Supercomputer Traces Neutron Stars’ Magnetic Tango

New simulations performed on NASA’s Pleiades supercomputer are providing scientists with the most comprehensive look yet into the interacting magnetic structures around city-sized neutron stars in the moments before they crash. The team identified potential signals emitted during the stars’ final moments that may be detectable by future observatories. Just before orbiting neutron stars merge, the magnetic fields and plasma around them, called magnetospheres, become entangled. The new simulations studied the last several orbits before the merger, when the magnetospheres undergo rapid and dramatic changes, and modeled potentially observable high-energy signals. Neutron star mergers produce a particular type of GRB (gamma-ray burst), the most powerful class of explosions in the cosmos. They create near-light-speed jets that emit gamma rays, powerful ripples in space-time called gravitational waves, and a so-called kilonova explosion that forges heavy elements like gold and platinum. So far, only one event, observed in 2017, has connected all three phenomena. Neutron stars pack more mass than our Sun into a ball about 15 miles (24 kilometers) across, roughly the length of Manhattan Island in New York City. Born out of supernova explosions, neutron stars can spin dozens of times a second and wield some of the strongest magnetic fields known, up to 10 trillion times stronger than a refrigerator magnet. That’s strong enough to directly transform gamma-rays into electrons and positrons and rapidly accelerate them to energies far beyond anything achievable in particle accelerators on Earth. In the simulations, which were performed on the Pleiades supercomputer at NASA’s Ames Research Center in California’s Silicon Valley, the linked magnetospheres behave like a magnetic circuit that continually rewires itself as the stars orbit. Field lines connect, break, and reconnect while currents surge through plasma moving at nearly the speed of light, and the rapidly varying fields can accelerate particles to high energies. The team ran hundreds of simulations of a system of two orbiting neutron stars, each with 1.4 solar masses. The goal was to explore how different magnetic field configurations affected the way electromagnetic energy light in all of its forms left the coalescing system. The research shows that the emitted light varies greatly in brightness and is not distributed evenly, so what a far-away observer might detect depends greatly on their perspective on the merger. In addition, the way the signals strengthen as the stars get closer and closer depends on the relative magnetic orientations of the neutron stars. If next-generation gravitational wave observatories can provide an early warning, future ground-based gamma-ray telescopes will be able to team up with space-based X-ray and gamma-ray telescopes to begin searching for the pre-merger emission seen in these simulations. Routine observation of events like these using two different “messengers” — light and gravitational waves — will provide a major leap forward in understanding this class of GRBs. Music credit: “A Theory Develops,” Pip Heywood [PRS], Universal Production Music Credit: NASA's Goddard Space Flight Center Scott Wiessinger (eMITS): Producer/editor Scott Wiessinger (eMITS): Narrator Francis Reddy (University of Maryland College Park):Science Writer This video can be freely shared and downloaded at https://svs.gsfc.nasa.gov/14884 While the video in its entirety can be shared without permission, the music and some individual imagery may have been obtained through permission and may not be excised or remixed in other products. Specific details on such imagery may be found here: https://svs.gsfc.nasa.gov/14884. For more information on NASA’s media guidelines, visit https://www.nasa.gov/nasa-brand-center/images-and-media/. If you liked this video, subscribe to the NASA Goddard YouTube channel: https://www.youtube.com/NASAGoddard Follow NASA’s Goddard Space Flight Center · Instagram: http://www.instagram.com/nasagoddard · X: http://twitter.com/NASAGoddard · Facebook: http://www.facebook.com/NASAGoddard · Flickr: http://www.flickr.com/photos/gsfc