Again! LIGO Detects second merger of a binary black hole

Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

Jun 16
Bram Slagmolen

Scientists have detected gravitational waves for a second time, caused by the collision of two black holes 14 and eight times the size of the sun.

The team, including scientists from Australian Consortium for Interferometric Gravitational Wave Astronomy (ACIGA), glimpsed the black holes orbiting each other 27 times in their last second before coalescing. The signal was 10 times longer than that of the first gravitational wave, which was announced in February this year.

The signal was detected by the two Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in the United States, said Professor Susan Scott, from the Australian National University.

“This has cemented the age of gravitational wave astronomy,” Scott said.

“This shows data is going to flow, that will enable us to map a lot more of the Universe than we’ve seen before.”

The violent collision happened approximately 1.4 billion years ago in a distant galaxy. During the journey to Earth, the gravitational waves died down so much that they stretched the LIGO detectors only a tiny fraction of the width of a proton.

"Each new detection of colliding black holes reveals something new about these mysterious and awe-inspiring objects," said Professor Andrew Melatos from the University of Melbourne.

"For example, by accumulating statistical data on black hole masses, and combining these data with computer modelling, we learn about the birth histories of black holes. The more events we capture, the more we learn!"

Gravitational waves are caused by violent cosmic events such as collisions between stars or black holes, or explosions such as supernovae. They were predicted by Albert Einstein in 1916, but he thought they would be too small for humans to ever detect.

“The fact that we have so quickly detected gravitational waves from a second pair of colliding black holes is very exciting as it suggests these events are more numerous than many researchers previously believed. We also anticipate that other sources of gravitational waves may be detected in the future as the detectors are made even more sensitive, ” said Dr Eric Thrane from Monash University.

Until gravitational waves were detected, nearly all astronomy had relied on electromagnetic observations – visible light, radio waves, X-rays and so on – said Dr Robert Ward, a LIGO researcher from the ANU.

“I'd always imagined there would be electromagnetic counterparts in our first discoveries, but instead we found these invisible collisions of black holes purely through the gravitational waves they emitted with no counterparts at all,” Dr Ward said.

The chair of the Australian Consortium for Interferometric Gravitational Astronomy, Dr Bram Slagmolen, said he was proud of the contribution Australian scientists had made to the detection.

“There’s massive enthusiasm among Australian scientists, we’ve come up with lots of innovative technology and ideas,” said Dr Slagmolen.

“Advanced LIGO is such a massive machine and it’s fantastic to see it operate in the way we intended.”

Professor David McClelland, from ANU and Leader of Australia’s Partnership in Advanced LIGO, said that Australian scientists were already working on projects which would enhance the sensitivity of the LIGO detectors.

“Our world-leading quantum optical devices will triple the searchable volume of our universe, we’ll see many more discoveries announced over the next few years.”

The discovery has been published in Physical Review Letters, PRL 116, 241103 (2016).

LISA Pathfinder Exceeds Expectations

The perfect free fall in space

Jun 07
Bram Slagmolen

The LISA Pathfinder satellite was launched late last year, and has since March 1st 2016 been running science operations.

The satellite hosts two identical gold-platinum cubes, about 2 kg in mass, seperated by 38 cm. Both cubes float as 'free mass' in space with the satellite hovering around, but not touching the cubes. Optical interferometry monitors the relative separation between the cubes. The reuslts of one of these experiments are presented in Phys. Rev. Lett. 116, 231101, with a staggering force sensitivity of 5 femto-g.

LIGO Founders Receive Prestigious Kavli Prize in Astrophysics

“for the direct detection of gravitational waves.”

Jun 02
Bram Slagmolen

The Kavli prizes get awarded every two years, in the fields of astrophysics, nanoscience and neuroscience. The awarded parties receive a $1M prize. The 2016 Kavli Prize in astrophysics is awarded to Ronals W.P. Drever, Kip S. Thorne and Reiner Weiss "for the direct detection of gravitational waves."

Although the committee acknowledge that the detection was a team effort, they singled out Ron, Kip and Rai for their “ingenuity, inspiration, intellectual leadership and tenacity”, to be the “driving force” behind the discovery.

Breakthrough Prize in Fundamental Physics

Breakthrough Prize in Fundamental Physics awarded to the LIGO co-founders and 1012 authors

May 02
Bram Slagmolen

It is fantastic to see the impact, of the LIGO discovery of the merger of two black-holes, on the gravitational wave community and the physics community in general. Today the Breakthrough Prize in Fundamental Physics was awarded to the LIGO founders Ronald W. P. Drever, Kip S. Thorne and Rainer Weiss and the 1012 contributors to the discovery (as in the author list of the publication "Observation of Gravitational Waves from a Binary Black Hole Merger" Published in PRL 116, 061102 (2016).

There are more then 40 Australian co-authors, as members of ACIGA, who have been part in the LIGO discovery and being recognized by this prize.