scholarly journals Sub-second periodicity in a fast radio burst

2021 ◽  
Author(s):  
Bridget C. Andersen ◽  
Kevin Bandura ◽  
Mohit Bhardwaj ◽  
P. J. Boyle ◽  
Charanjot Brar ◽  
...  
Keyword(s):  
Neutron Star ◽  
Binary System ◽  
Radio Burst ◽  
Radio Bursts ◽  
Radio Waves ◽  
Pulse Profile ◽  
Intensity Mapping ◽  
Giant Pulses ◽  
Component Pulse ◽  
Fast Radio Burst

Abstract 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.

scholarly journals No Evidence for Galactic Latitude Dependence of the Fast Radio Burst Sky Distribution

2021 ◽  
Vol 923 (1) ◽  
pp. 2 ◽  
Author(s):  
A. Josephy ◽  
P. Chawla ◽  
A. P. Curtin ◽  
V. M. Kaspi ◽  
M. Bhardwaj ◽  
...  
Keyword(s):  
Radio Burst ◽  
Sensitivity Threshold ◽  
Galactic Latitude ◽  
Radio Bursts ◽  
Intensity Mapping ◽  
Latitude Dependence ◽  
Kolmogorov Smirnov ◽  
Coin Flipping ◽  
Fast Radio Burst ◽  
Anderson Darling

Abstract We investigate whether the sky rate of fast radio bursts (FRBs) depends on Galactic latitude using the first catalog of FRBs detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project. We first select CHIME/FRB events above a specified sensitivity threshold in consideration of the radiometer equation, and then we compare these detections with the expected cumulative time-weighted exposure using Anderson–Darling and Kolmogorov–Smirnov tests. These tests are consistent with the null hypothesis that FRBs are distributed without Galactic latitude dependence (p-values distributed from 0.05 to 0.99, depending on completeness threshold). Additionally, we compare rates in intermediate latitudes (∣b∣ < 15°) with high latitudes using a Bayesian framework, treating the question as a biased coin-flipping experiment–again for a range of completeness thresholds. In these tests the isotropic model is significantly favored (Bayes factors ranging from 3.3 to 14.2). Our results are consistent with FRBs originating from an isotropic population of extragalactic sources.

scholarly journals Multiwavelength Observations of Fast Radio Bursts

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 76
Author(s):  
Luciano Nicastro ◽  
Cristiano Guidorzi ◽  
Eliana Palazzi ◽  
Luca Zampieri ◽  
Massimo Turatto ◽  
...  
Keyword(s):  
Radio Burst ◽  
High Energy ◽  
Medium Size ◽  
Radio Bursts ◽  
Starting Point ◽  
Key Points ◽  
Fast Radio Burst ◽  
Theoretical Results ◽  
Observational Strategy ◽  
Shed Light

The origin and phenomenology of the Fast Radio Burst (FRB) remains unknown despite more than a decade of efforts. Though several models have been proposed to explain the observed data, none is able to explain alone the variety of events so far recorded. The leading models consider magnetars as potential FRB sources. The recent detection of FRBs from the galactic magnetar SGR J1935+2154 seems to support them. Still, emission duration and energetic budget challenge all these models. Like for other classes of objects initially detected in a single band, it appeared clear that any solution to the FRB enigma could only come from a coordinated observational and theoretical effort in an as wide as possible energy band. In particular, the detection and localisation of optical/NIR or/and high-energy counterparts seemed an unavoidable starting point that could shed light on the FRB physics. Multiwavelength (MWL) search campaigns were conducted for several FRBs, in particular for repeaters. Here we summarize the observational and theoretical results and the perspectives in view of the several new sources accurately localised that will likely be identified by various radio facilities worldwide. We conclude that more dedicated MWL campaigns sensitive to the millisecond–minute timescale transients are needed to address the various aspects involved in the identification of FRB counterparts. Dedicated instrumentation could be one of the key points in this respect. In the optical/NIR band, fast photometry looks to be the only viable strategy. Additionally, small/medium size radiotelescopes co-pointing higher energies telescopes look a very interesting and cheap complementary observational strategy.

scholarly journals A neutron star–white dwarf binary model for periodically active fast radio burst sources

