Giant Pulses Research Articles

A comparison between repeating bursts of FRB 121102 and 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 fluence ≥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 · 1037 erg), the best-fitting slope is 2.90 +0.55−0.44 , 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.

Pulsar B0531 + 21 in the Crab Nebula

The Crab Nebula and its pulsar PSR B0531 + 21 is the space laboratory for the study of fundamental physical processes. From the beginning of the current century up to date, the giant pulses of the pulsar in the Crab Nebula are regularly observed on the Large Phased Array of the Pushchino Radio Astronomy Observatory of the Lebedev Physical Institute at a frequency 111 MHz. The connection between the scattering time scale of radio pulses and the dispersion measure of the pulsar, which was established earlier together with Jodrell Bank, is confirmed. The observed variations in the scattering of radio pulses and their partial correlation with the dispersion measure are explained by the eclipse of the pulsar by dense plasma clouds with fluctuations in the electron density significantly exceeding the corresponding fluctuations in the interstellar medium. The question of a possible connection between period failers (glitches), dispersion measure variations, radio pulses scattering and gamma-ray flares is discussed.

Detection of giant pulses in PSR J1047−6709

ABSTRACT 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.

High-energy counterpart for fast radio bursts

The fast radio bursts (FRB) are a type of radio bursts with a high dispersion and short time scale. Most of them are known to be located in the high galactic latitude area and the light curve is known to be a simple single pulse structure. The total energy released by FRB is approximately 1038–1040 erg in the duration of approximately several milliseconds; and the rate of FRB is about approximately 103–104 Gpc−3 yr−1, which is much higher than that of GRB under the same condition. At present, >100 FRB events have been published, and theoretical models have been constructed to explain such phenomena, such as the combination of double compact stars, the collapse of compact stars, the collision and interaction between neutron stars and small celestial bodies, the giant flare of magnetic stars and the giant pulse of the pulsars. However, it is difficult to distinguish between these models based on a single radio band, and the multi-band radiation of FRB is likely to effectively distinguish or restrict this model and its mechanism; hence, multi-band detection is very important for the research of FRB. In this paper, the main theoretical models of FRB are summarized and organized in detail, and the situation of high-energy electromagnetic radiation in these theories has been emphatically analyzed. In addition, the GECAM satellite under construction in China will be expected to actualize the monitoring of gamma-ray in the whole sky, full time and wide energy range, and its future detection results will be expected to screen and verify these theoretical models.

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.

Giant pulses from J1823−3021A observed with the MeerKAT telescope

ABSTRACT The millisecond pulsar J1823−3021A is a very active giant pulse emitter in the globular cluster NGC 6624. New observations with the MeerKAT radio telescope have revealed 14350 giant pulses over 5 h of integration time, with an average wait time of about 1 s between giant pulses. The giant pulses occur in phases compatible with the ordinary radio emission, follow a power-law distribution with an index of −2.63 ± 0.02, and contribute 4 per cent of the total integrated flux. The spectral index of the giant pulses follows a Gaussian distribution centred around −1.9 with a standard deviation of 0.6 and is on average flatter than the integrated emission, which has a spectral index of −2.81 ± 0.02. The waiting times between the GPs are accurately described by a Poissonian distribution, suggesting that the time of occurrence of a GP is independent from the times of occurrence of other GPs. 76 GPs show multiple peaks within the same rotation, a rate that is also compatible with the mutual independence of the GP times of occurrence. We studied the polarization properties of the giant pulses finding, on average, linear polarization only at the 1 per cent level and circular polarization at the 3 per cent level, similar to the polarization percentages of the total integrated emission. In four cases, it was possible to measure the RM of the GPs that are highly variable and, in two cases, is inconsistent with the mean RM of the total integrated pulsar signal.

Generation of giant periodic pulses in the array of erbium-doped fiber lasers by controlling multistability

We propose an experimental arrangement to increase pulse energy in the array of erbium-doped fiber lasers (EDFLs). The experimental setup consists of three coupled periodically modulated multistable EDFLs; one master laser and two slave lasers. The master laser is tuned to the coexisting attractor with the largest peak amplitude and synchronizes the slave lasers to maintain them in the same attractor as the master laser. Summing the outputs of the slave lasers we obtain laser pulsations with a double peak intensity. The number of slave lasers can be augmented to further increase the sum peak power.

