Dense magnetized plasma associated with a fast radio burst

Journal name:
Nature
Volume:
528,
Pages:
523–525
Date published:
DOI:
doi:10.1038/nature15769
Received
Accepted
Published online

Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source1, 2, 3, 4, 5, 6, 7. The inferred all-sky burst rate8 is comparable to the core-collapse supernova rate9 out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models12, 13, 14, 15, 16, 17. One fast burst6 revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density10, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.

At a glance

Figures

  1. Brightness temperature spectra versus time for FRB 110523.
    Figure 1: Brightness temperature spectra versus time for FRB 110523.

    The diagonal black curve shows the pulse of radio brightness sweeping over time. The arrival time is differentially delayed (dispersed) by plasma along the line of sight. A pair of curves in white, bracketing the FRB pulse, show that the delay function matches the one expected from cold plasma. The grey horizontal bars show where data has been omitted owing to resonances within the GBT receiver. The inset shows fluctuations in brightness caused by scintillation.

  2. FRB 110523 spectra in total intensity and polarization.
    Figure 2: FRB 110523 spectra in total intensity and polarization.

    Plotted is the pulse fluence (time-integrated flux) for total intensity (Stokes I), and linear polarization (Stokes Q and U). Solid curves are model fits. In addition to noise, scatter in the measurement around the models is due to the scintillation visible in Fig. 1. The decline of intensity with frequency is primarily due to motion of the telescope beam across the sky and is not intrinsic to the source.

  3. Polarized pulse profiles averaged over spectral frequency.
    Figure 3: Polarized pulse profiles averaged over spectral frequency.

    Plotted is total intensity (I), linear polarization (P+ and P×), and circular polarization (V, which may be instrumental). Before taking the noise-weighted mean over frequency, the data are scaled to 800 MHz using the best-fit spectral index and the linear polarization is rotated to compensate for the best-fit Faraday rotation. The linear polarization basis coordinates are aligned with (+), and rotated with respect to (×), the mean polarization over time. The bottom panel shows the polarization angle (where measurable) in these coordinates. The error bars show the standard deviation of 10,000 simulated measurements with independent noise realizations.

  4. Events in frequency–time and DM–time space.
    Extended Data Fig. 1: Events in frequency–time and DM–time space.

    From left to right are shown data for FRB 110523, a simulated FRB, a known pulsar PSR J2257+5909, and man-made radio frequency interference (RFI). Brightness temperature is shown in frequency–time space (upper panels) and the same data in DM–time space (lower panels). The relative dispersion measure is the difference between the DM and the event DM; event DM values are 622.8 pc cm−3, 610.3 pc cm−3, 151.0 pc cm−3 and 1132.1 pc cm−3 from left to right. The time axes of the frequency–time plots show time relative to the zero time in DM–time space. The colour scale in the lower panels represents broadband flux, with red showing a bright source.

  5. Pulse profiles for FRB 110523 in three sub-bands.
    Extended Data Fig. 2: Pulse profiles for FRB 110523 in three sub-bands.

    Each sub-band has width of 66 MHz. The pulse width decreases with frequency (at 2.6σ significance), consistent with models of scattering in the interstellar medium. Also shown in black is the best-fit model profile for the middle band.

  6. Spectral brightness correlation function of FRB 110523.
    Extended Data Fig. 3: Spectral brightness correlation function of FRB 110523.

    The intensity spectrum has structure that is correlated for frequency separations less than fdc = 1.2 MHz. Error bars are the standard deviation of 3,268 simulated measurements with 817 independent noise realizations and are correlated.

Tables

  1. FRB 110523 parameters
    Extended Data Table 1: FRB 110523 parameters

References

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Author information

Affiliations

  1. Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia V6T 1Z1, Canada

    • Kiyoshi Masui
  2. Canadian Institute for Advanced Research, CIFAR Program in Cosmology and Gravity, Toronto, Ontario M5G 1Z8, Canada

    • Kiyoshi Masui &
    • Ue-Li Pen
  3. McWilliams Center for Cosmology, Carnegie Mellon University, Department of Physics, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA

    • Hsiu-Hsien Lin,
    • Jeffrey B. Peterson,
    • Alexander Roman &
    • Tabitha Voytek
  4. Astrophysics and Cosmology Research Unit, School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4001, South Africa

    • Jonathan Sievers &
    • Tabitha Voytek
  5. National Institute for Theoretical Physics (NITheP), KZN node, Durban 4001, South Africa

    • Jonathan Sievers
  6. Department of Physics, University of Wisconsin, Madison, Wisconsin 53706-1390, USA

    • Christopher J. Anderson &
    • Peter T. Timbie
  7. Academia Sinica Institute of Astronomy and Astrophysics, 11F Astro-Math Building, AS/NTU 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan

