Comparison of Terrestrial and Lunar Time Scales by Giant Pulsar Impulses

We have developed a model for the time delay of pulse arrival between stations on the Moon and Earth. Comparison of the lunar and terrestrial time scales is proposed to be carried out by comparing the arrival time moments of giant pulses from pulsars. A method for such a comparison has been developed based on the cross-correlation analysis of the received pulses. Using the example of giant pulses from the pulsar PSR 0531+21, we showed that the error of comparing scales in the case of a high signal-to-noise ratio reaches a sub-discrete level and, thus, is determined by the reception band of the recording equipment.

Narrow-band giant pulses from the Crab pulsar

ABSTRACT We used a new spectral-fitting technique to identify a subpopulation of 6 narrow-band giant pulses from the Crab pulsar out of a total of 1578. These giant pulses were detected in 77 min of observations with the 46-m dish at the Algonquin Radio Observatory at 400–800 MHz. The narrow-band giant pulses consist of both main- and inter-pulses, thereby being more likely to be caused by an intrinsic emission mechanism as opposed to a propagation effect. Fast radio bursts (FRBs) have demonstrated similar narrow-band features, while only little has been observed in the giant pulses of pulsars. We report the narrow-band giant pulses with Δν/ν of the order of 0.1, which is close to the value of 0.05 reported for the repeater FRB 20190711A. Hence, the connection between FRBs and giant pulses of pulsars is further established.

Sub-second periodicity in a fast radio burst

The origin of fast radio bursts (FRBs), millisecond-duration flashes of radio waves that are visible at distances of billions of light-years, remains an open astrophysical question. Here we report the detection of the multi-component FRB 20191221A with the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project (CHIME/FRB), and the identification of a periodic separation of 216.8(1) ms between its components with a significance of 6.5 sigmas. The long (~ 3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. We also report two additional FRBs, 20210206A and 20210213A, whose multi-component pulse profiles show some indication of periodic separations of 2.8(1) and 10.7(1) ms, respectively, suggesting the possible existence of a group of FRBs with complex and periodic pulse profiles. Such short periodicities provide strong evidence for a neutron-star origin of these events. Moreover, our detections favour emission arising from the neutron-star magnetosphere, as opposed to emission regions located further away from the star, as predicted by some models. Possible explanations for the observed periodicity include super-giant pulses from a neutron star that are possibly related to a magnetar outburst and interacting neutron stars in a binary system.

Detection of giant pulses in PSR J1047−6709

We report the emission variations in PSR J1047−6709 observed at 1369 MHz using the Parkes 64 m radio telescope. This pulsar shows two distinct emission states: a weak state and a bright emission state. We detected giant pulses (GPs) in the bright state for the first time. We found 75 GPs with pulse width ranging from 0.6 to 2.6 ms. The energy of GPs follows a power-law distribution with the index α = −3.26 ± 0.22. The peak flux density of the brightest GP is 19 Jy which is 110 times stronger than the mean pulse profile. The polarization properties of the average profile of GPs are similar to that of the pulses with energy less than 10 times average pulse energy in the bright state. This indicates that the emission mechanism is basically the same for them. Our results provide a new insight into the origin of the GPs in pulsars.

Excitation of the main giant pulses from the Crab pulsar

ABSTRACT A model for the source of microwave main giant pulses (GPs) from the Crab pulsar is proposed and partly investigated. Pulse excitation takes place in a relativistic pair plasma with a strong magnetic field through the beam pulse amplifier (BPA) mechanism, in which short noise pulses of a certain type are amplified by energetic electrons at the Cherenkov resonance, even without strong anisotropy in the distribution function. The wave gain is shown to be as high as with an instability of hydrodynamic type, and wave escaping from the excitation region into the pulsar magnetosphere may not involve significant attenuation. The basic parameters of the source which explains the observed characteristics of the GP electromagnetic bursts have been analysed and are consistent with accepted ideas about physical conditions in the pulsar magnetosphere. The BPA mechanism explains the important properties of the GPs, such as the extremely short pulse duration (extreme nanoshots), the extremely high brightness temperature of the radiation source, the formation of radiation in a wide frequency range, and the possibility of radiation reaching the periphery of the pulsar magnetosphere.