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A dead star emits a never-before-seen mixture of radiation



A dead star emits a never-before-seen mixture of radiation

The impression of this artist is a diagram of how the built-in ESA satellite of the integrated satellite ESA (IBIS) can reconstruct images of such powerful events as gamma-ray bursts (GRB), using radiation that passes through the side telescope Integral. IBIS uses two layers of detectors, one on top of the other, while most gamma-ray telescopes contain only one layer of detector. In IBIS, higher energy gamma rays trigger the first layer of the detector (called ISGRI), losing some energy in the process, but they are not fully absorbed. This is known as Compton scattering. The deflected gamma rays then pass through the layer below (called PICSIT), where they can be captured and absorbed by PICSIT crystals because they have given off some energy as they pass through the first layer. The blue shaded part of the image describes the fully encoded field of view of the device. IBIS can see at angles, as the gamma rays from the most powerful GRBs would pass through a lead screen that is protected on the side of the telescope and then through the first layer of the detector before turning on the second layer. Scattering sites in the two layers of the detector and energy deposits can then be used to determine the direction of GRB. Credit: ESA / C.Carreau

The global collaboration of telescopes, including the ESA’s High-Energy Integrated Space Observatory, has uncovered a unique mixture of radiation that exploded from a dead star in our galaxy – something that has never been seen before in this type of star and could solve a long-standing space mystery.

The find connects two types of interesting cosmic phenomena: magnets and fast radio bursts. Magnets are stellar remnants with some of the most intense magnetic fields in the universe. When they become “active”, they can produce short bursts of high-energy radiation, which usually last not a second, but billions of times brighter than the sun.

The rapid explosion of radio is one of the main unsolved mysteries of astronomy. First detected in 2007, these events pulsate brightly in the radio for a few milliseconds before fading, and they are rarely seen again. Their true nature remains unknown, and no such explosion has been observed in the Milky Way, with known origins, or radiation of any other radiation outside the radio wave region – so far.

At the end of April, SGR 1935 + 2154, a magnet discovered six years ago in the constellation Vulpecula, became active again after a significant burst of X-rays. Astronomers soon discovered something amazing: this magnet emitted not only its usual X-rays, but also radio waves.

“We detected a high-energy or hard X-ray magnet exploding with Integral on April 28,” said Sandro Meregetti of the National Institute of Astrophysics (INAF – IASF) in Milan, Italy, lead author of a new study of this source based on integrated data.

Integral’s “explosion notification system” automatically notifies observatories around the world of the detection within seconds. It was hours before any other notices were published, which allowed the scientific community to act quickly and to study this source in more detail. “

Astronomers on Earth noticed a short and extremely bright burst of radio waves from the direction of SGR 1935 + 2154, using the CHIME radio telescope in Canada on the same day, for the same period of time as X-rays. This was independently confirmed a few hours later by a survey of transient astronomical radio emissions 2 (STARE2) in the United States.

“We’ve never seen an explosion of radio waves, reminiscent of a rapid explosion of radio, from a magnet,” adds Sandro.

“Most importantly, the IBIS image in Integral allowed us to pinpoint the origin of the explosion, eliminating its connection to the magnet,” said co-author Volodymyr Savchenko of the Integrated Data Science Center at the University of Geneva in Switzerland.

A dead star emits a never-before-seen mixture of radiation

Impressions of the artist from SGR 1935 + 2154, a strongly magnetized stellar remnant, also known as a magnet. Credit: ESA

“Most of the other satellites that participated in the joint study of this event were unable to measure its position in the sky – and this was crucial in discovering that the radiation did indeed originate from SGR1935 + 2154.”

“This is the first connection in the history of observation between magnets and fast radio bursts,” explains Sandro.

“It really is a major discovery and helps to bring the origins of these mysterious phenomena into focus.”

This connection strongly supports the idea that rapid radio explosions emanate from magnets, and demonstrates that bursts of these highly magnetized objects can also be observed at radio wavelengths. Magnets are becoming increasingly popular among astronomers because they are believed to play a key role in the motion of a number of different transient events in the universe, from superluminal supernova explosions to distant and energetic gamma-ray bursts.

Founded in 2002, Integral has a set of four devices capable of simultaneously observing and capturing space objects in gamma rays, X-rays and visible light.

At the time of the explosion, the magnet was in a 30-degree field of view in the 30-degree field of the IBIS, which led to the automatic detection of the Burst Alert satellite alarm software package, managed by the Geneva Integrated Science Center, immediately notifying observatories around the world. At the same time, the Integral Spectrometer (SPI) also detected an X-ray explosion along with another space mission, the Insight China Rigid X-ray Modulation Telescope (HXMT).

“This type of common, multi-wave approach and its discovery points to the importance of timely, large-scale coordination of research efforts,” adds Eric Kuulkers, ESA Integrated Project Scientist.

“By combining observations from the high-energy part of the spectrum to radio waves, from around the world and in space, scientists have been able to unravel a long-held mystery in astronomy. We are pleased that the integral has played a key role in this.”

Report “INTEGRATED detection of an explosion with concomitant radio radiation from a magnet SGR 1935 + 2154” S. Meregetti et al. published in Letters of the astrophysical journal.


An extremely intense radio explosion was detected from a magnet SGR 1935 + 2154


More information:
S. Mereghetti and others. INTEGRATED Opening of a burst with the connected radio radiation from magnetic SGR 1935 + 2154, Astrophysical Journal (2020). DOI: 10.3847 / 2041-8213 / aba2cf

Provided by the European Space Agency



Citation: A dead star emits an unprecedented mixture of radiation (2020, July 28), received on July 28, 2020 from https://phys.org/news/2020-07-dead-star-emits-never-before.html

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