Long-term study of extreme giant pulses from PSR B0950+08 with AARTFAAC

ABSTRACT We report on the detection of extreme giant pulses (GPs) from one of the oldest known pulsars, the highly variable PSR B0950+08, with the Amsterdam-ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC), a parallel transient detection instrument operating as a subsystem of the LOw Frequency ARray (LOFAR). During processing of our Northern Hemisphere survey for low-frequency radio transients, a sample of 275 pulses with fluences ranging from 42 to 177 kJy ms were detected in one-second snapshot images. The brightest pulses are an order of magnitude brighter than those previously reported at 42 and 74 MHz, on par with the levels observed in a previous long-term study at 103 MHz. Both their rate and fluence distribution differ between and within the various studies done to date. The GP rate is highly variable, from 0 to 30 per hour, with only two 3-h observations accounting for nearly half of the pulses detected in the 96 h surveyed. It does not vary significantly within a few-hour observation, but can vary strongly one from day to the next. The spectra appear strongly and variably structured, with emission sometimes confined to a single 195.3 kHz subband, and the pulse spectra changing on a time-scale of order 10 min.

Deterministic Optical Rogue Waves in Nd:YVO4 Lasers Induced by Near-Degenerate Transverse Modes

We identify the role of transverse modes in causing temporal instability in an all-solid-state laser system and thus propose a new method to trigger deterministic optical rogue waves. Experimental investigations show that the near-degenerate transverse modes with mode frequency difference close to the relaxation oscillation frequency is responsible for the rogue waves. By tilting the reflective mirror, the transverse modes beating frequency decreases and gets close to relaxation oscillation frequency, thus the system exhibits self-pulsing behavior and rarely-arising giant pulses. The statistical distribution of the pulse intensity deviates from the exponential statistics to the L-shaped distributions with long tails, indicating the appearance of optical rogue waves. The conclusion can be extended to other Class-B lasers where the population inversion cannot be eliminated adiabatically.

Radio Sounding Measurements of the Solar Corona Using Giant Pulses of the Crab Pulsar in 2018

Observations of the Crab pulsar at 327 MHz were made at the Toyokawa Observatory of the Institute for Space-Earth Environmental Research, during the solar occultation in mid-June 2018 to investigate the coronal plasma density in the weak sunspot cycle, Cycle 24. The dispersion measurements (DMs) were determined using giant pulses detected from observations of the Crab pulsar. The systematic increase in DM over the background level, observed during the period of the closest approach of the Crab pulsar’s line-of-sight to the Sun, was ascribed to the effect of the coronal plasma. A coronal density model assuming spherical symmetry was determined by fitting it to the DM data, and was compared with those determined in past solar cycles. The best-fit model had large errors, and indicated a systematically higher value than those derived from past observations. The results obtained here are likely to be significantly affected by latitude/longitude variation in coronal plasma density, the time variation of the interstellar medium, mainly the Crab nebula, and increased measurement errors due to the reduced occurrence of giant pulses. Hence, further observations are needed to derive conclusions about a change of coronal density in the current cycle.

Control of dissipative rogue waves in nonlinear cavity optics: Optical injection and time-delayed feedback.

We investigate and review the formation of two-dimensional dissipative rogue waves in cavity nonlinear optics with transverse effects. Two spatially extended systems are considered for this purpose: the driven Kerr optical cavities subjected to optical injection and the broad-area surface-emitting lasers with a saturable absorber. We also consider a quasi-two-dimensional system (the two dimensions being space and time) of a fiber laser describing the complex cubic-quintic Ginzburg-Landau equation. We show that rogue waves are controllable by means of time-delayed feedback and optical injection. We show that without delayed feedback, transverse structures are stationary or oscillating. However, when the strength of the delayed feedback is increased, all the systems generate giant two-dimensional pulses that appear with low probability and suddenly appear and disappear. We characterize their formation by computing the probability distribution, which shows a long tail. Besides, we have computed the significant wave height, which measures the mean wave height of the highest third of the waves. We show that for all systems, the distribution tails expand beyond two times the significant wave height. Furthermore, we also show that optical injection may suppress the rogue wave formation in a semiconductor laser with a saturable absorber.

Fast Radio Burst Counterparts and Their Implications for the Central Engine

Abstract While the radiation mechanism of fast radio bursts (FRBs) is unknown, coherent curvature radiation and synchrotron maser are promising candidates. We find that both radiation mechanisms work for a neutron star (NS) central engine with G, while for a synchrotron maser, the central engine can also be an accreting black hole (BH) with G and a white dwarf (WD) with G. We study the electromagnetic counterparts associated with such central engines, i.e., nebulae for repeating FRBs and afterglows for nonrepeating FRBs. In general, the energy spectrum and flux density of the counterpart depend strongly on its size and total injected energy. We apply the calculation to the nebula of FRB 121102 and find that the persistent radio counterpart requires the average energy injection rate into the nebula to be between and , and the minimum injected energy to be in around 7 yr. Consequently, we find that for FRB 121102 and its nebula: (1) WD and accretion BH central engines are disfavored; (2) a rotation-powered NS central engine works when with initial period ms, but the radio emission must be more efficient than that in typical giant pulses of radio pulsars; and (3) a magnetic-powered NS central engine works when its internal magnetic field G. We also find that the radio-emitting electrons in the nebula could produce a significant rotation measure (RM), but cannot account for the entire observed RM of FRB 121102.

