Astronomers have combined data from multiple wavelengths across the electromagnetic spectrum to study the emission limits of the only known repeating fast radio burst.
Fast radio bursts (FRBs) are extragalactic bursts of radio emission that last for just a few milliseconds. In 2017 an international team of astronomers, which included researchers from the Joint Institute for VLBI ERIC (JIVE), reported for the first time the exact location of the only known repeating FRB: FRB 121102. The team was subsequently able to pinpoint the origin of FRB 121102, which has in turn allowed extensive research of this phenomenon.
"One of the key questions that we have been trying to answer is if this repeating FRB produces only radio emission, or whether we can also detect it at other wavelengths on the electromagnetic spectrum." Explains Benito Marcote, corresponding author from JIVE in the Netherlands. "It is hoped that by doing this we can better understand the physical origins of FRBs, such as FRB 121102, as this is currently still unclear."
To understand if FRB 121102 emits bursts at other wavelengths rather than radio, the team simultaneously observed FRB 121102 over the course of a year, beginning in September 2016. To do this they used the radio telescope at Arecibo Observatory in Puerto Rico, and the MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes in Spain, which observe energetic gamma rays - a form of electromagnetic radiation. The MAGIC telescopes detect the cascades of visible light produced in our atmosphere when energetic gamma rays interact with the atmospheric molecules. They also include fast optical cameras that can search for optical bursts that only last milliseconds.
"Using Arecibo we detected five bursts of radio emission. We then used the MAGIC telescopes to search for optical and high-energy gamma-ray emission during both the times of the radio bursts and the whole observation period. During the observations no gamma-ray bursts were detected. This allows us to place upper-limits on the possible models to explain FRB 121102, suggesting that an origin similar to the one of the most known pulsar, the Crab, could not explain the current observations" Says Tarek Hassan from the Institute of High Energy Physics (IFAE, Spain). "We also conducted the deepest optical searches of an FRB to date. Only one optical burst was detected, four seconds before one of the radio bursts. However its association with FRB121102 is not confirmed, and it is thought that it could have originated from a meteor."
Whether FRBs emit at other wavelengths remains a mystery, however the results from this study put strong limits on the possible extension of such emissions. The upcoming generation of facilities at radio wavelengths, for example the Square Kilometer Array, and at energetic gamma-rays, e.g. the Cherenkov Telescope Array, CTA, will provide unparalleled sensitivity and increasing potential to answer such open questions.
This study appears in the December 2018 edition of the Monthly Notices of the Royal Astronomical Society (vol. 481, issue 2, pages 2479-2486), which can be accessed here, and has been led by Tarek Hassan from the Institute of High Energy Physics (IFAE, Spain), Benito Marcote from the Joint Institute for VLBI ERIC (JIVE, The Netherlands), Susumu Inoue from the University of Tokyo (Japan), and John Hoang from the University Complutense of Madrid (UCM, Spain).
Gina Maffey - Science Communication Officer
The Joint Institute for VLBI ERIC (JIVE)
Phone: +31 521 596 543
Benito Marcote - Corresponding author
The Joint Institute for VLBI ERIC (JIVE)
Phone: +31 521-596 508
The main research was conducted by the MAGIC Collaboration (comprised of 20 institutions across the globe), together with radio astronomers from other institutions including Benito Marcote from the Joint Institute for VLBI ERIC and Jason Hessels from ASTRON (The Netherlands Institute for Radio Astronomy). The corresponding authors for the paper are: Tarek Hassan from the Institute of High Energy Physics (IFAE, Spain), Benito Marcote from the Joint Institute for VLBI ERIC (JIVE, The Netherlands), Susumu Inoue from the University of Tokyo (Japan), and John Hoang from the University Complutense of Madrid (UCM, Spain).
The Joint Institute for VLBI ERIC is an international institute based in the Netherlands that provides support, conducts leading research and forwards technical development in the field of radio astronomy. Its primary mission is to operate and develop a powerful supercomputer, known as the correlator, which processes data from the European VLBI Network (EVN) - an array of radio telescopes located across the globe.
JIVE is funded by six member countries: the Netherlands, France, Latvia, Spain, Sweden and the United Kingdom; it is also supported by four participating research institutes: the National Astronomical Observatories of China, the Max Planck Institute for Radio Astronomy, the Italian National Institute of Astrophysics and the National Research Foundation. JIVE is hosted at the offices of the Netherlands Institute for Radio Astronomy (ASTRON) in the Netherlands.
One of the MAGIC (Major Atmospheric Gamma Imaging Cherenkov) telescopes in Spain - Benito Marcote and MAGIC Collaboration