Insight-HXMT gives insight into origin of fast radio bursts

February 19, 2021

The latest observations from Insight-HXMT were published online in Nature Astronomy on Feb. 18. Insight-HXMT has discovered the very first X-ray burst associated with a fast radio burst (FRB) and has identified that it originated from soft-gamma repeater (SGR) J1935+2154, which is a magnetar in our Milky Way.

Insight-HXMT is the first to identify the double-spike structure of this X-ray burst as the high energy counterpart of FRB 200428. This discovery, together with results from other telescopes, proves that FRBs can come from magnetar bursts, thus resolving the longstanding puzzle concerning the origin of FRBs.

These results from Insight-HXMT also help explain the emission mechanism of FRBs, as well as the trigger mechanism of magnetar bursts.

This work was conducted by scientists from the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences, Beijing Normal University, University of Nevada Las Vegas, Tsinghua University and other institutions.

FRBs, first discovered in 2007, are a great mystery in astronomy. They release a huge amount of energy in only several milliseconds. About a hundred such events have been detected in different regions of our universe. Moreover, repeated FRBs have been found from the same direction.

Considering the narrow field of view of radio telescopes, the event rate of FRBs is very high: Every day thousands of such bursts reach Earth. However, before this discovery by Insight-HXMT and several other space X-ray instruments, no FRB radiation at any other wavelength had ever been detected, and all FRBs with fairly good localization were from distant extragalactic sources, whose identity and nature are yet unknown. The origin and mechanisms of such mysterious phenomena constitute one of the biggest questions in astronomy today.

Scientists have proposed many models to explain the physical origin of FRBs, such as the merger of two compact objects, the collapse of a compact star, magnetar bursts, the collision of a neutron star and an asteroid, or even signals from aliens. In recent years, more observations have revealed more properties of FRBs, intensifying the debate on their origin.

In order to understand the nature of FRBs, we need to answer two questions: What is the source of FRBs, and what do FRBs look like in other wavebands?

On April 28, 2020 at 14:34 GMT, the Canadian CHIME experiment and the STARE2 experiment in the U.S. independently detected a very bright FRB, which was named FRB 200428. It came from roughly the same direction as the Galactic magnetar SGR J1935+2154. Based on the FRB's dispersion measurement, the source of this FRB was located about 30,000 light-years away, which approximately agrees with the distance to SGR J1935+2154.

Magnetars are a group of neutron stars with extreme surface magnetic fields that are around 100 trillions of times stronger than the Earth's magnetic field. When it's active, a magnetar can emit bright short X-ray bursts. Therefore, theorists speculate that magnetars can also emit FRBs. In mid-April 2020, SGR J1935+2154 entered a new active period and hundreds of X-ray bursts were released.

In response to this opportunity, Insight-HXMT changed its observation plan and began a very long-duration pointing observation of SGR J1935+2154. About 8.6 second before FRB 200428, Insight-HXMT detected a very bright X-ray burst from SGR J1935+2154. This X-ray burst 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 interstellar medium. This indicates that the X-ray and radio emissions are from the same explosion.

Furthermore, Insight-HXMT was well able to localize this bright X-ray burst based on the unique design of its collimators, thus proving that both the X-ray burst and FRB 200428 originated from magnetar SGR J1935+2154. This represents not only the first confirmed source of an FRB, but also the first FRB originating in our Galaxy. It is a milestone in understanding the nature of FRBs and magnetars. The discovery of FRB 200428 and related research were recognized as one of the top 10 discoveries of 2020 by Nature and Science magazines.

In comparison with observational data from other high energy satellites, the observational data on FRB 200428 from Insight-HXMT are the most statistically rich and cover the broadest energy band, thus providing the most detailed temporal and spectral information on the X-ray burst.

Insight-HXMT is one of two satellites that independently localized this X-ray burst, showing much greater accuracy than two radio telescopes that detected FRB 200428. Insight-HXMT also detected, in the light curve of this X-ray burst, two X-ray spikes very closely aligned temporally with the FRB, a result later confirmed by other satellite data.

Finally, Insight-HXMT is the only instrument providing data for detailed analysis of the spectral evolution of this X-ray burst. Specifically, the X-ray spectrum of these two spikes is significantly different from spectra from other parts of the burst as well as from the majority of X-ray bursts from magnetars. These results are critical to understanding the physical mechanism of FRBs.

In summary, Insight-HXMT has discovered that this X-ray burst is from magnetar SGR J1935+2154, the two spikes of this X-ray burst are the high energy counterpart of FRB 200428, and the spectrum of this X-ray burst is special. These observations also show that Insight-HXMT is very powerful as a space observatory.

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 the China National Space Administration and CAS. IHEP is responsible for satellite payloads, the science data center and scientific research. The 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 institutes 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, Ferrara University in Italy and the Max Planck Institute for Extraterrestrial Physics.

Since its launch on June 15, 2017, Insight-HXMT has successfully operated in orbit for more than 3.5 years. It has achieved a series of important scientific results on black holes, neutron stars and other phenomena.

As Insight-HXMT smoothly operates in orbit, the enhanced X-ray Timing and Polarimetry (eXTP) space mission, developed by IHEP and many other domestic and international partner institutions, has entered phase-B (design phase), after more than 10 years of preliminary study and key technology development. It will increase the capacity for studying neutron stars and black holes by an order of magnitude or more, compared with other similar satellites.

eXTP will bring China and the eXTP international consortium to the frontier of high energy space astronomy. The high energy counterparts of extragalactic FRBs are very weak due to their great distance. eXTP will be an ideal instrument for detecting them.

Chinese Academy of Sciences Headquarters

Related Black Holes Articles from Brightsurf:

The black hole always chirps twice: New clues deciphering the shape of black holes
A team of gravitational-wave scientists led by the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) reveal that when two black holes collide and merge, the remnant black hole 'chirps' not once, but multiple times, emitting gravitational waves--intense ripples in the fabric space and time--that inform us about its shape.

Black holes? They are like a hologram
Spherical, smooth and simple according to the theory of relativity, or extremely complex and full of information as, according to quantum laws, Stephen Hawking used to say?

Under pressure, black holes feast
A new, Yale-led study shows that some supermassive black holes actually thrive under pressure.

Staining cycles with black holes
In the treatment of tumors, microenvironment plays an important role.

Black holes sometimes behave like conventional quantum systems
A group of Skoltech researchers led by Professor Anatoly Dymarsky have studied the emergence of generalized thermal ensembles in quantum systems with additional symmetries.

Scientists may have discovered whole new class of black holes
New research shows that astronomers' search for black holes might have been missing an entire class of black holes that they didn't know existed.

Are black holes made of dark energy?
Two University of Hawaii at Manoa researchers have identified and corrected a subtle error that was made when applying Einstein's equations to model the growth of the universe.

Telescopes in space for even sharper images of black holes
Astronomers have just managed to take the first image of a black hole, and now the next challenge facing them is how to take even sharper images, so that Einstein's Theory of General Relativity can be tested.

Can entangled qubits be used to probe black holes?
Information escapes from black holes via Hawking radiation, so it should be possible to capture it and use it to reconstruct what fell in: if given time longer than the age of the universe.

How black holes power plasma jets
Cosmic robbery powers the jets streaming from a black hole, new simulations reveal.

Read More: Black Holes News and Black Holes Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to