Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

# Chromatic periodic activity down to 120 megahertz in a fast radio burst

## Abstract

Fast radio bursts (FRBs) are extragalactic astrophysical transients1 whose brightness requires emitters that are highly energetic yet compact enough to produce the short, millisecond-duration bursts. FRBs have thus far been detected at frequencies from 8 gigahertz (ref. 2) down to 300 megahertz (ref. 3), but lower-frequency emission has remained elusive. Some FRBs repeat4,5,6, and one of the most frequently detected, FRB 20180916B7, has a periodicity cycle of 16.35 days (ref. 8). Using simultaneous radio data spanning a wide range of wavelengths (a factor of more than 10), here we show that FRB 20180916B emits down to 120 megahertz, and that its activity window is frequency dependent (that is, chromatic). The window is both narrower and earlier at higher frequencies. Binary wind interaction models predict a wider window at higher frequencies, the opposite of our observations. Our full-cycle coverage shows that the 16.3-day periodicity is not aliased. We establish that low-frequency FRB emission can escape the local medium. For bursts of the same fluence, FRB 20180916B is more active below 200 megahertz than at 1.4 gigahertz. Combining our results with previous upper limits on the all-sky FRB rate at 150 megahertz, we find there are 3–450 FRBs in the sky per day above 50 Jy ms. Our chromatic results strongly disfavour scenarios in which absorption from strong stellar winds causes FRB periodicity. We demonstrate that some FRBs are found in ‘clean’ environments that do not absorb or scatter low-frequency radiation.

This is a preview of subscription content, access via your institution

## Relevant articles

• ### Fast radio bursts at the dawn of the 2020s

The Astronomy and Astrophysics Review Open Access 29 March 2022

## Access options

\$39.95

Prices may be subject to local taxes which are calculated during checkout

## Data availability

Raw data were generated by the Apertif system on the Westerbork Synthesis Radio Telescope and by the International LOFAR Telescope. The Apertif data that support the findings of this study are available through the ALERT archive, http://www.alert.eu/FRB20180916B. The LOFAR data are available through the LOFAR Long Term Archive, https://lta.lofar.eu/, by searching for ‘Observations’ at J2000 coordinates RA = 01:57:43.2000, Dec. = +65:42:01.020, or by selecting COM_ALERT in ‘Other projects’ and downloading data which includes R3 in the ‘Observation description’.

## Code availability

The custom code used to generate these results is publicly available at https://doi.org/10.5281/zenodo.4559593 (ref. 80).

## References

1. Lorimer, D. R., Bailes, M., McLaughlin, M. A., Narkevic, D. J. & Crawford, F. A bright millisecond radio burst of extragalactic origin. Science 318, 777–780 (2007).

2. Gajjar, V. et al. Highest-frequency detection of FRB 121102 at 4–8 GHz using the breakthrough listen digital backend at the Green Bank Telescope. Astrophys. J. 863, 2 (2018).

3. Chawla, P. et al. Detection of repeating FRB 180916.J0158+65 down to frequencies of 300 MHz. Astrophys. J. 896, L41 (2020).

4. Spitler, L. G. et al. A repeating fast radio burst. Nature 531, 202–205 (2016).

5. The CHIME/FRB Collaboration. A second source of repeating fast radio bursts. Nature 566, 235–238 (2019).

6. Fonseca, E. et al. Nine new repeating fast radio burst sources from CHIME/FRB. Astrophys. J. 891, L6 (2020).

7. The CHIME/FRB Collaboration et al. CHIME/FRB detection of eight new repeating fast radio burst sources. Astrophys. J. 885, L24 (2019).

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

9. Maan, Y. & van Leeuwen, J. Real-time searches for fast transients with Apertif and LOFAR. In IEEE Proc. URSI GASS https://doi.org/10.23919/URSIGASS.2017.8105320 (IEEE, 2017).

10. Stappers, B. W. et al. Observing pulsars and fast transients with LOFAR. Astron. Astrophys. 530, A80 (2011).

11. Pleunis, Z. et al. LOFAR detection of 110–188 MHz emission and frequency-dependent activity from FRB 20180916B. Astrophys. J. Lett. 911, L3 (2021).

