Since its initial discovery, the Fast radio burst (FRB) FRB 121102 has been found to be repeating with millisecond-duration pulses. Very recently, 15 new bursts were detected by the Green Bank Telescope (GBT) during its continous monitoring observations. In this letter, we show that the burst energy distribution has a power law form which is very similar to the Gutenberg-Richter law of earthquakes. In addition, the waiting time of the burst has a Gaussian distribution, which is also a distinctive feature of earthquakes. These findings suggest that the repeating FRB pulses may originate from the starquakes of a pulsar. Noting that the soft gamma-ray repeaters (SGRs) also exhibit such distributions, the FRB could be powered by some mechanism associated with the SGRs, including crustal acitivity of a magnetar, solidification-induced stresss of a young strangeon star, and oscillation-drivern magnetic activities of a slowly rotating pulsar. These conjectures could be tested with more repeating samples.
The repeating FRB 121102 (the "repeater") shows {repetitive bursting activities} and was localized in a host galaxy at $z=0.193$. On the other hand, despite dozens of hours of telescope time spent on follow-up observations, no other FRBs have been observed to repeat. Yet, it has been speculated that the repeater is the prototype of FRBs, and that other FRBs should show similar repeating patterns. Using the published data, we compare the repeater with other FRBs in the observed time interval ($Δt$) - flux ratio ($S_i / S_{i+1}$) plane. We find that whereas other FRBs occupy the upper (large $S_…
Fast radio bursts (FRBs) are one of the most mysterious astronomical transients. Observationally, they can be classified into repeaters and apparently non-repeaters. However, due to the lack of continuous observations, some apparently repeaters may have been incorrectly recognized as non-repeaters. In a series of two papers, we intend to solve such problem with machine learning. In this second paper of the series, we focus on an array of unsupervised machine learning methods. We apply multiple unsupervised machine learning algorithms to the first CHIME/FRB catalog to learn their features and c…
Fast Radio Bursts (FRBs) are the short, strong radio pulses lasting several milliseconds. They are subsequently identified, for the most part, as emanating from unknown objects at cosmological distances. At present, over one hundred FRBs have been verified, classified into two groups: repeating bursts (20 samples) and apparently non-repeating bursts (91 samples). Their origins, however, are still hotly debated. Here,we investigate the statistical classifications for the two groups of samples to see if the non-repeating and repeating FRBs have different origins by employing Anderson-Darling (A-…
Observationally, fast radio bursts (FRBs) can be divided into repeating and apparently non-repeating (one-off) ones. It is unclear whether all FRBs repeat and whether there are genuine non-repeating FRBs. We attempt to address these questions using Monte Carlo simulations. We define a parameter $T_c$ at which the accumulated number of non-repeating sources becomes comparable to the total number of the repeating sources, which is a good proxy to denote the intrinsic repeater fraction among FRBs. Assuming that both types of sources exist and that their burst energies follow power law distributio…
The observed Fast Radio Burst (FRB) population can be divided into one-off and repeating FRB sources. Either this division is a true dichotomy of the underlying sources, or selection effects and low activity prohibit us from observing repeat pulses from all constituents making up the FRB source population. We attempt to break this degeneracy through FRB population synthesis. With that aim we extend frbpoppy, which earlier only handled one-off FRBs, to also simulate repeaters. We next model the Canadian Hydrogen Intensity Mapping Experiment FRB survey (CHIME/FRB). Using this implementation, we …
We further explored the radius-to-frequency mapping in cases of FRBs. An analytical treatment of Lyutikov (2020) is presented. The frequency dependence of the drifting rate and the drifting timescale are obtained. The aberration effect and the twist of the magnetic field lines may result in drifting in both directions. For one FRB, the burst width is larger at lower frequency according to the radius-to-frequency mapping. For the FRB population, the magnetic fields of the repeaters may be larger than that of the non-repeaters. Then, according to the radius-to-frequency mapping, the burst widths…
