Canberra/Bonn After a decade of silence, one of the most powerful magnets in the universe suddenly came back to life in late 2018. The reawakening of this "magnetar", a city-sized star named XTE J1810-197 that was born from a supernova explosion, was an incredibly violent affair.
The breaking and unraveling of entangled magnetic fields releases enormous amounts of energy in the form of gamma rays, X-rays and radio waves.
By capturing such magnetar bursts in action, astronomers are beginning to understand what causes their erratic behavior. We're also looking for potential links to the mysterious flashes of radio light seen from distant galaxies, called fast radio bursts.In two new pieces of research published in Nature Astronomy, we used three of the world's largest radio telescopes to capture in unprecedented detail never-before-seen changes in the radio waves emitted by one of these rare objects.
Magnetic monsters Magnetars are young neutron stars, whose magnetic fields are billions of times stronger than our most powerful Earth-based magnets. The slow decay of their magnetic fields creates enormous amounts of stress in their hard outer crust until it eventually cracks. It bends the magnetic field and releases large amounts of energetic X-rays and gamma rays when released.
These alien stars were initially discovered in 1979 when an intense gamma-ray burst emitted from a star was picked up by spacecraft in the Sola system.Since then, we have found 30 other magnetars, most of which have been detected only as sources of X-rays and gamma rays. However, a rare Fe has since also been found emitting radio wave flashes. The first of these "radio-loud" magnetars is known as Discovered it as a bright source of X-rays, then discovered that it emitted bright pulses of radio waves whenever I turned around every 5.54. sec.
Unfortunately, the intensity of the radio pulse decreased rapidly, and within two years it disappeared completely from sight. The XTE J1810-197 remained in this absolutely cool state for over a decade.A Faltering Start On December 11, 2018, astronomers using the University of Manchester's 76-meter Lowell Telescope at Jodrell Bank Observatory noticed that XTE J1810-197 was once again emitting bright radio pulses. This was quickly confirmed by both the 100-metre Effelsberg Radio Telescope of the Max-Planck-Institute in Germany and the 64-metre Parkes Radio Telescope of Murrian, CSIRO, in Australia.
Following confirmation, the three telescopes began an intensive campaign to explore how the magnetar's radio emissions evolved over time. The reactivated radio pulses from XTE J1810-197 were found to be highly linearly polarized, either up or down , appear to rotate from left to right, or a combination of both. Careful measurement of the polarization direction allowed us to determine how the magnet's magnetic field and spin direction are oriented with respect to the Earth.Our diligent tracking of the polarization direction revealed something remarkable: The star's direction of rotation was gradually wobbly. By comparing the measured wobble against the simulation, we were able to determine that the surface of the magnetar had become slightly lumpy due to the explosion.
The volume of the lump was very small, only a millimeter away from the full sphere, and it gradually disappeared within three months of XTE J1810-91 waking up.Twisted Light
Normally, magnetars emit only very small amounts of circularly polarized Radi waves, which travel in a spiral pattern. Unusually, we detected a large amount of circular polarization in XTE J1810-197 during the 2018 outburst.Our observations with Muriang revealed that normally linearly polarized Radi waves were converting into circularly polarized waves.
This "linear-to-spherical transformation" was long predicted to occur when Radi waves travel through the super-hot soup of particles that reside in neutron star magnetic fields.
However, theoretical predictions for how the effect should change with observation frequency did not match our observations, although we were not surprised. The environment around the magnetar in an explosion is a complex place and there can be many effects that have not been modeled with this relatively simple theory in mind. Tying it all together
The discovery of slight fluctuations and circular polarization in the radiative emission of XTE J1810-197 represents an exciting leap forward in how we can study the outbursts of radio-loud magnetars.It also paints a more complete picture of the 2018 outburst. We now know that the rupture of the magnetar's surface caused it to deform and wobble for a short time, while the magnetic field became filled with super-hot particles rotating at almost the speed of light. goes.
Combined with other observations, the amount of wobble can be used to test our theories about how matter should behave at much higher densities than can be replicated in laboratories on Earth. The inconsistency of the linear-to-circular conversion with theory, on the other hand, prompts us to formulate a more comprehensive idea of how radio waves escape their magnetic fields.
What's next? While XTE J1810-197 is still active today, it has since settled into a more relaxed state and shows no signs of wobble or linear-to-circular conversion.However there are indications that both phenomena may have been observed before observations of other radio-loud magnetars, and may be a common feature of their outbursts.