12. Coenen, T. et al. The LOFAR pilot surveys for pulsars and fast radio transients. Astron. Astrophys. 570, A60 (2014).

13. Karastergiou, A. et al. Limits on fast radio bursts at 145 MHz with ARTEMIS, a real-time software backend. Mon. Not. R. Astron. Soc. 452, 1254–1262 (2015).

14. Marcote, B. et al. A repeating fast radio burst source localized to a nearby spiral galaxy. Nature 577, 190–194 (2020).

15. Hessels, J. W. T. et al. FRB 121102 bursts show complex time-frequency structure. Astrophys. J. 876, L23 (2019).

16. Cordes, J. M. & Lazio, T. J. W. NE2001.I. A new model for the Galactic distribution of free electrons and its fluctuations. Preprint at http://arXiv.org/abs/astro-ph/0207156 (2003).

17. McQuinn, M. Locating the “missing” baryons with extragalactic dispersion measure estimates. Astrophys. J. 780, L33 (2014).

18. Chamma, M. A., Rajabi, F., Wyenberg, C. M., Mathews, A. & Houde, M. Evidence of a shared law between sources of repeating fast radio bursts. Preprint at http://arXiv.org/abs/2010.14041 (2020).

19. Josephy, A. et al. CHIME/FRB detection of the original repeating fast radio burst source FRB 121102. Astrophys. J. 882, L18 (2019).

20. Aggarwal, K. et al. VLA/realfast detection of burst from FRB180916.J0158+65 and tests for periodic activity. Res. Notes AAS 4, 94 (2020).

21. Rajwade, K. M. et al. Possible periodic activity in the repeating FRB 121102. Mon. Not. R. Astron. Soc. 495, 3551–3558 (2020).

22. Lyutikov, M., Barkov, M. & Giannios, D. FRB-periodicity: mild pulsar in tight O/B-star binary. Astrophys. J. 893, L39 (2020).

23. Ioka, K. & Zhang, B. A binary comb model for periodic fast radio bursts. Astrophys. J. 893, L26 (2020).

24. Levin, Y., Beloborodov, A. M. & Bransgrove, A. Precessing flaring magnetar as a source of repeating FRB 180916.J0158+65. Astrophys. J. 895, L30 (2020).

25. Zanazzi, J. J. & Lai, D. Periodic fast radio bursts with neutron star free/radiative precession. Astrophys. J. 892, L15 (2020).

26. Tong, H., Wang, W. & Wang, H. G. Periodicity in fast radio bursts due to forced precession by a fallback disk. Res. Astron. Astrophys. 20, 142 (2020).

27. Metzger, B. D., Margalit, B. & Sironi, L. Fast radio bursts as synchrotron maser emission from decelerating relativistic blast waves. Mon. Not. R. Astron. Soc. 485, 4091–4106 (2019).

28. Beniamini, P., Wadiasingh, Z. & Metzger, B. D. Periodicity in recurrent fast radio bursts and the origin of ultra long period magnetars. Mon. Not. R. Astron. Soc. 496, 3390–3401 (2020).

29. Sand, K. R. et al. Low-frequency detection of FRB180916 with the uGMRT. Astron. Telegr. 13781 (2020).

30. Marthi, V. R. et al. Detection of 15 bursts from FRB 180916.J0158+65 with the uGMRT. Mon. Not. R. Astron. Soc. Lett. 499, L16–L20 (2020).

31. Oosterloo, T., Verheijen, M. & van Cappellen, W. The latest on Apertif. In Proc. ISKAF2010 Science Meeting 043 (Proceedings of Science, Vol. 112, 2010).

32. Adams, E. A. K. & van Leeuwen, J. Radio surveys now both deep and wide. Nature Astron. 3, 188 (2019).

33. Connor, L. et al. A bright, high rotation-measure FRB that skewers the M33 halo. Mon. Not. R. Astron. Soc. 499, 4716–4724 (2020).

34. Oostrum, L. C. et al. Repeating fast radio bursts with WSRT/Apertif. Astron. Astrophys. 635, A61 (2020).

35. van Leeuwen, J. ARTS – the Apertif Radio Transient System. In Proc. The Third Hot-wiring the Transient Universe Workshop https://www.slac.stanford.edu/econf/C131113.1/proceedings.html (eds Wozniak, P. R., Graham, M. J., Mahabal, A. A. & Seaman, R.) 79 (LANL, 2014).

