Magnetar SGR 0501+4516 is a neutron star that has an extremely powerful magnetic field. It is interesting enough in its own noticeable movement due to which the place of its birth remains definitively undetermined. A new study has only added more mystery to the story.
Strange magnetar SGR 0501+4516
Researchers using NASA’s Hubble Space Telescope have studied a magnetar called SGR 0501+4516 that is traveling through our galaxy, and the place of its formation remains unknown. Scientists say this runaway is the most likely candidate in the Milky Way galaxy for a neutron star that was not born from a supernova explosion, as previously thought. It is so strange that it may even provide clues to the mechanism of events known as fast radio bursts.
Neutron stars like SGR 0501+4516 have a magnetic field that is about a trillion times more powerful than Earth’s. If any of them flew past the Earth at half the distance of the Moon, its intense field would destroy every credit card on our planet. If a person were 600 miles away, the magnetar would turn into the proverbial sci-fi death ray that would tear every atom inside the body to shreds.
The magnetar’s awesomeness was discovered using sensitive instruments from the Hubble telescope, as well as precise benchmarks from the European Space Agency’s (ESA) Gaia spacecraft.
The mysterious magnetar was first discovered in 2008 when NASA’s Swift observatory detected short, intense bursts of gamma rays from around the Milky Way. The source, which turned out to be one of about 30 known magnetars in the Milky Way, was named SGR 0501+4516.
Magnetar’s position in the sky
Since magnetars are neutron stars, the natural explanation for their formation is that they are born in supernovae, when a star explodes and can collapse into a superdense object. This is evident in the case of SGR 0501+4516, which is close to a supernova remnant called HB9. The distance between the magnetar and the center of the supernova remnant in the sky is only 80 arcminutes, or a little wider than your little finger when viewed from the end of an outstretched hand.
But a decade-long study with Hubble has cast doubt on the birthplace of the magnetar. After first observations with ground-based telescopes shortly after the discovery of SGR 0501+4516, researchers used the sensitivity and stable pointing of the space telescope to spot the faint infrared glow of the magnetar in 2010, 2012, and 2020.
Each of these images was aligned to a frame of reference determined by observations from the Gaia spacecraft, which has created an extremely accurate three-dimensional map of nearly two billion stars in the Milky Way. This method made it possible to detect the subtle movement of the magnetar in the sky.
By tracking the position of the magnetar, the team was able to measure the apparent motion of the object across the sky. Both the velocity and direction of SGR 0501+4516 showed that the magnetar could not be associated with a nearby supernova remnant. Tracing the trajectory of the magnetar thousands of years into the past has shown that there are no other supernova remnants or massive star clusters to which it can be linked.
Origin of the magnetar SGR 0501+4516
If SGR 0501+4516 was not born in a supernova outburst, then the magnetar should either be more than 20,000 years old or it could have formed in another way. Magnetars can also form from the merger of two neutron stars of lower mass or in a process called accretion-induced collapse.
Accretion-induced collapse requires a binary star system containing a white dwarf, the core of a dead Sun-like star. If a white dwarf pulls in gas from its companion, it could become too massive to support itself, leading to an explosion — or possibly the formation of a magnetar.
“Normally, this scenario leads to the ignition of nuclear reactions, and the white dwarf exploding, leaving nothing behind. But it has been theorized that under certain conditions, the white dwarf can instead collapse into a neutron star. We think this might be how SGR 0501 was born,” added Andrew Levan of Radboud University in the Netherlands and the University of Warwick in the UK.
Understanding fast radio bursts
SGR 0501+4516 is currently the best candidate for a magnetar in our galaxy that may have formed by merger or accretion-induced collapse. Magnetars formed by accretion-induced collapse may provide an explanation for some of the mysterious fast radio bursts, which are short but powerful flashes of radio waves. In particular, this scenario may explain the origin of fast radio bursts that occur in stellar populations that are too old to have newly birthed stars massive enough to explode as supernovae.
“Magnetar birth rates and formation scenarios are among the most pressing questions in high-energy astrophysics, with implications for many of the universe’s most powerful transient events, such as gamma-ray bursts, superluminous supernovae, and fast radio bursts,” said Nanda Rea of the Institute of Space Sciences in Barcelona, Spain.
The research team is planning further Hubble observations to study the origin of other magnetars in the Milky Way, which will help us understand how these extreme magnetic objects form.
According to phys.org