2020 ◽  
Vol 497 (2) ◽  
pp. 1543-1546 ◽  
Author(s):  
Wei-Min Gu ◽  
Tuan Yi ◽  
Tong Liu
Keyword(s):  
Neutron Star ◽  
Radio Burst ◽  
Duty Cycle ◽  
White Dwarf ◽  
Burst Activity ◽  
Compact Binary ◽  
Binary Model ◽  
Duty Cycles ◽  
Curvature Radiation ◽  
Fast Radio Burst

ABSTRACT We propose a compact binary model with an eccentric orbit to explain periodically active fast radio burst (FRB) sources, where the system consists of a neutron star (NS) with strong dipolar magnetic fields and a magnetic white dwarf (WD). In our model, the WD fills its Roche lobe at periastron, and mass transfer occurs from the WD to the NS around this point. The accreted material may be fragmented into a number of parts, which arrive at the NS at different times. The fragmented magnetized material may trigger magnetic reconnection near the NS surface. The electrons can be accelerated to an ultrarelativistic speed, and therefore the curvature radiation of the electrons can account for the burst activity. In this scenario, the duty cycle of burst activity is related to the orbital period of the binary. We show that such a model may work for duty cycles roughly from 10 min to 2 d. For the recently reported 16.35-d periodicity of FRB 180916.J0158 + 65, our model does not naturally explain such a long duty cycle, since an extremely high eccentricity (e &gt; 0.95) is required.

scholarly journals A Decade and a Half of Fast Radio Burst Observations

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 453
Author(s):  
Manisha Caleb ◽  
Evan Keane
Keyword(s):  
Magnetic Field ◽  
Radio Burst ◽  
Line Of Sight ◽  
Radio Bursts ◽  
Radio Observations ◽  
The Past ◽  
Interstellar Media ◽  
Propagation Effects ◽  
Fast Radio Burst ◽  
The Universe

Fast radio bursts (FRBs) have a story which has been told and retold many times over the past few years as they have sparked excitement and controversy since their pioneering discovery in 2007. The FRB class encompasses a number of microsecond- to millisecond-duration pulses occurring at Galactic to cosmological distances with energies spanning about 8 orders of magnitude. While most FRBs have been observed as singular events, a small fraction of them have been observed to repeat over various timescales leading to an apparent dichotomy in the population. ∼50 unique progenitor theories have been proposed, but no consensus has emerged for their origin(s). However, with the discovery of an FRB-like pulse from the Galactic magnetar SGR J1935+2154, magnetar engine models are the current leading theory. Overall, FRB pulses exhibit unique characteristics allowing us to probe line-of-sight magnetic field strengths, inhomogeneities in the intergalactic/interstellar media, and plasma turbulence through an assortment of extragalactic and cosmological propagation effects. Consequently, they are formidable tools to study the Universe. This review follows the progress of the field between 2007 and 2020 and presents the science highlights of the radio observations.

scholarly journals First Discovery of New Pulsars and RRATs with CHIME/FRB

2021 ◽  
Vol 922 (1) ◽  
pp. 43
Author(s):  
D. C. Good ◽  
B. C. Andersen ◽  
P. Chawla ◽  
K. Crowter ◽  
F. Q. Dong ◽  
...  
Keyword(s):  
Radio Burst ◽  
Single Pulse ◽  
Radio Sources ◽  
Pulse Emission ◽  
Intensity Mapping ◽  
Fast Radio Burst ◽  
Radio Transients ◽  
Galactic Sources ◽  
Rotating Radio Transients ◽  
Galactic Radio

Abstract We report the discovery of seven new Galactic pulsars with the Canadian Hydrogen Intensity Mapping Experiment’s Fast Radio Burst (CHIME/FRB) backend. These sources were first identified via single pulses in CHIME/FRB, then followed up with CHIME/Pulsar. Four sources appear to be rotating radio transients, pulsar-like sources with occasional single-pulse emission with an underlying periodicity. Of those four sources, three have detected periods ranging from 220 ms to 2.726 s. Three sources have more persistent but still intermittent emission and are likely intermittent or nulling pulsars. We have determined phase-coherent timing solutions for the latter two. These seven sources are the first discovery of previously unknown Galactic sources with CHIME/FRB and highlight the potential of fast radio burst detection instruments to search for intermittent Galactic radio sources.

scholarly journals A fast radio burst source at a complex magnetised site in a barred galaxy

