scholarly journals Narrow-band giant pulses from the Crab pulsar

2021 ◽  
Vol 508 (2) ◽  
pp. 1947-1953
Author(s):  
Parasar Thulasiram ◽  
Hsiu-Hsien Lin
Keyword(s):  
Narrow Band ◽  
Crab Pulsar ◽  
Radio Bursts ◽  
Propagation Effect ◽  
Emission Mechanism ◽  
Radio Observatory ◽  
Spectral Fitting ◽  
Giant Pulses ◽  
Intrinsic Emission

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.

scholarly journals Enhanced x-ray emission coinciding with giant radio pulses from the Crab Pulsar

Science ◽  
2021 ◽  
Vol 372 (6538) ◽  
pp. 187-190
Author(s):  
Teruaki Enoto ◽  
Toshio Terasawa ◽  
Shota Kisaka ◽  
Chin-Ping Hu ◽  
Sebastien Guillot ◽  
...  
Keyword(s):  
Optical Emission ◽  
Crab Pulsar ◽  
Radio Bursts ◽  
Emission Mechanism ◽  
Pulsar Emission ◽  
X Ray ◽  
Percentage Points

Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars that last a few microseconds and are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside of radio wavelengths is from the Crab Pulsar, where optical emission is enhanced by a few percentage points during GRPs. We observed the Crab Pulsar simultaneously at x-ray and radio wavelengths, finding enhancement of the x-ray emission by 3.8 ± 0.7% (a 5.4σ detection) coinciding with GRPs. This implies that the total emitted energy from GRPs is tens to hundreds of times higher than previously known. We discuss the implications for the pulsar emission mechanism and extragalactic fast radio bursts.

scholarly journals LOFAR radio search for single and periodic pulses from M 31

2020 ◽  
Vol 634 ◽  
pp. A3 ◽  
Author(s):  
Joeri van Leeuwen ◽  
Klim Mikhailov ◽  
Evan Keane ◽  
Thijs Coenen ◽  
Liam Connor ◽  
...  
Keyword(s):  
Low Frequency ◽  
Crab Pulsar ◽  
Radio Bursts ◽  
Pulse Emission ◽  
Giant Pulses ◽  
Wide Range ◽  
The Galaxy ◽  
Order Of Magnitude ◽  
M 31 ◽  
Pulsar Populations

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.

scholarly journals Giant Pulses from the Crab Pulsar

2000 ◽  
Vol 177 ◽  
pp. 165-170
Author(s):  
Timothy H. Hankins
Keyword(s):  
Pulse Width ◽  
Crab Pulsar ◽  
Emission Mechanism ◽  
Frequency Range ◽  
Low Frequencies ◽  
High Frequencies ◽  
Polarization Structure ◽  
Giant Pulses ◽  
Pulse Structure

AbstractRecent observations of the “giant” radio pulses received from the Crab pulsar are reviewed. The frequency range over which they have been detected spans at least two decades, and individual pulses appear to have a frequency span of 3:1 or more. The pulse structure is dominated by scattering at frequencies below about 2 GHz; at higher frequencies the intrinsic pulse width is about 1µs with nanostructure extending down to 10 ns. The polarization structure may be contaminated by scattering at low frequencies and the polarization is weak and highly variable at high frequencies. No definitive emission mechanism with testable hypotheses for the giant pulses has been put forth. One of the most promising, based on the collapse of plasma solitons, predicts nanostructure bandwidths narrower than what is seen for the giant pulses themselves, though the observations do not show wideband correlation of the shortest resolvable intensity structure.

