Closest magnetar to Earth is exhibiting unprecedented behavior

Utilizing the Murriyang, CSIRO’s Parkes radio telescope, scientists have discovered extraordinary radio emissions activity from a magnetar, a star with a potent magnetic field, that had previously shown no activity.

Magnetars, a subset of neutron stars, are the universe’s most powerful magnets. This particular magnetar, known as XTE J1810-197, and situated about 8,000 light years away, is the nearest of its kind to our planet.

Unlike the polarized light typically emitted by most magnetars, the light from XTE J1810-197 is circularly polarized, creating a spiral pattern as it travels through the cosmos.

Unexpected signals

Lead author Marcus Lower, a postdoctoral fellow at CSIRO, described the magnetar activity as both unexpected and unparalleled.

“Unlike the radio signals we’ve seen from other magnetars, this one is emitting enormous amounts of rapidly changing circular polarization. We had never seen anything like this before.” 

Study co-author Manisha Caleb, an astrophysicist at the University of Sydney, pointed out the significance of studying magnetars for understanding the physics behind intense magnetic fields and the conditions they create.

“The signals emitted from this magnetar imply that interactions at the surface of the star are more complex than previous theoretical explanations,” said Caleb.

Possible explanations for this rare magnetar activity 

The occurrence of radio pulses from magnetars is a rare phenomenon; XTE J1810-197 is among the few known to produce them.

The team hypothesizes that a superheated plasma above the magnetar’s magnetic pole, behaving like a polarizing filter, might explain the unusual behavior, although the exact mechanism remains under investigation. ​

“Our model of the effect deviates from simple theoretical expectations for radio waves propagating through a magnetized plasma,” wrote the study authors. 

“Birefringent self-coupling between the transmitted wave modes, line-of-sight variations in the magnetic field direction and differences in particle charge or energy distributions above the magnetic pole are explored as possible explanations.” 

Detailed observation of magnetars 

XTE J1810-197’s radio emissions were initially detected in 2003, then ceased for over a decade before being picked up again in 2018 by the University of Manchester‘s 76-m Lovell telescope at Jodrell Bank Observatory, and subsequently by Murriyang.

Murriyang stands out for its advanced ultra-wide bandwidth receiver, engineered by CSIRO, which allows for the detailed observation of magnetars due to its sensitivity to changes in brightness and polarization across a wide range of radio frequencies.

This research into magnetars sheds light on various extreme and peculiar cosmic phenomena, including plasma dynamics, X-ray and gamma-ray bursts, and possibly even the origins of fast radio bursts.

More about magnetars

As discussed above, magnetars are a rare and fascinating type of neutron star that possess the strongest magnetic fields known in the cosmos.

These extraordinary objects form when massive stars collapse in supernova explosions, leaving behind incredibly dense cores composed almost entirely of neutrons.

Intense magnetic fields

Magnetars boast magnetic fields that reach a staggering 10^15 gauss, which is a quadrillion times stronger than the Earth’s magnetic field.

These powerful fields cause the surface of the magnetar to crack and shift, creating starquakes that release tremendous amounts of energy in the form of gamma rays and X-rays.

Magnetars are rare and elusive

Astronomers estimate that only about one in ten supernova explosions produce a magnetar. This rarity, combined with their relatively short lifespans of approximately 10,000 years, makes magnetars difficult to detect and study.

However, advancements in technology and space-based observatories have allowed scientists to identify and observe these elusive objects more effectively.

Extreme conditions and potential hazards

The extreme magnetic fields of magnetars give rise to unique and fascinating phenomena. They can slow down the rotation of the star, causing it to spin once every few seconds to every few minutes.

Additionally, the intense fields can generate powerful currents in the magnetar’s crust, causing it to heat up to temperatures of over a billion degrees Celsius.

Despite their distance from Earth, magnetars pose a potential threat to our planet. If a magnetar were to experience a starquake within a few thousand light-years of Earth, the intense gamma-ray burst could disrupt our atmosphere, causing widespread damage to power grids and satellite communications.

Continued research on the horizon

Scientists continue to study magnetars to better understand their properties, formation, and the extreme physics at play within these objects.

By unraveling the mysteries of magnetars, researchers hope to gain new insights into the fundamental forces that shape our universe and the life cycles of stars.

As our knowledge of these fascinating objects grows, magnetars continue to captivate the scientific community and the public alike, reminding us of the awe-inspiring wonders that exist in the vast expanse of the cosmos.

The study is published in the journal Nature Astronomy.

Video/ Image Credit: CSIRO

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