A Radio Continuum and Polarization Study of SNR G57.2+0.8 Associated with Magnetar SGR 1935+2154

Kothes, R.; Sun, Xiaohui; Gaensler, B. M.; Reich, W.

doi:10.3847/1538-4357/aa9e89

Cited by 80 publications

(88 citation statements)

References 56 publications

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“…Subsequent discovery of the coherent X-ray pulsations of SGR 1935+2154with the Chandra X-ray Observatory established the spin period of the magnetar,  P 3.2 s (Israel et al 2014(Israel et al , 2016. Observations of the source with XMM-Newton and NuSTAR during outburst in 2015 provided the magnetar's spin-down rate,  ´--P 1.43 10 s s 11 1 , which implies a surface dipolar magnetic field B 2.2 10 G 14 , spin-down luminosity Ĺ 1.7 10 sd 34 erg s −1 , and characteristic spin-down age   P P 2 3600 yr. We note, however, that the age estimate based on the SNR association, 16 kyr, is significantly older (Zhou et al 2020; see also Kothes et al 2018). This discrepancy between the dipolar and SNR age estimates is similar to the one observed in the other magnetar associated with an SNR, Swift J1834.9-0846 (Granot et al 2017; with a spin-down age of 4.9 kyr and an SNR age between 5 and 100 kyr).…”

supporting

confidence: 62%

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Implications of a Fast Radio Burst from a Galactic Magnetar

Margalit

Beniamini

Sridhar

et al. 2020

ApJL

156

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A luminous radio burst was recently detected in temporal coincidence with a hard X-ray flare from the Galactic magnetar SGR 1935+2154with a time and frequency structure consistent with cosmological fast radio bursts (FRBs) and a fluence within a factor of 10 of the least energetic extragalactic FRB previously detected. Although active magnetars are commonly invoked FRB sources, several distinct mechanisms have been proposed for generating the radio emission that make different predictions for the accompanying higher-frequency radiation. We show that the properties of the coincident radio and X-ray flares from SGR 1935+2154, including their approximate simultaneity and relative fluence~-E E 10 radio X 5 , as well as the duration and spectrum of the X-ray emission, are consistent with extant predictions for the synchrotron maser shock model. Rather than arising from the inner magnetosphere, the X-rays are generated by (incoherent) synchrotron radiation from thermal electrons heated at the same internal shocks that produce the coherent maser emission as ultrarelativistic flare ejecta collides with a slower particle outflow (e.g., as generated by earlier flaring activity) on a radial scale of~10 11 cm. Although the rate of SGR 1935+2154-like bursts in the local universe is not sufficient to contribute appreciably to the extragalactic FRB rate, the inclusion of an additional population of more active magnetars with stronger magnetic fields than the Galactic population can explain both the FRB rate and the repeating fraction, but only if the population of active magnetars are born at a rate that is at least 2 orders of magnitude lower than that of the SGR 1935+2154-like magnetars. This may imply that the more active magnetar sources are not younger magnetars formed in a similar way to the Milky Way population (e.g., via ordinary supernovae) but are instead formed through more exotic channels, such as superluminous supernovae, accretion-induced collapse, or neutron star mergers.

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supporting

confidence: 62%

“…The source is associated with supernova remnant (SNR) G57.2+0.8 (Gaensler 2014). Distance estimates are uncertain, ranging from 4.4 to 12.5 kpc (Sun et al 2011;Pavlović et al 2013;Kothes et al 2018;Mereghetti et al 2020a;Zhou et al 2020), and throughout this paper, we adopt a distance of = d d 10 kpc…”

Section: Sgr 1935+2154mentioning

confidence: 99%

Implications of a Fast Radio Burst from a Galactic Magnetar

Margalit

Beniamini

Sridhar

et al. 2020

ApJL

156

123

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“…We consider a scenario in which temporal broadening arises close to the source in Appendix A. SGR 1935+2154 was first associated with the SNR G57.2 +0.8 by Gaensler (2014). This association is supported by the recent work of Kothes et al (2018), who find that the geometric center of SNR G57.2+0.8 (l=57°. 24, b=0°.81) is very close to SGR 1935+2154 (l=57°.25, b=0°.82).…”

