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Can-Min Deng

Publications and source records attributed to Can-Min Deng.

At least 19 recordsLinked to original sources

A Bayesian Framework for Constraining Magnetar Magnetic Fields from Repeating FRB Statistics

Fast radio bursts (FRBs) are widely considered to be associated with magnetars, motivated by the detection of an FRB-like radio burst from the Galactic magnetar SGR~1935+2154. However, constraining the magnetic field strength of extragalactic FRB sources remains challenging. In this work, we develop a Bayesian framework that models FRB time--energy sequences as a marked point process, combining burst waiting-time statistics with energy distributions to quantify the magnetic field strengths required to sustain the observed bursting activity under the magnetar powered scenario. Applying this method to a sample of repeating FRBs, we derive constraints on their magnetic fields by incorporating an empirical prior on the radio emission efficiency calibrated from the Galactic event. Under a conservative assumption for the activity duty cycle, most sources require magnetic energy reservoirs consistent with magnetar strength fields, with characteristic field strengths of order $10^{13}$--$10^{15}$ G, although the constraints remain sensitive to the poorly known efficiency and duty-cycle parameters. FRB~20200120E provides an interesting case with a substantially lower field requirement, highlighting the importance of source environment and evolutionary history in interpreting FRB activity. Our framework provides a statistical approach for connecting transient burst properties with magnetic energy reservoirs, with potential applications to FRBs and other magnetically powered transients.

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A systematic search for physical associations between fast radio bursts and astrophysical transients

The physical origin of fast radio bursts (FRBs) remains an unsolved mystery in astrophysics, with the magnetar central engine model as the leading framework. Systematically searching for physical associations between FRBs and the energetic astrophysical transients (ATs) that form magnetars provides a critical test of this scenario, and key clues to FRB progenitors. We perform a systematic search for FRB-AT associations using a sample of 3765 unique FRBs, combining the second CHIME/FRB catalog with 124 additional localized FRBs with measured redshifts. We develop a 3D Bayesian inference framework that jointly incorporates angular separation, positional uncertainty, and redshift constraints to quantify the association probability of candidate pairs. Through spatial cross-matching, we identify 14 FRB-optical transient and 15 FRB-gamma-ray burst (GRB) candidate pairs. Our framework recovers the previously reported high-significance association between FRB 20180916B and AT 2020hur, with an association probability of 0.9998. For the proposed candidate FRB 20190309A and short GRB 060502B, our analysis yields an association probability of 0.83, which is insufficient to claim statistically significant association. No new statistically significant FRB-AT associations are found for all remaining candidates. Our work demonstrates that small angular separation alone is insufficient to confirm FRB-AT associations, and high-precision FRB localization is essential for definitive identification.

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Possible Multi-band Afterglows of FRB 20171020A and its Implication

Fast Radio Bursts (FRBs) are millisecond-duration radio transients of mysterious origin, with growing evidence linking at least some of them to magnetars. While FRBs are primarily observed in the radio band, their potential multi-wavelength afterglows remain largely unexplored. We investigate the possible afterglow of FRB 20171020A, a rare nearby and bright FRB localized in a galaxy at only 37 Mpc. Assuming that this source produces a future bright burst, we model the expected afterglow emission in the radio, optical, and X-ray bands under both uniform and wind-like ambient media, within the framework of the magnetar model. Our results show that the optical afterglow is the most promising for detection, but it fades rapidly and requires follow-up within a few hundred seconds post-burst. The radio afterglow may be detectable under favorable conditions in a dense stellar wind, whereas the X-ray counterpart is too faint for current telescopes. These findings suggest that rapid optical follow-up offers the best opportunity to detect the afterglow of the next bright burst from FRB 20171020A, providing unique insights into the progenitor and its environment. To assess observational feasibility, we estimate the event rate of nearby FRBs with sufficient energy to power detectable afterglows, finding a rate of $\sim$0.3 per year for CHIME surveys. Although this rate is low and the optical detection timescale is short, coordinated fast-response strategies using global telescope networks could significantly improve the chance of success. As more nearby FRBs are discovered, multi-wavelength observations will be essential in unveiling the physical nature of these enigmatic events.