36. Oostrum, L. C. Fast Radio Bursts with Apertif. PhD thesis, Univ. Amsterdam (2020).

37. Sclocco, A., van Leeuwen, J., Bal, H. E. & van Nieuwpoort, R. V. Real-time dedispersion for fast radio transient surveys, using auto tuning on many-core accelerators. Astronomy and Computing 14, 1–7 (2016).

38. Sclocco, A., Heldens, S. & van Werkhoven, B. AMBER: a real-time pipeline for the detection of single pulse astronomical transients. SoftwareX 12, 100549 (2020).

39. Sclocco, A., Vohl, D. & van Nieuwpoort, R. V. Real-time rfi mitigation for the apertif radio transient system. In Proc. 2019 RFI Workshop — Coexisting with Radio Frequency Interference (RFI) 1–8 (IEEE, 2019).

40. Oostrum, L. C. loostrum/darc: version 2.1. https://doi.org/10.5281/zenodo.3784870 (2020).

41. Connor, L. & van Leeuwen, J. Applying deep learning to fast radio burst classification. Astron. J. 156, 256 (2018).

42. Yao, J. M., Manchester, R. N. & Wang, N. A new electron density model for estimation of pulsar and FRB distances. Astrophys. J. 835, 29 (2017).

43. Ransom, S. M. New Search Techniques For Binary Pulsars. Ph.D. thesis, Harvard Univ. (2001).

44. van Haarlem, M. P. et al. LOFAR: The LOw-Frequency ARray. Astron. Astrophys. 556, A2 (2013).

45. Maan, Y., van Leeuwen, J. & Vohl, D. Fourier domain excision of periodic radio frequency interference. Astron. Astrophys. 650, A80 (2021).

46. Perley, R. A. & Butler, B. J. An accurate flux density scale from 50 MHz to 50 GHz. Astrophys. J. Suppl. Ser. 230, 7 (2017).

47. Cordes, J. M. & McLaughlin, M. A. Searches for fast radio transients. Astrophys. J. 596, 1142–1154 (2003).

48. Maan, Y. & Aswathappa, H. A. Deep searches for decametre-wavelength pulsed emission from radio-quiet gamma-ray pulsars. Mon. Not. R. Astron. Soc. 445, 3221–3228 (2014).

49. Houben, L. J. M. et al. Constraints on the low frequency spectrum of FRB 121102. Astron. Astrophys. 623, A42 (2019).

50. Sanidas, S. et al. The LOFAR Tied-Array All-Sky Survey (LOTAAS): survey overview and initial pulsar discoveries. Astron. Astrophys. 626, A104 (2019).

51. Kondratiev, V. I. et al. A LOFAR census of millisecond pulsars. Astron. Astrophys. 585, A128 (2016).

52. Bilous, A. V. et al. A LOFAR census of non-recycled pulsars: average profiles, dispersion measures, flux densities, and spectra. Astron. Astrophys. 591, A134 (2016).

53. Pilia, M. et al. The lowest frequency fast radio bursts: Sardinia Radio Telescope detection of the periodic FRB 180916 at 328 MHz. Astrophys. J. 896, L40 (2020).

54. Huijse, P. et al. Robust period estimation using mutual information for multiband light curves in the synoptic survey era. Astrophys. J. Suppl. Ser. 236, 12 (2018).

55. Scholz, P. et al. Simultaneous X-ray and radio observations of the repeating fast radio burst FRB 180916.J0158+65. Astrophys. J. 901, 165 (2020).

56. Pearlman, A. B. et al. Multiwavelength radio observations of two repeating fast radio burst sources: FRB 121102 and FRB 180916.J0158+65. Astrophys. J. 905, L27 (2020).

57. Scott, D. W. Multivariate Density Estimation: Theory, Practice, and Visualization (Wiley & Sons, 2015).

58. Lyutikov, M. Radius-to-frequency mapping and FRB frequency drifts. Astrophys. J. 889, 135 (2020).

59. Purcell, C. R., Van Eck, C. L., West, J., Sun, X. H. & Gaensler, B. M. RM-Tools: rotation measure (RM) synthesis and Stokes QU-fitting. (Astrophysics Source Code Library, ascl:2005.003, 2020).

60. Ordog, A., Booth, R. A., Van Eck, C. L., Brown, J.-A. C. & Landecker, T. L. Faraday rotation of extended emission as a probe of the large-scale galactic magnetic field. Galaxies 7, 43 (2019).

