![]() To that end, the researchers plan to use these two sophisticated telescopes to observe other repeating FRBs. ![]() I expect that from our measurements a wealth of new, better models will spring.” We are clearly getting closer, but the puzzle is certainly not solved yet. ![]() “That would mean the source would be spinning much more slowly than any other known neutron star though, an idea that will require some getting used to. “The observations we present actually match slow-spinning isolated magnetar models very well,” van Leeuwen said. A magnetar that emits pulses while it slowly rotates might create the kind of pattern seen in FRB 20180916B, with its active phase caused by an orientation toward Earth and its dormant phase correlated to its tilt away from our planet. The results imply that the source of FRB 20180916B is in a “clean” environment, without much stellar debris or interfering winds from a nearby star to block these longer wavelengths from freely traveling across space to Earth.Ī more likely source of periodic FRB repeaters, according to the study, is a type of hyper-dense dead star known as a magnetar. Westerbork/Apertif observed shorter and more familiar wavelengths, which were followed by delayed bursts of longer wavelengths seen by LOFAR. The researchers were surprised to find that both telescopes observed radio signals, but that they didn’t pick up the same bursts. It alerts us every time an FRB goes off.” “Westerbork/Apertif is a very sensitive and new system that works at a frequency we know FRBs emit at. “We connected two of the biggest radio telescopes in the world to investigate this,” van Leeuwen explained. The Westerbork/Apertif facility observed this cycle for 388 hours at normal radio frequencies, while automatically keeping LOFAR in the loop about its progress. The team snagged the exceptional observations by monitoring several cycles of FRB 20180916B, which exhibits a 16-day pattern: an active bursting period of four days, followed by a dormant period lasting 12 days. Many scientists have tried to detect FRBs at such low frequencies, but this study offers the first successful attempt to capture them. “It would also rule out that, for example, a dense stellar wind continuously eclipses the FRB at low frequencies.” “So, we were aiming to try and detect such low-frequency waves from an FRB, because that would rule out FRBs are emitted by, for example, neutron stars that were only just formed in a supernova, and still shrouded by material from the explosion,” he continued. ![]() “Low frequency radio waves have trouble escaping from dense nebular environments such as the remnants of stellar explosions,” said Joeri van Leeuwen, a radio astronomer at the Netherlands Institute for Radio Astronomy (ASTRON) who co-authored the study, in an email. This exceptionally deep look at FRB 20180916B revealed unexpected insights that “strongly disfavor” the idea that messy environments cause periodicity in FRBs, according to a study published on Wednesday in Nature. Whereas past studies have probed FRBs down to radio frequencies of 300 MHz, LOFAR detected frequencies as low as 150 MHz from the periodic repeater, which correspond to very long wavelengths measuring three meters (ten feet). Scientists led by Inés Pastor-Marazuela, a PhD student at the University of Amsterdam’s Anton Pannekoek Institute of Astronomy, have captured never-before-achieved observations of a periodic repeater known as FRB 20180916B, with the help of two advanced instruments: the Westerbork Synthesis Radio Telescope/Apertif and the Low Frequency Array (LOFAR). Now, however, a new study has ruled this explanation out. In other words, the regular cycles of some repeater signals may be caused by environmental factors rather than some characteristic of the source itself. This stellar material could intermittently block radio signals from our perspective on Earth, creating the active and dormant phases, or so this hypothesis suggests. ![]() Some scientists have proposed that this periodicity is caused by FRB sources located in messy environments that are clouded with supernova debris or wind-swept gas from companion stars. It gets weirder: two of those repeaters show periodicity in their pulses, meaning that they have distinct active and dormant phases. ![]()
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