Observations of Giant Pulses of the Crab Pulsar

2008 ◽  
Vol 8 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Ling-Jun Kong ◽  
Ali Esamdin ◽  
Cheng-Shi Zhao ◽  
Zhi-Yong Liu ◽  
Jian-Ping Yuan
Keyword(s):  
Crab Pulsar ◽  
Giant Pulses

scholarly journals Localizing FRBs through VLBI with the Algonquin Radio Observatory 10 m Telescope

2022 ◽  
Vol 163 (2) ◽  
pp. 65
Author(s):  
T. Cassanelli ◽  
Calvin Leung ◽  
M. Rahman ◽  
K. Vanderlinde ◽  
J. Mena-Parra ◽  
...  
Keyword(s):  
Current System ◽  
Wide Field ◽  
Crab Pulsar ◽  
Host Galaxies ◽  
Radio Observatory ◽  
Intensity Mapping ◽  
Long Baseline ◽  
Wide Field Of View ◽  
Clock Stability ◽  
Single Baseline

Abstract The Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB experiment has detected thousands of fast radio bursts (FRBs) due to its sensitivity and wide field of view; however, its low angular resolution prevents it from localizing events to their host galaxies. Very long baseline interferometry (VLBI), triggered by FRB detections from CHIME/FRB will solve the challenge of localization for non-repeating events. Using a refurbished 10 m radio dish at the Algonquin Radio Observatory located in Ontario Canada, we developed a testbed for a VLBI experiment with a theoretical λ/D ≲ 30 mas. We provide an overview of the 10 m system and describe its refurbishment, the data acquisition, and a procedure for fringe fitting that simultaneously estimates the geometric delay used for localization and the dispersive delay from the ionosphere. Using single pulses from the Crab pulsar, we validate the system and localization procedure, and analyze the clock stability between sites, which is critical for coherently delay referencing an FRB event. We find a localization of ∼200 mas is possible with the performance of the current system (single-baseline). Furthermore, for sources with insufficient signal or restricted wideband to simultaneously measure both geometric and ionospheric delays, we show that the differential ionospheric contribution between the two sites must be measured to a precision of 1 × 10−8 pc cm−3 to provide a reasonable localization from a detection in the 400–800 MHz band. Finally we show detection of an FRB observed simultaneously in the CHIME and the Algonquin 10 m telescope, the first non-repeating FRB in this long baseline. This project serves as a testbed for the forthcoming CHIME/FRB Outriggers project.

scholarly journals Variable emission mechanism of a Type IV radio burst

2019 ◽  
Vol 623 ◽  
pp. A63 ◽  
Author(s):  
D. E. Morosan ◽  
E. K. J. Kilpua ◽  
E. P. Carley ◽  
C. Monstein
Keyword(s):  
Frequency Band ◽  
Radio Burst ◽  
Extreme Ultraviolet ◽  
Imaging Spectroscopy ◽  
Continuum Emission ◽  
Particle Accelerators ◽  
Radio Bursts ◽  
Emission Mechanism ◽  
Type Iv ◽  
Dynamic Spectra

Context. The Sun is an active star and the source of the largest explosions in the solar system, such as flares and coronal mass ejections (CMEs). Flares and CMEs are powerful particle accelerators that can generate radio emission through various emission mechanisms. Aims. CMEs are often accompanied by Type IV radio bursts that are observed as continuum emission in dynamic spectra at decimetric and metric wavelengths, but their emission mechanism can vary from event to event. Here, we aim to determine the emission mechanism of a complex Type IV burst that accompanied the flare and CME on 22 September 2011. Methods. We used radio imaging from the Nançay Radioheliograph, spectroscopic data from the e-Callisto network, ARTEMIS, Ondrejov, and Phoenix3 spectrometers combined with extreme-ultraviolet observations from NASA’s Solar Dynamic Observatory to analyse the Type IV radio burst and determine its emission mechanism. Results. We show that the emission mechanism of the Type IV radio burst changes over time. We identified two components in the Type IV radio burst: an earlier stationary Type IV showing gyro-synchrotron behaviour, and a later moving Type IV burst covering the same frequency band. This second component has a coherent emission mechanism. Fundamental plasma emission and the electron-cyclotron maser emission are further investigated as possible emission mechanisms for the generation of the moving Type IV burst. Conclusions. Type IV bursts are therefore complex radio bursts, where multiple emission mechanisms can contribute to the generation of the wide-band continuum observed in dynamic spectra. Imaging spectroscopy over a wide frequency band is necessary to determine the emission mechanisms of Type IV bursts that are observed in dynamic spectra.

