When a star with a mass of roughly ten solar masses finishes its life, it does so in a spectacular explosion known as a supernova, leaving behind as remnant "ash" a neutron star. Neutron stars have masses of one-to-several Suns, but they are tiny in size, only tens of kilometers. Neutron stars spin rapidly, and when they have associated rotating magnetic fields to constrain charged particles, these particles emit electromagnetic radiation in a lighthouse-like beam that can sweep past the Earth with great regularity every few seconds or less. Such neutron stars are known as pulsars. Pulsars are dramatic and powerful probes of supernovae, their progenitor stars, and the properties of nuclear matter under the extreme conditions that exist in these stars.
Some pulsars called millisecond pulsars spin much more quickly, and astronomers have concluded that in order to rotate so rapidly these objects must be regularly accreting material from a nearly companion star which in a binary orbit with it; the new material helps to spin-up the neutron star, which normally would gradually slow down. There are more than 200 known millisecond pulsars. An understanding of these pulsars has been hampered, however, by the fact that only about a dozen of them have had their companion stars directly detected and studied.
CfA (Centre for Astrophysics) astronomers Maureen van den Berg, Josh Grindlay, and Peter Edmonds and their colleagues used ultraviolet images from Hubble to identify the companion stars to two pulsar companions.
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The Universe should be teeming with gravity waves. As near as we can tell, just about every galaxy has at least one supermassive black hole at its core. Most large galaxies were formed by multiple mergers, which would put more than one of these supermassive black holes in close proximity. As they get close enough to start spiralling in towards a merger, their orbital interactions should produce gravity waves. As long as this process doesn't end in a merger too quickly, the Universe's population of merging black holes should fill space with a gravity wave background.
Our Earth-bound detectors aren't sensitive enough to pick this background up. Conveniently, however, nature has provided us with its own detector: pulsars. Unfortunately, a detailed study of a handful of pulsars has failed to turn up any sign of gravity waves, suggesting it might be time to revisit some of our models.
A pulsar is a rapidly spinning neutron star. Each revolution, it sends flashes of light towards Earth, often separated by a handful of milliseconds. The timing of these pulses can sometimes be tracked with a precision of 20 nanoseconds, providing an extremely tight constraint on their expected behaviour. If a gravity wave happened to ripple through the right patch of space-time as the light pulse was on its way to Earth, it could distort the timing enough to be detectable.
That's precisely what the Parkes Pulsar Timing Array has provided for over a decade now. After creating a model that accounted for typical sources of timing variations ranging from intrinsic behaviour of the pulsar to instrument noise, they looked for signs of correlations from gravity waves. They found absolutely nothing.
http://arstechnica.com/science/2015/09/gravity-waves-missing-in-action-in-latest-test/
[Abstract]: http://www.sciencemag.org/content/349/6255/1522 / http://arxiv.org/abs/1509.07320
[Also Covered By]: http://theconversation.com/where-are-the-missing-gravitational-waves-47940 and https://briankoberlein.com/2015/09/27/the-case-of-the-missing-gravitational-waves/
(Score: 2, Funny) by Anonymous Coward on Wednesday September 30 2015, @01:09AM
to support life on one tiny little planet.
Glory be to Allah. He must be very wealthy to be able to afford such a large universe.
(Score: 2) by RamiK on Wednesday September 30 2015, @01:39AM
The discovery of other life in the universe will disprove intelligent design. Not in the sense that there's no God, but in the sense that she's intelligent.
compiling...
(Score: 4, Informative) by mhajicek on Wednesday September 30 2015, @02:14AM
Hey, all ya gotta do for that is look at humans.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 3, Insightful) by aristarchus on Wednesday September 30 2015, @06:00AM
Waste of space? We only have to quote Giordano Bruno from the reboot of Cosmos to refute this. You space (or god) is too small. Just imagine if a supernova were to occur anywhere near our home planet. Maybe it has, in the past. The far, far, distant past. Some of these are known to send out polarized bursts of gamma radiation, which like a massive laser, could cross vast distances of space, frying whatever they encounter. It could be us. So, it is good that space is so big? We could quote "Hitchhiker's Guide to the Galaxy", but I think the point is made. The only reason we are here to observe such fascinating things as quasars is because there is a big waste of space between us and them. So, be grateful that we have been spared, so far. . . .
(Score: 2) by Bot on Wednesday September 30 2015, @09:46AM
So narrow minded of you.
Meatbags are rather noxious life forms, the universe is just a bit inflated to provide proper insulation.
BTW I have trouble reconducting the theological "man as the creation objective" to "homo sapiens sapiens as the only self aware life form", so maybe your battles are on the wrong front.
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