This artist’s impression provides an outline of how the on-board imager on ESA’s Comprehensive Satellite (IBIS) can reconstruct images of powerful events such as gamma-ray bursts (GRB) using radiation that passes through the imaging telescope. from Integral. IBIS uses two detection layers, one on top of the other, while most gamma ray telescopes contain a single detection layer. In IBIS, the higher energy gamma rays activate the first layer of the detector (called ISGRI), losing some energy in the process, but not being fully absorbed. This is known as a Compton dispersion. The deflected gamma rays then pass to the lower layer (called PICSIT) where they can be captured and absorbed by the PICSIT crystals because they have given up a bit of energy as they pass through the first layer. The blue shaded part of the image describes the instrument’s fully coded field of view. IBIS can see around the corners because the gamma rays from the most powerful GRBs would pass through the lead shield on the side of the telescope, then through the first layer of the detector before resting on the second layer. The scatter locations in the two detection layers and the energy deposits can be used to determine the direction of the GRB. Credit: ESA / C. Carreau
A global collaboration of telescopes, including ESA’s comprehensive high-energy space observatory, has detected a unique mixture of radiation that explodes from a dead star in our galaxy, something that has never been seen before in this type of star and that can solve a long-standing cosmic. mystery.
The finding involves two types of interesting cosmic phenomena: magnetars and fast radio bursts. Magnetars 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 that generally last not even a second, but are billions of times brighter than the Sun.
Rapid radio bursts are one of the main unsolved mysteries of astronomy. First discovered in 2007, these events pulse brightly on radio waves for a few milliseconds before disappearing, and are rarely seen again. Its true nature remains unknown, and such an explosion has never been observed within the Milky Way, with a known origin, or emitting any other type of radiation beyond the domain of radio waves, until now.
In late April, SGR 1935 + 2154, a magnetar discovered six years ago in the Vulpecula constellation, after a substantial X-ray burst, was activated again. Soon after, astronomers saw something amazing: This magnetar radiated not only its usual X-rays, but also radio waves.
“We detected the high-energy or ‘hard’ X-ray burst of the magnetar using Integral on April 28,” says Sandro Mereghetti of the National Institute of Astrophysics (INAF-IASF) in Milan, Italy, lead author of a new study of this source based on comprehensive data.
“The ‘Burst Alert System’ at Integral automatically alerted observatories around the world to the discovery in just seconds. This was hours before other alerts were issued, allowing the scientific community to act quickly and explore this source in more detail. “
Astronomers on the ground saw a brief 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, during the same time period as the X-ray emission. This was confirmed independently a few hours later by the Transient Astronomical Radio Emission Survey 2 (STARE2) in the US.
“We have never before seen a burst of radio waves, which resembled a fast radio burst, from a magnetar,” adds Sandro.
“Crucially, the Integral IBIS imager allowed us to precisely identify the source of the explosion, pinning its association with the magnetar,” says co-author Volodymyr Savchenko of the University of Geneva Comprehensive Science Data Center, Switzerland. .
Artist impression of SGR 1935 + 2154, a highly magnetized stellar remnant, also known as magnetar. Credit: ESA
“Most of the other satellites involved in the collaborative study of this event were unable to measure their position in the sky, and this was crucial in identifying that the emission actually came from SGR1935 + 2154.”
“This is the first observation connection between magnetars and fast radio bursts,” explains Sandro.
“It really is an important discovery and helps to focus on the origin of these mysterious phenomena.”
This connection strongly supports the idea that fast radio bursts emanate from magnetars, and demonstrates that bursts from these highly magnetized objects can also be detected at radio wavelengths. Magnetars are becoming increasingly popular with astronomers as they are believed to play a key role in driving a number of different transient events in the Universe, from superluminous supernova explosions to distant and energetic gamma-ray bursts.
Launched in 2002, Integral carries a set of four instruments capable of simultaneously observing and taking images of cosmic objects in gamma rays, X-rays, and visible light.
At the time of the explosion, the magnetar was in the 30-by-30-degree field of view of the IBIS instrument, leading to automatic detection by the satellite’s Explosion Alert System software package, operated by the Comprehensive Science Data Center in Geneva: immediate alert to observatories around the world. At the same time, the Integral Spectrometer (SPI) also detected the X-ray blast, along with another space mission, the China Hard Insight X-Ray Modulation Telescope (HXMT).
“This type of collaborative multi-wavelength approach and the resulting discovery highlights the importance of timely and large-scale coordination of scientific research efforts,” adds ESA’s Integral project scientist Erik Kuulkers.
“By gathering 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-standing mystery in astronomy. We are delighted that Integral has played a key role. in this “.
The article “INTEGRAL Discovery of an explosion with associated radio emission from magnetar SGR 1935 + 2154” by S. Mereghetti et al. is published in the Astrophysical charts.
Extremely intense radio explosion detected from magnetar SGR 1935 + 2154
S. Mereghetti et al. INTEGRAL discovery of an explosion with associated radio emission from the Magnetar SGR 1935 + 2154, The Astrophysical Journal (2020). DOI: 10.3847 / 2041-8213 / aba2cf
Provided by the European Space Agency
Citation: Dead star emits never-before-seen radiation mix (2020, July 28) retrieved July 28, 2020 from https://phys.org/news/2020-07-dead-star-emits-never-before .html
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