The Hubble Space Telescope was used by astronomers to monitor the positions of five very brief and intense fast radio bursts (FRBs).
Astronomers have been getting closer to answering (with Hubble’s help) a perplexing question for the past decade: what is the origin of the elusive, high-energy radio signals that ping Earth and then disappear without a trace?
There have been a lot of random hypotheses proposed to explain these fast radio bursts, or FRBs: aliens, of course; exotic physics; highly magnetized stars… the list goes on and on.
FRBs are phenomena that produce the same amount of energy in a thousandth of a second as the sun does in a year. FRBs are transient by default and vanish faster than the blink of an eye. Scientists have had trouble identifying where they come from due to the speed at which they appear and vanish.
The first step in identifying what type of object or objects causes FRBs is to figure out where they come from. Typically, astronomers have no idea where to search for a FRB’s source. Hubble has conducted a survey of eight FRBs to aid scientists in narrowing down the field of possibilities.
The first FRB was discovered in Parks Radio Observatory archive data on July 24, 2001.
1000 FRBs have been discovered since then, but scientists have only been able to connect about 15 of them to specific galaxies. Hubble conducted observations that offered a high-resolution view of a population of FRBs and discovered that five of them are clustered near or on the spiral arms of a galaxy.
Scientists can investigate what’s going on right at the FRB position thanks to Hubble’s resolution.
The discovery of the first FRB emanating from our home galaxy was revealed in a series of papers published in the journal Nature in November 2020. Magnetars, an unusual type of dead star, were found to be the source of the millisecond bursts. However, the connection has yet to be proved conclusively, so astronomers continue their search.
Observations with NASA’s workhorse Hubble Space Telescope have helped researchers pinpoint the position of five FRBs to the spiral arms of distant galaxies, according to a new paper set to be published in the Astrophysical Journal and available as a preprint on arXiv.
The team studied eight FRBs, the majority of which were discovered in 2019 and 2020, but three of them remain unidentified.
NASA’s Hubble played an important role in the search. Astronomers used Hubble to pin them all to unique host galaxies and identify the types of locations they came from. Hubble discovered one FRB in 2017 and the other seven in 2019 and 2020.
Astronomers are still unsure what triggers FRBs, but they intend to use context when it becomes usable. Other forms of transient phenomena, such as supernovae and gamma-ray bursts, can also be identified using this method.
The galaxies Hubble studied were viewed billions of years ago, when the universe was only half as old as it is now. The images show how the stars are distributed in the features, ranging from tightly wound to more diffuse spiral-arm structure.
FRBs can be triggered by the violent death of massive stars that produce gamma-ray bursts or other forms of supernovae, according to NASA. The merging of neutron stars is another unlikely cause.
Hubble’s findings support another hypothesis that FRBs are generated by young magnetar outbursts. A magnetar is a type of neutron star with a strong magnetic field, and astronomers discovered a correlation between observations of a FRB in the Milky Way and a known magnetar’s location.