Observations by Chandra show extraordinary magnetar

Chandra studies extraordinary magnetar

This image contains an extraordinary magnetar, a type of neutron star with very powerful magnetic fields. Astronomers have found evidence that this object is the latest known magnetar (about 500 years old in Earth). It is also the fastest turn yet discovered (turns about 1.4 times per second). This image shows the X-ray magnetar of Chandra (purple) in the center of the image in combination with Spitzer and WISE infrared data showing the wider field of view. Magnetars form when a massive star’s nuclear fuel runs out and its core collapses. Credit: X-ray: NASA / CXC / Univ. of West Virginia / H. Blumer; Infrared (Spitzer and Wise): NASA / JPLCalTech / Spitzer

In 2020, astronomers added a new member to an exclusive family of exotic objects with the discovery of a magnetar. New observations from NASA’s Chandra X-ray Observatory support the idea that it is also a pulse, which means that it emits regular light pulses.

Magnetare is a kind of neutron star, an incredibly dense object consisting mainly of densely packed neutron, which is formed during a supernova from the folded core of a massive star.

What distinguishes magnetars from other neutron stars is that they also have the most powerful magnetic fields in the universe. For the context, the strength of our planet’s magnetic field has a value of about one Gauss, while a fridge magnet measures about 100 Gauss. Magnetars, on the other hand, have magnetic fields of about one million billion Gauss. If a magnetar were a sixth of the way to the Moon (about 40,000 miles), it would erase the data of all the credit cards on earth.

On March 12, 2020, astronomers detected a new magnetar with NASA’s Neil Gehrels Swift Telescope. It is only the 31st known magnetar, out of the approximately 3000 known neutron stars.

After follow-up observations, researchers determined that this object, named J1818.0-1607, was special for other reasons. First, it may be the latest known magnetar, with an age of about 500 years old. This is based on how fast the rotational speed slows down, and the assumption that it was born much faster. Second, it also rotates faster than any previously discovered magnetar, rotating every 1.4 seconds.






Chandra’s observations of J1818.0-1607 were obtained less than a month after the discovery with Swift, and gave astronomers the first high resolution of this object in X-rays. The Chandra data revealed a point source where the magnetar was located, which is surrounded by diffuse X-ray emission, probably caused by X-rays reflecting off dust in its vicinity. (Some of this diffuse X-ray emission may also come from winds blowing away from the neutron star.)

Harsha Blumer of the University of West Virginia and Samar Safi-Harb of the University of Manitoba in Canada recently published results from the Chandra observations of J1818.0-1607 in The Astrophysical Journal Letters.

This composite image contains a wide field of view in the infrared from two NASA missions, the Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (WISE), taken before the discovery of the magnetar. Chandra’s X-rays show the magnetar in purple. The magnetar is located near the level of the Milky Way galaxy, about 21,000 light-years from Earth.

Other astronomers also observed J1818.0-1607 with radio telescopes, such as the Karl Jansky Very Large Array (VLA) of the NSF, and determined that it emitted radio waves. This implies that it also has properties similar to those of a typical ‘rotation-driven pulsar’, a type of neutron star that emits radiation rays that are detected as repetitive emission pulses as they rotate and decelerate. Only five magnets, including these, have been recorded to act as pulsars, accounting for less than 0.2% of the known neutron star population.

The Chandra observations may also support this general idea. Safi-Harb and Blumer studied how efficiently J1818.0-1607 converts energy from its decreasing speed of rotation in X-rays. They concluded that this efficiency is lower than that typically found for magnetars, and probably within range for other rotation-driven pulses.

The explosion that created a magnetar of this era would be expected to leave a noticeable rubbish field. To search for this supernova remnant, Safi-Harb and Blumer looked at Chandra’s X-rays, Spitzer’s infrared data, and the VLA’s radio data. Based on the Spitzer and VLA data, they found possible evidence for a remnant, but at a relatively large distance from the magnetar. To cover this distance, the magnetar would have to move at a velocity much higher than that of the fastest known neutron stars, even assuming that it is much older than expected, which would allow more travel time.


Observations reveal dynamic magnetosphere of the magnetar Swift J1818.0-1607


More information:
Harsha Blumer et al. Chandra observations of the newly discovered Magnetar Swift J1818.0-1607, The Astrophysical Journal (2020). DOI: 10.3847 / 2041-8213 / abc6a2

Provided by Harvard-Smithsonian Center for Astrophysics

Quotation: Chandra’s observations reveal extraordinary magnetar (2021, January 8), accessed January 8, 2021 from https://phys.org/news/2021-01-chandra-reveal-extraordinary-magnetar.html

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