| 1. |
- Amiri, M., et al.
(author)
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Periodic activity from a fast radio burst source
- 2020
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 582:7812, s. 351-355
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Journal article (peer-reviewed)abstract
- 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 events2–4. Despite searches for periodicity in repeat burst arrival times on timescales from milliseconds to many days2,5–7, 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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| 2. |
- Scholz, P., et al.
(author)
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Simultaneous X-Ray and Radio Observations of the Repeating Fast Radio Burst FRB similar to 180916.J0158+65
- 2020
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 901:2
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Journal article (peer-reviewed)abstract
- We report on simultaneous radio and X-ray observations of the repeating fast radio burst source FRB 180916.J0158+65 using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Effelsberg, and Deep Space Network (DSS-14 and DSS-63) radio telescopes and the Chandra X-ray Observatory. During 33 ks of Chandra observations, we detect no radio bursts in overlapping Effelsberg or Deep Space Network observations and a single burst during CHIME/FRB source transits. We detect no X-ray events in excess of the background during the Chandra observations. These non-detections imply a 5 sigma limit of <5 x 10(-10)erg cm(-2)for the 0.5-10 keV fluence of prompt emission at the time of the radio burst and 1.3 x 10(-9)erg cm(-2)at any time during the Chandra observations. Given the host-galaxy redshift of FRB 180916.J0158+65 (z similar to 0.034), these correspond to energy limits of <1.6 x 10(45)erg and <4 x 10(45)erg, respectively. We also place a 5 sigma limit of <8 x 10(-15)erg s(-1) cm(-2)on the 0.5-10 keV absorbed flux of a persistent source at the location of FRB 180916.J0158+65. This corresponds to a luminosity limit of <2 x 10(40)erg s(-1). Using an archival set of radio bursts from FRB 180916.J0158+65, we search for prompt gamma-ray emission in Fermi/GBM data but find no significant gamma-ray bursts, thereby placing a limit of 9 x 10(-9)erg cm(-2)on the 10-100 keV fluence. We also search Fermi/LAT data for periodic modulation of the gamma-ray brightness at the 16.35 days period of radio burst activity and detect no significant modulation. We compare these deep limits to the predictions of various fast radio burst models, but conclude that similar X-ray constraints on a closer fast radio burst source would be needed to strongly constrain theory.
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| 3. |
- Marcote, B., et al.
(author)
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A repeating fast radio burst source localized to a nearby spiral galaxy
- 2020
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 577:7789, s. 190-194
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Journal article (peer-reviewed)abstract
- Fast radio bursts (FRBs) are brief, bright, extragalactic radio flashes1,2. Their physical origin remains unknown, but dozens of possible models have been postulated3. Some FRB sources exhibit repeat bursts4–7. Although over a hundred FRB sources have been discovered8, only four have been localized and associated with a host galaxy9–12, and just one of these four is known to emit repeating FRBs9. The properties of the host galaxies, and the local environments of FRBs, could provide important clues about their physical origins. The first known repeating FRB, however, was localized to a low-metallicity, irregular dwarf galaxy, and the apparently non-repeating sources were localized to higher-metallicity, massive elliptical or star-forming galaxies, suggesting that perhaps the repeating and apparently non-repeating sources could have distinct physical origins. Here we report the precise localization of a second repeating FRB source6, FRB 180916.J0158+65, to a star-forming region in a nearby (redshift 0.0337 ± 0.0002) massive spiral galaxy, whose properties and proximity distinguish it from all known hosts. The lack of both a comparably luminous persistent radio counterpart and a high Faraday rotation measure6 further distinguish the local environment of FRB 180916.J0158+65 from that of the single previously localized repeating FRB source, FRB 121102. This suggests that repeating FRBs may have a wide range of luminosities, and originate from diverse host galaxies and local environments.
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| 4. |
- Pleunis, Z., et al.
(author)
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LOFAR Detection of 110-188MHz emission and frequency-dependent activity from FRB20180916B
- 2021
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Journal article (peer-reviewed)abstract
- The object FRB 20180916B is a well-studied repeating fast radio burst source. Its proximity (∼150 Mpc), along with detailed studies of the bursts, has revealed many clues about its nature, including a 16.3 day periodicity in its activity. Here we report on the detection of 18 bursts using LOFAR at 110-188 MHz, by far the lowest-frequency detections of any FRB to date. Some bursts are seen down to the lowest observed frequency of 110 MHz, suggesting that their spectra extend even lower. These observations provide an order-of-magnitude stronger constraint on the optical depth due to freëCfree absorption in the source's local environment. The absence of circular polarization and nearly flat polarization angle curves are consistent with burst properties seen at 300-1700 MHz. Compared with higher frequencies, the larger burst widths (∼40-160 ms at 150 MHz) and lower linear polarization fractions are likely due to scattering. We find ∼2-3 rad m variations in the Faraday rotation measure that may be correlated with the activity cycle of the source. We compare the LOFAR burst arrival times to those of 38 previously published and 22 newly detected bursts from the uGMRT (200-450 MHz) and CHIME/FRB (400-800 MHz). Simultaneous observations show five CHIME/FRB bursts when no emission is detected by LOFAR. We find that the burst activity is systematically delayed toward lower frequencies by about 3 days from 600 to 150 MHz. We discuss these results in the context of a model in which FRB 20180916B is an interacting binary system featuring a neutron star and high-mass stellar companion.
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