LGS electro-optically Q-switched Er,Pr:YAP crystal laser operated at 2.7 µm

We demonstrate an optimized 2.7 µm Er,Pr:YAP laser in both free-running and Q-switched modes. In free running mode, a maximum energy of 346 mJ is obtained with repetition frequency of 5 Hz. In Q-switched mode, a giant pulse with 63.4 mJ energy and 40 ns pulse width is realized at 5 Hz, which corresponds to an energy extraction efficiency of 47% and a peak power of 1.59 MW. Additionally, the M2 factor and laser spectrum are also measured in two modes. These results indicate that the LGS Q-switched 2.7 µm Er,Pr:YAP laser is a promising candidate for the mid-infrared pulse laser device.

Are fast radio bursts made by neutron stars?

ABSTRACT Popular models of repeating fast radio bursts (FRBs; and perhaps of all FRBs) involve neutron stars because of their high rotational or magnetostatic energy densities. These models take one of two forms: giant but rare pulsar-like pulses like those of rotating radio transients, and outbursts like those of soft gamma repeaters. Here I collate the evidence, recently strengthened, against these models, including the absence of Galactic micro-FRBs, and attribute the 16 d periodicity of FRB 180916.J0158+65 to the precession of a jet produced by a massive black hole’s accretion disc.

Cavity dumping by the second harmonic generation in the Q-switched Nd : YAG laser

This paper presents the cavity dumping method by the second harmonic generation in a neodymium laser operating in the Q-switched mode. Theoretical modeling of the laser generation in dynamics is performed. The main characteristics of the output pulses and their dependence on the pump power and coefficient of losses are calculated. The proposed method can be implemented in the laser with a second harmonic crystal inside the cavity and an electro-optical crystal, which is operated by a step voltage pulse. The switching pulse length is defined by the time needed to achieve the maximum giant pulse intensity in the cavity, and is in the order of 0.1–1.0 ms depending on the pump power. Moreover, the voltage pulse jitter should not exceed several nanoseconds. In such case the second harmonic pulses with nanosecond duration and peak intensity of 10 –100 MW/cm2 are generated at the laser output. The output pulses duration is defined only by the cavity length under the conditions of a small response time of the electro-optical crystal compared to the cavity round-trip time. To achieve the maximal peak intensity, one should decrease the coefficient of inactive losses to the possible minimum and increase the pump power.

Statistics of VHEγ-rays in temporal association with radio giant pulses from the Crab pulsar

Aims.The aim of this study is to search for evidence of a common emission engine between radio giant pulses (GPs) and very-high-energy (VHE,E &gt; 100 GeV)γ-rays from the Crab pulsar.Methods.We performed 16 h of simultaneous observations of the Crab pulsar at 1.4 GHz with the Effelsberg radio telescope and the Westerbork Synthesis Radio Telescope (WSRT), and at energies above 60 GeV we used the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes. We searched for a statistical correlation between the radio and VHEγ-ray emission with search windows of different lengths and different time lags to the arrival times of a radio GP. A dedicated search for an enhancement in the number of VHEγ-rays correlated with the occurrence of radio GPs was carried out separately for the P1 and P2 phase ranges, respectively.Results.In the radio data sample, 99444 radio GPs were detected. We find no significant correlation between the GPs and VHE photons in any of the search windows. Depending on phase cuts and the chosen search windows, we find upper limits at a 95% confidence level on an increase in VHEγ-ray events correlated with radio GPs between 7% and 61% of the average Crab pulsar VHE flux for the P1 and P2 phase ranges, respectively. This puts upper limits on the flux increase during a radio GP between 12% and 2900% of the pulsed VHE flux, depending on the search window duration and phase cuts. This is the most stringent upper limit on a correlation betweenγ-ray emission and radio GPs reported so far.

