Fast Radio Bursts Include Lower Frequency Radio Waves, Too!

by | Apr 22, 2021 | Daily Space, Fast Radio Bursts, Neutron Stars / Pulsars | 0 comments

IMAGE: A burst from the periodically active repeating fast radio burst source 20180916B arrives at the LOFAR telescope. The higher frequency radio waves (purple) arrive earlier than the lower frequency radio waves (red). The inset shows an optical image from the host galaxy of the fast radio burst source and the position of the source in the host galaxy. CREDIT: Futselaar / ASTRON / Tendulkar

One of our regular topics, fast radio bursts (FRBs), has a new advancement. First discovered in 2007, these are literally momentary flashes of energy that reach Earth in the radio portion of the electromagnetic spectrum. Often, there will be just a single flash from a place in the sky, and we can’t link to a single star or another object. Other times, we see recurring flashes. 

To try and get a better sense of what might be happening, joint observations were made with the CHIME radio telescope in British Columbia and LOFAR in the northern Netherlands. CHIME operates at 500-800 Mhz, while LOFAR sees at longer wavelengths from 10 to 240 MHz, which extends to either side of the FM radio band. Working together, they observed recurring fast radio burst 20180916B. They discovered that the FRB emitted energy at the longer wavelengths, and these lower-energy photons arrived at LOFAR three days after the higher energy light was seen by CHIME. 

According to study co-author Daniele Michilli: This systematic delay rules out explanations for the periodic activity that do not allow for the frequency dependence and thus brings us a few steps closer to understanding the origin of these mysterious bursts. 

This work appears in The Astrophysical Journal Letters and was led by Ziggy Pleunis.

While we don’t know what fast radio bursts are, there are hints they are some kind of neutron star that has a massive magnetic field that periodically rearranges itself and lets off a massive burst of energy. We see other objects, including our own Sun with its solar flares, exhibiting this kind of energetic, magnetic field-related behavior. If fast radio bursts do come from neutron stars, this means that some of the smallest glowing objects in the sky are also responsible for some of the most energetic crackles we detect.

More Information

McGill University press release

LOFAR Detection of 110–188 MHz Emission and Frequency-dependent Activity from FRB 20180916B,” Z. Pleunis et al., 2021 April 9, The Astrophysical Journal Letters

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