61. Nimmo, K. et al. Highly polarized microstructure from the repeating FRB 20180916B. Nature Astron. 5, 594–603 (2021).

62. Blaskiewicz, M., Cordes, J. M. & Wasserman, I. A relativistic model of pulsar polarization. Astrophys. J. 370, 643 (1991).

63. Cho, H. et al. Spectropolarimetric analysis of FRB 181112 at microsecond resolution: implications for fast radio burst emission mechanism. Astrophys. J. Lett. 891, L38 (2021).

64. Beloborodov, A. M. A flaring magnetar in FRB 121102? Astrophys. J. 843, L26 (2017).

65. Hotan, A. W., van Straten, W. & Manchester, R. N. Psrchive and Psrfits: an open approach to radio pulsar data storage and analysis. Publ. Astron. Soc. Aust. 21, 302–309 (2004).

66. Caleb, M. et al. Simultaneous multi-telescope observations of FRB 121102. Mon. Not. R. Astron. Soc. 496, 4565–4573 (2020).

67. Wang, W., Zhang, B., Chen, X. & Xu, R. On the time-frequency downward drifting of repeating fast radio bursts. Astrophys. J. 876, L15 (2019).

68. Rajabi, F., Chamma, M. A., Wyenberg, C. M., Mathews, A. & Houde, M. A simple relationship for the spectro-temporal structure of bursts from FRB 121102. Mon. Not. R. Astron. Soc. 498, 4936–4942 (2020).

69. Krishnakumar, M. A., Joshi, B. C. & Manoharan, P. K. Multi-frequency scatter broadening evolution of pulsars. I. Astrophys. J. 846, 104 (2017).

70. Maan, Y., Joshi, B. C., Surnis, M. P., Bagchi, M. & Manoharan, P. K. Distinct properties of the radio burst emission from the magnetar XTE J1810–197. Astrophys. J. 882, L9 (2019).

71. Rane, A. et al. A search for rotating radio transients and fast radio bursts in the Parkes high-latitude pulsar survey. Mon. Not. R. Astron. Soc. 455, 2207–2215 (2016).

72. Lawrence, E., Wiel, S. V., Law, C. J., Spolaor, S. B. & Bower, G. C. The non-homogeneous Poisson process for fast radio burst rates. Astron. J. 154, 117 (2017).

73. Vedantham, H. K., Ravi, V., Hallinan, G. & Shannon, R. The fluence and distance distributions of fast radio bursts. Astrophys. J. 830, 75 (2016).

74. Keane, E. F. & Petroff, E. Fast radio bursts: search sensitivities and completeness. Mon. Not. R. Astron. Soc. 447, 2852–2856 (2015).

75. Connor, L. Interpreting the distributions of FRB observables. Mon. Not. R. Astron. Soc. 487, 5753–5763 (2019).

76. ter Veen, S. et al. The FRATS project: real-time searches for fast radio bursts and other fast transients with LOFAR at 135 MHz. Astron. Astrophys. 621, A57 (2019).

77. Tingay, S. J. et al. A search for fast radio bursts at low frequencies with Murchison Widefield Array high time resolution imaging. Astron. J. 150, 199 (2015).

78. Rowlinson, A. et al. Limits on fast radio bursts and other transient sources at 182 MHz using the Murchison Widefield Array. Mon. Not. R. Astron. Soc. 458, 3506–3522 (2016).

79. Sokolowski, M. et al. No low-frequency emission from extremely bright fast radio bursts. Astrophys. J. 867, L12 (2018).

80. Pastor-Marazuela, I. Reproduction package for “Chromatic periodic activity down to 120 megahertz in a fast radio burst”. https://doi.org/10.5281/zenodo.4559593 (2021).