LOFAR radio search for single and periodic pulses from M 31

Bright short radio bursts are emitted by sources at a wide range of distances: from the nearby Crab pulsar to remote fast radio bursts (FRBs). FRBs are likely to originate from distant neutron stars, but our knowledge of the radio pulsar population has been limited to the Galaxy and the Magellanic Clouds. In an attempt to increase our understanding of extragalactic pulsar populations and their giant-pulse emission, we employed the low-frequency radio telescope LOFAR to search the Andromeda galaxy (M 31) for radio bursts emitted by young Crab-like pulsars. For direct comparison we also present a LOFAR study on the low-frequency giant pulses from the Crab pulsar; their fluence distribution follows a power law with slope 3.04 ± 0.03. A number of candidate signals were detected from M 31, but none proved persistent. FRBs are sometimes thought of as Crab-like pulsars with exceedingly bright giant pulses; based on our sensitivity, we can rule out that M 31 hosts pulsars that are more than an order of magnitude brighter than the Crab pulsar if their pulse scattering follows that of the known FRBs.

STARE2: Detecting Fast Radio Bursts in the Milky Way

There are several unexplored regions of the short-duration radio transient phase space. One such unexplored region is the luminosity gap between giant pulses (from pulsars) and cosmologically located fast radio bursts (FRBs). The Survey for Transient Astronomical Radio Emission 2 (STARE2) is a search for such transients out to 7 Mpc. STARE2 has a field of view of 3.6 steradians and is sensitive to 1 millisecond transients above ∼300 kJy. With a two-station system we have detected and localized a solar burst, demonstrating that the pilot system is capable of detecting short duration radio transients. We found no convincing non-solar transients with duration between 65 μs and 34 ms in 200 days of observing, limiting with 95% confidence the all-sky rate of transients above ∼300 kJy to <40 sky−1 yr−1. If the luminosity function of FRBs could be extrapolated down to 300 kJy for a distance of 10 kpc, then one would expect the rate to be ∼2 sky−1 yr−1.

A search for pulsars in subdwarf B binary systems and discovery of giant-pulse emitting PSR J0533−4524

ABSTRACT Binary millisecond pulsars (MSPs) provide several opportunities for research of fundamental physics. However, finding them can be challenging. Several subdwarf B (sdB) binary systems with possible neutron star companions have been identified, allowing us to perform a targeted search for MSPs within these systems. Six sdBs with companions in the neutron star mass range, as determined from their optical light curves, were observed with the Green Bank and Westerbork radio telescopes. The data were searched for periodic signals as well as single pulses. No radio pulsations from sdB systems were detected, down to an average sensitivity limit of $0.11\,$mJy. We did, however, discover a pulsar in the field of sdB HE0532−4503. Follow-up observations with the Giant Metrewave Radio Telescope showed that this pulsar, J0533−4524, is not spatially coincident with the sdB system. The pulsar has a relatively low magnetic field but still emits giant pulses. We place an upper limit of three to the number of radio pulsars in the six sdB systems. The non-detections may be explained by a combination of the MSP beaming fraction, luminosity, and a recycling fraction &amp;lt;0.5. Alternatively, the assumption of corotation between the MSP and sdB may break down, which implies the systems are more edge-on than previously thought. This would shift the predicted companion masses into the white dwarf range. It would also explain the relative lack of edge-on sdB systems with massive companions.

The MeerKAT telescope as a pulsar facility: System verification and early science results from MeerTime

AbstractWe describe system verification tests and early science results from the pulsar processor (PTUSE) developed for the newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. MeerKAT is a high-gain (${\sim}2.8\,\mbox{K Jy}^{-1}$) low-system temperature (${\sim}18\,\mbox{K at }20\,\mbox{cm}$) radio array that currently operates at 580–1 670 MHz and can produce tied-array beams suitable for pulsar observations. This paper presents results from the MeerTime Large Survey Project and commissioning tests with PTUSE. Highlights include observations of the double pulsar$\mbox{J}0737{-}3039\mbox{A}$, pulse profiles from 34 millisecond pulsars (MSPs) from a single 2.5-h observation of the Globular cluster Terzan 5, the rotation measure of Ter5O, a 420-sigma giant pulse from the Large Magellanic Cloud pulsar PSR$\mbox{J}0540{-}6919$, and nulling identified in the slow pulsar PSR J0633–2015. One of the key design specifications for MeerKAT was absolute timing errors of less than 5 ns using their novel precise time system. Our timing of two bright MSPs confirm that MeerKAT delivers exceptional timing. PSR$\mbox{J}2241{-}5236$exhibits a jitter limit of$&lt;4\,\mbox{ns h}^{-1}$whilst timing of PSR$\mbox{J}1909{-}3744$over almost 11 months yields an rms residual of 66 ns with only 4 min integrations. Our results confirm that the MeerKAT is an exceptional pulsar telescope. The array can be split into four separate sub-arrays to time over 1 000 pulsars per day and the future deployment of S-band (1 750–3 500 MHz) receivers will further enhance its capabilities.