The universe sends mysterious signals from all over the sky. We don’t really know what these are or what constitutes them; But a new analysis of where they come from gives us clues about the sources of the strange emissions we call fast radio bursts (FRBs).

An international team led by astronomer Kriti Sharma of the Caltech Institute conducted a census and determined that FRBs are most likely to come from galaxies with relatively young stellar populations. This is somewhat expected. What the researchers didn’t expect was that these galaxies would be quite large and contain many stars, which is actually quite rare.

This suggests that there may be something unusual in the way FRBs are produced.

We already have a pretty good idea of ​​what FRBs are. First, an explanation: This is a very strong but very brief emission of radio light, lasting from fractions of a millisecond to several seconds. They come from all over the sky, their sources millions to billions of light-years away, and they often appear to shine once and never shine again.

This makes them impossible to predict and difficult to track, but with extensive research we are getting better at spotting them and better identifying their host galaxies.

As for what these are, we pay attention to that as well. Spoiler alert: It’s not aliens. In contrast, the first FRB detected in the Milky Way in 2020 was associated with a magnetar, a type of neutron star with a magnetic field 1000 times stronger than a normal neutron star. Prolonged interaction between an object’s magnetic field and gravity can cause meteor showers, which send flashes of radio light into the sky.

Not all FRBs behave the same way, so it is possible to have more than one source type. Narrowing down the location of these sources gives us information about the environmental conditions that caused them, which helps us understand what they are.

In a new effort to detect and localize FRBs, Sharma and colleagues collected observations using a radio interferometer called the Deep Synoptic Array. They carefully examined the properties of 30 large FRB galaxies and determined that radio bursts typically originate from galaxies with young star populations.

This is not surprising if the FRB precursors are magnetars. Neutron stars are the collapsed cores of massive stars that become supernova through core collapse, and the lifespan of massive stars is shorter than that of smaller stars. Magnetars are young neutron stars, so we expect to find them in places where most stars are young and short-lived.

Although some FRBs have been previously detected in old stellar populations and low-mass galaxies, the team’s analysis found that the most common precursors are high-mass galaxies with young stars. This suggests that massive young stellar environments are important for the formation of FRB precursors; If it weren’t, we’d see a wider distribution of galaxy types.

The reason for this is unknown, but researchers believe the metallic structure of these massive star-forming galaxies may play a role. Massive galaxies tend to have much higher metal contents and form heavier stars than less massive galaxies.

But there is another problem. Supernova core collapses occur at a rate similar to the rate of star formation in the universe. If FRB-producing magnetars form in this way, the FRB distribution should be generally consistent with the distribution of collapsing supernovae, even for low-mass galaxies, but this is not the case. This suggests that core collapse magnetars are not the main progenitor of FRBs.

The team ran simulations and found a solution. FRB-emitting magnetars can be formed by the merger of binary stars. This is more likely in environments with larger stars, such as the galaxies the researchers identified.

We still don’t have a complete explanation for the origin of FRBs, but the research greatly strengthens the case for magnetars and suggests that special conditions play a role in the formation of these magnetars.

Studies of FRBs are still ongoing, but astronomers are constantly discovering new, strange signals. The more we find, the more data we can collect to solve the mystery of the origin of FRBs. This is an incredibly exciting time to be alive and studying the stars. The study was published on: Nature.