Four new detections of gravitational waves have been announced at the Gravitational Waves Physics and Astronomy Workshop, at the University of Maryland in the United States.
In the 1980s, scientists started discovering a new class of extremely bright sources of X-rays in galaxies. These sources were a surprise, as they were clearly located away from the supermassive black holes found in the center of galaxies. At first, researchers thought that many of these ultraluminous X-ray sources, or ULXs, were black holes containing masses between about a hundred and a hundred thousand times that of the sun. Later work has shown some of them may be stellar-mass black holes, containing up to a few tens of times the mass of the sun.
There was much excitement when scientists witnessed the violent collision of two ultra-dense, massive stars more than 100m light years from the Earth earlier this year. Not only did they catch the resulting gravitational waves – ripples in the fabric of spacetime – they also saw a practically instantaneous flash of light. This is exciting in itself and was the first direct evidence for a merger of neutron stars.
For thousands of years, humans have searched for a way to turn matter into gold. Ancient alchemists considered this precious metal to be the highest form of matter. As human knowledge advanced, the mystical aspects of alchemy gave way to the sciences we know today. And yet, with all our advances in science and technology, the origin story of gold remained unknown. Until now.
Rumours have been swirling for weeks that scientists have detected gravitational waves – tiny ripples in space and time – from a source other than colliding black holes. Now we can finally confirm that we’ve observed such waves produced by the violent collision of two massive, ultra-dense stars more than 100m light years from the Earth.
When LIGO, the Laser Interferometer Gravitational-Wave Observatory, first detected gravitational waves from merging black holes, it opened up a new window in astrophysics and provided the most powerful confirmation yet of Einstein’s theory of general relativity. Now LIGO has done it again, together with the Virgo interferometer, this time by observing merging neutron stars – something astrophysicists had known must happen but had never been able to detect definitively until now.
NASA’s Neutron Star Interior Composition Explorer, or NICER, is an X-ray telescope launched on a SpaceX Falcon 9 rocket in early June 2017. Installed on the International Space Station, by mid-July it will commence its scientific work – to study the exotic astrophysical objects known as neutron stars and examine whether they could be used as deep-space navigation beacons for future generations of spacecraft.