Were The LIGO Gravitational Waves Made By Ancient Black Holes?

Astrophysicists have proposed that the recently-discovered gravitational waves were created out of black holes formed just after the birth of the Universe.

AsianScientist (Aug. 17, 2016) – Researchers in Japan have put forward a scenario proposing that the binary black holes that the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors found in September 2015 are primordial black holes. The study was published in Physical Review Letters.

Binary black holes are a pair of black holes bound together by gravity to orbit each other. Primordial black holes, like the name suggests, were formed soon after the Big Bang that created the universe.

In tandem with its historic announcement on the first detection of gravitational waves, the LIGO-Virgo collaboration of US and European scientists also reported that the gravitational waves were created by a merger of two massive black holes each weighing about 30 times the mass of the Sun.

After this discovery, many astrophysicists were left wondering how such heavy black holes were created and how their binary system was formed.

Led by Assistant Professor Teruaki Suyama from the University of Tokyo, the researchers built their study on the premise that primordial black holes are distributed randomly in space. The researchers then calculated the incidence of black hole mergers in the present epoch.

Based on the hypothesis that primordial black holes constitute about one-thousandth of all dark matter in the universe, they found that their estimated event rate of black hole mergers closely matches the frequency of mergers returned using LIGO-Virgo’s observational data.

When a sufficient amount of data related to black hole binaries have been collected, it will become possible to test this primordial black hole scenario, further promoting our understanding of black holes and the early universe.

“Since the research topic was timely with (LIGO’s) detection of gravitational waves, we quickly wrote the paper, completing it within two weeks,” said Suyama.

He continued, “We expect that the proposed scenario will be tested in the future when much more observational data has been collected.”

The article can be found at: Sasaki et al. (2016) Primordial Black Hole Scenario for the Gravitational-Wave Event GW150914.


Source: University of Tokyo; Photo: Pixabay.
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