Extremely fast radio signals from an unexpected source. A cluster of ancient stars (left) near the spiral nebula Messier 81 (M81) is the source of short and extremely intense radio signals. The image reveals in blue-white a graph of how one flashs brightness altered throughout only tens of split seconds. Credit: Daniëlle Futselaar, artsource.nl
Astronomers have actually been surprised by the closest source of mystical flashes in the sky called fast radio bursts. Precision measurements with radio telescopes expose that the bursts are made amongst old stars, and in a method that no one was anticipating. The source of the flashes, in nearby spiral nebula M 81, is the closest of its kind to Earth.
Fast radio bursts are unforeseeable, exceptionally short flashes of light from space. Astronomers have struggled to understand them ever since they were very first found in 2007. Up until now, they have actually just ever been seen by radio telescopes.
Each flash lasts just thousandths of a second. Each one sends out as much energy as the Sun offers out in a day. A number of hundred flashes go off every day, and they have been seen all over the sky. Most lie at huge ranges from Earth, in galaxies billions of light-years away.
In two documents published in parallel today in the journals Nature and Nature Astronomy, a global group of astronomers present observations that take scientists a step closer to solving the mystery– while also raising new puzzles. The team is led jointly by Franz Kirsten (Chalmers, Sweden, and ASTRON, Netherlands) and Kenzie Nimmo (ASTRON and University of Amsterdam).
Source of mystical radio signals: an artists impression of a magnetar in a cluster of ancient stars (in red) near the spiral galaxy Messier 81 (M81). Credit: Daniëlle Futselaar, artsource.nl
The scientists set out to make high-precision measurements of a duplicating burst source discovered in January 2020 in the constellation of Ursa Major, the Great Bear.
” We wished to look for hints to the bursts origins. Using many radio telescopes together, we knew we might pinpoint the sources place in the sky with extreme accuracy. That offers the chance to see what the regional community of a quick radio burst looks like,” states Franz Kirsten.
To study the source at the greatest possible resolution and level of sensitivity, the scientists combined measurements from telescopes in the European VLBI Network (EVN). By integrating data from 12 dish antennas spread out across half the globe, Sweden, Latvia, The Netherlands, Russia, Germany, Poland, Italy, and China, they were able to learn exactly where in the sky they were coming from.
The EVN measurements were matched with information from numerous other telescopes, amongst them the Karl G. Jansky Very Large Array (VLA) in New Mexico, USA.
Close but surprising place
When they analyzed their measurements, the astronomers discovered that the repeated radio flashes were coming from somewhere no one had anticipated. They traced the bursts to the borders of the close-by spiral nebula Messier 81 (M 81), about 12 million light-years away. That makes this the closest-ever detection of a source of quick radio bursts.
There was another surprise in shop. The place matched precisely with a dense cluster of extremely old stars, called a globular cluster.
” Its remarkable to discover quick radio bursts from a globular cluster. Even more out in the universe, quick radio bursts have been found in locations where stars are much younger.
Many fast radio bursts have been discovered surrounded by young, huge stars, much larger than the Sun. In those locations, star surges prevail and leave highly allured residues. Researchers have actually concerned think that fast radio bursts can be produced in objects referred to as magnetars. Magnetars are the incredibly dense residues of stars that have taken off. And they are the universes most powerful known magnets.
” We expect magnetars to be brand-new and shiny, and absolutely not surrounded by old stars. If what were looking at here really is a magnetar, then it cant have actually been formed from a young star blowing up. There has to be another way,” states employee Jason Hessels, University of Amsterdam and ASTRON.
The scientists think that the source of the radio flashes is something that has been anticipated, however never seen before: a magnetar that formed when a white dwarf became massive enough to collapse under its own weight.
” Strange things happen in the multi-billion-year life of a tight cluster of stars. Here we believe were seeing a star with an uncommon story,” discusses Franz Kirsten.
Provided time, normal stars like the Sun age and transform into small, dense, brilliant objects called white overshadows. Lots of stars in the cluster live together in binary systems. Of the 10s of countless stars in the cluster, a couple of get close enough that one star collects product from the other.
That can result in a situation referred to as “accretion-induced collapse,” Kirsten explains.
” If one of the white dwarfs can catch enough extra mass from its companion, it can become an even denser star, referred to as a neutron star. Thats an unusual occurrence, however in a cluster of ancient stars, its the easiest way of making quick radio bursts,” says staff member Mohit Bhardwaj, McGill University, Canada.