## Acknowledgements

This research was supported by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement no. 617199 (‘ALERT’), and by Vici research programme ‘ARGO’ with project number 639.043.815, financed by the Dutch Research Council (NWO). Instrumentation development was supported by NWO (grant 614.061.613 ‘ARTS’) and the Netherlands Research School for Astronomy (‘NOVA4-ARTS’, ‘NOVA-NW3’ and ‘NOVA5-NW3-10.3.5.14’). PI of aforementioned grants is J.v.L. We further acknowledge funding from an NWO Veni Fellowship to E.P.; from Netherlands eScience Center (NLeSC) grant ASDI.15.406 to D.V. and A.S.; from National Aeronautics and Space Administration (NASA) grant number NNX17AL74G issued through the NNH16ZDA001N Astrophysics Data Analysis Program (ADAP) to S.S.; by the WISE research programme, financed by NWO, to E.A.K.A.; from FP/2007-2013 ERC grant agreement no. 291531 (‘HIStoryNU’) to T.v.d.H.; and from VINNOVA VINNMER grant 2009-01175 to V.M.I. I.P.-M. and Y.M. thank M. A. Krishnakumar for providing a software module that was useful in estimating the scatter-broadening timescale. This work makes use of data from the Apertif system installed at the Westerbork Synthesis Radio Telescope owned by ASTRON. ASTRON, the Netherlands Institute for Radio Astronomy, is an institute of NWO. This paper is based (in part) on data obtained with the International LOFAR Telescope (ILT) under project code COM_ALERT. These data are accessible through the LOFAR Long Term Archive, https://lta.lofar.eu/. LOFAR (Methods) is the low frequency array designed and constructed by ASTRON. It has observing, data processing and data storage facilities in several countries, that are owned by various parties (each with their own funding sources), and that are collectively operated by the ILT foundation under a joint scientific policy. The ILT resources have benefitted from the following recent major funding sources: CNRS-INSU, Observatoire de Paris and Université d’Orléans, France; BMBF, MIWF-NRW, MPG, Germany; Science Foundation Ireland (SFI), Department of Business, Enterprise and Innovation (DBEI), Ireland; NWO, The Netherlands; The Science and Technology Facilities Council, UK; Ministry of Science and Higher Education, Poland. We acknowledge use of the CHIME/FRB Public Database, provided at https://www.chime-frb.ca/ by the CHIME/FRB Collaboration.

## Author information

Authors

### Contributions

I.P.-M., L.C., J.v.L., Y.M., S.t.V., A.B., L.O., E.P., S.S. and D.V. analysed and interpreted the data. I.P.-M., L.C., J.v.L., Y.M. and S.t.V. contributed to the LOFAR data acquisition, and to the conception, design and creation of LOFAR analysis software. I.P.-M., L.C. and J.v.L. conceived and drafted the work, and Y.M., S.t.V., A.B., L.O., E.P., S.S. and D.V. contributed substantial revisions. L.O., J.A., O.M.B., E.K., D.v.d.S., A.S., R.S., E.A.K.A., B.A., W.J.G.d.B., A.H.W.M.C., S.D., H.D., K.M.H., T.v.d.H., B.H., V.M.I., A.K., G.M.L., D.M.L., A.M., V.A.M., H.M., M.J.N., T.O., E.O., M.R. and S.J.W. contributed to the conception, design and creation of the Apertif hardware, software and firmware used in this work, and to the Apertif data acquisition.

### Corresponding author

Correspondence to Joeri van Leeuwen.

## Ethics declarations

### Competing interests

The authors declare no competing interests.

Peer review information Nature thanks Scott Ransom and Matthew Bailes for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

## Extended data figures and tables

### Extended Data Fig. 1 The FRB 20180916B fluence distribution at Apertif and at LOFAR.

For each fluence F we plot how many brighter bursts are detected per hour, Rate (>F) (h−1). The light green data points show the cumulative distribution function (CDF) of all Apertif bursts, with dash-dotted, dotted and dashed lines giving the power-law fit respectively to bursts with fluences lower than 3.2 Jy ms, between 3.2 Jy ms and 7.8 Jy ms, and above 7.8 Jy ms. The coloured solid lines correspond to different phase ranges within the active window, with no discernible difference between them other than the rate scaling. The LOFAR fluence distribution is shown in crimson. The fit to a broken power law (‘broken pl’) with a fluence turnover at 104 Jy ms is shown as a grey dotted line. For the same fluence, FRB 20180916B is more active at 150 MHz than 1,370 MHz, even at the peak activity phases observed by Apertif.

