NWO: astronomers: a mysterious source of radio bursts is in an astonishingly extreme and unusual environment

Arecibo high – FRB’s spiral Image design: Danielle

THE HAGUE, 17-Jan-2018 — /EuropaWire/ — An international team of astronomers has used two of the world’s largest radio telescopes to show that a mysterious source of radio bursts is in an astonishingly extreme and unusual environment.

This discovery suggests that the strange source is in the close vicinity of a massive black hole, or within a nebula of unprecedented power. The team presented their findings at the American Astronomical Society’s winter meeting (#AAS231) in Washington, DC. The results appear on the cover of the January 11th edition of Nature.

Fast Radio Bursts (FRBs) are a recently discovered type of astrophysical signal coming from deep in extragalactic space. Their physical origin remains a mystery. Using data from the Arecibo Observatory, Puerto Rico, and the Green Bank Telescope, West Virginia, astronomers have now shown that the radio bursts from the source FRB 121102 have a property known as polarization. The behavior of this polarized light allows them to probe the source’s environment in a new way and to ‘peer into the lair’ of the mysterious burster.

Polarized light is likely familiar to anyone who has used polarized sunglasses to cut down on the glare of sunlight reflected off water. If polarized radio waves travel through a region with a magnetic field, the polarization gets “twisted” by an effect known as Faraday rotation: the stronger the magnetic field, the greater the twisting. The amount of twisting observed in FRB 121102’s radio bursts is among the largest ever measured in a radio source, and the researchers conclude that the bursts are passing through an exceptionally strong magnetic field in a dense plasma (a hot, ionized gas).

“The only known sources in the Milky Way that are twisted as much as FRB 121102 are in the Galactic center, which is a dynamic region near a massive black hole. Maybe FRB 121102 is in a similar environment in its host galaxy,” says Daniele Michilli, PhD candidate at the University of Amsterdam and ASTRON, the Netherlands Institute for Radio Astronomy. “However, the twisting of the radio bursts could also be explained if the source is located in a powerful nebula or supernova remnant,” he adds.

Key to the discovery was detecting the bursts at higher radio frequency than ever before. “We developed a new observing setup at the Arecibo Observatory to do this, and our colleagues from the Breakthrough Listen project at the Green Bank Telescope confirmed the results with observations at even higher radio frequencies,” says Andrew Seymour, USRA astronomer at Arecibo Observatory. “What’s more, the polarization properties and shapes of these bursts are similar to radio emission from young, energetic neutron stars in our galaxy. This provides support to the models that the radio bursts are produced by a neutron star,” he adds.

Article:

An extreme magneto-ionic environment associated with fast radio burst source FRB121102. D. Michilli, A. Seymour, J. W. T. Hessels, L. G. Spitler, V. Gajjar, A. M. Archibald, G. C. Bower, S. Chatterjee, J. M. Cordes, K. Gourdji, G. H. Heald, V. M. Kaspi, C. J. Law, C. Sobey, E. A. K. Adams, C. G. Bassa, S. Bogdanov, C. Brinkman, P. Demorest, F. Fernandez, G. Hellbourg, T. J. W. Lazio, R. S. Lynch, N. Maddox, B. Marcote, M. A. McLaughlin, Z. Paragi, S. M. Ransom, P. Scholz, A. P. V. Siemion, S. P. Tendulkar, P. Van Rooy, R. S. Wharton, D. Whitlow

DOI:

http://nature.com/articles/doi:10.1038/nature25149

Futselaar – Photo usage: Brian P. Irwin / Dennis van de Water / Shutterstock.com

Source: ASTRON Netherlands Institute for Radio Astronomy/ NWO