    • Tzu-Ching Chang,
    • Cheng-Yu Kuo &
    • Yu-Wei Liao
  8. National Astronomical Observatories, Chinese Academy of Science, 20A Datun Road, Beijing 100012, China

    • Xuelei Chen &
    • Yi-Chao Li
  9. Center of High Energy Physics, Peking University, Beijing 100871, China

    • Xuelei Chen
  10. Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics, and Computer Science, University of KwaZulu-Natal, Durban 4001, South Africa

    • Apratim Ganguly
  11. Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, Ontario M5S 3H4, Canada

    • Miranda Jarvis
  12. Department of Physics, National Sun Yat-Sen University No. 70, Lianhai Road, Gushan District, Kaohsiung City 804, Taiwan

    • Cheng-Yu Kuo
  13. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA

    • Maura McLaughlin
  14. Canadian Institute for Theoretical Astrophysics, 60 St George Street, Toronto, Ontario M5S 3H8, Canada

    • Ue-Li Pen
  15. Perimeter Institute, 31 Caroline Street, Waterloo N2L 2Y5, Canada

    • Ue-Li Pen
  16. Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli, PO 140306, India

    • Jaswant K. Yadav

Contributions

K.M. integrated the FRB search routines into a software program; calibrated and filtered the raw FRB event data; performed scintillation analysis; led survey planning; produced Figs 2 and 3 and Extended Data Fig. 3; and contributed to model fits to the FRB event, result interpretation, beam characterization, observations, data handling, and data validation. H.-H.L. performed the visual search of the search of over 6,000 images, and discovered the FRB event. H.-H.L. also coproduced Fig. 1, produced Extended Data Fig. 2, and contributed to the FRB search software program, observations, data handling, and data validation. J.S. wrote dedispersion and FRB search software routines; performed model fits to the FRB event (including extracting the dispersion measure, rotation measure, scattering tail, and polarization angle swing); and contributed to result interpretation. C.J.A. contributed to observations, data handling, and data validation. T.-C.C. contributed to survey planning, observations, and data validation. X.C. contributed to data validation. A.G. contributed to FRB search algorithm validation. M.J. contributed to observations and data validation. C.-Y.K. contributed to observations and data validation. Y.-C.L. performed scintillation analysis on the foreground pulsar and contributed to data validation. Y.-W.L. contributed to polarization leakage characterization, calibration methods, and data validation. M.McL. contributed to result interpretation, analysis of the follow-up data, scintillation analysis on the foreground pulsar, and edited the manuscript. U.-L.P. carried out Faraday rotation measure synthesis (resulting in the detection of linear polarization) and contributed to result interpretation, scintillation analysis, survey planning, and data validation. J.B.P. led manuscript preparation and contributed to result interpretation, survey planning and data validation. A.R. surveyed archival multi-wavelength catalogues for coincident sources, coproduced Fig. 1, produced Extended Data Fig. 3, and added event simulation functionality to the FRB search software program. P.T.T. contributed to observations and data validation and editing of the manuscript. T.V. led the observational campaign and contributed to calibration methods, survey planning, data handling, and data validation. J.K.Y. contributed to data validation.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

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Author details

Extended data figures and tables

Extended Data Figures

  1. Extended Data Figure 1: Events in frequency–time and DM–time space. (329 KB)

    From left to right are shown data for FRB 110523, a simulated FRB, a known pulsar PSR J2257+5909, and man-made radio frequency interference (RFI). Brightness temperature is shown in frequency–time space (upper panels) and the same data in DM–time space (lower panels). The relative dispersion measure is the difference between the DM and the event DM; event DM values are 622.8 pc cm−3, 610.3 pc cm−3, 151.0 pc cm−3 and 1132.1 pc cm−3 from left to right. The time axes of the frequency–time plots show time relative to the zero time in DM–time space. The colour scale in the lower panels represents broadband flux, with red showing a bright source.

  2. Extended Data Figure 2: Pulse profiles for FRB 110523 in three sub-bands. (182 KB)

    Each sub-band has width of 66 MHz. The pulse width decreases with frequency (at 2.6σ significance), consistent with models of scattering in the interstellar medium. Also shown in black is the best-fit model profile for the middle band.

  3. Extended Data Figure 3: Spectral brightness correlation function of FRB 110523. (55 KB)

    The intensity spectrum has structure that is correlated for frequency separations less than fdc = 1.2 MHz. Error bars are the standard deviation of 3,268 simulated measurements with 817 independent noise realizations and are correlated.

Extended Data Tables

  1. Extended Data Table 1: FRB 110523 parameters (259 KB)

Additional data