GB1 - Fast radio bursts: observations, ideas and prospects |
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Speaker |
Michilli, Daniele |
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Coauthors |
Michilli, Daniele; Seymour, Andrew; Hessels, Jason W. T.; Spitler, Laura G.; Gajjar, Vishalkumar; Archibald, Anne M.; Bower, Geoffrey C.; Chatterjee, Shami; Cordes, James M.; Gourdji, Kelly; Heald, George H.; Kaspi, Victoria M.; Law, Casey J.; Sobey Charlotte |
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Observational properties and possible origins of the fast radio burst source FRB 121102 |
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Abstract |
Fast radio bursts (FRBs) are millisecond-duration radio transients of apparent extragalactic origin. Their origins remain enigmatic, though many possible models have been proposed. FRB 121102 is the only such source currently known to emit multiple bursts, and may have a different physical origin compared to the apparently non-repeating FRBs that have been detected. The repeatability allows us to study FRB 121102 with unprecedented detail, giving important insights into its physical origin and nature. It is located in a low-metallicity dwarf galaxy at a redshift of 0.193. Such host galaxies are also often the sites of other extreme transients such as super-luminous supernovae and long gamma-ray bursts. FRB 121102 has also been localised within the tiny host galaxy to an active star-forming region, where a persistent radio source was found coincident with the burst source. The persistent source, with a size upper limit of 0.7 pc, is plausibly a highly energetic supernova remnant or a low-luminosity accreting massive black hole. We studied the characteristics of the local environment of FRB 121102 by analysing the Faraday rotation of the polarised radio bursts. The astonishingly high value obtained for the rotation measure (RM ~ 100,000 rad m-2), and its high variability (since the first detections the RM has dropped by about 30% in 16 months) indicates a hot, dense and dynamic environment where strong and highly ordered magnetic fields are present. These new insights are consistent with scenarios in which FRB 121102 is a very young neutron star in a dense environment, and possibly in the vicinity of a massive black hole. In this talk, I will review these observational facts in the context of possible models for FRB 121102, and FRBs in general. |
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