Tag Archives: magnetar

Spooky “transient” object detected in our galactic neighborhood

Astronomers from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Australia have found something unlike anything previously seen. Researchers suspect it could be a completely new type of star.

Artists depiction of what the unknown object might look like. (Credit: ICRAR)

A team mapping radio waves in the cosmos has discovered something unusual that releases a giant burst of energy every 18 minutes. They believe it could be a neutron star or white dwarf with an insanely strong magnetic field — something that hasn’t been observed until now (and researchers weren’t even sure can exist).

“This object was appearing and disappearing over a few hours during our observations,” said Natasha Hurley-Walker, who led the team that made the discovery. “That was completely unexpected. It was kind of spooky for an astronomer because there’s nothing known in the sky that does that.”

The object in question lies only 4,000 light-years away — technically far away, but still in our galactic neighborhood. It was discovered using the Murchison Widefield Array (MWA) telescope in outback Western Australia. The MWA’s wild field of view made it perfect for detecting the unorthodox object. But even equipped with this tool, it was challenging to find it.

These strange patterns of behavior which can’t be physically observed are called ‘transients’. But no transient like this one has been discovered so far.

‘Slow transients’, such as supernovae, can appear over the course of a few days and disappear after a few months. The other side of the spectrum are ‘fast transients’, such as a pulsar. These flash on and off within milliseconds or seconds.

However, discovering something that illuminated for only a minute didn’t seem to fit with either of those. The new mysterious object was incredibly bright and smaller than the Sun, emitting highly-polarized radio waves, suggesting the entity had an extremely strong magnetic field.

Hurley-Walker said the observations match a predicted astrophysical object called an ‘ultra-long period magnetar’ — a magnetar being an exotic type of neutron star with an extremely powerful magnetic field. So far, it’s only been something thought to exist, but never actually observed.

“It’s a type of slowly spinning neutron star that has been predicted to exist theoretically,” she said. “But nobody expected to directly detect one like this because we didn’t expect them to be so bright. Somehow it’s converting magnetic energy to radio waves much more effectively than anything we’ve seen before. More detections will tell astronomers whether this was a rare one-off event or a vast new population we’d never noticed before.”

The study was published in Nature.

Astronomers detect magnetic star flashing in an instant with the energy produced by the sun in 100,000 years

Artist impression of the GRB 2001415 magnetar. Credit: Universitat de València.

Sure we might have enormous gas giants and menacing asteroids, but compared to other corners of the universe, our solar system is pretty vanilla. There are black holes whose mass exceeds billions of solar masses, generating a gravitational pull so intense that they shape the formation and evolution of entire galaxies. Then there are magnetars, much less famous than black holes but incredibly powerful in their own right. Case in point, astronomers in Spain have witnessed such an object erupt with as much energy as the sun produces in 100,000 years, concentrating it in just 0.1 seconds.

When truly massive stars die, they do so with a bang, triggering a supernova explosion. In the aftermath, some collapse under their own weight, forming into black holes. Those that don’t make the cut, often become neutron stars, second only to black holes in their stupendous density. A teaspoon of neutron star material would weigh around a billion tons, for instance.

There are multiple types of neutron stars, including magnetars. These objects have extremely powerful magnetic fields, a thousand trillion times stronger than the Earth’s, and between 100 and 1,000 times stronger than that of a radio pulsar. They’re essentially the most powerful magnets in the universe.

Magnetars are quite rare, with only a couple dozen such objects having been identified so far. One of them, located in the Sculptor Galaxy about 13 million light-years away, was under observation by astronomers using the Atmosphere-Space Interactions Monitor (ASIM) aboard the International Space Station when a giant flare was detected.

The flare, known as the GRB 2001415 event, released roughly the energy the sun radiates in about 100,000 years in just two short quasi-periodic pulsations that lasted approximately 160 milliseconds.