### Extended Data Fig. 2 Dynamic spectra of Apertif bursts A01–A27.

We display PA (top panel), Stokes parameters I, L and V (central panel) and dynamic spectra (bottom panel), for bursts with full Stokes data (for example, panel A01 at top left). Bursts with only intensity data, such as A02, are limited to the total intensity profile. Burst identifiers are given in the top left corners, and activity cycle number in the top-right corners. Data have been dedispersed to DM = 348.75 pc cm−3, and downsampled 2× in time and 8× in frequency.

### Extended Data Fig. 3 Dynamic spectra of Apertif bursts A28–A54.

As in Extended Data Fig. 2.

### Extended Data Fig. 4 Observations and detections as a function of phase.

a, b, Shown are histograms of burst detections (‘N. Bursts’; a) and of observation duration (‘Obs. Duration’; b), both as a function of phase for the best period fitted to Apertif and CHIME/FRB data (16.29 days). In both panels, instruments are colour-coded by central frequency, with blue for high frequencies and red for low frequencies. This figure was generated using an adaptation of the frbpa package20.

### Extended Data Fig. 5 Comparison of simulated and observed activity window P values.

ac, Each panel compares the P value obtained through the Kolmogorov–Smirnov statistic on two instrument burst samples. The vertical black lines give the observed P value, whereas the histograms correspond to 105 simulations of the P value that would be obtained if both instrument burst samples were drawn from the same distribution. N is the number of resulting simulations per P value. Shown are comparisons of burst samples from Apertif and LOFAR (a), Apertif and CHIME/FRB (b), and CHIME/FRB and LOFAR (c). In all panels, the vertical grey dotted, dash-dotted and dashed lines show respectively the P value where 68.27% (1σ), 95.45% (2σ) and 99.73% (3σ) of the simulations give a larger P value.

### Extended Data Fig. 6 Stacked LOFAR bursts.

After dedispersion to the S/N-maximizing DM of 349.00 pc cm−3, the individual bursts were co-added. a, The pulse profiles in eight different frequency bands of the co-added total, and fits to the scattering tail. The central frequency of the band is indicated on the vertical-axis labels. b, The dynamic spectrum of the stacked bursts.

### Extended Data Fig. 7 Apertif burst properties against phase.

a, The structure-optimized DM, with the 348.75 pc cm−3 average as a reference. b, The drift rate of bursts with multiple components. c, d, The fluence (c) and the average polarization position angle (PA) (d) of each burst. In all panels, bursts are colour-coded by activity cycle. Each colour corresponds to a different activity cycle (see key at bottom left), and the data points with a black edge represent bursts with S/N > 20. The error bars represent 1σ (s.d.) errors.

### Extended Data Fig. 8 Five of the bursts with a measurable drift rate.

ae, For each burst, the top panel shows the pulse profile as a solid black line and the fitted multi-component Gaussian in grey (the burst name is given at top left.). Coloured regions indicate the subcomponent position. The main panels show the dynamic spectra, the subcomponent centroids with 1σ (s.d.) errors and the fitted drift rate $$\dot{\nu }$$ (white line). The right panels display the spectra and the fitted Gaussian of each subcomponent, with the same colour as the shaded region of the pulse profile.

### Extended Data Fig. 9 Finding the best period.

al, The periodograms between 0.03 day and 20 day periods of four instrument combinations and three different period searching techniques. Each column corresponds, from left to right, to all detections combined (blue), Apertif detections (green), CHIME/FRB detections (yellow) and CHIME/FRB and Apertif detections combined (red). Each row corresponds to a different search technique, with Pearson’s χ2 test7 at the top, maximum continuous fraction in the centre21, and the normalized QMIEU method54 at the bottom. The vertical grey lines mark the position of the aliased periods, solid lines for fN = (Nfsid + f0) and dotted lines for fN = (Nfsidf0). The number in the top left corner of each plot indicates the best period using the given burst data set and periodicity search method, with errors giving the full-width at half-maximum.

## Rights and permissions

Reprints and Permissions

Pastor-Marazuela, I., Connor, L., van Leeuwen, J. et al. Chromatic periodic activity down to 120 megahertz in a fast radio burst. Nature 596, 505–508 (2021). https://doi.org/10.1038/s41586-021-03724-8

• Accepted:

• Published:

• Issue Date:

• DOI: https://doi.org/10.1038/s41586-021-03724-8

• ### Fast radio bursts at the dawn of the 2020s

• E. Petroff
• J. W. T. Hessels
• D. R. Lorimer

The Astronomy and Astrophysics Review (2022)