Astronomers found the youngest and fastest spinning magnetar ever detected

In 2020, astronomers detected an exotic cosmic object known as a magnetar. Further investigations through NASA Chandra X-ray Observatory tells us the magnetar is also a pulsar. Let us learn about Neutron stars, pulsars, magnetars and what the recent study implies.

Neutron stars, Magnetars and Pulsars:

What are Neutron stars?

Neutron stars are one of the most extraordinary and violent things in the universe.

Almost like black holes, Neutron stars form when a massive star over eight times the mass of our sun star runs out of fuel and collapses under its gravity. When the central core of the star collapses, it squeezes together with an enormous, titanic force. The pressure involved is immense; it crushes even the subatomic particle, such as protons and electrons, forming neutrons. These newly formed neutrons stop any further gravitational collapse and give birth to a neutron star.

But Neutron stars form only when the disintegrating star core is somewhere around 1 and 3 solar masses. Stars with core masses more than that will continue their collapse giving birth to stellar-mass black holes.

There are many neutron stars found scattered throughout our galaxy. But they are quiet and mostly go undetected because they barely emit enough radiation to make it to our telescopes.

But we find the absolute best kind of neutron stars in binary star systems. They spread out energy as gravitational waves, ripples in spacetime, their orbits can collapse, and they can crash into and kill each other in a kilonova explosion that spews out their guts.

When they do, the conditions become so extreme that, for a moment, they make heavy nuclei again. The heavy neutron-rich matter falls apart and reassembles into heavier elements.

These explosions are probably the origin of most of the heavy elements in the universe,

like gold, silver, uranium, platinum, and much more.

Magnetars and pulsars are the commonly existing types of neutron stars types which we can detect.

What are pulsars?

Pulsars are the most widely detectable neutron stars. Pulsars are neutron stars that rotate. As their name suggests, pulsars emit pulses of radiation at somewhat regular intervals. When neutron stars first collapse, they spin very rapidly, like an ultra-high-speed top.

Pulsars have a potent magnetic field because of the density of matter present in them. The region surrounding the pulsar dominated by its magnetic field is the magnetosphere.

When charged particles like electrons and protons, or atoms pass near the magnetosphere, they speed up to extraordinarily high velocities. When charged particles accelerate, they radiate light. This process causes the magnetosphere of the pulsar generates light in the optical and X-ray range. Neutron stars that give off long-lasting radio beams are the radio pulsars.

What are Magnetars?

Magnetars are neutron stars with tremendously strong magnetic fields. When compared to earth, their magnetic fields are quadrillion times stronger. This magnetic field generates a pressure that disrupts the stellar surface resulting in starquakes. These disruptions release bursts of X-rays and gamma rays we can observe through our devices on earth. There are currently 30 magnetars known in our galaxy and the Magellanic Clouds.

NASA's Chandra X-ray Observatory's recent discovery:

On March 12, 2020, the NASA Neil Gehrels Swift Telescope detected a new magnetar; this is the 31st magnetar observed among the 3000 known neutron stars.

After follow-up observations, researchers named it Swift J1818.0-1607. The Swift mission found J1818.0−1607 when it took off its peak activity. In this stage, its X-ray radiation became ten times brighter than usual. These outbursting events mostly start with a rapid increase in brightness over days or weeks, then declines as the magnetar returns to its normal brightness range.

Astronomers must act fast if they want to observe peak activity from one of these rare stars. The Swift mission alerted the global astronomy community, XMM-Newton and NuSTAR performed quick studies.

Magnetars not only emit X-rays but also release magnificent bursts of gamma rays and can also emit steady beams of radio waves. (Gamma rays are the high-energy form of light in the universe and radio waves are the lowest energy form of light in the universe)

Neutron stars, or cores leftover from exploded stars, are some of the densest objects in the universe. There are several types of neutron stars, including magnetars and pulsars.  NuSTAR is a Small Explorer mission led by Caltech in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington
Different Types of Neutron Stars :Image credit: NASA/JPL-Caltech

What is special about magnetar Swift J1818.0-1607?

Chandra’s observations of J1818.0-1607 gave astronomers the first high-resolution view of this object in X-rays. The magnetar is at a distance of about 21,000 light-years from earth. The following facts are its special features,

  1. It is the youngest known magnetar. Astronomers have estimated its age to be about 500 years old.

  2. Second, it also spins faster than any known magnetar. The rotation takes place at the rate of once every 1.4 seconds.

  3. Astronomers have also observed J1818.0-1607 with radio telescopes and discovered that it gives off radio waves as well. J1818.0-1607 also has properties similar to that of a slowed down radio pulsar. Less than 0.2% of the known magnetar population also act like pulsars.

  4. The explosion that created a magnetar of this age would have left behind visible debris. But scientists have found potential evidence for a remnant at an enormous distance away from the magnetar. In order to cover this distance, the magnetar would need to have travelled at speeds far exceeding those of the fastest known neutron stars.

Chandra’s observations in less than a month after the discovery with Swift has given astronomers the first-ever high-resolution image of this magnetar in X-rays. Diffuse X-ray emission surrounds the point of detection. This effect is possibly caused by X-rays bouncing off dust in the star's vicinity. The emission may again be from the winds rushing off the neutron star itself.

The below composite image comprises a wide field of view using infrared observations from the Spitzer Space Telescope and the Wide-Field Infrared Survey Explorer (WISE), taken before the magnetar’s discovery. X-rays from Chandra highlights the magnetar in purple for visibility.

Read more from NASA's Chandra X-ray Observatory.

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