The origins of fast radio bursts (FRBs), astronomical transients with millisecond timescales, remain unknown. One of the difficulties stems from the possibility that observed FRBs could be heterogeneous in origin; as some of them have been observed to repeat, and others have not. Due to limited observing periods and telescope sensitivities, some bursts may be misclassified as non-repeaters. Therefore, it is important to clearly distinguish FRBs into repeaters and non-repeaters, to better understand their origins. In this work, we classify repeaters and non-repeaters using unsupervised machine …
Radio Monitoring Campaign of Active Repeater FRB 20220912A with CHIME
McGill University（麦吉尔大学）；MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（麻省理工学院卡弗里天体物理与空间研究所）；Massachusetts Institute of Technology（麻省理工学院）；Tel Aviv University（特拉维夫大学）；National Research Council of Canada, Herzberg Astronomy and Astrophysics（加拿大国家研究委员会赫茨伯格天文学与天体物理学研究所）；University of British Columbia（不列颠哥伦比亚大学）
Fast radio bursts (FRBs) are extremely strong radio flares lasting several milliseconds, most of which come from unidentified objects at a cosmological distance. They can be apparently repeating or not. In this paper, we analyzed 18 repeaters and 12 non-repeating FRBs observed in the frequency bands of 400-800 MHz from CHIME. We investigated the distributions of FRB isotropic-equivalent radio luminosity, considering the K correction. Statistically, the luminosity distribution can be better fitted by Gaussian form than by power-law. Based on the above results, together with the observed FRB eve…
Fast radio bursts (FRBs) are extremely strong radio flares lasting several micro- to milliseconds and come from unidentified objects at cosmological distances, most of which are only seen once. Based on recently published data in the CHIME/FRB Catalog 1 in the frequency bands 400-800 MHz, we analyze 125 apparently singular FRBs with low dispersion measure (DM) and find that the distribution of their luminosity follows a lognormal form according to statistical tests. In our luminosity measurement, the FRB distance is estimated by using the Macquart relation which was obtained for 8 localized FR…
Fast radio bursts (FRBs) are extragalactic radio transients with millisecond duration and extremely high brightness temperature. Very recently, some highly circularly polarized bursts were found in a repeater, FRB 20201124A. The significant circular polarization might be produced by coherent curvature radiation by bunches with the line of sight (LOS) deviating from the bunch central trajectories. In this work, we carry out simulations to study the statistical properties of burst polarization within the framework of coherent curvature radiation by charged bunches in the neutron star magnetosphe…
The first Fast Radio Burst (FRB) to be precisely localized was associated with a luminous persistent radio source (PRS). Recently, a second FRB/PRS association was discovered for another repeating source of FRBs. However, it is not clear what makes FRBs or PRS or how they are related. We compile FRB and PRS properties to consider the population of FRB/PRS sources. We suggest a practical definition for PRS as FRB associations with luminosity greater than $10^{29}$ erg s$^{-1}$ Hz$^{-1}$ that is not attributed to star-formation activity in the host galaxy. We model the probability distribution o…
There are insufficient catastrophic events (collapse, explosion or merger of stars or compact objects) to explain the cosmologically local rate of apparently non-repeating FRB if each such catastrophic event produces a single FRB. Unless produced by some novel and unsuspected but comparatively frequent event, apparently non-repeating FRB must actually repeat many times in the lifetimes of their sources. Yet no such infrequent repetitions (in contrast to the frequent activity of FRB known to repeat) have been observed, constraining their repetition rates and active lifetimes. The absence of mor…
Gravitational self-lensing of Fast Radio Bursts in neutron star magnetospheres: II. Applications to strong repeaters and the CHIME population
INAF – Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Dipartimento di Fisica e Astronomia “Augusto Righi”, Università di Bologna（博洛尼塔大学物理与天文学“奥古斯托·里吉”系）；INAF – Istituto di Radioastronomia（意大利国家天体物理研究所射电天文研究所）；INAF – Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）
The recent discovery of a Galactic fast radio burst (FRB) associated with a hard X-ray burst from the soft gamma-ray repeater (SGR) J1935+2154 has established the magnetar origin of at least some FRBs. In this work, we study the statistical properties of soft gamma-/hard X-ray bursts from SGRs 1806--20 and J1935+2154 and of radio bursts from the repeating FRB 121102. For SGRs, we show that the probability density functions for the differences of fluences, fluxes, and durations at different times have fat tails with a $q$-Gaussian form. The $q$ values in the $q$-Gaussian distributions are appro…
Are Repeaters Prevalent Among the Known Fast Radio Burst Sources?
