For years, fast radio bursts (FRBs) – intense, millisecond-long pulses of radio waves – have puzzled astronomers. These cosmic events release as much energy as the sun does in several days, a truly mind-boggling feat. While the first FRB was detected in 2007, it wasn’t until 2017, with the advent of the Canadian Hydrogen Intensity Mapping Experiment (CHIME), that frequent discoveries began, fueling intense research into their origins. Over 50 hypotheses have been proposed, but a new study suggests a compelling explanation: the catastrophic collision of asteroids with neutron stars.
This research, led by University of Toronto scientist Dang Pham and colleagues, builds upon earlier suggestions linking FRBs and asteroid impacts on neutron stars. Pham’s team demonstrates that the frequency of such events, considering the abundance of interstellar objects (ISOs) – asteroids and comets present between stars – is sufficient to account for the observed rate of FRBs. Their calculations show that the impact properties – duration, energy, and frequency – align remarkably well with the characteristics of FRBs observed across the universe.
But how can an asteroid impact release such phenomenal energy? The answer lies in the extreme nature of neutron stars. These stellar remnants are formed when massive stars collapse, concentrating the mass of our sun into a sphere no larger than a city. The result is an object possessing the densest matter and strongest magnetic fields known in the universe. Oxford University astrophysicist Matthew Hopkins explains that the immense gravitational and magnetic forces of a neutron star unleash an explosive release of energy upon impact, resulting in a flash of radio waves visible across vast cosmic distances.
To illustrate this, consider the impact of a single marshmallow on a neutron star. According to NASA’s Goddard Flight Center, the gravitational pull would accelerate the marshmallow to millions of miles per hour, resulting in an energy release comparable to a thousand simultaneous hydrogen bomb detonations! The actual energy released from an asteroid impact depends on the asteroid’s size and the neutron star’s magnetic field strength, but even a 1-kilometer asteroid impacting a neutron star with a strong magnetic field could release approximately 10^29 Joules – enough energy to power humanity for 100 million years!
While this theory elegantly explains the energy output of single-occurrence FRBs, the existence of repeating FRBs presents a different challenge. The model suggests that single FRBs are a result of rare, random collisions. Repeating FRBs, however, occur at a much higher frequency, potentially suggesting a different mechanism. Research suggests that these might involve a neutron star interacting with an asteroid belt, a scenario not fully addressed in this current study.
The research team emphasizes that further observations are needed to fully understand the intricacies of FRBs. The rate of neutron star-interstellar object collisions is expected to vary depending on the type of galaxy (elliptical or spiral), making the study of host galaxies crucial. Ongoing and future projects like CHIME, CHORD, and ASKAP will play a vital role in gathering the data needed to refine and test this exciting new theory, potentially unlocking even more secrets of the universe.
The team’s findings have been accepted for publication in the Astrophysical Journal and a preprint version is available on arXiv. This research marks a significant step forward in our understanding of these enigmatic cosmic events and promises to ignite further investigation into the explosive relationship between asteroids and neutron stars.
