Frequency-dependent polarization of repeating fast radio bursts—implications for their origin

Feng, Yi; Li, Di; Yang, Yuan-Pei; Zhang, Yongkun; Zhu, Weiwei; Zhang, Bing; Lu, W.; Wang, Pei; Dai, Shi; Lynch, R.; Yao, Jumei; Jiang, Jiancheng; Niu, Jiarui; Zhou, D. J.; Xu, Heng; Miao, Chenchen; Niu, Chenhui; Meng, L.; Qian, Lei; Tsai, Chao-Wei; Wang, Bo-Jun; Xue, Mengyao; Yue, Youling; Yuan, Mao; Zhang, S. B.; Zhang, L.

doi:10.1126/science.abl7759

“…The degree of linear polarization dropped to less than 10%, while it was as high as 80% in 2019. The change in the observed polarization properties may be related to the propagation effects of the FRBs, and may probe the immediate environment around the FRB source (Xu et al 2021;Feng et al 2022). However, no significant change in the high energy emission properties, which depend on the intrinsic radiation mechanism, is expected.…”

Section: Radio Burst Propertiesmentioning

confidence: 99%

Simultaneous View of FRB 180301 with FAST and NICER during a Bursting Phase

Laha

¹

,

Younes

²

,

Wadiasingh

³

et al. 2022

ApJ

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FRB 180301 is one of the most actively repeating fast radio bursts (FRBs) that has shown polarization angle changes in its radio burst emission, an indication for their likely origin in the magnetosphere of a highly magnetized neutron star. We carried out a multiwavelength campaign with the FAST radio telescope and NICER X-ray observatory to investigate any possible X-ray emission temporally coincident with the bright radio bursts. The observations took place on 2021 March 4, 9 and 19. We detected five bright radio bursts with FAST, four of which were strictly simultaneous with the NICER observations. The peak flux density of the radio bursts ranged between 28 and 105 mJy, the burst fluence between 27 and 170 mJy ms, and the burst durations between 1.7 and 12.3 ms. The radio bursts from FRB 180301 exhibited a complex time domain structure, and subpulses were detected in individual bursts, with no significant circular polarization. The linear degree of polarization in the L band reduced significantly compared to the 2019 observations. We do not detect any X-ray emission in excess of the background during the 5, 10, 100 ms, 1 and 100 s time intervals at/around the radio-burst barycenter-corrected arrival times, at a > 5σ confidence level. The 5σ upper limits on the X-ray (a) persistent flux is <7.64 × 10−12 erg cm−2 s−1, equivalent to L X < 2.50 × 1045 erg s−1 and (b) 5 ms fluence is <2 × 10−11 erg cm−2, at the radio burst regions. Using the 5 ms X-ray fluence upper limit, we can estimate the radio efficiency η R/X ≡ L radio/L X−ray ≳ 10−8. The derived lower limit on η R/X is consistent with both magnetospheric models and synchrotron maser models involving relativistic shocks.

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“…The relativistic electrons responsible for the PRS would not contribute to dispersion or scattering, but the upper limit on L X could potentially support a scenario where dispersion and scattering arise within a supernova remnant or merger ejecta surrounding a magnetar and synchrotron nebula ). This physical model may also be relevant to the extreme RM variations observed from FRB 190520, which may originate within the plasma region that also appears relevant to scattering (Anna-Thomas et al 2022;Dai et al 2022;Feng et al 2022).…”

Section: Discussion and Summarymentioning

confidence: 92%

The Large Dispersion and Scattering of FRB 20190520B Are Dominated by the Host Galaxy

