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Astronomers using data collected by the Parkes radio telescope,
Murriyang, have found their strongest evidence yet for low-frequency
gravitational waves.
For nearly 20 years the Parkes Pulsar Timing Array collaboration has
monitored a set of radio pulsars -- rapidly spinning neutron stars.
In 1916 Albert Einstein proposed space-time as a four-dimensional
fabric, and that events such as exploding stars and merging black
holes create ripples – or gravitational waves – in this fabric.
Almost a century later, in 2015, researchers from the LIGO and Virgo
collaborations made the first direct observation of gravitational
waves caused by the collision of two stellar-mass black holes.
In contrast to these gravitational waves, which oscillate multiple
times per second, the Parkes Pulsar Timing Array collaboration is
searching for gravitational waves emitted by binary supermassive black
holes at the centres of galaxies, which have masses of millions
or billions of solar-masses. These gravitational waves oscillate
over timescales of many years.
In a coordinated release of papers, other collaborations in
China (CPTA), Europe (EPTA), India (InPTA) and North America
(NANOGrav) also report seeing a similar signal in their data.
Through the International Pulsar Timing Array consortium, the
individual groups around the globe – including the Parkes Pulsar
Timing Array collaboration in Australia – are working together to
combine their data to better characterise the signal and confirm its
origin.
More detail is given in
this article in The Conversation.
(Image and text credit: OzGrav)
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