How the mysterious signs of space recorded 50 years ago changed our view of the universe


This article was originally published in The Conversation. Read the original article.

A pulsar is a small, rotating star, a giant ball of neutrons, that remains after a normal star has died in a burst of fire.

With a diameter of only 19 miles, the star rotates up to hundreds of times per second, while sending a beam of radio waves (and sometimes other radiations, such as X-rays). When the beam points in our direction towards our telescopes, we see a pulse.

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This year marks 50 years since the pulsars were discovered. At that time, we have found more than 2,600 pulsars (mainly in the Milky Way), and we use them to look for low frequency gravitational waves, to determine the structure of our galaxy and to test the general theory of relativity.

The discovery

In the middle of 1967, when thousands of people enjoyed the "Summer of love", a young Ph.D. A student at the University of Cambridge, in the United Kingdom, he was helping to build a telescope.

It was a matter of poles and cables, what astronomers call a "dipole matrix." It covered a little less than two hectares, the area of ​​57 tennis courts.

In July, it was completed. The student, Jocelyn Bell (now Dame Jocelyn Bell Burnell), became responsible for executing it and badyzing the data it generated. The data came in the form of pen-on-paper chart records, more than 100 feet of them each day. Bell badyzed them by eye.

  Pulsar Astronomers using the Chandra X-ray Observatory of NASA found this pulsar, known as PSR J0357 + 3205 (or PSR J0357 for short) Image of the NASA brochure launched on August 18, 2011. This year marks 50 years since the pulsars were discovered. NASA / Reuters

The radio telescope of the Commonwealth Organization for Scientific and Industrial Research (CSIRO) ) Parkes in Australia made his first observation of a pulsar in 1968, a sighting commemorated later (along with the Parkes telescope) on the first $ 50 Australian note.

Fifty years later, Parkes has found More than half of the known pulsars. The Molonglo Telescope at the University of Sydney also played a central role. Both remain active in the search and synchronization of pulsars today.

Internationally, one of the most exciting new instruments on the scene is the 500 meter (1,640 ft) Aperture Spherical Telescope, or FAST. He has recently located several new pulsars, confirmed by the Parkes telescope and a team of CSIRO astronomers working with their Chinese colleagues.

Why look for pulsars?

We want to understand what pulsars are, how they work and how to fit into the general population of stars. The extreme cases of pulsars, those that are super fast, super slow or extremely mbadive, help to focus the possible models of how pulsars work, telling us more about the structure of matter at ultra high densities. To find these extreme cases, we need to find many pulsars.

Pulsars often orbit companion stars in binary systems, and the nature of these companions helps us to understand the history of pulsar formation. We have made a lot of progress with the "what" and the "how" of pulsars, but there are still unanswered questions.

In addition to understanding the pulsars themselves, we also use them as a clock. For example, the time of the pulsar is pursued as a way to detect the low background noise of low frequency gravitational waves throughout the universe.

The pulsars have also been used to measure the structure of our galaxy, by observing how they altered as they travel through denser regions of material in space.

Pulsars are also one of the best tools we have for testing Einstein's theory of general relativity.

 Albert_Einstein_1947 Albert Einstein in 1947 The theory of Einstein's relativity has survived 100 years of the most sophisticated tests that astronomers have been able to perform. CC

This theory has survived 100 years of the most sophisticated tests that astronomers have been able to perform. But it does not work very well with our other more successful theory of how the universe works, quantum mechanics, so it must have a small defect somewhere. The pulsars help us to try to understand this problem.

What keeps astronomers pulsating at night (literally!) Is the hope of finding a pulsar in orbit around a black hole. This is the most extreme system we can imagine to prove general relativity.

Finally, pulsars have some more applications with their feet on the ground. We are using them as a teaching tool in our PULSE @ Parkes program, in which students control the Parkes telescope through the Internet and use it to observe pulsars. This program has reached more than 1,700 students in Australia, Japan, China, the Netherlands, the United Kingdom and South Africa.

The pulsars also offer a promise as a navigation system to guide vessels traveling in deep space. In 2016, China launched a satellite, XPNAV-1, which carried a navigation system that uses periodic X-ray signals from certain pulsars.

 The Conversation Pulsars have changed our understanding of the universe, and their true importance is still developing.

George Hobbs is the team leader for the Parkes Pulsar Timing Array project at CSIRO; Dick Manchester is a fellow of CSIRO, CSIRO Astronomy and Space Science, CSIRO; and Simon Johnston is a senior research scientist, CSIRO, Australia.

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