Developing theories about fast radio bursts
In September 2018, sensors on Earth picked up a blast of radio waves called FRBs (fast radio bursts) from outer space. These kinds of bursts happen with a fair amount of frequency but aren’t documented nearly as often as they may occur. However, at least 85 of them have been discovered since they were first documented.
At just 1.3 milliseconds, the duration of the most recent wave was typically brief, but astronomers were able to trace them through the Australian Square Kilometer Array Pathfinder. This was only the second time the bursts have been captured since they were first discovered and the information allowed researchers to discern something new that might provide a clue about what was happening. What they found may impact researchers’ progress toward a better understanding of what is happening.
A different view of the origin of an FRB
With the information they learned in the trace of this FRB, scientists were able to gain an idea of the possible location of the bursts, something that’s critical to understanding their cause. Researchers have traced them to a bright home galaxy dominated by older stars and approximately 4 billion light-years away from earth. The galaxy was well-established and similar to our own Milky Way.
This location is most notably different from the location that was established in the first trace. The first location was less bright and featured newer, more emerging stars. The first location was also more closely located next to a constantly glowing source of radio waves than the second traced burst was.
A possible cause
Within the last few months, Brian Metzger, an astrophysicist at Columbia University, has been part of a group that advanced the theory about the origins FRBs. The group expanded the theory that the waves come from explosions in a distant region of space cluttered by dense particles and magnetic fields, and that young stars called magnetars, may be involved as it ejects charged particles that produce a shock wave. Most distinctly, Metzger’s group proposed specific parameters to predict what future FRB’s will act like. A full discussion of the suspected causes of FRB’s and how Metzger’s team advanced them is available here.
Whether these theories are correct or not, it serves a purpose. It provides a basis for experts to work against, testing the specifics of the theory against new or more detailed observations. As the research progresses scientists may prove the Metzger team’s theory right, or my learn new things that allow their research to progress. They will also work to understand if FRB’s can emanate from older as well as younger galaxies if they always need to come from younger star-sources typified by magnetars.
Multiple theories about what causes FRBs
Since they were first identified and recognized, FRBs have captured experts’ imagination. In fact, more than 48 theories have been proposed and listed online through a Wikipedia page with specific guidelines that help experts list and discuss what is known about the phenomenon. Interestingly, many of these theories were based on both observations and on the tracings of the first FRB. Now that a second burst has been traced and Metzger has posted his predictions, the added knowledge may inspire additional theories and may develop the theories that already exist and eventually lead to a concrete explanation.
Challenges of future research
While Metzger’s idea and the information provided from this second traced burst will bring astrophysicists closer to understanding FRBs, more information is also needed. Capturing the burst to trace it isn’t easy and the second burst was only caught by the luck of having all of the satellites pointed in the right direction at the right time. However, scientists are continuing to make progress. There is optimism that work towards understanding FRBs will tell them as much about the universe as it will tell them about the phenomenon’s cause.