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Pulsars can be thought of as the lighthouses of our cosmos. In a recent Nature paper, scientists have observed that material surrounding the pulsar distorts the light emitted from the pulsar. The material focusses the light, increasing the observed brightness of the pulsar.
Pulsars are astrophysical objects that emit two narrow beams of radiation in opposite directions. The pulsar spins, which in turn causes the beams of radiation to spin like a lighthouse. From Earth, the pulsar appears to flicker ‘on’ and ‘off’. The radiation beam is normally made of radio waves. Pulsars are a class of neutron star. A neutron star is part of the later life of a star’s lifetime. Neutron stars are stars that are much bigger than our Sun and have run out of fuel. As a result, there is no force to overcome the gravitational pull and so the star collapses in on itself, a supernova occurs and the remnant is a dense object, the neutron star. To give you an idea of how dense a neutron star is, a sugar cube of neutron star material would weigh about 1 billion tons. Scientists believe pulsars are produced when a star steals material from a companion star adding momentum into the system, causing the star to spin. The material from the companion star surrounds the star in a cloud and the radiation beams ionize the surrounding material. This ionized material is known as a plasma. Plasma is the fourth state of matter and can be thought of as a ‘soup’ of ions and electrons.
Scientists from the Canadian Institute for Theoretical Astrophysics used the William E. Gordon Telescope at the Arecibo Observatory in Puerto Rico to measure the brightness of pulsars. In particular, the 305-meter diameter telescope was used to detect the changes in observed brightness of the pulsar with time, where the shortest timescale was microseconds. It was found that at the edges of the plasma cloud there was an increase in brightness before and after it’s eclipsed for a few milliseconds. At some points, the brightness increased by up to 80 times.
Main and his team believe that the increase in brightness could be a result of the edges of the plasma cloud acting as a lens and focusing the light. Because of lensing, scientists can measure variations on the kilometer scale even though objects are ~10,600 light years away . This is equivalent to measuring the width of a strand of hair that is on Mars from Earth. Moreover, this type of lensing known as plasma lensing can help scientists delve deeper into the cosmos. Even though the telescopes used were built decades ago, the advancements in computing have allowed scientists to see into our Universe with greater detail. Watch this space.
