arXiv subjects

Bing Zhang

Publications and source records attributed to Bing Zhang.

At least 19 recordsLinked to original sources

arXiv2026

Redshift Classification of Optical Gamma-Ray Bursts using Supervised Learning

Modern satellite missions localize many gamma-ray bursts (GRBs), but spectroscopic redshifts remain scarce because rapid optical follow-up is often unavailable. Optical plateau classification differs fundamentally from its X-ray counterpart: heterogeneous ground-based follow-up, dust extinction, and chromatic afterglow behavior introduce greater incompleteness than in the X-ray data. We present a supervised machine-learning classification of long-duration GRBs (duration $>$ 2 s) with measured redshifts and possessing optical plateau emission. As predictors, we combine plateau and prompt-emission observables. Using 171 such GRBs, we evaluate binary classification --- whether a GRB is high- or low-$z$ --- at thresholds $z_t = 2.0, 2.5$, and $3.0$. The best classifier, at $z_t = 2.0$, achieves a training-set true positive rate (TPR) of 0.741 and an area under the curve (AUC) of 0.841, with a train-to-test AUC difference within 4 percent. The novelty of this work is a classifier built on an optical-plateau-selected sample. Prompt-emission and absorption variables are favored over plateau parameters at $z_t = 2.0$ on the raw (complete-case) data with the Least Absolute Shrinkage and Selection Operator (LASSO), thus allowing a reliable classifier without waiting for the plateau signatures in the light curve. The X-ray absorption column density, $\log(\mathrm{NH})$, and the prompt-emission peak flux, $\log(\mathrm{PeakFlux})$, are stably selected by both the optical and X-ray classifiers. We publicly release a web-based application for the optical classifier, complementing the available X-ray classifier \citep{dainotti2025grbredshiftclassifierfollowup}, to help the community rapidly select high-$z$ GRBs for follow-up.

astro-ph.HE↗

arXiv2026

EP241021a as An Off-nuclear Month-duration Transient in a Dwarf Starburst Galaxy

EP241021a is a peculiar fast X-ray transient exhibiting a long X-ray plateau and an optical rebrightening, both challenging the traditional jet afterglow model. Whether its nature is a stellar explosion or a tidal disruption event (TDE) remains debated. Here we present late-time HST/WFC3 and Gemini-N/GMOS observations of its host galaxy at $z=0.748$. After $\sim300$ days post-trigger, the transient emission had faded below detection, revealing a dwarf disk galaxy with an effective radius $R_e=1.7$ kpc, a stellar mass $M_\star\sim3\times10^8M_\odot$, and a high star formation rate of $\sim5\ M_\odot\ {\rm yr}^{-1}$. Combined with previous very long baseline interferometry measurements, the transient can be located in the galactic disk with a projected physical offset of $0.95\pm0.13$ kpc from the galaxy center. Host-subtracted optical light curves show that the rebrightening ceased at $\sim47$ days, followed by a sudden drop with a power-law index steeper than $-3.3$, coincident with a similar drop in the X-ray light curve. This synchronous drop in both bands is consistent with jet shut-off, and the required month-long jet activity suggests a persistently accreting compact object fed by a TDE. Among the TDE scenarios, the off-nuclear location and the starburst host galaxy slightly favor the post-supernova micro-TDE scenario in a binary system, in which a natal kick drives the newborn compact object into a tidal disruption of its companion. Nevertheless, an off-nuclear intermediate-mass black hole TDE or a stellar-mass black hole TDE induced by dynamical scattering in a dense stellar cluster cannot yet be excluded.

astro-ph.HE↗

arXiv2026

Improving the Energy-Efficiency of the Code Generated by LLMs through Effective Prompting