“Even in an inactive state, magnetars can be one hundred thousand times more luminous than our Sun, but in the case of GRB 2001415, the energy that was released is equivalent to that which our Sun radiates in 100,000 years,” said Dr. Alberto Castro-Tirado, an astrophysicist with the Instituto de Astrofísica de Andalucía del Consejo Superior de Investigaciones Científicas (IAA-CSIC) and the Universidad de Málaga. “It’s a true cosmic monster,” added Professor Víctor Reglero, an astrophysicist at the Universitat de València and co-author of the new study.

The magnetar explosion was detected on April 15, 2020 thanks to an artificial intelligence system integrated with ASIM. If this kind of system wasn’t in place, the astronomers would have been oblivious to the event, whose signal decayed into background noise within a fraction of a second.

No one’s really sure what triggered the eruption, but the researchers believe it could have been due to instabilities in the magnetosphere or ‘earthquakes’ produced in their crust. Further research could help scientists reveal the mechanisms that trigger these frightening but, at the same time, fascinating cosmic burps.

“Although these eruptions had already been detected in two of the thirty known magnetars in our Galaxy and in some other nearby galaxies, GRB 2001415 would be the most distant magnetar eruption captured to date, being in the Sculptor group of galaxies about 11 million light-years,” said Professor Reglero.

“Seen in perspective, it has been as if the magnetar wanted to indicate its existence to us from its cosmic solitude, singing in the kHz with the force of a Pavarotti of a billion suns.”

The findings appeared in the journal Nature.

Astronomers may have discovered a new cosmic phenomena — and we don’t really know what it is

Two mysterious objects which erupted into dramatic X-ray bursts have been detected, and astronomers are hard at work trying to understand just what they are.

Galaxy NGC 5128, with the flaring object highlighted in the square. Image credits NASA / J.Irwin et al. 2016

University of Alabama astronomer Jimmy Irwin set out to look for unusual X-ray activity following the detection of an extremely bright flaring near the NGC 4697 galaxy. The flaring took place in 2005, but nobody had any idea what caused it. So Irwin and his team set to work on finding similar phenomena by shifting through archival data collected by NASA’s Chandra Observatory recording 70 different galaxies. The team found two X-ray sources in two different galaxies that might be the same thing as the mysterious NGC source.

At their peak emissions, these objects qualify as ultraluminous X-ray sources (ULX). However, their flaring behavior doesn’t resemble anything we’ve seen up to now, leaving astronomers quite baffled.

“We’ve never seen anything like this,” says astronomer Jimmy Irwin from the University of Alabama. “Astronomers have seen many different objects that flare up, but these may be examples of an entirely new phenomenon.”

The first object was found near NGC 4636, roughly 47 million light-years away from us, and flared in February of 2003. The second one, which was captured five times between 2007 and 2014, is found near galaxy NGC 5128, only 14 million light-years from Earth.

While that could make it sound that the flares take place only rarely, it may not necessarily be the case. Since Chandra has had a limited amount of time to look at each galaxy, these events could be taking place much more frequently, and we’d have no way of knowing about them. They could go off every day, and we’d have no idea.

“These flares are extraordinary,” says co-author Peter Maksym from the Harvard-Smithsonian Centre for Astrophysics. “For a brief period, one of the sources became one of the brightest ULX to ever be seen in an elliptical galaxy.”

The most similar activity to these flarings come from magnetars, young neutron stars with hugely powerful magnetic fields. When these “pop”, however, the X-rays decline in just a few seconds after the burst. These mysterious sources build-up more slowly, taking about a minute to peak, then taking about an hour to decline. From what we know to date, the phenomena seems to originate from normal binary systems, which are composed of a black hole or neutron star accompanied by a regular star just like our Sun. Whatever their source may be, the bursts don’t seem to disrupt the systems in which the sources are located.

So while we don’t know for sure what causes these bursts, astronomers have advanced a few theories. It’s possible that the X-rays are generated by matter being sucked from the companion star into the black hole or neutron star. Whatever the case may be, scientists are now eager to get to the bottom of the truth — especially since the NGC 4697 outbursts don’t seem to have been a fluke.

