Inexplicable radio flashes: Impacts on neutron stars as a possible source
For more than 15 years, astronomers have been puzzling over immensely energetic radio flashes. One of dozens of hypotheses now sounds more likely.
The Chime observatory searches for radio flashes
(Image: Chime)
The mysterious radio flashes that have puzzled astronomers for years could be at least partly due to interstellar celestial bodies colliding with neutron stars. This is the opinion of a research team that has tested a previously proposed theory. As they found out, the rate of observed fast radio bursts (FRB) matches the expected frequency of the collisions described. This could therefore be a sufficient explanation, at least for the non-periodic radio bursts. The collisions release the enormous amounts of energy that make up a fast radio burst. The extreme conditions on a neutron star are responsible for this.
Enormous amounts of energy possible
As research leader Dang Pham from the University of Toronto explains to the US magazine Space.com, the theory being tested is one of more than 50: "We've done the math." It was already known that impacts of interstellar celestial bodies on neutron stars can release enormous – and sufficient – amounts of energy for FRB. This is due to the extreme gravity on their surface. NASA once calculated that the collision of a marshmallow with a neutron star would release as much energy as an early atomic bomb. A collision with a much larger interstellar object would release enough energy to power humanity for 100 million years.
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So while fundamental questions about a possible connection with the FRBs had already been clarified, it was still unclear whether such collisions occur frequently enough to explain the numerous detections of radio flashes. His team has now shown that interstellar objects, i.e. asteroids and comets traveling between stars, are probably frequent enough to explain the number of FRBs. However, this only concerns the non-periodic radio bursts, which make up the vast majority of detections. According to their calculations, a collision between an interstellar object and a neutron star in our Milky Way should occur approximately once every 10 million years.
Fast radio bursts have been detected since 2007 and there has been much speculation about their origin. They have even been suggested as possible traces of extraterrestrial spaceships, but a natural origin is usually assumed. During the short but extremely violent bursts of radiation, more energy is emitted within fractions of a second than our sun generates in a year. Periodic FRBs have also been discovered time and again since 2012. Particularly high hopes have been pinned on them when it comes to clarifying the physical processes behind them. The work on non-repeating FRBs has now been accepted for publication in the Astrophysical Journal.
(mho)