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Prediction of Multi-Wavelength Afterglows Associated with FRB 20200120E and FRB 20201124A

Fast radio bursts (FRBs) are mysterious radio transients with uncertain origins and environments. Recent studies suggest that some active FRBs may originate from compact objects in binary systems. In this work, we develop a unified theoretical framework to model the multi-wavelength afterglows of FRBs resided in binary systems and apply it to two representative repeaters, FRB 20200120E and FRB 20201124A. By solving the dynamics and radiation processes of FRB ejecta interacting with the surrounding medium, we compute afterglow light curves in the radio, optical, and X-ray bands. Our results show that radio afterglows offer the best prospects for detection, with their brightness highly sensitive to ejecta kinetic energy and ambient density. Future high-sensitivity radio telescopes, such as the Square Kilometre Array (SKA), could detect these signals. Optical afterglows, though short-lived and challenging to observe, may be significantly enhanced in dense environments, potentially making them detectable with facilities like the Large Synoptic Survey Telescope (LSST). In contrast, X-ray afterglows are predicted to be too faint for detection with current instruments. Our study highlights the potential of multi-wavelength afterglows as probes of FRB progenitors and their surrounding environments, offering crucial insights into the nature of these mysterious transients.

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A Comprehensive Study of the Energy and Redshift Distributions of the Fast Radio Burst Population Based on the First CHIME/FRB Catalog

Fast radio bursts (FRBs) are brief, high-energy bursts of radio waves from extragalactic sources, and their origin remains an open question. In this paper, we perform a comprehensive analysis of the FRB population using the first CHIME/FRB catalog, focusing on their energy and redshift distribution, with careful consideration of selection effects. We investigate a range of models, including the Schechter function and the broken power-law function for the energy distribution, and several redshift evolution models, such as the star formation history (SFH) model, as well as models incorporating time delays relative to the SFH or additional redshift evolution factors. Our results indicate that the energy distribution of FRBs is best described by the Schechter function, with a power-law index of $\gamma = -1.49^{+0.37}_{-0.27}$ and a characteristic cutoff energy of $E_\mathrm{c} = 2.82^{+2.43}_{-1.47} \times 10^{41}$ erg. Furthermore, we find no evidence for redshift evolution in the energy distribution of FRBs. In terms of their redshift distribution, our analysis shows that it follows the cosmic SFH, without requiring additional delayed components or redshift evolution factors, suggesting that most FRBs likely originate from young stellar populations. Simultaneously, we infer a local volumetric rate of $\Phi_0 = 4.68^{+4.66}_{-2.39} \times 10^{4} \rm \ Gpc^{-3}yr^{-1}$ for $E>10^{39}$ erg. These results, robust against CHIME observational biases, may provide new insights into the underlying properties of the FRB population.

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Constraints on the progenitor models of fast radio bursts from population synthesis with the first CHIME/FRB catalog

Fast radio bursts (FRBs) are enigmatic extragalactic radio transients with unknown origins. We performed comprehensive Monte Carlo simulations based on the first CHIME/FRB catalog to test whether the FRB population tracks the cosmic star formation history directly or requires a delay. By fully considering CHIME's complex selection effects and beam response, we find that the hypothesis that the FRB population tracks the SFH is not ruled out by the current data, although a small delay is preferred. This is consistent with the scenario in which young magnetars formed through core-collapse supernovae serve as the progenitors of FRBs. However, we estimate the local volumetric rate of FRB sources with energy above $10^{38}$ erg to be $2.3^{+2.4}_{-1.2} \times 10^5~\rm{Gpc}^{-3}~\rm{yr}^{-1}$, which is consistent with previous results. This high volumetric rate means the core-collapse magnetar scenario alone cannot fully account for the observed population. Further theoretical efforts are required to explore alternative or additional progenitor channels for FRBs.

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The Impact of Accretion on FRB Radiation Mechanisms in Binary Systems: Constraints and Implications

Fast Radio Bursts (FRBs) are intense, millisecond-duration radio transients that have recently been proposed to arise from coherent radiation mechanisms within the magnetosphere of neutron stars. Observations of repeating FRBs, including periodic activity and large variations in Faraday rotation measures, suggest that these bursts may have binary system origins, with massive companion. In this work, we investigate how accretion from a massive companion influences the FRB radiation within the magnetosphere of the neutron star. Focusing on two widely accepted pulsar-like coherent radiation mechanisms, we establish the parameter space for neutron stars that allows FRB generation, even in the presence of accreted matter. Our analysis shows that coherent curvature radiation is only viable within a narrow range of parameters, while the magnetic reconnection mechanism operates across a broader range. In both cases, the neutron star must possess a strong magnetic field with strength $\gtrsim 10^{13}$ G. These findings at least indicate that the central engines responsible for producing observable FRBs in binary systems are indeed magnetars.

