The latest insights from Insight-HXMT were published online at Astronomy of nature on Feb. 18. Insight-HXMT has detected the first X-ray explosion associated with a rapid radio explosion (FRB) and has been identified to have come from a soft gamma (SGR) repeater J1935 + 2154, which is a magnetar in the Milky Way.
Insight-HXMT is the first to recognize the two-spike structure of this X-ray explosion as the high energy comparator of FRB 200428. This finding, along with results from other telescopes, confirms that FRBs can come from magnetar explosions, thus solving the long-standing puzzle about the origin of FRBn.
These results from Insight-HXMT will also help explain the FRBn transmission mechanism, as well as the excitation mode of magnetar explosions.
This work was carried out by scientists from the Institute of High Power Physics (IHEP) of the Chinese Academy of Sciences, Beijing Normal University, Nevada University of Las Vegas, Tsinghua University and other institutes.
FRBn, first discovered in 2007, is a major mystery in astronomy. They emit a lot of energy in just a few thousand million. Around one hundred such events have been found in different parts of our universe. In addition, FRBs were again detected from the same side.
Considering the narrow range of radio telescopes, the incidence rate of FRB is quite high: Every day thousands of such explosions reach the Earth. However, prior to this discovery by Insight-HXMT and several other space X-ray instruments, FRB radiation at any other wavelength was never detected, and all FRBs had moderately good separation from sources. distant extragalactic, the identity and nature of which are not yet known. . The origin and mechanisms of such mysteries are one of the greatest questions in astronomy today.
Scientists have proposed many models to explain the physical origin of FRBn, such as a single two-dimensional object, a dense star collapse, a magnetar explosion, a neutron and asteroid star collision, or even signals from monsters. In the last few years, more and more ideas have emerged about more buildings of FRBs, strengthening the debate about where they came from.
To understand the nature of FRBn, we need to answer two questions: Where is FRBn, and what is FRBn like in other waves?
On April 28, 2020 at 14:34 GMT, the Canadian CHIME test and the US STARE2 test independently detected a very clear FRB, named FRB 200428. It came from the same side as the SGR Galactic magnet J1935 + 2154. Based on the FRB emission measurement, the source of this FRB was located about 30,000 light-years away, which roughly agrees with the distance to SGR J1935 + 2154.
Magnetars are a group of neutron stars with true surface magnetic fields that are about 100 trillion times stronger than the Earth’s magnetic field. When active, a magnetar can emit short clear X-ray explosions. Therefore, theorists argue that magnetars can also transmit FRBs. In mid-April 2020, SGR J1935 + 2154 entered a new operational period and hundreds of X-ray explosions were released.
In response to this opportunity, Insight-HXMT changed their observation plan and began a long look at SGR J1935 + 2154. About 8.6 seconds before FRB 200428, Insight-HXMT detected a very clear X-ray explosion from SGR J1935 + 2154. This X-ray explosion was also detected by the European satellite INTEGRAL, the Russian detector Konus-Wind and the Italian satellite AGILE.
The time difference is consistent with the time delay of the radio signal due to the interspecific medium. This shows that the X-ray and radio emissions are from the same explosion.
In addition, Insight-HXMT was able to localize this clear X-ray explosion based on the unique design of the beaters, thus confirming that both the 200428 X-ray and FRB explosion originated from magnet magnet SGR J1935 + 2154. This represents not only the first proven source of FRB, but also the first FRB that came from our Galaxy. It is a milestone in understanding the nature of FRBs and magnetars. The 2004 FRB discovery and related research was identified as one of the top 10 discoveries in 2020 by the journals of Nature and Science.
Compared to observation data from other high-energy satellites, the FRB 200428 observation data from Insight-HXMT are the statistically richest and cover the widest energy band, thus providing the most detailed temporal and spectral information on X-ray explosions.
Insight-HXMT is one of two satellites that independently sent this X-ray explosion independently, featuring much more precision than the two radio telescopes discovered by the 200428 FRB. Insight-HXMT also detected, in a curve light of this X-ray explosion, two X-ray spikes temporarily closely linked to the FRB, a result that was later confirmed by other satellite data.
Finally, Insight-HXMT is the only instrument that provides data for detailed analysis of the spectral evolution of this X-ray explosion. In particular, the X-ray spectrum of these two spikes is quite different from spectra from other parts of the explosion as well as from most X-ray explosions from magnetars. These results are crucial for understanding the physical mechanics of FRBn.
In summary, Insight-HXMT has found that this X-ray explosion from the SGR magnet J1935 + 2154, the two spikes of this X-ray explosion are the high energy comparison of FRB 200428, and the spectrum of this X-ray explosion is unique. These observations also show that Insight-HXMT is very powerful as a space observer.
Insight-HXMT is China’s first X-ray observatory in space. It was first proposed by LI Tipei and WU Mei of IHEP in 1993. Insight-HXMT is funded by China National Space Administration and CAS. IHEP relies on satellite payloads, the science data center and scientific research. China Academy of Space Technology is the builder of the Insight-HXMT satellite platform. Tsinghua University, the National Space Science Center, Beijing Normal University and other institutions have also contributed to the Insight-HXMT mission. The calibration of the detectors on board Insight-HXMT was supported by the National Institute of Metrology, the University of Ferrara in Italy and the Max Planck Institute for External Physics.
Since its launch on June 15, 2017, Insight-HXMT has been operating successfully in orbit for over 3.5 years. He has achieved a series of important scientific findings on black holes, neutron stars and other onions.
As Insight-HXMT works smoothly in orbit, the enhanced X-ray and Polarimetry (eXTP) space mission, developed by IHEP and many domestic and international partner centers, has gone into B-level (design stage), after more than 10 years of pre-inspection and major technological development. It increases the ability to study neutron stars and black holes in order of magnitude or more, compared to other similar satellites.
China’s eXTP and eXTP’s international consortium will end high-space space astronomy. The high energy peers of extragalactic FRBs are very weak due to their high speed. EXTP will be a great tool for finding them.
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