On April 15, 2020, a brief explosion of full-energy light came through the solar system, taking instruments on several NASA and European spacecraft. Now, several international science teams conclude that the explosion came from a supermagnetized stellar debris called a magnetar located in a neighboring galaxy.
This discovery confirms a long-standing suspicion that some gamma-ray explosions (GRBs) – cosmic explosions found in the sky almost every day – are in fact powerful flames from magnets relatively close to the home.
“This has always been considered a potential, and several GRBs observed since 2005 have provided interesting evidence,” said Kevin Hurley, Senior Space Associate with the University of California, Berkeley, space science laboratory , who came together with several scientists to discuss the explosion at the actual 237th meeting of the Astronomical Society of America. “The April 15 event is a game changer because we found out that the explosion is almost certainly lying inside the disk of the nearby galaxy NGC 253.”
Papers analyzing various aspects of the event and its impact were published on January 13 in the magazines. Nature and Astronomy of nature.
GRBs, the most powerful explosions in the cosmos, can be traced over billions of light years. Those lasting less than about two seconds, called short GRBs, occur when a pair of neutral stars rotate – both the remnants of explosive stars – spinning inwards. each other and come together. Astronauts confirmed this position for at least some short GRBs in 2017, when an explosion followed gravitational waves – ripples in space-time – erupted when neutron stars came together 130 million light-years away.
Neutron stars are magnetars with the strongest magnetic fields, with up to a thousand times the intensity of normal neutron stars and up to 10 trillion times the strength of a cooling magnet. Minor disturbances on the magnetic field can cause magnetars to explode with sporadic X-ray explosions for weeks or longer.
Magnetars rarely emit large explosions called large flames that produce gamma rays, the highest energy type of light.
Most of the 29 magnetars now cataloged in our Milky Way galaxy show occasional X-ray activity, but only two have produced large flames. The most recent event, discovered on December 27, 2004, brought measurable changes in the Earth’s upper atmosphere despite exploding from a magnetar that was about 28,000 light-years away.
Shortly before 4:42 a.m. EDT on April 15, 2020, a short, powerful explosion of X-rays and gma rays swept past Mars, bringing Russia’s Neutron High Energy Detector aboard the Mars Odyssey spacecraft NASA, which has been orbiting the Red Planet ever since. 2001. About 6.6 minutes later, the explosion erupted a Russian Konus instrument aboard NASA’s wind satellite, which orbits a point between Earth and the Sun that is about 930,000 miles (1.5 million kilometers) away. After another 4.5 seconds, the radiation passed on Earth, triggering instruments on NASA’s Fermi Gamma-ray Space Telescope, as well as the European Space Agency’s INTEGRAL satellite and the Atmosphere-Space Interactions Monitor (ASIM) aboard the Earth. International Space Station.
The explosion occurred outside the Burst Alert (BAT) Telescope sighting at NASA’s Neil Gehrels Swift Observatory, so his onboard computer did not warn astronauts on the ground. However, thanks to a new capability called the Gamma-ray Emergency Archive for Novel Channels (GUANO), the Swift team can retrieve BAT data when other satellites trigger an explosion. Analysis of this data provided further insight into the event.
A radiation stroke lasted just 140 milliseconds – as fast as an eye crush or a lump of a finger.
The Fermi, Swift, Wind, Mars Odyssey and INTEGRAL missions all participate in a GRB detection system called the InterPlanetary Network (IPN). Now funded by the Fermi project, the IPN has been operating since the late 1970s using various spacecraft located throughout the solar system. Since the signal reached each detector at different times, any pair can help reduce the position of an explosion in the air. The greater the distances between a spacecraft, the better the accuracy of the technology.
The IPN sent an April 15 explosion, known as GRB 200415A, squarely in the center of the NGC 253 region, a brightly spiral galaxy located about 11.4 million light-years away in the Constellation Sculptor. This is the most accurate sky setting yet tested for a magnetar located outside the Magellanic Cloud, a satellite of our galaxy and hosted by a giant flame in 1979, the first ever discovered.
Large flames from magnetars in the Milky Way and its satellites grow in a specific way, with a rapid rise to maximum brightness and then a more gradual tail of variable emissions. These changes are due to the rotation of the magnetar, which in turn brings the position of the flames in and out of view from Earth, like a lighthouse.
