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Periodic activity from a fast radio burst source


Fast radio bursts (FRBs) are bright, millisecond-duration radio transients originating from sources at extragalactic distances1, the origin of which is unknown. Some FRB sources emit repeat bursts, ruling out cataclysmic origins for those events2,3,4. Despite searches for periodicity in repeat burst arrival times on timescales from milliseconds to many days2,5,6,7, these bursts have hitherto been observed to appear sporadically and—although clustered8—without a regular pattern. Here we report observations of a 16.35 ± 0.15 day periodicity (or possibly a higher-frequency alias of that periodicity) from the repeating FRB 180916.J0158+65 detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project4,9. In 38 bursts recorded from 16 September 2018 to 4 February 2020 utc, we find that all bursts arrive in a five-day phase window, and 50 per cent of the bursts arrive in a 0.6-day phase window. Our results suggest a mechanism for periodic modulation either of the burst emission itself or through external amplification or absorption, and disfavour models invoking purely sporadic processes.

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Fig. 1: Periodograms of FRB 180916.J0158+65 and control samples.
Fig. 2: Timeline of the daily exposure of CHIME/FRB to FRB 180916.J0158+65.
Fig. 3: Burst properties against phase.

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We thank the Dominion Radio Astrophysical Observatory, operated by the National Research Council Canada, for hospitality and expertise. The CHIME/FRB Project is funded by a grant from the Canada Foundation for Innovation 2015 Innovation Fund (project 33213), as well as by the Provinces of British Columbia and Québec, and by the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto. Additional support was provided by the Canadian Institute for Advanced Research (CIFAR), McGill University and the McGill Space Institute via the Trottier Family Foundation, and the University of British Columbia. Research at Perimeter Institute is supported by the Government of Canada through Innovation, Science and Economic Development Canada and by the Province of Ontario through the Ontario Ministry of Economic Development, Job Creation and Trade. The National Radio Astronomy Observatory is a facility of the National Science Foundation (NSF) operated under cooperative agreement by Associated Universities, Inc. FRB research at the University of British Columbia is supported by an NSERC Discovery Grant and by the Canadian Institute for Advanced Research. The CHIME/FRB baseband system is funded in part by a CFI John R. Evans Leaders Fund grant to I.H.S. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. A.S.H. was partly supported by the Dunlap Institute at the University of Toronto. B.M. acknowledges support from the Spanish Ministerio de Economía y Competitividad (MINECO) under grants AYA2016-76012-C3-1-P and MDM-2014-0369 of ICCUB (Unidad de Excelencia ‘María de Maeztu’). B.M.G. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) through grant RGPIN-2015-05948, and of the Canada Research Chairs programme. D.M. is a Banting Fellow. M.B. is supported by a Fonds de recherche du Québec – Nature et technologies (FRQNT) Doctoral Research Award. M.D. is supported by a Killam Fellowship and receives support from an NSERC Discovery Grant, CIFAR, and from the FRQNT Centre de Recherche en Astrophysique du Québec. P.C. is supported by an FRQNT Doctoral Research Award. P.S. is a Dunlap Fellow and an NSERC Postdoctoral Fellow. S.M.R. is a CIFAR Fellow and is supported by the NSF Physics Frontiers Center award 1430284. U.-L.P. receives support from the Ontario Research Fund – Research Excellence (ORF-RE) programme, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Simons Foundation, Thoth Technology Inc. and the Alexander von Humboldt Foundation. V.M.K. holds the Lorne Trottier Chair in Astrophysics and Cosmology and a Canada Research Chair and receives support from an NSERC Discovery Grant and Herzberg Award, from an R. Howard Webster Foundation Fellowship from the Canadian Institute for Advanced Research (CIFAR), and from the FRQNT Centre de Recherche en Astrophysique du Québec. Z.P. is supported by a Schulich Graduate Fellowship. F.K. acknowledges support by the Swedish Research Council. J.W.K. is supported by NSF OIA Award 1458952. The European VLBI Network is a joint facility of independent European, African, Asian and North American radio astronomy institutes. Scientific results from EVN data presented in this publication are derived from the following EVN project code: EM135. This work is based in part on observations with the 100-m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg. We thank L. Spitler, M. Cruces and M. Kramer for their help in acquiring Effelsberg observing time. We thank R. Archibald for discussions regarding the H test. We thank S. Chatterjee for pointing out the aliasing possibility to us.