As AI-assisted programming becomes increasingly mainstream, the environmental impact of AI-generated software has emerged as an important consideration. This motivates evaluating LLM-generated code beyond functional correctness by considering execution efficiency and energy consumption. However, despite substantial advances in code generation, frontier LLMs are rarely evaluated based on the energy efficiency of the code they produce. In this work, we conduct a comprehensive evaluation of 21 prompting strategies for energy-efficient code generation and identify 8 strategies for evaluation across 10 widely used open-weight and proprietary LLMs. We evaluate their effectiveness for both Python and C++ code generation relative to a baseline prompt. Across the evaluated models, the selected prompting strategies achieved energy reductions of up to 25% for Python and 17% for C++ code generation. At the model level, Python energy reductions reached up to 50% for Granite-4.0-H-Small, 39% for Claude 4.5 Haiku, and 28% for MiniMax M3, while C++ reductions reached up to 57% for Granite-4.0-H-Small and 6.4% for Qwen3-Coder-480B-A35B-Instruct. These results demonstrate that prompting strategies can substantially influence the energy consumption of LLM-generated code, although their effectiveness varies across models and programming languages. Our findings highlight the importance of incorporating energy efficiency into the evaluation and optimization of LLM-based code generation and provide practical insights into designing prompts for more sustainable AI-assisted programming.

cs.SE↗

arXiv2026

No Strong Evidence for Plasma Lensing in FRB 20240114A

FRB 20240114A is an extremely active repeating fast radio burst for which plasma lensing has been proposed to explain its burst-rate variations, spectral evolution, and apparently ``carbon-copy'' burst pairs. Using FAST data and publicly available Parkes observations, we test this interpretation with the predictions of a one-dimensional Gaussian plasma-lens model. Although the burst-rate enhancements may be fitted separately for Parkes and FAST, the corresponding magnification peaks and demagnification troughs between the two datasets are offset from each other, inconsistent with plasma lensing predictions. The enhancement peaks also do not show consistent periodicity, disfavoring a binary plasma lensing origin. The burst bandwidths are not systematically narrower during the proposed lensing interval than in other episodes. Most importantly, the burst energy distribution, which shows an intrinsic turnover peak at low energies, shows no significant shift of the turnover during the magnification interval, providing a model-independent test to the plasma-lensing interpretation. All these suggest that there is no strong evidence in favor of a plasma lensing interpretation to the source. Rather, all the burst property variations are consistent with being caused by the intrinsic variations of the FRB central engine.

astro-ph.HE↗

arXiv2026

LC-TSRNet: A Land-Cover-Guided Two-Stage Network for Annual MODIS Surface Reflectance Time Series Reconstruction

MODIS surface reflectance (SR) products often suffer from data gaps due to cloud contamination and sensor malfunctions, limiting their applications in long-term and large-scale studies. Most existing methods rely on cloud-free observations from optical time series or introduce SAR time series as auxiliary information. However, due to the coarse spatial resolution of MODIS, cloud-free reference images are difficult to obtain, and SAR imagery is not well matched to the spatial resolution of MODIS, making it difficult to provide effective prior constraints. To address these issues, this study proposes LC-TSRNet for seamless reconstruction of annual MODIS SR products. In the first stage, an annual land cover map is introduced as prior knowledge, and CSPM is designed by leveraging the spectral similarity within identical land cover types, thereby providing prior spectral constraints for missing regions. In the second stage, to address large-area, persistent, and overlapping gaps in MODIS imagery, SMRM is designed to adaptively exploit and integrate multi-scale spatiotemporal contextual information. Meanwhile, to address the limited collaborative utilization of spatio-temporal-spectral information, 3DAM is designed to impose cross-dimensional joint constraints. Considering the lack of publicly available MODIS sample datasets, this study constructs the AIRMOD-TSR dataset. Extensive experimental results show that LC-TSRNet outperforms the comparison methods and achieves better reconstruction accuracy and spectral fidelity. Under the spatially adjacent scenario, LC-TSRNet improves PSNR by 0.56 dB and reduces SAM by 0.13°. The vegetation monitoring application further verifies the practical value of the reconstructed SR time series.

cs.CV↗

arXiv2026

Extreme superluminal expansion traces an ultra-narrow GRB jet across relativistic regimes