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Repeating fast radio bursts from synchrotron maser radiation in localized plasma blobs: Application to FRB 20121102A

The radiation physics of repeating fast radio bursts (FRBs) remains enigmatic. Motivated by the observed narrow-banded emission spectrum and ambiguous fringe pattern of the spectral peak frequency ($\nu_{\rm pk}$) distribution of some repeating FRBs, such as FRB 20121102A, we propose that the bursts from repeating FRBs arise from synchrotron maser radiation in localized blobs within weakly magnetized plasma that relativistically moves toward observers. Assuming the plasma moves toward the observers with a bulk Lorentz factor of $\Gamma=100$ and the electron distribution in an individual blob is monoenergetic ($\gamma_{\rm e}\sim300$), our analysis shows that bright and narrow-banded radio bursts with peak flux density $\sim$ 1 ${\rm Jy}$ at peak frequency ($\nu_{\rm pk}$) $\sim 3.85$ GHz can be produced by the synchrotron maser emission if the plasma blob has a magnetization factor of $\sigma\sim10^{-5}$ and a frequency of $\nu_{\rm P}\sim 4.5$ MHz. The spectrum of bursts with lower $\nu_{\rm pk}$ tends to be narrower. Applying our model to the bursts of FRB 20121102A, the distributions of both the observed $\nu_{\rm pk}$ and isotropic energy $E_{\rm iso}$ detected by the Arecibo telescope at the L band and the Green Bank Telescope at the C band are successfully reproduced. We find that the $\nu_{\rm P}$ distribution exhibits several peaks, similar to those observed in the $\nu_{\rm pk}$ distribution of FRB 20121102A. This implies that the synchrotron maser emission in FRB 20121102A is triggered in different plasma blobs with varying $\nu_{\rm P}$, likely due to the inhomogeneity of relativistic electron number density.

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Scintillation velocity and arc observations of FRB 20201124A

We present the scintillation velocity measurements of FRB~20201124A from the FAST observations, which reveal an annual variation. This annual variation is further supported by changes detected in the scintillation arc as observed from the secondary spectrum. We attribute the annual velocity variation to the presence of a moderately anisotropic scattering screen located at a distance of 0.4$\pm$0.1~kpc from Earth. Our results prove that the scintillation of this FRB is mainly caused by material close to Earth on a Galactic scale. However, scintillation observations of other FRBs may expose their surrounding environment or uncover possible orbital motion if scintillation is caused by materials in their host galaxy.

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The primordial black holes solution to the cosmological monopole problem

Recently, the pulsar timing array (PTA) collaborations, including CPTA, EPTA, NANOGrav, and PPTA, announced that they detected a stochastic gravitational wave background spectrum in the nHz band. This may be relevant to the cosmological phase transition suggested by some models. Magnetic monopoles and primordial black holes (PBHs), two unsolved mysteries in the universe, may also have their production related to the cosmological phase transition. Inspired by that, we revisit the model proposed by Stojkovic and Freese, which involves PBHs accretion to solve the cosmological magnetic monopole problem. We further develop it by considering the increase in the mass of the PBHs during accretion and taking the effect of Hawking radiation into account. With these new considerations, we find that solutions to the problem still exist within a certain parameter space. In {addition}, we also generalize the analysis to PBHs with {an} extended distribution in mass. This may be a more interesting scenario because PBHs that have accreted magnetic monopoles might produce observable electromagnetic signals if they are massive enough to survive in the late universe.

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Searching for Associations Between Short Gamma-ray Bursts and Fast Radio Burst

The physical origin of fast radio bursts (FRBs) is still unclear. However, young magnetars associated with short-duration gamma-ray bursts (SGRBs) have been thought to be possible central engines for some FRBs. In this paper, we perform a systematic search for SGRBs that are associated with FRBs in a sample including 623 FRBs (601 one-off bursts and 22 repeaters) and 168 SGRBs with precise localizations. We find that FRB 190309A is spatially associated with GRB 060502B, with a chance probability of 0.05 when temporal and redshift information is taken into account. Considering the high chance probability (the statistical significance is < 3σ), we examine other observational properties such as the host galaxy, the dispersion measure, and the energy budget of the central engine to check the possibility of their association. Although the available observational information is insufficient to determine whether they are physically associated, it does not rule out such a possibility. As the only pair of FRB and GRB that are spatially associated, it remains an interesting case worthy of further attention