2021 ◽  
Author(s):  
K.J. Lee ◽  
Heng Xu ◽  
J.R. Niu ◽  
P. Chen ◽  
Weiwei Zhu ◽  
...  
Keyword(s):  
Optical Observations ◽  
Host Galaxy ◽  
Radio Bursts ◽  
Radio Waves ◽  
Galactocentric Distance ◽  
Burst Source ◽  
Radiation Mechanism ◽  
Circular Polarisation ◽  
Rotation Measure ◽  
Fast Radio Burst

Abstract Fast radio bursts (FRBs) are highly dispersed radio bursts prevailing in the universe. The recent detection of FRB~200428 from a Galactic magnetar suggested that at least some FRBs originate from magnetars, but it is unclear whether the majority of cosmological FRBs, especially the actively repeating ones, are produced from the magnetar channel. Here we report the detection of 1863 polarised bursts from the repeating source FRB~20201124A during a dedicated radio observational campaign of Five-hundred-meter Aperture Spherical radio Telescope (FAST). The large sample of radio bursts detected in 88 hr over 54 days indicate a significant, irregular, short-time variation of the Faraday rotation measure (RM) of the source during the first 36 days, followed by a constant RM during the later 18 days. Significant circular polarisation up to 75\% was observed in a good fraction of bursts. Evidence suggests that some low-level circular polarisation originates from the conversion from linear polarisation during the propagation of the radio waves, but an intrinsic radiation mechanism is required to produce the higher degree of circular polarisation. All of these features provide evidence for a more complicated, dynamically evolving, magnetised immediate environment around this FRB source. Its host galaxy was previously known. Our optical observations reveal that it is a Milky-Way-sized, metal-rich, barred-spiral galaxy at redshift z=0.09795+-0.00003, with the FRB residing in a low stellar density, interarm region at an intermediate galactocentric distance, an environment not directly expected for a young magnetar formed during an extreme explosion of a massive star.

scholarly journals Young magnetars with fracturing crusts as fast radio burst repeaters

2019 ◽  
Vol 488 (4) ◽  
pp. 5887-5897 ◽  
Author(s):  
A G Suvorov ◽  
K D Kokkotas
Keyword(s):  
Statistical Analysis ◽  
Power Law ◽  
Radio Burst ◽  
Rapid Evolution ◽  
Compact Objects ◽  
Tectonic Activity ◽  
Radio Bursts ◽  
Crustal Field ◽  
Long Time ◽  
Fast Radio Burst

Abstract Fast radio bursts are millisecond-duration radio pulses of extragalactic origin. A recent statistical analysis has found that the burst energetics of the repeating source FRB 121102 follow a power law, with an exponent that is curiously consistent with the Gutenberg–Richter law for earthquakes. This hints that repeat bursters may be compact objects undergoing violent tectonic activity. For young magnetars, possessing crustal magnetic fields which are both strong (B ≳ 1015 G) and highly multipolar, Hall drift can instigate significant field rearrangements even on ≲ century long time-scales. This reconfiguration generates zones of magnetic stress throughout the outer layers of the star, potentially strong enough to facilitate frequent crustal failures. In this paper, assuming a quake scenario, we show how the crustal field evolution, which determines the resulting fracture geometries, can be tied to burst properties. Highly anisotropic stresses are generated by the rapid evolution of multipolar fields, implying that small, localized cracks can occur sporadically throughout the crust during the Hall evolution. Each of these shallow fractures may release bursts of energy, consistent in magnitude with those seen in the repeating sources FRB 121102 and FRB 180814.J0422+73.

scholarly journals The performance and calibration of the CRAFT fly’s eye fast radio burst survey

2019 ◽  
Vol 36 ◽  
Author(s):  
C. W. James ◽  
K. W. Bannister ◽  
J.-P. Macquart ◽  
R. D. Ekers ◽  
S. Oslowski ◽  
...  
Keyword(s):  
Radio Burst ◽  
Phased Array ◽  
Radio Frequency Interference ◽  
Radio Bursts ◽  
System Noise ◽  
Fast Transients ◽  
Fast Radio Burst ◽  
Power Law Index ◽  
Phased Array Feeds ◽  
Best Fit