Fastest ever
Looking for additional clues by zooming into their information, the astronomers found another surprise. Some of the flashes were even much shorter than they had anticipated.
” The flashes flickered in brightness within as low as a couple of 10s of nanoseconds. That informs us that they need to be originating from a small volume in area, smaller than a soccer pitch and perhaps just tens of meters across,” states Kenzie Nimmo.
Lightning-fast signals have been seen from one of the skys most famous things, the Crab pulsar. It is a tiny, thick, remnant of a supernova explosion that was seen from Earth in 1054 CE in the constellation of Taurus, the Bull. Both magnetars and pulsars are different type of neutron stars: super-dense items with the mass of the Sun in a volume the size of a city, and with strong magnetic fields.
” Some of the signals we measured are exceptionally powerful and short, in simply the exact same way as some signals from the Crab pulsar. That suggests that we are indeed seeing a magnetar, however in a location that magnetars havent been found prior to,” says Kenzie Nimmo.
Future observations of this system and others will help to tell whether the source actually is an uncommon magnetar, or something else, like a black hole or an uncommon pulsar and a thick star in a close orbit.
” These quick radio bursts seem to be providing us brand-new and unexpected insight into how stars pass away and live. If thats true, they could, like supernovae, have things to inform us about stars and their lives throughout the entire universe,” states Franz Kirsten.
Referrals:
” A repeating quick radio burst source in a globular cluster” by F. Kirsten, B. Marcote, K. Nimmo, J. W. T. Hessels, M. Bhardwaj, S. P. Tendulkar, A. Keimpema, J. Yang, M. P. Snelders, P. Scholz, A. B. Pearlman, C. J. Law, W. M. Peters, M. Giroletti, Z. Paragi, C. Bassa, D. M. Hewitt, U. Bach, V. Bezrukovs, M. Burgay, S. T. Buttaccio, J. E. Conway, A. Corongiu, R. Feiler, O. Forssén, M. P. Gawroński, R. Karuppusamy, M. A. Kharinov, M. Lindqvist, G. Maccaferri, A. Melnikov, O. S. Ould-Boukattine, A. Possenti, G. Surcis, N. Wang, J. Yuan, K. Aggarwal, R. Anna-Thomas, G. C. Bower, R. Blaauw, S. Burke-Spolaor, T. Cassanelli, T. E. Clarke, E. Fonseca, B. M. Gaensler, A. Gopinath, V. M. Kaspi, N. Kassim, T. J. W. Lazio, C. Leung, D. Z. Li, H. H. Lin, K. W. Masui, R. Mckinven, D. Michilli, A. G. Mikhailov, C. Ng, A. Orbidans, U. L. Pen, E. Petroff, M. Rahman, S. M. Ransom, K. Shin, K. M. Smith, I. H. Stairs and W. Vlemmings, 23 February 2022, Nature.DOI: 10.1038/ s41586-021-04354-w.
” Burst timescales and luminosities as links between young pulsars and quick radio bursts” by K. Nimmo, J. W. T. Hessels, F. Kirsten, A. Keimpema, J. M. Cordes, M. P. Snelders, D. M. Hewitt, R. Karuppusamy, A. M. Archibald, V. Bezrukovs, M. Bhardwaj, R. Blaauw, S. T. Buttaccio, T. Cassanelli, J. E. Conway, A. Corongiu, R. Feiler, E. Fonseca, O. Forssén, M. Gawroński, M. Giroletti, M. A. Kharinov, C. Leung, M. Lindqvist, G. Maccaferri, B. Marcote, K. W. Masui, R. Mckinven, A. Melnikov, D. Michilli, A. G. Mikhailov, C. Ng, A. Orbidans, O. S. Ould-Boukattine, Z. Paragi, A. B. Pearlman, E. Petroff, M. Rahman, P. Scholz, K. Shin, K. M. Smith, I. H. Stairs, G. Surcis, S. P. Tendulkar, W. Vlemmings, N. Wang, J. Yang and J. P. Yuan, 23 February 2022, Nature Astronomy.DOI: 10.1038/ s41550-021-01569-9.
A cluster of ancient stars (left) close to the spiral galaxy Messier 81 (M81) is the source of extraordinarily intense and short radio signals. Precision measurements with radio telescopes expose that the bursts are made amongst old stars, and in a method that no one was anticipating. Even more out in the universe, quick radio bursts have been found in places where stars are much younger. Lots of fast radio bursts have been discovered surrounded by young, huge stars, much larger than the Sun. Of the 10s of thousands of stars in the cluster, a couple of get close enough that one star collects material from the other.