scholarly journals SHORT-LIVED RADIO BURSTS FROM THE CRAB PULSAR

2010 ◽  
Vol 722 (2) ◽  
pp. 1908-1920 ◽  
Author(s):  
J. H. Crossley ◽  
J. A. Eilek ◽  
T. H. Hankins ◽  
J. S. Kern
Keyword(s):  
Crab Pulsar ◽  
Radio Bursts

scholarly journals Comparative analysis of solar radio bursts before and during CME propagation

2019 ◽  
Vol 625 ◽  
pp. A63 ◽  
Author(s):  
G. Dididze ◽  
B. M. Shergelashvili ◽  
V. N. Melnik ◽  
V. V. Dorovskyy ◽  
A. I. Brazhenko ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Radio Emission ◽  
Instantaneous Frequency ◽  
Narrow Band ◽  
Radio Bursts ◽  
Frequency Bandwidth ◽  
Plasma Parameters ◽  
Type Iii ◽  
Type Iv ◽  
Band Type

Context. As is well known, coronal mass ejection (CME) propagation often results in the fragmentation of the solar atmosphere on smaller regions of density (magnetic field) enhancement (depletion). It is expected that this type of fragmentation may have radio signatures. Aims. The general aim of the present paper is to perform a comparative analysis of type III solar and narrow-band type-III-like radio burst properties before and during CME events, respectively. The main goal is to analyze radio observational signatures of the dynamical processes in solar corona. In particular, we aim to perform a comparison of local plasma parameters without and with CME propagation, based on the analysis of decameter radio emission data. Methods. In order to examine this intuitive expectation, we performed a comparison of usual type III bursts before the CME with narrow-band type-III-like bursts, which are observationally detectable on top of the background type IV radio bursts associated with CME propagation. We focused on the analysis of in total 429 type III and 129 narrow-band type-III-like bursts. We studied their main characteristic parameters such as frequency drift rate, duration, and instantaneous frequency bandwidth using standard statistical methods. Furthermore, we inferred local plasma parameters (e.g., density scale height, emission source radial sizes) using known definitions of frequency drift, duration, and instantaneous frequency bandwidth. Results. The analysis reveals that the physical parameters of coronal plasma before CMEs considerably differ from those during the propagation of CMEs (the observational periods 2 and 4 with type IV radio bursts associated with CMEs). Local density radial profiles and the characteristic spatial scales of radio emission sources vary with radial distance more drastically during the CME propagation compared to the cases of quasistatic solar atmosphere without CME(s) (observational periods 1 and 3). Conclusions. The results of the work enable us to distinguish different regimes of plasma state in the solar corona. Our results create a solid perspective from which to develop novel tools for coronal plasma studies using radio dynamic spectra.

scholarly journals Numerical Simulation of Type III Bursts

1980 ◽  
Vol 86 ◽  
pp. 299-302
Author(s):  
T. Takakura
Keyword(s):  
Numerical Simulation ◽  
Analytical Method ◽  
Solar Radio ◽  
Plasma Waves ◽  
Radio Bursts ◽  
Emission Mechanism ◽  
Normal Type ◽  
Solar Radio Bursts ◽  
Radio Emissions ◽  
Type Iii

By the use of semi-analytical method, modeling of three kinds of type III solar radio bursts have been made. Many basic problems about the type III bursts and associated solar electrons have been solved showing some striking or unexpected results. If the fundamental radio emissions should be really observed as the normal type III bursts, the emission mechanism would not be the currently accepted one, i.e. the scattering of plasma waves by ions.

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