The long-term evolution of gamma-ray burst (GRB) jets from ultra-relativistic launch to a slowly expanding radio source remains a fundamental problem in high-energy astrophysics, rarely resolved directly by imaging. We use very long baseline interferometry (VLBI) to trace the radio angular scale of GRB 221009A, the brightest GRB ever detected, from 5 to 299 days after the burst, and constrain the jet's geometry and dynamics. The Very Long Baseline Array data at 8.4 and 15.2 GHz are calibrated and imaged with AIPS and Difmap, and the source size is characterized by a circular-Gaussian model fitted to the complex visibilities. The jet dynamics, multi-wavelength emission, and source size are modeled within a two-shell collision scenario. A hydrodynamic simulation confirms that such an ultra-narrow jet undergoes lateral spreading. The observations reveal apparent superluminal expansion, with the expansion speed declining from about 90c at 5 days to about 6c at 300 days, tracing the jet's deceleration from the ultra-relativistic to the mildly relativistic regime and placing GRB 221009A far beyond the luminosity--velocity envelope of active galactic nuclei and microquasar jets. Combined with the multi-wavelength afterglow, they establish an ultra-narrow relativistic jet with a half-opening angle of about 0.01--0.03 radians, propagating through a wind-like medium at small radii before entering an interstellar-medium-like profile at larger radii. Joint modeling favors a two-phase size evolution with tentative evidence for lateral spreading. These results provide a direct geometric view of a GRB outflow and establish GRB 221009A as a benchmark for relativistic jet physics.

astro-ph.HE↗

arXiv2026

Fast Radio Bursts from Induced Upscattering. I. Magnetar Polar Fireballs

The extreme brightness temperatures of fast radio bursts (FRBs) demand a coherent process that converts magnetar burst energy into millisecond radio emission. We propose that FRBs can be produced within magnetar magnetospheres by induced (stimulated) upscattering in a relativistic fireball outflow. In this paper, we focus on induced Compton upscattering in an electron--positron fireball launched from the polar region of a magnetar. Radiation from the X-ray burst accelerates the polar fireball outflow to Lorentz factors of $Γ\sim10$--$10^3$. Low-frequency seed waves, such as fast magnetosonic or Alfvén waves, entering the outflow from the side or against its motion undergo induced scattering and are Lorentz-boosted by the relativistic bulk motion from $ν_0\sim10\mathrm{kHz}$ to $ν_{\rm obs}\simΓ^2ν_0\sim\mathrm{GHz}$. Combining the polar fireball dynamics with the linear growth and nonlinear saturation of the induced scattering instability, we derive the FRB luminosity $L_{\rm FRB}^{\rm iso}$ and fractional spectral bandwidth $Δν/ν_{\rm c}$. By considering the possible range of pair densities and temperatures, we find that this polar channel can account for the luminosity of Galactic FRB~20200428 and reach luminosities comparable to those of the brightest extragalactic FRBs. If the pair-loaded region is narrower than the relativistic beaming angle $1/Γ$, the model also produces a narrow spectrum and predicts $L_{\rm FRB}^{\rm iso}\propto(Δν/ν_{\rm c})^2$, a trend consistent with observations of repeating FRBs. The induced upscattering model thus connects magnetar X-ray bursts to FRBs through a coherent emission process grounded in plasma physics and makes observationally testable predictions.

astro-ph.HE↗

arXiv2026

Evidence for a Delayed Progenitor Population for CHIME non-repeating Fast Radio Bursts from a Self-Consistent Forward and Backward Inference Framework

Fast radio bursts (FRBs) are luminous extragalactic radio transients whose physical origins remain uncertain. Using over one thousand non-repeating events from CHIME/FRB Catalog 2, we infer the intrinsic FRB demographics with a self-consistent framework that combines backward non-parametric inference and forward population synthesis while accounting for probabilistic dispersion measure--redshift estimates, baseband-to-catalog fluence corrections, and the latest fuzzy multidimensional selection function. We first apply a backward non-parametric method, the weighted Lynden--Bell $C^{-}$ estimator, to recover the intrinsic redshift and energy distributions without assuming any population model. Independently, we perform forward Monte Carlo population synthesis in observable dispersion measure--fluence space, treating candidate intrinsic redshift and energy distributions as population hypotheses and comparing the resulting selected synthetic catalogs with observations. We find that the intrinsic redshift distribution peaks at $z\sim1$, significantly lower than the cosmic star formation history (SFH) peak at $z\sim1.7$, indicating clear tension with a pure SFH-tracking scenario, suggesting that at least some FRBs are delayed with respect to SFH. The intrinsic energy distribution is consistent with a power law of index $α\approx1.9$ and steepens at higher energies. We find no significant evidence for a redshift-energy distribution correlation.