“Now that we’ve discovered these flaring objects, observational astronomers and theorists alike are going to be working hard to figure out what’s happening,” says Gregory Sivakoff from the University of Alberta.

The full paper titled “Ultraluminous X-ray bursts in two ultracompact companions to nearby elliptical galaxies” was published in the journal Nature.

Astronomers detect biggest explosion we’ve seen

The phenomenon was observed for the first time in June, but it’s still radiating massive amounts of energy, making it shine 570 billion times stronger than our Sun.

An artist’s impression of the record-breakingly powerful, superluminous supernova ASASSN-15lh as it would appear from an exoplanet located about 10,000 light years away in the host galaxy of the supernova. (Credit: Beijing Planetarium / Jin Ma)

Astronomers believe that at the core of this explosion lies a magnetar – a neutron star with an extremely powerful magnetic field. The object itself is not large, being about as big as London, but it’s spinning at incredibly fast rates – in order for this effect to take place, it would have to spin at least 1000 times a second! With this, it could spur an incredibly powerful supernova.

Prof Christopher Kochanek, from The Ohio State University, US and a member of the discovery team explains how magnetars can supercharge supernovas:

“The idea is that this thing at the centre is very compact. It’s probably about the mass of our Sun, and the garbage into which it is dumping its energy is about five to six times the mass of our Sun, and expanding outwards at a rate of, let’s say, 10,000km/s.
“The trick in getting the supernova to last a long time is to keep dumping energy into this expanding garbage for as long as you can. That’s how you get maximum bang for your buck,” he said this week.

Indeed, there is a lot of bang for the buck – at its peak, the explosion was 200 times more powerful than the average supernova.

The explosion (SASSN-15lh) was spotted some 3.8 billion light-years from Earth, in a quite distant part of the Universe. The team used the All Sky Automated Survey for SuperNovae (ASAS-SN), a suite of Nikon long lenses in Cerro Tololo, Chile that sweeps the night sky for sudden explosions. Of course, it couldn’t miss one of this caliber.

“ASASSN-15lh is the most powerful supernova discovered in human history,” said study lead author Subo Dong, an astronomer and a Youth Qianren Research Professor at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University. “The explosion’s mechanism and power source remain shrouded in mystery because all known theories meet serious challenges in explaining the immense amount of energy ASASSN-15lh has radiated.”

In fact, it’s so big that we might actually have to rethink some of the things we thought we knew about the Universe.

“If it really is a magnetar, it’s as if nature took everything we know about magnetars and turned it up to 11,” Stanek said. (For those not familiar with the comedy, the statement basically translates to “11 on a scale of 1 to 10.”).

Thankfully, the Hubble telescope will help us answer these questions, as it will turn its eyes on the host galaxy surrounding the object. If we realize that this object lies in the center of the galaxy, then it’s a pretty clear indication that it isn’t a magnetar at all, but rather a supermassive black hole, accompanied by a never-before-seen phenomenon.

 

Astronomers observe spinning neutron star suddenly slowing down

In a never-before seen feat, astronomers using NASA’s Swift X-ray Telescope have observed a spinning neutron star suddenly slowing down, something which can provide valuable clues to understanding these mysterious objects.

Neutron stars

neutron star

Neutron stars are the cores of former high-mass stars, the remains of supernovae after the blow-up. As the core of the massive star is compressed during a supernova, and collapses into a neutron star, it retains most of its angular momentum. However, since it only has a small fraction of its original mass and radius, a neutron star is formed with very high rotation speed, and then gradually slows down; we’re talking about massive speeds, some neutron stars have been known to have rotation periods from about 1.4 ms to 30 seconds.

They emit a beam of radiation as it spins, and this can make it look like a blinking pulsar to us, which has a very precise period. By analyzing that blink, astrophysicists can analyze how the neutron star is rotating.

However, some neutron stars, like the one in case, have a much stronger magnetic field than most, and they spin slower.

