Where are the missing gravitational waves?

Neutron stars – the dead stellar remnants of old, burned-out stars – are some of the most extreme objects in the universe. They weigh as much as the entire Sun, but are small enough to fit into Sydney’s CBD, and they rotate up to 700 times every second. Imagine that: a whole star rotating faster than the fastest kitchen blender.

Astronomers know of a few thousand neutron stars, but one in particular is a stand-out. As part of the Parkes Pulsar Timing Array, we have been observing pulsar J1909-3744 with the CSIRO’s Parkes Radio Telescope for 11 years.

During this time, we have accounted for every single one of the neutron star’s 116 billion rotations (115,836,854,515, to be precise). We know the rotational period of this star to 15 decimal places, making it truly one of the most accurate clocks in the universe.

But, as we show in a paper published in the journal Science, it was not supposed to be this way. Gravitational waves from all of the black holes in the universe were supposed to ruin the timing precision of this pulsar. But they have not.

And further:

Why no gravitational waves?

But we want to be very clear that our lack of a detection does not imply that Einstein’s theory of relativity is wrong, nor does it imply that gravitational waves don’t exist. While we don’t know the real solution, we have a number of ideas...

We suggest to read the whole article>>
https://theconversation.com/where-are-the-missing-gravitational-waves-47940

The paper published September 25, 2015 in the journal Science>>
http://www.sciencemag.org/content/349/6255/1522

Read here, too>>
http://www.alphagalileo.org/ViewItem.aspx?ItemId=156569&CultureCode=en

Image explanation: A visualisation of gravitational waves emitted by two orbiting supermassive black holes.
Credit: Michael Koppitz / aei

#gravitational_waves #universe #astrophysics #pulsarJ1909_3744 #research
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