Giving us a rare, unique window into the environment and emission history of the strongest magnets in the cosmos
Space news (astrophysics: wind nebulas; Swift J1834.9-0846) – 13,000 light-years toward the constellation Scutum in the midst of a vast cloud of high-energy, particles surrounding supernova remnant W41 –
Astronomers studying the strongest magnets discovered during the human journey to the beginning of space and time, magnetars, have detected one they haven’t seen before. A magnetar, a rare highly magnetic neutron star with a vast cloud of high-energy, recently-emitted particles called a wind nebula streaming from it. Offering a unique window into the characteristics, environment and emission history of one of the most enigmatic and eye-opening objects ever detected.
“Right now, we don’t know how J1834.9 developed and continues to maintain a wind nebula, which until now was a structure only seen around young pulsars,” said lead researcher George Younes, a postdoctoral researcher at George Washington University in Washington. “If the process here is similar, then about 10 percent of the magnetar’s rotational energy loss is powering the nebula’s glow, which would be the highest efficiency ever measured in such a system.”
An object around 13 miles (20 kilometers) in diameter, or about the length of Manhattan Island, only 29 magnetars have been detected, so far. In this particular case, the source of detected emissions is called Swift J1834.9-0846, a rare type of ultra-magnetic neutron star detected by the Swift Gamma-ray Burst Satellite on August 7, 2011. It was subsequently looked at closer a month later by a team led by Younes using the European Space Agency’s (ESA) XMM-Newton X-ray Observatory. It was at this time astronomers realized and confirmed the first wind nebula ever detected around a magnetar.
“For me, the most interesting question is, why is this the only magnetar with a nebula? Once we know the answer, we might be able to understand what makes a magnetar and what makes an ordinary pulsar,” said co-author Chryssa Kouveliotou, a professor in the Department of Physics at George Washington University’s Columbian College of Arts and Sciences.
Neutron stars are the crushed cores of massive stars left over after they have gone supernova and the densest objects astrophysicists have been able to directly observe during the human journey to the beginning of space and time. All neutron star magnetic fields detected, so far, are 100 to 10 trillion times stronger than Earth’s, and magnetar fields reach levels thousands of times stronger. Astrophysicists have no ideas on how magnetic fields of such immense strength are formed.
“Making a wind nebula requires large particle fluxes, as well as some way to bottle up the outflow so it doesn’t just stream into space,” said co-author Alice Harding, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We think the expanding shell of the supernova remnant serves as the bottle, confining the outflow for a few thousand years. When the shell has expanded enough, it becomes too weak to hold back the particles, which then leak out and the nebula fades away. This naturally explains why wind nebulae are not found among older pulsars, even those driving strong outflows.“
“The nebula around J1834.9 stores the magnetar’s energetic outflows over its whole active history, starting many thousands of years ago,” said team member Jonathan Granot, an associate professor in the Department of Natural Sciences at the Open University in Ra’anana, Israel. “It represents a unique opportunity to study the magnetar’s historical activity, opening a whole new playground for theorists like me.”
Astrophysicists think a magnetar outburst’s powered by energy stored in its super-strong magnetic field produced gamma rays and x-rays, along with the gales of accelerated particles making up the nebula wind detected in the case of Swift J1834.9-0846. Now, they have a mystery to figure out, and new theories to deduce to explain the way a magnetar produces a nebula wind.
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Read more about Swift J1834.9-0846.
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