A surprising observation

magnetar

This neutron star, 1E 2259+586, is located about 10,000 light-years away toward the constellation Cassiopeia. It is one of about two dozen observed neutron stars called magnetars. Last year, on April 28, , data showed the spin rate had decreased abruptly, by 2.2 millionths of a second, and the magnetar was spinning down at a faster rate.

The opposite has been observed on several occasions and can be accounted for, but this case is unique so far.

“Astronomers have witnessed hundreds of events, called glitches, associated with sudden increases in the spin of neutron stars, but this sudden spin-down caught us off guard,” said Victoria Kaspi, a professor of physics at McGill University in Montreal. She leads a team that uses Swift to monitor magnetars routinely.

This “anti-glitch” has pretty much baffled astronomers, who are trying to find a valid explanation.

“It affected the magnetar in exactly the opposite manner of every other clearly identified glitch seen in neutron stars.”, said co-author Neil Gehrels, principal investigator of the Swift mission at NASA’s Goddard Space Flight Center in Greenbelt, Md.

This could also have significant implications for understanding the extreme environment of the neutron stars. Since no lab on Earth can simulate them, we have to rely on observations conducted in outer space. A report on the findings appears today,in the May 30 edition of the journal Nature.

More puzzles

This adds yet another mystery to the already long list regarding neutron stars. Current theories suggest that a neutron star has a crust made up of electrons and ions, while the interior is made up of very bizarre… stuff – a neutron superfluid (a state of matter that has 0 viscosity and 0 friction) and a surface that accelerates streams of high-energy particles through the star’s intense magnetic field.

This theory can explain the “glitch”, but not the “anti-glitch” (as far as we can tell so far) – the particles which are ejected from the star drain the energy, but as the crust slows down as a result, the interior (which remember, is frictionless) resists being slowed. The crust fractures under the strain. When this happens, a glitch occurs. There is an X-ray outburst and the star gets a speedup kick from the faster-spinning interior. But for the opposite, there’s no explanation with what we know now.

“What is really remarkable about this event is the combination of the magnetar’s abrupt slowdown, the X-ray outburst, and the fact we now observe the star spinning down at a faster rate than before,” said lead author Robert Archibald, a graduate student at McGill.

Via NASA

Astronomers Pinpoint Origin Of Nature’s Most Powerful Magnetic Bursts

magnetar
Those bursts are from magnetars. You may have some idea about what a white dwarf is, or a  black hole or even a pulsar, but what are magnetars?

Magnetars are neutron stars with an extremely powerful magnetic field; their decay powers the emission of copious amounts of high-energy electromagnetic radiation, particularly X-rays and gamma-rays. They pack the mass of a sun into a body the size of Manhattan Island – and that’s not the most awesome thing about them. Tiny magnetars have magnetic fields that are at least 100 trillion times as powerful as Earth’s magnetic field.

Their origin is a mistery but this is probably how they are formed: when, in a supernova, a star collapses to a neutron star (it has too much mass to become a white dwarf), its magnetic field increases dramatically in strength.The supernova might lose 10% of its mass in the explosion, or even more. In order for such large stars (10–30 solar masses) not to collapse straight into a black hole, they have to shed a larger proportion of their mass. About 1 in 10 supernova explosions result in a magnetar. In the solid crust of a magnetar, tensions can arise that lead to ‘starquakes’ – astrophysical phenomenons that occur when the crust of a neutron star undergoes a sudden adjustment, analogous to an earthquake on Earth.

Astronomers discovered a magnetar with the NASA’s X-Ray Timing Explorer in July 2003, when it brightened by about 100 times its usual faint luminosity. After that they studied it with the European Photon Imaging Camera, known as EPIC until about March 2006, when the object faded to its pre-outburst brightness. As the magnetar faded, EPIC recorded changes in the energies of the X-rays released.

Then they were able to calculate and describe the physical properties of a magnetar’s surface and magnetic field. The scientists say they are encouraged because the measurement is similar to an earlier estimate made based on how fast the source is “spinning down,” which is the change in the spin period over time. They plan to study more magnetars, using more data from X-ray observatories and they are probably going to find answers to the questions they have.