Detection of Quasi-periodic Oscillations in SGR 150228213

The detection of quasi-periodic oscillations(QPOs)in magnetar giant flares(GFs)has brought a new perspective to studies of the mechanism of magnetar bursts.Due to the scarcity of GFs,searching for QPOs in magnetar short bursts is reasonable.Here we report the detection of a narrow QPO at approximately 110 Hz and a wide QPO at approximately 60 Hz in the short magnetar burst SGR 150228213,with a confidence level of 3.35σ.This burst was initially attributed to 4U 0142+61 by Fermi/GBM on location,but we have not detected such QPOs in other bursts from this magnetar.We also found that there was a repeating fast radio burst associated with SGR 150228213 on location.Finally,we discuss the possible origins of SGR 150228213.

Prediction for the Multi-band Afterglows of FRB 200428 and its Implication

The physical mechanism of fast radio bursts(FRBs) is still unknown. On 2020 April 28, a special radio burst, FRB200428, was detected and believed to be associated with the Galactic magnetar SGR 1935+2154. It confirms that at least some of the FRBs were generated by magnetars, although the radiation mechanism continues to be debated.To this end, we study in detail the multiband afterglows of FRB 200428 described by the synchrotron fireball shock model. We find the prediction for the optical and radio afterglows of FRB 200428 is consistent with the observations when considering the post-FRB optical and radio upper limits from the literature. We also show that the follow up detection of the afterglows from fast radio bursts like—FRB 200428 is possible at the radio band,though challenging. Based on our model, one can obtain information about the energy of the fireball, the radiation zone, and the nature of the surrounding medium. That may shed light on the physical mechanism of FRBs.

Scintillation Arc from FRB 20220912A

We present the interstellar scintillation analysis of fast radio burst(FRB)20220912A during its extremely active episode in 2022using data from the Five-hundred-meter Aperture Spherical Radio Telescope(FAST).We detect a scintillation arc in the FRB’s secondary spectrum,which describes the power in terms of the scattered FRB signals’time delay and Doppler shift.The arc indicates that the scintillation is caused by a highly localized region.Our analysis favors a Milky Way origin of the ionized interstellar medium(IISM)for the localized scattering medium but cannot rule out a host galaxy origin.We present our method for detecting the scintillation arc,which can be applied generally to sources with irregularly spaced bursts or pulses.These methods could help shed light on the complex interstellar environment surrounding the FRBs and in our Galaxy.

A comparison between repeating bursts of FRB 121102 an giant pulses from Crab pulsar and its applications

There are some similarities between bursts of repeating fast radio bursts(FRBs)and giant pulses(GPs)of pulsars.To explore possible relations between them,we study the cumulative energy distributions of these two phenomena using the observations of repeating FRB 121102 and the GPs of Crab pulsar.We find that the power-law slope of GPs(with fuence≥130 Jy.ms)is 2.85±0.10.The energy distribution of FRB 121102 can be well fitted by a smooth broken power-law function.For the bursts of FRB 121102 above the break energy(1.22×10^(37)erg),the best-ftting slope is 2.90^(+0.55)_(-0344),similar to the index of GPs at the same observing frequency(~1.4 GHz).We further discuss the physical origin of the repeating FRB 121102 in the framework of the super GPs model.And we find that the super GPs model involving a millisecond pulsar is workable and favored for explaining FRB 121102 despite that the magnetar burst model is more popular.