Ocker

¹

,

Cordes

²

,

Chatterjee

³

et al. 2022

ApJ

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The repeating fast radio burst FRB 20190520B is localized to a galaxy at z = 0.241, much closer than expected given its dispersion measure DM = 1205 ± 4 pc cm−3. Here we assess implications of the large DM and scattering observed from FRB 20190520B for the host galaxy’s plasma properties. A sample of 75 bursts detected with the Five-hundred-meter Aperture Spherical radio Telescope shows scattering on two scales: a mean temporal delay τ(1.41 GHz) = 10.9 ± 1.5 ms, which is attributed to the host galaxy, and a mean scintillation bandwidth Δν d(1.41 GHz) = 0.21 ± 0.01 MHz, which is attributed to the Milky Way. Balmer line measurements for the host imply an Hα emission measure (galaxy frame) EMs = 620 pc cm−6 × (T/104 K)0.9, implying DMHα of order the value inferred from the FRB DM budget, DM h = 1121 − 138 + 89 pc cm−3 for plasma temperatures greater than the typical value 104 K. Combining τ and DMh yields a nominal constraint on the scattering amplification from the host galaxy F ˜ G = 1.5 − 0.3 + 0.8 ( pc 2 km ) − 1 / 3 , where F ˜ describes turbulent density fluctuations and G represents the geometric leverage to scattering that depends on the location of the scattering material. For a two-screen scattering geometry where τ arises from the host galaxy and Δν d from the Milky Way, the implied distance between the FRB source and dominant scattering material is ≲100 pc. The host galaxy scattering and DM contributions support a novel technique for estimating FRB redshifts using the τ–DM relation, and are consistent with previous findings that scattering of localized FRBs is largely dominated by plasma within host galaxies and the Milky Way.

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“…It is also possible that a blastwave from a magnetar causes a bright optical flare when it collides into a hot wind bubble produced by a previous flare (Beloborodov 2020, hereafter B20). The existence of complex magneto-ionic environments near a few repeating FRBs, which possibly supports the blastwave scenario, has been indicated by the analysis of observed frequency-dependent polarization (Feng et al 2022). However, search for an optical FRB counterpart on a timescale that is comparable to the timescale of an FRB is especially challenging because most of the existing observing facilities require longer observing timescale than a few seconds (see, e.g., Andreoni et al 2020;Kilpatrick et al 2021;Xin et al 2021 for searches of optical emission from an FRB on longer timescales).…”

Section: Introductionmentioning

confidence: 79%

Deep Simultaneous Limits on Optical Emission from FRB 20190520B by 24.4 fps Observations with Tomo-e Gozen

Niino

¹

,

Doi

²

,

Sako

³

et al. 2022

ApJ

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We conduct 24.4 fps optical observations of repeating fast radio burst (FRB) 20190520B using Tomo-e Gozen, a high-speed CMOS camera mounted on the Kiso 105 cm Schmidt telescope, simultaneously with radio observations carried out using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We succeeded in the simultaneous optical observations of 11 radio bursts that FAST detected. However, no corresponding optical emission was found. The optical fluence limits as deep as 0.068 Jy ms are obtained for the individual bursts (0.029 Jy ms on the stacked data) corrected for the dust extinction in the Milky Way. The fluence limit is deeper than those obtained in the previous simultaneous observations for an optical emission with a duration ≳0.1 ms. Although the current limits on radio-optical spectral energy distribution (SED) of FRBs are not constraining, we show that SED models based on observed SEDs of radio variable objects such as optically detected pulsars, and a part of parameter spaces of theoretical models in which FRB optical emission is produced by inverse Compton scattering in a pulsar magnetosphere or a strike of a magnetar blastwave into a hot wind bubble, can be ruled out once a similar fluence limit as in our observation is obtained for a bright FRB with a radio fluence ≳5 Jy ms.

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Frequency-dependent polarization of repeating fast radio bursts—implications for their origin

Cited by 78 publications

References 57 publications

Simultaneous View of FRB 180301 with FAST and NICER during a Bursting Phase

Simultaneous View of FRB 180301 with FAST and NICER during a Bursting Phase

The Large Dispersion and Scattering of FRB 20190520B Are Dominated by the Host Galaxy

Deep Simultaneous Limits on Optical Emission from FRB 20190520B by 24.4 fps Observations with Tomo-e Gozen

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