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Authors and Affiliations



All authors from the CHIME/FRB collaboration had either leadership or major supporting roles in one or more of: the management, development and construction of the CHIME telescope, the CHIME/FRB instrument and the CHIME/FRB software data pipeline, the commissioning and operations of the CHIME/FRB instrument, the data analysis and preparation of this manuscript. All authors from the CHIME collaboration had either leadership or major supporting roles in the management, development and construction of the CHIME telescope. K.N., J.W.T.H., B.M., Z.P., A.K., F.K. and R.K. performed the analysis of the EVN and Effelsberg single-dish data.

Corresponding author

Correspondence to D. Z. Li.

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Peer review information Nature thanks Vikram Ravi and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Dynamic spectra of newly reported bursts (bursts 12–28 in Extended Data Table 1).

Bursts with separations of less than 0.1 s are shown in joint spectra (bursts 24 and 25). All bursts are dedispersed to 348.82 pc cm−3. The sequence number of the burst and the arrival date (in MJD) is given in each top-left corner. The arrival phase of the bursts within the 16.35-d cycle is given in the top left corner of each spectrum. Each plot also gives the 0.98304-ms time-resolution dedispersed intensity data with the integrated burst profile on top and the on-pulse spectrum on the right (arbitrary units). Intensity values are saturated at the 5th and 95th percentiles. Pulse widths—defined as the width of the boxcar with the highest S/N after convolution with the burst profile—are given in the top-right corner. The shaded region in each profile (four times the pulse width) was used for the extraction of the on-pulse spectrum. The shaded region in the on-pulse spectrum shows the full width at tenth maximum of a Gaussian fit. In each burst profile, the black line is the integration over the full width at tenth maximum of the spectrum and the grey line is the integration over the full bandwidth. For better visualization, we downsampled the full-resolution data (16,384 channels) to 64 sub-bands, each with a bandwidth of 6.25 MHz. Horizontal white bands represent missing or masked data. There are underlying missing or masked channels at full resolution, resulting in an average effective bandwidth of 224 MHz.

Extended Data Fig. 2 Dynamic spectra of newly reported bursts (bursts 29–38 in Extended Data Table 1).

As in Extended Data Fig. 1. Bursts 31 and 32 are shown in joint spectra.

Extended Data Fig. 3 Dynamic spectra of the bursts with available baseband data.

ad, Bursts 9 (a), 10 (b), 18 (c) and 20 (d) (see Extended Data Table 1), dedispersed to their per-burst optimal DM, which is listed in each top-right corner. The sampling time (ts) after downsampling is listed in each top-left corner. Intensity values are saturated at the 1st and 99th percentiles. 64 frequency sub-bands with a 6.25-MHz sub-band bandwidth are shown for all bursts. Horizontal white bands represent missing or masked data. pc/cc, pc cm−3.

Extended Data Fig. 4 Cumulative distribution of burst fluences.

The distribution is composed of both the newly detected bursts and those previously detected. Excluding bursts detected beyond the 600-MHz FWHM of any CHIME/FRB synthesized beam, this includes 25 bursts split into sub-bursts, yielding 33 fluence measurements. The black solid line represents the maximum-likelihood estimated power law with differential distribution index α = −2.3 ± 0.3 ± 0.1, where the first error is the statistical uncertainty from the maximum-likelihood estimator and the second error is the standard deviation of the distribution of power-law indices obtained from a Monte Carlo simulation that resamples the fluences according to their uncertainties. The black dashed vertical line denotes the 5.3 Jy ms threshold determined by minimizing the Kolmogorov–Smirnov distance between a power-law fit and the underlying data. The blue dash-dotted vertical line denotes the 5.2 Jy ms active period 90% confidence completeness threshold.

Extended Data Table 1 Burst properties
Extended Data Table 2 Effelsberg observations

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The CHIME/FRB Collaboration*. Periodic activity from a fast radio burst source. Nature 582, 351–355 (2020).

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