On Christmas Eve 2016, Andrew Seymour, an astronomer at the Arecibo Observatory in Puerto Rico, kissed his 4-year-old daughter, Cora Lee, goodnight, telling her he was off to track Santa. He walked to the well-worn telescope, occasionally passing revelers riding horses through the empty streets — a common sight in Arecibo during the holidays. Sometimes a lonely firework would light up in the distance. Close to midnight, he nodded to a guard and entered the nearly empty complex.

The radio dish was on a break from its regular schedule, so Seymour decided to test out new hardware that he and his colleagues had been working on, writes Katia Moskvitch in Quanta Magazine. Soon after he began recording his observations, an extremely powerful radio source, 3 billion light-years away, decided to say hello. Seymour didn’t find Santa that Christmas, but rather an unexpected twist in the tale of one of the most mysterious objects in the cosmos.

The object that Seymour caught that night was the only known repeating fast radio burst(FRB), an ultra-brief flash of energy that flickers on and off at uneven intervals. Astronomers had been debating what might be causing the mysterious repeater, officially called FRB 121102 and unofficially the “Spitler burst,” after the astronomer who discovered it.

In the weeks following that Christmas detection, Arecibo registered 15 more bursts from this one source. These flashes were the highest frequency FRBs ever captured at the time, a measurement made possible by the hardware Seymour and his team had just installed. Based on the new information, the scientists have concluded in a study released in the journal Nature that whatever object is creating the bursts, it must be in a very odd and extreme cosmic neighborhood, something akin to the environment surrounding a black hole with a mass of more than 10,000 suns.

The new work helps to strengthen the theory that at least some FRBs might be produced by magnetars — highly magnetized, rotating neutron stars, which are the extremely dense remains of massive stars that have gone supernova, said Shami Chatterjee, an astrophysicist at Cornell University. In the case of the repeater, it could be a neutron star “that lives in the environment of a massive black hole,” he said. Or it might also be like nothing we’ve seen before — a different kind of magnetar ensconced in a very intense, magnetically dense birth nebula, unlike any known to exist in our galaxy — “quite extraordinary circumstances,” he said.

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Source and reference: Quanta Magazine

A long time ago in a galaxy far away two neutron stars collided and created a spectacular light show shown above known as a “kilonova,” a hot, dense expanding cloud of debris that shook the universe, emitting some 200 million suns’ worth of energy as perturbations in the fabric of spacetime called gravitational waves. For weeks much of the world’s astronomical community watched the kilonova as it slowly faded from view. Such collisions are thought to produce much of the universe's gold, platinum and other elements heavier than iron. But they can also have catastrophic consequences for any nearby habitable planets. (NASA's Goddard Space Flight Center, CI Lab).

After billions of years spent slowly circling each other in their last moments the two degenerate stars spiraled around each other thousands of times before finally smashing together at a significant fraction of light-speed, likely creating a black hole reported John Wenz in Scientific American. "The merger was so violent it shook the universe, emitting some 200 million suns’ worth of energy as perturbations in the fabric of spacetime called gravitational waves. Those waves propagated out from the merger like ripples on a pond, eventually washing over Earth—and into our planet’s premiere gravitational-wave detectors, the U.S.-built LIGO and European-built Virgo observatories.

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The world of neutron stars is a quite strange to scientists. Neutron stars are one of the most interesting objects of the universe so far we have observed. Neutron stars are the one of the most exotic objects of the universe. Ordinary matter or stuff we are made of and are familiar with is made of atoms. We know that most of the space in the atoms is empty. Suppose we generate enough force to squeeze the emptiness in the atoms of a rock roughly of the size of a football stadium. After applying this force and removing the emptiness of atoms, leaving no space between the electrons and nuclei, the stone will be squeezed down to the grain of a sand but still weighed 4 million tons. Suppose an island that dense instead of a grain of sand, but the size of an island is 20km. That is a neutron star.

When a massive star runs out of fuel and collapses, neutron stars are created . As the star collapses the density becomes so enormous that electrons and protons are squeezed together to form neutrons. The end result of this squeezing process of electrons and protons is a Neutron Star of 20 km wide but more massive than our sun and is mostly consist of neutrons. These exotic objects possess enormous gravitational field one hundred billion times stronger than we feel on earth. Neutron stars have very strong magnetic field. Neutron stars are tiniest stars known to exist in the universe. Among all the known neutron stars 5% are members of binary system. The companion of a neutron star in a binary system could be either white dwarfs, ordinary stars or other neutron stars. The formation of neutron star in a binary system is quite complicated process. There are about 2000 known neutron stars in the Milky Way and the Magellanic Clouds.

The majority of observed neutron stars in the Milky Way and the Magellanic Clouds are radio pulsars. If the star that has gone for supernova has mass 8 to 20 times of the sun than the core of the star will form neutron star. If the star has a mass less than 8 times to that of the sun than the star after completely burning its fuel will result a white dwarf. Stars more than 20 times massive than sun will result a black hole. The neutron star has mass 1.5 to 3 times to that of sun. Due to the conservation of angular momentum neutron stars starts to spin very rapidly. This is a pulsar. A pulsar is a spinning core of a star that has collapsed into neutron star. There is a type of neutron stars that can rotate more than 100 times per second. Original star before supernova event has magnetic field and after collapsing to a neutron star the magnetic field become stronger. When these magnetic fields rotate along with the neutron star, they produce radio waves shooting out of the North and South Pole of the neutron star. In general the direction of this radio beam is not actually along the same axis that the neutron star is spinning on. Due to this we can observe them with radio telescopes. Milliseconds pulsars also produce gamma rays. Fermi Telescope launched by NASA has detected many pulsars. This telescope is actually mapping the whole sky in gamma rays and gamma rays are even more energetic than X-rays. Many young pulsars emit gamma rays and it’s a common fact among scientists. Fermi has observed that all the millisecond pulsars produce gamma rays and this was a surprise to many scientists. Some physicists long before this observation have already theoretically predicted that we may see gamma rays from millisecond pulsars.