Section: A Two-screen Model For the Spectral Properties Of The Two-comentioning

confidence: 74%

Scintillation Can Explain the Spectral Structure of the Bright Radio Burst from SGR 1935+2154

Simard

Ravi

2020

ApJL

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The discovery of a fast radio burst (FRB) associated with a magnetar in the Milky Way by the Canadian Hydrogen Intensity Mapping Experiment FRB collaboration (CHIME/FRB) and the Survey for Transient Astronomical Radio Emission 2 has provided an unprecedented opportunity to refine FRB emission models. The burst discovered by CHIME/FRB shows two components with different spectra. We explore interstellar scintillation as the origin for this variation in spectral structure. Modeling a weak scattering screen in the supernova remnant associated with the magnetar, we find that a superluminal apparent transverse velocity of the emission region of >9.5c is needed to explain the spectral variation. Alternatively, the two components could have originated from independent emission regions >8.3×10 4 km apart. These scenarios may arise in "far-away" models where the emission originates from well beyond the magnetosphere of the magnetar (for example, through a synchrotron maser mechanism set up by an ultrarelativistic radiative shock), but not in "close-in" models of emission from within the magnetosphere. If further radio observations of the magnetar confirm scintillation as the source of the observed variation in spectral structure, this scattering model thus constrains the location of the emission region.

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“…However, a thermal origin is preferred for normal short bursts from magnetars 26,27 . We notice that ∼ 6% of the bursts (7/109) from SGR J1935+2154 detected with Fermi/GBM between 2014 and 2016 can be best fit with a power-law model 13 19 , then the observed fluence should be ∼ 4 × 10 −15 erg cm −2 in 1-250 keV, which is far below the sensitivity limits of the X-ray telescopes currently in orbit (or in the foreseeable future). This may explain the non-detection of the X-ray counterpart of any cosmological FRB so far.…”

Section: Insight-hxmt Detected a Series Of 11 Bursts Within About 17 mentioning

confidence: 79%

Identification of a non-thermal X-ray burst with the Galactic magnetar SGR J1935+2154 and a fast radio burst using Insight-HXMT

Li¹,

Lin²,

Xiong³

et al. 2020

Preprint

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Fast radio bursts (FRBs) are short pulses observed in radio band from cosmological distances, some of which emit repeating bursts. The physical origins of these mysterious events have been subject to wide speculations and heated debates. One class of models invoke soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs. Magnetars are rotating neutron stars with extremely strong magnetic field and can sporadically emit bursts from X-ray (keV) to soft gamma-ray (sub-MeV) with duration from 10􀀀2 s to 102 s. However, even though some bright radio bursts have been observed from some magnetars, no FRB-like events had been detected to be associated with any magnetar burst, including one giant flare, and no radio burst has been associated with any X-ray event from any magnetar. Therefore, there is still no observational evidence for magnetar-FRB association up to today. Recently, a pair of FRB-like bursts (FRB~200428 hereafter) separated by 30 milliseconds (ms) were detected from the general direction of the Galactic magnetar SGR~J1935+2154. Here we report the detection of a non-thermal X-ray burst in the 1--250\,keV energy band with the Insight-HXMT satellite, which we identify as emitted from SGR~J1935+2154. The burst showed two hard peaks with a separation of ms, consistent with the separation between the two bursts in FRB~200428. The delay time between the double radio and X-ray peaks is 8:57s, fully consistent with the dispersion delay of FRB~200428. We thus identify the non-thermal X-ray burst is associated with FRB~200428 whose high energy counterpart is the two hard peaks in X-ray. Our results suggest that the non-thermal X-ray burst and FRB~200428 share the same physical origin in an explosive event from SGR~J1935+2154.

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A Radio Continuum and Polarization Study of SNR G57.2+0.8 Associated with Magnetar SGR 1935+2154

Cited by 80 publications

References 56 publications

Implications of a Fast Radio Burst from a Galactic Magnetar

Implications of a Fast Radio Burst from a Galactic Magnetar

Scintillation Can Explain the Spectral Structure of the Bright Radio Burst from SGR 1935+2154

Identification of a non-thermal X-ray burst with the Galactic magnetar SGR J1935+2154 and a fast radio burst using Insight-HXMT

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