Chandra image of the Galactic Center; inset: region near the supermassive black hole and variable magnetar
Credit: NASA/CXC/INAF/F.Coti Zelati et al

Extremes in the Fields

Matter creates, at every point in space, a force of attraction which can make another bit of matter change its position and velocity. This gravitational force of attraction in space is sometimes visualized as a gravitational force field, though in Einstein's view, this force field is simply a manifestation of the way matter bends and shakes the fabric of spacetime. Some types of matter also possess an electric charge, in addition to the gravitational charge. A stationary charged particle can be thought of creating, at each point in space, an electric force field analogous to the gravitational one, but one that is only felt by electrically-charged bits of matter. Magnetic fields arise from moving electric charges. Extreme examples of both gravitational and magnetic fields can be found at the center of the Milky Way. There lurks a monster black hole containing 4 million times the mass of the Sun packed into a region only 17 times the Sun's radius in size. We don't see this object directly, but we do see X-ray emission from somewhere near the black hole. We can also see nearby stars dancing through the gravitational field of this monster. Next door to this monster black hole is an object astronomers classify as a magnetar, an extreme type of neutron star with an incredibly strong magnetic field. This object was discovered in 2013 when astronomers were looking at the Galactic center in hopes of watching a cloud of gas fall into the supermassive black hole. As they watched, they saw a bright burst of X-ray radiation from this previously unsuspected magnetar. The magnetic fields of magnetars like this one are hundreds of millions of times stronger than any magnet ever created on earth, and so powerful they could wipe out all the information on the magnetic strip on every credit card on earth from half the distance to the moon. Astronomers have continued to keep their eye on this magnetic beast, and found something unusual: the X-ray emission produced by the outburst has not faded as astronomers expected. Could there be some strange connection between these extreme fields?
Published: July 30, 2018

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Page Author: Dr. Michael F. Corcoran
Last modified Monday, 06-Aug-2018 12:38:40 EDT