Like cats, it's impossible to predict what Magnetar will do next. But with current and future upgrades to telescopes in Australia, Germany and North America, we are now more prepared than ever to pounce the next time it decides to wake up.(talk) NSANSA
The breaking and unraveling of entangled magnetic fields releases enormous amounts of energy in the form of gamma rays, X-rays and radio waves.
By capturing such magnetar bursts in action, astronomers are beginning to understand what causes their erratic behavior. We're also looking for potential links to the mysterious flashes of radio light seen from distant galaxies, called fast radio bursts.In two new pieces of research published in Nature Astronomy, we used three of the world's largest radio telescopes to capture in unprecedented detail never-before-seen changes in the radio waves emitted by one of these rare objects.
Magnetic monsters Magnetars are young neutron stars, whose magnetic fields are billions of times stronger than our most powerful Earth-based magnets. The slow decay of their magnetic fields creates enormous amounts of stress in their hard outer crust until it eventually cracks. It bends the magnetic field and releases large amounts of energetic X-rays and gamma rays when released.
These alien stars were initially discovered in 1979 when an intense gamma-ray burst emitted from a star was picked up by spacecraft in the Sola system.Since then, we have found 30 other magnetars, most of which have been detected only as sources of X-rays and gamma rays. However, a rare Fe has since also been found emitting radio wave flashes. The first of these "radio-loud" magnetars is known as Discovered it as a bright source of X-rays, then discovered that it emitted bright pulses of radio waves whenever I turned around every 5.54. sec.
Unfortunately, the intensity of the radio pulse decreased rapidly, and within two years it disappeared completely from sight. The XTE J1810-197 remained in this absolutely cool state for over a decade.A Faltering Start On December 11, 2018, astronomers using the University of Manchester's 76-meter Lowell Telescope at Jodrell Bank Observatory noticed that XTE J1810-197 was once again emitting bright radio pulses. This was quickly confirmed by both the 100-metre Effelsberg Radio Telescope of the Max-Planck-Institute in Germany and the 64-metre Parkes Radio Telescope of Murrian, CSIRO, in Australia.
Following confirmation, the three telescopes began an intensive campaign to explore how the magnetar's radio emissions evolved over time. The reactivated radio pulses from XTE J1810-197 were found to be highly linearly polarized, either up or down , appear to rotate from left to right, or a combination of both. Careful measurement of the polarization direction allowed us to determine how the magnet's magnetic field and spin direction are oriented with respect to the Earth.Our diligent tracking of the polarization direction revealed something remarkable: The star's direction of rotation was gradually wobbly. By comparing the measured wobble against the simulation, we were able to determine that the surface of the magnetar had become slightly lumpy due to the explosion.
The volume of the lump was very small, only a millimeter away from the full sphere, and it gradually disappeared within three months of XTE J1810-91 waking up.Twisted Light
Normally, magnetars emit only very small amounts of circularly polarized Radi waves, which travel in a spiral pattern. Unusually, we detected a large amount of circular polarization in XTE J1810-197 during the 2018 outburst.Our observations with Muriang revealed that normally linearly polarized Radi waves were converting into circularly polarized waves.
This "linear-to-spherical transformation" was long predicted to occur when Radi waves travel through the super-hot soup of particles that reside in neutron star magnetic fields.
However, theoretical predictions for how the effect should change with observation frequency did not match our observations, although we were not surprised. The environment around the magnetar in an explosion is a complex place and there can be many effects that have not been modeled with this relatively simple theory in mind. Tying it all together
The discovery of slight fluctuations and circular polarization in the radiative emission of XTE J1810-197 represents an exciting leap forward in how we can study the outbursts of radio-loud magnetars.It also paints a more complete picture of the 2018 outburst. We now know that the rupture of the magnetar's surface caused it to deform and wobble for a short time, while the magnetic field became filled with super-hot particles rotating at almost the speed of light. goes.
Combined with other observations, the amount of wobble can be used to test our theories about how matter should behave at much higher densities than can be replicated in laboratories on Earth. The inconsistency of the linear-to-circular conversion with theory, on the other hand, prompts us to formulate a more comprehensive idea of how radio waves escape their magnetic fields.
What's next? While XTE J1810-197 is still active today, it has since settled into a more relaxed state and shows no signs of wobble or linear-to-circular conversion.However there are indications that both phenomena may have been observed before observations of other radio-loud magnetars, and may be a common feature of their outbursts.
Like cats, it's impossible to predict what Magnetar will do next. But with current and future upgrades to telescopes in Australia, Germany and North America, we are now more prepared than ever to pounce the next time it decides to wake up.(talk) NSANSA