The observation of this variable tail is conclusive evidence of a great flame. Seeing from millions of light years away, however, this spread is too low to be found with today’s instruments. With these signatures missing, large flames in our galactic neighborhood may escalate as union GRBs far farther and more powerful.
A detailed analysis of data from the Fermi Gamma-ray Burst Monitor (GBM) and BAT Swift provides strong evidence that the April 15 incident was not unlike any union-related explosion, Oliver Roberts noted. near, an associate scientist at the Institute of Science and Technology Association of Space Research Universities. in Huntsville, Alabama, led the study.
In particular, this was the first major flame known since Fermi happened in 2008, and GBM’s ability to resolve changes at microsecond timescales was critical. The observations come in several blows, with the first one appearing in just 77 microseconds – about 13 times the speed of a camera flash and nearly 100 times faster than the fastest-growing GRBs produced by unions. The GBM also discovered unprecedented rapid changes in energy over the flame.
“Large flames inside our galaxy are so brilliant that they are overflowing with our instruments, leaving them hanging on their mysteries,” Roberts said. “For the first time, GRB 200415A and distant flames as it allows our instruments to capture all features and study these powerful explosions in unprecedented depth. “
Large flames are not understood, but astronomers believe they are the result of a sudden rearrangement of the magnetic field. One possibility is that the high range above the surface of the magnetar may be too complex, releasing energy abruptly while settling in a more stable alignment. On the other hand, mechanical failure in the crust of the magnetar – an earthquake – could trigger a sudden reshaping.
Roberts and colleagues say the data show little evidence of seismic vibration at the time of the explosion. The highest energy X-rays recorded by GBM Fermi reached 3 million volts of electron (MeV), or about a million times the energy of blue light, itself a record for large flames. The researchers say that this emission arose from a cloud of lightning and positrons moving at about 99% of the speed of light. Its short duration of emission and its brightness and variable energy reflect the rotation of the magnetar, ramping up and down like car lights making a turn. Roberts says it starts out as an obscure blob – it looks like it’s like a torpedo photon from the “Star Trek” franchise – that expands and spreads as it travels.
The torpedo will also feature in one of the event’s biggest surprises. Fermi’s main instrument, the Large Area Telescope (LAT), discovered three gamma rays, with a power of 480 MeV, 1.3 billion electron volts (GeV), and 1.7 GeV – the highest energy light ever detected from a large flame magnetar. What is surprising is that all of these gamma rays appeared long after the flame diminished in other instruments.
Nicola Omodei, a senior research scientist at Stanford University in California, led the LAT team studying these gamma rays, which arrived between 19 seconds and 4.7 minutes after the main event. The scientists conclude that this signal most likely comes from the magnetar flame. “For the LAT to find a short random GRB in the same area of the sky and at about the same time as the flame, we had to wait, on average, at least 6 million years,” he explained.
A magnetar produces a steady outflow of fast grains. As it moves through space, this outflow plows in, slows down and moves interspecific gas. The gas accumulates, heats and compresses, and forms a kind of shock wave called a arc shock.
In the model proposed by the LAT team, the initial pulse of gamma rays travels out at the speed of light, followed by a cloud of emitted material, which moves almost as fast. After several days, the two of them reach the shock of the bow. The gamma rays pass through. Seconds later, the cloud of grains – now extended into a large thin shell – hits with accumulated gas at the shock of the bow. This interaction creates intense waves that accelerate particles, emitting the highest energy gamma rays after the main explosion.
The April 15 flare confirms that these events make up their own GRB class. Eric Burns, professor of physics and astronomy at Louisiana State University in Baton Rouge, led a study examining suspects using data from several missions. The findings will appear in the Astrophysical Journal Letters. Explosions near the galaxy M81 in 2005 and the galaxy Andromeda (M31) in 2007 were reported as large flames, and in addition the team identified a flame in M83, which is also seen in 2007 but was reported new. Add to this the big flare from 1979 and the ones seen in our Milky Way in 1998 and 2004.
“It’s a small sample, but we now have a better idea of their true energies, and how far we can find them,” Burns said. Short GRBs like large magnetic flames. In fact, they are perhaps the most common high-energy revolutions we have found to date beyond our galaxy – about five times more frequent than supernovae. “
Video: https://www.youtube.com/watch?v=x66BEB6pSKM&feature=emb_logo