A Magnetar’s Unexpected Origins Add New Depth to a Cosmic Mystery

On the edge of our galaxy, one of the universe’s rarest stellar objects just became even more puzzling.Using data from the Hubble Space Telescope and the Gaia observatory, astronomers examined the environment around SGR 0501+4516, a magnetar — a highly magnetized type of neutron star. Their findings suggest that our current understanding of how magnetars form might be off the mark. In fact, the theory once believed to explain their origin appears unrelated to this particular object.

The surprising results raise fresh doubts about long-standing ideas regarding magnetar formation.

What Makes Magnetars So Unique

Neutron stars themselves are incredibly dense — second only to black holes — and are typically born from the explosive collapse of massive stars, a process known as a core-collapse supernova. Magnetars follow this same basic formation path, but with a twist: their magnetic fields are the strongest in the known universe — up to a quadrillion times more powerful than Earth’s magnetic field and significantly stronger than that of standard neutron stars.

Though scientists have assumed that magnetars must also form from core-collapse supernovae, SGR 0501+4516 seemed to support that assumption — until now.

Located close to a supernova remnant called HB9, SGR 0501+4516 was thought to have originated from the same stellar explosion, especially since no other neutron stars are known to exist near HB9. It seemed a reasonable connection.

A New Perspective From Hubble and Gaia

But recent data from Hubble, guided by Gaia’s precise measurements of stellar positions and motion, suggests otherwise.

A research team led by Ashley Chrimes of the European Space Agency tracked SGR 0501+4516’s movement through space and discovered that its velocity and trajectory do not match any link to HB9. And with no other remnants in the vicinity, astronomers are now reconsidering everything they thought they knew about this object’s birth.

This leads to two possibilities.

One is that SGR 0501+4516 is much older than previously believed — old enough that the remnants of its supernova have dissipated over time. The challenge with this idea is that magnetars are thought to be a short-lived phase in a neutron star’s life, lasting only tens of thousands of years before their intense activity wanes.

The other, more intriguing idea is that this magnetar didn’t form from a traditional supernova at all. Instead, it may have originated from the merger of two small neutron stars — or even from the collapse of a white dwarf, a dense remnant of a lower-mass star.

White dwarfs often exist in binary systems and can gain mass from their companion stars. When they gather too much material, they typically ignite in a thermonuclear explosion, leaving nothing behind. But some theories suggest that under specific conditions, a white dwarf could collapse into a neutron star rather than explode — a possible explanation for SGR 0501+4516’s unusual nature.

“This may be how SGR 0501 formed,” says Andrew Levan, an astronomer at Radboud University and the University of Warwick.

A Game-Changing Discovery

Although the exact origin remains unclear, the evidence now strongly suggests that a core-collapse supernova is not responsible for this magnetar — making it the most compelling example among the fewer than 30 known magnetars in the Milky Way to support an alternative formation process.

And that’s a fascinating revelation.

Understanding how magnetars form is one of the big questions in high-energy astrophysics,” says Nanda Rea of the Institute of Space Sciences in Spain. “It has major implications for our understanding of extreme cosmic events, like gamma-ray bursts, unusually bright supernovae, and fast radio bursts.

Read the original article on: Science Alert

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