September 29, 2023

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Astronomers have discovered a mysterious stellar object that emits radio waves every 22 minutes

An artist’s impression of an extra long period magnet. Astronomers discovered the object using the Murchison Widefield Array (MWA), a radio telescope in Wajarri Yamaji Country in remote Western Australia. Credit: ICRAR

Researchers have discovered a new stellar object, potentially an extremely long-period magnetar, that challenges current understanding of neutron stars. Emitting radio waves every 22 minutes, the longest ever recorded, this object challenges current theories but offers promising insights into neutron star Physics and magnetic evolution. The team plans to research further, hoping to discover more of these unusual celestial bodies.

An international team led by astronomers from the Curtin University node of the International Center for Research in Radio Astronomy (ICRAR) have discovered a new type of stellar object that challenges our understanding of neutron star physics.

The object could be a very tall magnetar, which is a rare type of star with extremely strong magnetic fields that can produce powerful bursts of energy.

Until recently, all known magnetars released energy at intervals of a few seconds to a few minutes. The newly discovered object emits radio waves every 22 minutes, making it the longest magnetic period ever discovered.

The research was published July 19 in the journal nature.

An animation that describes the detection, the behavior of the object, and what it might look like. Credit: ICRAR

Observations and results

Astronomers discovered the object using the Murchison Widefield Array (MWA), a radio telescope in Wajarri Yamaji Country in remote Western Australia.

The magnetar, named GPM J1839−10, is 15,000 light-years from Earth in the constellation of Scutum, said lead author Dr. Natasha Hurley-Walker.

“This remarkable object challenges our understanding of neutron stars and magnetars, which are some of the most exotic and extreme objects in the universe,” she said.

The stellar body is only the second of its kind ever discovered after the discovery of the first by undergraduate student Tyrone O’Doherty at Curtin University.

The Murchison Widefield Array radio telescope monitors a long-range magnet

An artist’s impression of the Murchison Widefield Array radio telescope observing the magnetar star Very Long Period, 15,000 light-years from Earth in the constellation of Scutum. Credit: ICRAR

New Understanding of Magnets

At first, the scientific community was baffled by their discovery.

They published a paper in nature in January 2022 describes a mysterious transient object that appears and disappears sporadically, emitting powerful beams of energy three times an hour.

The first thing surprised us, said Dr Hurley Walker – O’Doherty’s honorary supervisor -.

“We were so confused,” she said. “So we started looking for similar objects to see if it was an isolated event or just the tip of the iceberg.”

Between July and September 2022, the team surveyed the sky with the MWA telescope. And they quickly found what they were looking for in GPM J1839−10. It emits bursts of energy that last up to five minutes – five times longer than the first object.

Composite Magnetar and Telecopes

The magnetar was discovered by the Murchison Widefield Array (MWA) radio telescope, with a host of other facilities around the world joining in to confirm the discovery and study the object. MeerKAT – Credit: South African Radio Astronomy Observatory (SARAO), Gran Telescopio Canarias – Credit: Daniel López / IAC, Murchison Widefield Array – Credit: Marianne Annereau, Giant Metrewave Radio Telescope – Credit: NCRA, Australian SKA Pathfinder – Credit: CSIRO / Dragonfly Media, Australia Very Large Array – Credit: AUI / NRAO, XMM-Newton – Credit: European Space Agency

Discovery confirmation

Other telescopes followed to confirm the discovery and learn more about the object’s unique properties.

These included three CSIRO radio telescopes in Australia, the MeerKAT radio telescope in South Africa, the Grantecan (GTC) 10 m telescope, and the XMM-Newton space telescope.

Armed with the celestial coordinates and their characteristics of GPM J1839−10, the team also began searching the observation archives of the world’s leading radio telescopes.

“It appeared in observations by the Giant Metrewave Radio Telescope (GMRT) in India, and the Very Large Array (VLA) in the US had observations going back to 1988,” she said.

“That was an amazing moment for me. I was five years old when our telescopes first recorded pulses from this object, but it went unnoticed, and it remained hidden in the data for 33 years.

“They missed it because they didn’t expect to find anything like it.”

The concept of magnetic art for a very long time

An artist’s impression of an extra long period magnet. The object has emitted a five-minute pulse of radio wavelength energy for at least 33 years. Credit: ICRAR

Challenge current paradigms

Not all magnetars produce radio waves. Some are below the “death line,” a critical threshold at which a star’s magnetic field becomes too weak to generate high-energy emissions.

“The object we detected is rotating very slowly to produce radio waves – it is below the death line,” said Dr. Hurley-Walker.

“Assuming it’s a magnetar, it shouldn’t be possible for this object to produce radio waves. But we do see them.

“And we’re not just talking about a tiny glimpse of a radio emission. Every 22 minutes, it emits a five-minute pulse of wavelength energy, and it’s been doing so for at least 33 years.

“Whatever the mechanism behind this is exceptional.”

Pawsey Supercomputing Research Center

The Pawsey Supercomputing Research Center was used to store and share the data used for this research. Credit: Pawsey Supercomputing Research Center

Looking forward to the future

This discovery has important implications for our understanding of the physics of neutron stars and the behavior of magnetic fields in extreme environments.

It also raises new questions about the formation and evolution of magnetism and could shed light on the origin of mysterious phenomena such as fast radio bursts.

The research team plans to make more observations of the magnetar to learn more about its properties and behaviour.

They also hope to discover more of these mysterious objects in the future, to determine if they are indeed magnets with very long periods, or even something more phenomenal.

Reference: “Long Range Radio Transient Active for Three Decades” by N. Hurley-Walker, N. Rea, SJ McSweeney, BW Meyers, E. Lenc, I. Heywood, SD Hyman, YP Men, TE Clarke, F. Coti Zelati, DC Price, C. Horváth, TJ Galvin, GE Anderson, A. cci, JS Morgan, KM Rajwade, B. Stappers and A. Williams, 1 July 9, 2023 nature.
DOI: 10.1038/s41586-023-06202-5

The MWA is a precursor to the world’s largest radio astronomy observatory, Square Kilometer Array, which is under construction in Australia and South Africa. MWA celebrates a significant milestone this year as it completes a decade of international scientific operations and discoveries.

The International Center for Radio Astronomy Research (ICRAR) is a joint project of Curtin University and the University of Western Australia with support and funding from the Western Australian State Government.

We acknowledge the Wajarri Yamaji as the traditional owners and original title holders of Inyarrimanha Ilgari Bundara, the site of the CSIRO Murchison Radio Astronomy Observatory where the Murchison Widefield Array is located.

The Pawsey Supercomputing Research Center in Perth – a Tier 1 funded national supercomputing facility – helped store and process the MWA observations used in this research.

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