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Detection of Quasi-periodic Oscillations in SGR 150228213

The detection of quasi-periodic oscillations (QPOs) in magnetar giant flares (GFs) has brought a new perspective to study the mechanism of magnetar bursts. Due to the scarcity of GFs, searching QPOs from magnetar short bursts is reasonable. Here we report the detection of a high frequency QPO at approximately 110 Hz and a wide QPO at approximately 60 Hz in a short magnetar burst SGR 150228213, with a confidence level of 3.35$σ$. This burst was initially attributed to 4U 0142+61 by $Fermi$/GBM on location, but we haven't detected such QPOs in other bursts from this magnetar. We also found that there was a repeating fast radio burst associated with SGR 150228213 on location. Finally, we discuss the possible origins of SGR 150228213.

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Confining Burst Energy Function and Spectral Fringe Pattern of FRB 20121102A with Multifrequency Observations

The observed spectral shapes variation and tentative bimodal burst energy distribution (E-distribution) of fast radio burst (FRB) 20121102A with the FAST telescope are great puzzles. Adopting the published multifrequency data observed with the FAST and Arecibo telescopes at $L$ band and the GBT telescope at $C$ band, we investigate these puzzles through Monte Carlo simulations. The intrinsic energy function (E-function) is modeled as $dp/dE\propto E^{-α_{\rm E}}$, and the spectral profile is described as a Gaussian function. A fringe pattern of its spectral peak frequency ($ν_{\rm p}$) in 0.5-8 GHz is inferred from the $ν_{\rm p}$ distribution of the GBT sample. We estimate the likelihood of $α_{\rm E}$ and the standard deviation of the spectral profile ($σ_{\rm s}$) by utilizing the Kolmogorov--Smirnov (K-S) test probability for the observed and simulated specific E-distributions. Our simulations yields $α_{\rm E}=1.82^{+0.10}_{-0.30}$ and $σ_{\rm s}=0.18^{+0.28}_{-0.06}$ ($3σ$ confidence level) with the FAST sample. These results suggest that a single power-law function is adequate to model the E-function of FRB 20121102A. The variations of its observed spectral indices and E-distributions with telescopes in different frequency ranges are due to both physical and observational reasons, i.e. narrow spectral width for a single burst and discrete $ν_{p}$ fringe pattern in a broad frequency range among bursts, and the selection effects of the telescope bandpass and sensitivity. The putative $ν_{p}$ fringe pattern cannot be explained with the current radiation physics models of FRBs. Some caveats of possible artificial effects that may introduce such a feature are discussed.

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Scintillation Arc from FRB 20220912A

We present the interstellar scintillation analysis of fast radio burst (FRB) 20220912A during its extremely active episode in 2022 using data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). We detect a scintillation arc in the FRB's secondary spectrum, which describes the power in terms of the scattered FRB signals' time delay and Doppler shift. The arc indicates that the scintillation is caused by a highly localized region of the ionized interstellar medium (IISM). Our analysis favors a Milky Way origin for the localized scattering medium but cannot rule out a host galaxy origin. We present our method for detecting the scintillation arc, which can be applied generally to sources with irregularly spaced bursts or pulses. These methods could help shed light on the complex interstellar environment surrounding the FRBs and in our Galaxy.

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Can a Single Population Account for the Discriminant Properties in Fast Radio Bursts?

To probe this question, we perform a statistical analysis using the first Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) catalog and identify a few discriminant properties between repeating and non-repeating FRBs such as the repetition rate, duration, bandwidth, spectral index, peak luminosity, and potential peak frequency. If repeating and non-repeating FRBs belong to one population, their distribution distinctions for the repetition rate and duration can be explained by the selection effect due to the beamed emission as in Connor et al. (2020). However, we obtain that the distribution distinctions for the spectral index and potentially the peak frequency cannot be explained by the beamed emission within the framework of either the coherent curvature radiation or synchrotron maser emission. This indicates that there could be two populations. We further discuss three possible scenarios for the required two populations.

