Four new gravitational wave detections announced, including the most massive yet

Mindy Sparks
December 6, 2018

It was one of four detections announced this week, using data from the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) which detects gravity waves, tiny ripples in space and time. Even though the before-mentioned article in the New Scientist journal suggested that it might've been a false-positive, more recent studies confirmed the origins of the signal - the most powerful black holes collision that astronomers have detected to date.

Gravitational waves are also thought to have been produced during the Big Bang. Occurring about nine billion years ago, it led to the formation of a new black hole about 80 times larger than the Sun. "It is also by far the most distant merger observed", said Susan Scott, a physicist at the ANU. In the coalescence, that happened nearly 9 billion years ago, an equivalent energy of nearly five solar masses has been converted into gravitational radiation.

The GW170818 event, which was detected by the global network formed by the LIGO and Virgo observatories, was very precisely pinpointed in the sky.

On the other hand, in late October an article in New Scientist, headlined Exclusive: Grave doubts over LIGO's discovery of gravitational waves raised the idea that it "might have been an illusion". So, gravitational wave events GW170729 were the result of the merging black holes with masses of approximately 51 and 34 solar masses (the total mass 85 solar masses); the energy of the waves thus passed about five solar masses.

The LIGO-Virgo detections are discussed in two research papers.

The collaboration picked up two more black-hole mergers from that first run.

"In just one year, LIGO and VIRGO working together have dramatically advanced gravitational-wave science, and the rate of discovery suggests the most spectacular findings are yet to come", said Dr. Denise Caldwell, Director of NSF's Division of Physics. As the field of gravitational-wave science has matured, new detections have taken on a different tone.

In October, the article "Exclusive: Grave doubts over LIGO's discovery of gravitational waves" appeared in the New Scientist journal. "It's an incredibly exciting time".

She said that technology advancements were finally giving scientists answers. Members of the Institute for Gravitational Wave Astronomy have developed and built components for the LIGO instruments, such as the high-performance sensors and control electronics for the suspension systems.

The research is described by the LIGO Scientific Collaboration and the Virgo Collaboration in two papers (here and here.) The aLIGO detectors are scheduled to be turned back on in early 2019.

Einstein's mathematics showed that massive accelerating objects, such as black holes orbiting each other, would disrupt space and time in such a way that waves of distorted space would radiate from the source.

Professor Scott says that the detection of these events will help improve our current understanding of the number of black holes in the universe, their masses and their spinning speed during a merger.

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