AbstractThe Commensal Real-time Australian Square Kilometre Array Pathfinder Fast Transients survey is the first extensive astronomical survey using phased array feeds. Since January 2017, it has been searching for fast radio bursts in fly’s eye mode. Here, we present a calculation of the sensitivity and total exposure of the survey that detected the first 20 of these bursts, using the pulsars B1641-45 and B0833-45 as calibrators. The beamshape, antenna-dependent system noise, and the effects of radio-frequency interference and fluctuations during commissioning are quantified. Effective survey exposures and sensitivities are calculated as a function of the source counts distribution. Statistical ‘stat’ and systematics ‘sys’ effects are treated separately. The implied fast radio burst rate is significantly lower than the 37 sky−1 day−1 calculated using nominal exposures and sensitivities for this same sample by Shannon et al. (2018). At the Euclidean (best-fit) power-law index of −1.5 (−2.2), the rate is $12.7_{-2.2}^{+3.3}$ (sys) ± 3.6 (stat) sky−1 day−1 ( $20.7_{-1.7}^{+2.1}$ (sys) ± 2.8 (stat) sky−1 day−1) above a threshold of 56.6 ± 6.6(sys) Jy ms (40.4 ± 1.2(sys) Jy ms). This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.

scholarly journals The Northern Cross fast radio burst project – I. Overview and pilot observations at 408 MHz

2020 ◽  
Vol 494 (1) ◽  
pp. 1229-1236 ◽  
Author(s):  
Nicola T Locatelli ◽  
Gianni Bernardi ◽  
Germano Bianchi ◽  
Riccardo Chiello ◽  
Alessio Magro ◽  
...  
Keyword(s):  
Radio Burst ◽  
System Performance ◽  
Field Of View ◽  
High Dispersion ◽  
Dispersion Measure ◽  
Radio Bursts ◽  
Radio Telescopes ◽  
Present Test ◽  
New Radio ◽  
Fast Radio Burst

ABSTRACT Fast radio bursts (FRBs) remain one of the most enigmatic astrophysical sources. Observations have significantly progressed over the last few years, due to the capabilities of new radio telescopes and the refurbishment of existing ones. Here, we describe the upgrade of the Northern Cross radio telescope, operating in the 400–416 MHz frequency band, with the ultimate goal of turning the array into a dedicated instrument to survey the sky for FRBs. We present test observations of the pulsar B0329+54 to characterize the system performance and forecast detectability. Observations with the system currently in place are still limited by modest sky coverage (∼9.4 deg2) and biased by smearing of high dispersion measure events within each frequency channels. In its final, upgraded configuration, however, the telescope will be able to carry out unbiased FRB surveys over a ∼350 deg2 instantaneous field of view up to z ∼ 5, with a (nearly constant) $\sim 760 \, (\tau /{\rm ms})^{-0.5}$ mJy rms sensitivity.

scholarly journals A unified picture of Galactic and cosmological fast radio bursts

2020 ◽  
Vol 498 (1) ◽  
pp. 1397-1405 ◽  
Author(s):  
Wenbin Lu ◽  
Pawan Kumar ◽  
Bing Zhang
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Radio Emission ◽  
Light Curve ◽  
Flux Ratio ◽  
Radio Bursts ◽  
X Ray ◽  
Volumetric Rate ◽  
Fast Radio Burst ◽  
Magnetic Disturbances

ABSTRACT The discovery of a fast radio burst (FRB) in our Galaxy associated with a magnetar (neutron star with strong magnetic field) has provided a critical piece of information to help us finally understand these enigmatic transients. We show that the volumetric rate of Galactic-FRB like events is consistent with the faint end of the cosmological FRB rate, and hence they most likely belong to the same class of transients. The Galactic FRB had an accompanying X-ray burst, but many X-ray bursts from the same object had no radio counterpart. Their relative rates suggest that for every FRB there are roughly 102–103 X-ray bursts. The radio light curve of the Galactic FRB had two spikes, separated by 30 ms in the 400–800 MHz frequency band. This is an important clue and highly constraining of the class of models where the radio emission is produced outside the light cylinder of the magnetar. We suggest that magnetic disturbances close to the magnetar surface propagate to a distance of a few tens of neutron star radii where they damp and produce radio emission. The coincident hard X-ray spikes associated with the two FRB pulses seen in this burst and the flux ratio between the two frequency bands can be understood in this scenario. This model provides a unified picture for faint bursts like the Galactic FRB as well as the bright events seen at cosmological distances.

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