The first detection of gravitational waves, this time associated with merging black holes, occurred in 2015. This was of monumental importance in the world of physics because it confirmed Albert Einstein’s 1915 general theory of relativity. It has also launched a whole new strand of physics — the field of gravitational-wave astronomy.
Gravitational waves carry information about the origins of black holes and about the nature of gravity that cannot otherwise be obtained.
Now, to cement the September 2015 finding, Northwestern University astrophysicists have detected a second example through analyzing data from the U.S.-based Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors. Importantly, the measured gravitational wave is completely consistent with the predictions of general relativity for strong gravitational fields.
The newly detected gravitational waves were produced during the final period of the merger of two black holes (an effect termed ‘dynamical formation’.) These space phenomena were14 and 8 times the mass of our Sun. The resultant formation was a single massive black hole, at around 21 times the mass of the Sun. Here a quantity of energy, approximately equal to the mass of the Sun, was transformed into gravitational waves. This event happened 1.4 billion years ago.
The detected gravitational waves released lasted one second. The scientists have converted the gravitational wave to a ‘sound’, by converting the gravitational wave’s oscillation and frequency to a sound wave.
As well as adding further evidence to Einstein’s theory, the discovery, according to Dr. Vicky Kalogera, director of Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics, also shows “binary black holes exist as a population, with a range of masses, forming from a range of different stars.”
In addition, she added: “We expect black holes with a range of masses, which we now are seeing, showing us that black holes form ubiquitously in the universe.” To add to this, Nature News&Comment (@NatureNews) tweeted: “LIGO’s 2nd detection of gravitational waves: This is going to be a new kind of astronomy.”
The finding has been reported to the journal Physical Review Letters. The research paper is headed: “GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence.”