Nanjing University（南京大学）；Qufu Normal University（曲阜师范大学）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（教育部现代天文与天体物理重点实验室（南京大学））；Anqing Normal University（安庆师范大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；University of Science and Technology of China（中国科学技术大学）；State Key Laboratory of Radio Astronomy and Technology, Xinjiang Astronomical Observatory, CAS（中国科学院新疆天文台射电天文与技术国家重点实验室）；Xinjiang Key Laboratory of Radi（新疆辐射重点实验室）
We report on the discovery of eight repeating fast radio burst (FRB) sources found using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These sources span a dispersion measure (DM) range of 103.5 to 1281 pc cm$^{-3}$. They display varying degrees of activity: six sources were detected twice, another three times, and one ten times. These eight repeating FRBs likely represent the bright and/or high-rate end of a distribution of infrequently repeating sources. For all sources, we determine sky coordinates with uncertainties of $\sim$10$^\prime$. FRB 180916.J0158+65 has a bu…
Quasi-periodic oscillation (QPO) signals are discovered in some fast radio bursts (FRBs) such as FRB 20191221A, as well as in the X-ray burst associated with the galactic FRB from SGR 1935+2154. We revisit the intermediate-field FRB model where the radio waves are generated as fast-magnetosonic waves through magnetic reconnection near the light cylinder. The current sheet in the magnetar wind is compressed by a low frequency pulse emitted from the inner magnetosphere to trigger magnetic reconnection. By incorporating the wave dynamics of the magnetosphere, we demonstrate how the FRB frequency,…
We present a targeted search for low-frequency (144--215\,MHz) FRB emission from five repeating FRBs using 23.3\,hr of archival data taken with the Murchison Widefield Array (MWA) Voltage Capture System (VCS) between 2014 September and 2020 May. This is the first time that the MWA VCS has been used to search for FRB signals from known repeaters, which enables much more sensitive FRB searches than previously performed with the standard MWA correlator mode. We performed a standard single pulse search with a temporal and spectral resolution of $400\,μ$s and 10\,kHz, respectively, over a $100\,\te…
Neutron stars are likely surrounded by gas, debris, and asteroid belts. Kozai-Lidov perturbations, induced by a distant, but gravitationally bound companion, can trigger the infall of such orbiting bodies onto a central compact object. These effects could lead to the emission of fast radio bursts (FRBs), for example by asteroid-induced magnetic wake fields in the wind of the compact object. A few percent of binary neutron star systems in the Universe, such as neutron star-main sequence star, neutron star-white dwarf, double neutron star, and neutron star-black hole systems, can account for the…
Fast radio bursts are millisecond-duration radio pulses of extragalactic origin. A recent statistical analysis has found that the burst energetics of the repeating source FRB 121102 follow a power-law, with an exponent that is curiously consistent with the Gutenberg-Richter law for earthquakes. This hints that repeat-bursters may be compact objects undergoing violent tectonic activity. For young magnetars, possessing crustal magnetic fields which are both strong ($B \gtrsim 10^{15}$ G) and highly multipolar, Hall drift can instigate significant field rearrangements even on $\lesssim$ century l…
FRB 180916 is a most intriguing source at 150 Mpc distance capable of producing repeating fast radio bursts with a periodic 16.35 day temporal pattern. We report on the X-ray and $γ$-ray observations of FRB 180916 obtained by AGILE and Swift. We focused on the recurrent 5-day time intervals of active radio bursting and present results obtained on Feb. 3 - 8; Feb. 25; Mar. 5 - 10; Mar. 22 - 28, 2020 during a multiwavelength campaign involving high-energy and radio observations. We also searched for temporal coincidences at millisecond timescales between all known radio bursts of FRB 180916 and …
A multi-telescope fit to the FRB population, allowing for FRB repetition
International Centre for Radio Astronomy Research, Curtin University（国际射电天文研究中心，科廷大学）；Department of Astronomy and Astrophysics, University of California, Santa Cruz（天文学与天体物理学系，加州大学圣克鲁兹分校）；ASTRON, Netherlands Institute for Radio Astronomy（ASTRON，荷兰射电天文研究所）
Fast radio bursts (FRB) are enigmatic powerful single radio pulses with durations of several milliseconds and high brightness temperatures suggesting coherent emission mechanism. For the time being a number of extragalactic FRBs have been detected in the high-frequency radio band including repeating ones. The most plausible explanation for these phenomena is magnetar hyperflares. The first observational evidence of this scenario was obtained in April 2020 when an FRB was detected from the direction of the Galactic magnetar and soft gamma repeater SGR1935+2154. The FRB was preceded with a numbe…
In this paper, we present a sample of 21 repeating fast radio bursts (FRBs) detected by different radio instruments before September 2021. Using the Anderson--Darling test, we compared the distributions of extra-Galactic dispersion measure ($DM_{\rm E}$) of non-repeating FRBs, repeating FRBs and all FRBs. It was found that the $ DM_{\rm E}$ values of three sub-samples are log-normally distributed. The $DM_{\rm E}$ of repeaters and non-repeaters were drawn from a different distribution on basis of the Mann--Whitney--Wilcoxon test. In addition, assuming that the non-repeating FRBs identified cur…
There are several phenomenological similarities between Soft Gamma Repeaters and Fast Radio Bursts, including duty factors, time scales and probable repetition. The sudden release of magnetic energy in a neutron star magnetosphere, as in popular models of SGR, can meet the energy requirements of FRB but requires both the presence of magnetospheric plasma in order that dissipation occur in a transparent region and a mechanism for releasing much of that energy quickly. FRB sources and SGR are distinguished by long-lived (up to thousands of years) current-carrying coronal arches remaining from fo…
Discovery of 30 Repeating Fast Radio Burst Sources and Uniform Population Statistics of 80 Repeating Sources from CHIME/FRB
McGill University（麦吉尔大学）；University of Amsterdam（阿姆斯特丹大学）；California Institute of Technology（加州理工学院）；Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）
Fast radio bursts (FRBs) are millisecond-duration radio signals occurring at cosmological distances. However the physical model of FRBs is mystery, many models have been proposed. Here we study the frequency distributions of peak flux, fluence, duration and waiting time for the repeating FRB 121102. The cumulative distributions of peak flux, fluence and duration show power-law forms. The waiting time distribution also shows power-law distribution, and is consistent with a non-stationary Poisson process. These distributions are similar as those of soft gamma repeaters (SGRs). We also use the st…
