By uncertain estimates, there could be an astronomical event producing a gravitational wave once every 10,000 years per galaxy.

With the upgraded equipment, LIGO has the sensitivity to detect gravitational waves from 100,000 galaxies.

Scientists said at the dedication that they did not have high hopes of a gravitational wave detection in the initial run. But when LIGO starts up again with increased sensitivity for a six-month run there is a high probability that a gravitational wave could be detected, they said.

Detecting and measuring gravity waves is anticipated to lead to advances in physics and astronomy, and a better understanding of the universe.

This story was originally published January 15, 2016 at 12:07 PM with the headline "LIGO ends run amidst rumor of gravitational wave detection."