Buzz
Gamma-ray bursts, like those emitted by SGR J1550-5418, could result from sudden fractures on a magnetar's surface, releasing energy trapped in its immense magnetic field. NASA/Goddard Space Flight Center Conceptual Image LabOur understanding of the universe continues to grow, mirroring the universe's own expansion. This often leads to new discoveries or revised theories to explain previously puzzling data. Among these phenomena are magnetars, a highly magnetic type of neutron star first theorized in 1979. That year, scientists proposed that intense bursts of gamma rays, X-rays, and radio waves could be attributed to stars with extraordinarily strong magnetic fields.
Over the years, astronomers have detected numerous magnetars within and near the Milky Way. If you're wondering what magnetars are, how they form, and why they are regarded as some of the most terrifying objects in the cosmos, keep reading.
How Magnetars Are Born
Just like everything else in the cosmos, stars undergo a life cycle. The fate of a star at the end of its life is determined by its mass. For instance, our sun is predicted to expand into a red giant, later transforming into a planetary nebula, and eventually settling as a white dwarf. Heavier stars, however, may swell into supergiants, explode as supernovae, and ultimately evolve into either neutron stars or black holes.
Magnetars are the remnants of massive stars that have exploded as supernovae and collapsed into neutron stars. While the exact reason why some supernovae produce magnetars instead of ordinary neutron stars or pulsars remains unclear, some theories suggest it may be linked to the original star's rotational velocity.
Magnetars are neutron stars with magnetic fields ranging from approximately 1013 to 1015 Gauss (a unit measuring magnetic density). This level of magnetic strength is almost unimaginable, but suffice it to say that magnetars are recognized as the most magnetic objects in the observable universe.
Magnetars in the Milky Way
Researchers have identified 23 confirmed magnetars, with an additional six candidates awaiting further data to determine if they qualify as magnetars. Most of these are situated within the Milky Way, but rest assured: none are in close proximity to Earth.
Among the magnetars relatively near Earth are AXP 1E 1048-59, positioned approximately 9,000 light-years away in the Carina constellation; SGR 1900+14, located 20,000 light-years distant in Aquila; SGR 1806−20, found 50,000 light-years away in Sagittarius; and SGR 0525−66, situated 165,000 light-years away in the Large Magellanic Cloud (just beyond the Milky Way). These vast distances far exceed any region humanity has explored or reached with probes like Voyager 1 or 2.
This artistic depiction illustrates the magnetar within the star cluster Westerlund 1, home to hundreds of extremely massive stars, some radiating nearly a million times the brightness of our sun. European Southern Observatory (ESO)/Wikimedia Commons (CC BY 4.0)Magnetars vs. Black Holes
Black holes often dominate the news – and for good reason, as they’re not something we’d want near Earth. But how do they compare to magnetars, the universe’s most powerful magnets? Phil Plait, an astronomer known as Bad Astronomer, explains via email that the answer depends on which force you’re evaluating.
"The gravitational pull of a black hole will always be stronger, since even the smallest black hole outweighs the heaviest neutron star," Plait states. "[However,] the magnetic force of a magnetar will generally be more intense."
Fortunately, we won’t face the threat of a black hole or magnetar near Earth, though both could theoretically influence our planet. "If a stellar-mass black hole consumes matter, it might emit radiation, but even then, I doubt it would be as impactful as the 2004 magnetar event," Plait notes, referencing the enormous gamma and X-ray burst that swept past Earth that year, disrupting satellite technology and causing other disturbances.
While magnetars might not outmatch black holes in a cosmic showdown, their power is still significant enough to impact Earth, making them worthy of attention whenever they make headlines.
Do We Need to Fear Magnetars?
Many astronomers consider magnetars to be some of the most terrifying objects in the galaxy. While you wouldn’t want to be near one, their colossal energy bursts can still affect Earth despite their vast distances. "I’m concerned about magnetars, especially after the 2004 event," Plait remarks. "[SGR 1806-20] is extraordinarily powerful. I don’t believe any stronger ones are closer [to Earth], but the effect on Earth increases with the inverse square of the distance. If one were just one-fifth as far, the impact would be 25 times greater."
As astronomer Paul Sutter explains in his 2015 Space.com article titled "Why Magnetars Should Freak You Out," a powerful magnetar pulse wouldn’t just disrupt our electronics and technology – it could also interfere with our physiology, including the bioelectricity in our bodies and the atomic structures of everything around us. Thankfully, the closest known magnetar is 9,000 light-years away, which is something we can all be grateful for.
Although the stellar process that leads to the formation of a magnetar can span millions or even billions of years, magnetars themselves have a relatively brief cosmic lifespan. Their magnetic fields start to weaken after about 10,000 years. This means the magnetars observable in our galaxy today represent only a fraction of those that have ever existed; scientists estimate there could be up to 30 million dormant magnetars in the Milky Way alone.