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Earth-mass primordial black hole mergers as sources for non-repeating FRBs

Fast radio bursts (FRBs) are mysterious astronomical radio transients with extremely short intrinsic duration. Until now, the physical origins of them still remain elusive especially for the non-repeating FRBs. Strongly inspired by recent progress on possible evidence of Earth-mass primordial black holes, we revisit the model of Earth-mass primordial black holes mergers as sources for non-repeating FRBs. Under the null hypothesis that the observed non-repeating FRBs are originated from the mergers of Earth-mass primordial black holes, we analyzed four independent samples of non-repeating FRBs to study the model parameters i.e. the typical charge value $q_{\rm{c}}$ and the power index $α$ of the charge distribution function of the primordial black hole population $ϕ(q) \propto (q/q_{\rm{c}})^{-α}$ which describe how the charge was distributed in the population. $q$ is the charge of the hole in the unit of $\sqrt{G} M$, where $M$ is the mass of the hole. It turns out that this model can explain the observed data well. {Assuming the monochromatic mass spectrum for primordial black holes}, we get the average value of typical charge $\bar{q}_{\rm{c}}/10^{-5}=1.59^{+0.08}_{-0.18}$ and the power index $\barα=4.53^{+0.21}_{-0.14}$ by combining the fitting results given by four non-repeating FRB samples. The event rate of the non-repeating FRBs can be explained in the context of this model, if the abundance of the primordial black hole populations with charge $q \gtrsim 10^{-6}$ is larger than $10^{-5}$ which is far below the upper limit given by current observations for the abundance of Earth-mass primordial black holes. In the future, simultaneous detection of FRBs and high frequency gravitational waves produced by mergers of Earth-mass primordial black holes may directly confirm or deny this model.

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An accreting stellar binary model for active periodic fast radio bursts

In this work, we propose an accreting stellar binary model for understanding the active periodic fast radio bursts (FRBs). The system consists of a stellar compact object (CO) and a donor star (DS) companion in an eccentric orbit, where the DS fills its own Roche lobe near the periastron. The CO accretes the material from the DS and then drive relativistic magnetic blobs. The interaction between the magnetic blobs and the stellar wind of the DS produces a pair of shocks. We find that both of the reverse shock and the forward shock are likely to produce FRBs via synchrotron maser mechanism. We show that this system can in principle sufficiently produce highly active FRBs with a long lifetime, and also can naturally explain the periodicity and the duty cycle of the activity as appeared in FRBs 180916 and 121102. The radio nebula excited by the long-term injection of magnetic blobs into the surrounding environment may account for the associated persistent radio source. In addiction, we discuss the possible multi-wavelength counterparts of FRB 180916 in the context of this model. Finally, we encourage the search for FRBs in the ultraluminous X-ray sources.

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Comparison of the Characteristics of Magnetars Born in Death of Massive Stars and Merger of Compact Objects With {\em Swift} Gamma-Ray Burst Data

Assuming that the shallow-decaying phase in the early X-ray lightcurves of gamma-ray bursts (GRBs) is attributed to the dipole radiations (DRs) of a newborn magnetar, we present a comparative analysis for the magnetars born in death of massive stars and merger of compact binaries with long and short GRB (lGRB and sGRB) data observed with the {\em Swift} mission. We show that the typical braking index ($n$) of the magnetars is $\sim 3$ in the sGRB sample, and it is $\sim 4$ for the magnetars in the lGRB sample. Selecting a sub-sample of the magnetars whose spin-down is dominated by DRs ($n\lesssim 3$) and adopting a universal radiation efficiency of $0.3$, we find that the typical magnetic field strength ($B_p$) is $10^{16}$ G {\em vs.} $10^{15}$ G and the typical initial period ($P_0$) is $\sim 20$ ms {\em vs.} $2$ ms for the magnetars in the sGRBs {\em vs.} lGRBs. They follow the same relation between $P_0$ and the isotropic GRB energy as $ P_0\propto E_{\rm jet}^{-0.4}$. We also extend our comparison analysis to superluminous supernovae (SLSNe) and stable pulsars. Our results show that a magnetar born in merger of compact stars tends to have a stronger $B_p$ and a longer $P_0$ by about one order of magnitude than that born in collapse of massive stars. Its spin-down is dominated by the magnetic DRs as old pulsars, being due to its strong magnetic field strength, whereas the early spin-down of magnetars born in massive star collapse is governed by both the DRs and gravitational wave (GW) emission. A magnetar with a faster rotation speed should power a more energetic jet, being independent of its formation approach.

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