Fast Radio Burst mystery solved?
ONE of the biggest puzzles in modern astronomy has been the existence of the mysterious Fast Radio Bursts, or FRBs for short.
This year has seen a breakthrough: an FRB originating from within our own galaxy has been shown to have come from a type of star called a magnet ar, so it seems clear that at least some FRBs originate from these objects.
FRBsar every brief burst s of radio-wavelength energy. The first one to be identified was found in 2007 in data gathered using the famous Parkes radio telescope — The “Dish” — in July 2001. Later study of the data showed another one that had occurred in the previous month.
Quite a number of these bursts have now been recorded. Some have been known to repeat, indicating, at least, that they could not have been the result of a catastrophic event.
There have been several suggestions by astronomers as to the cause of the bursts. A type of star called a flare star was a possibility, as were phenomena associated with black holes or dark matter.
Some early “detections” at Park es were traced to radiation from a microwave oven, but it was clear that this was not the normalreason!
Another of the possibilities suggested was that magnetars could be responsible.
A magnet ar is a type of neutron star—the collapsed, extremely dense core of a star, about 20km in diameter, that often remains after a super nova explosion.
The difference with a magnet ari sits exceptionally strong magnetic field: it is typically at least 10 trillion times as strong as the magnetic field of our Earth (of which we make use each time we check directions with a magnetic compass ).
Up to this year, known FRBs all came from other galaxies.
This was clear partly because their distribution of directions did not coincide with the plane of our spiral-shaped Milky Way Galaxy. (Had they mainly come from our own galaxy, they would have tended to be concentrated along the galactic plane, which is easily identifiable by casual stargazers in clear, dark conditions by looking for the famous “Milky Way” glow stretching acrossthesky.)
On April 28 this year, an instrument in Canada called CHIME (Canadian Hydrogen Intensity Mapping Experiment), which is also well suited to detecting FRBs, recorded a pair of these bursts from a known magnetar called SGR 1935+2154, which is about 30,000 light years from us.
Another instrument, called ST ARE 2( the Survey for Transient Astronomical Radio Emission 2), was used to measure the energy of the burst.
Although STARE 2’s result showed that the energy release was much less than that of FRBs from other galaxies, astronomers are confident that the pair from SGR 1935+2154 were indeed FRBs, and the CHIME/FRB Collaboration has written up its conclusions in a paper published in the week before last in the journal Nature.
It is quite plausible that such an intense burst of radiation can come from the release of energy stored in the magnetic field of a magnet ar,o rash if tin the star’s crust.
However, we can’t be sure that all FRBs come from magnetars. In particular, astronomers need to understand why FRBs from other galaxies have much greater energy than the ones so far observed in our galaxy.
Even so, this is a huge step forward. Identifying SGR 1935+2154 as one“culprit” producingFRBs certainly suggests that other magnet ar scan do so.
The authors of the research paper point out that perhaps the more intense bursts coming from other galaxies are generated by more energetic sources, such as younger magnetars.
This type of research once again reminds us of the amazing capabilities that we have to learn about the universe from our observation point here on Earth, and of the great distances involved. Travelling at the speed of light, the bursts recorded in April actually took place 30,000 years ago—long before the beginning of recorded human history.