astro-ph.HE↗

arXiv2026

EP250302a: violent shell collision in a soft-X-ray-selected GRB-like transient

The Einstein Probe opens a previously unexplored soft X-ray window onto gamma-ray bursts, filling a critical observational gap in the soft X-ray coverage of their prompt emission. In this letter, we present EP250302a, a soft-X-ray-selected, GRB-like transient at $z=1.131$ detected by the Einstein Probe. Follow-up observations from X-ray to radio reveal a narrow X-ray flare at $\sim 1.1$\, ks and subsequent achromatic optical and X-ray rebrightening. These features challenge a standard single-component afterglow model and indicate the need for multiple ejecta components. A violent collision between a late relativistic shell and the decelerated leading blast wave provides a plausible interpretation: the flare arises from internal dissipation of the late ejecta, while the rebrightening is powered by the shocked emission produced in the collision. Quantitative modeling constrains the kinetic energy ratio between the late shell and the initial ejecta to $E_{\rm k,iso,2}/E_{\rm k,iso,1} \sim 5$ (with $E_{\rm k,iso,2} \sim 10^{53}$~erg and $E_{\rm k,iso,1} \sim 2\times10^{52}$~erg), as well as the Lorentz factor contrast to $Γ_{2,0}/Γ_{1,0} \approx 0.98$--$2.27$, required to reproduce the observed flare luminosity and rebrightening amplitude. Such an energetic late shell can be launched in a radiatively inefficient second episode of central-engine activity. Thanks to the well-sampled, early-time multiband coverage facilitated by the EP trigger, EP250302a provides a valuable case to test the physical connection between central-engine activity and shell collisions.

astro-ph.HE↗

arXiv2026

MambaX: Image Super-Resolution with State Predictive Control

Image super-resolution (SR) is a critical technology for overcoming the inherent hardware limitations of sensors. However, existing approaches mainly focus on directly enhancing the final resolution, often neglecting effective control over error propagation and accumulation during intermediate stages. Recently, Mamba has emerged as a promising approach that can represent the entire reconstruction process as a state sequence with multiple nodes, allowing for intermediate intervention. Nonetheless, its fixed linear mapper is limited by a narrow receptive field and restricted flexibility, which hampers its effectiveness in fine-grained images. To address this, we created a nonlinear state predictive control model \textbf{MambaX} that maps consecutive spectral bands into a latent state space and generalizes the SR task by dynamically learning the nonlinear state parameters of control equations. Compared to existing sequence models, MambaX 1) employs dynamic state predictive control learning to approximate the nonlinear differential coefficients of state-space models; 2) introduces a novel state cross-control paradigm for multimodal SR fusion; and 3) utilizes progressive transitional learning to mitigate heterogeneity caused by domain and modality shifts. Our evaluation demonstrates the superior performance of the dynamic spectrum-state representation model in both single-image SR and multimodal fusion-based SR tasks, highlighting its substantial potential to advance spectrally generalized modeling across arbitrary dimensions and modalities.

cs.CV↗

arXiv2026

Second Repeating FRB 180814.J0422+73: Ten-year Fermi-LAT Upper limits and Implications

The second repeating fast radio burst source, FRB 180814.J0422+73, was detected recently by the CHIME collaboration. We use the ten-year Fermi Large Area Telescope (LAT) archival data to place a flux upper limit in the energy range of 100 MeV-10 GeV at the position of the source, which is $\sim {1.1\times 10^{-11}}$ erg cm$^{-2}$ s$^{-1}$ for a six-month time bin on average, and $\sim {2.4\times 10^{-12}}$ erg cm$^{-2}$ s$^{-1}$ for the entire ten-year time span. For the maximum redshift of $z=0.11$, the ten-year upper limit of luminosity is $\sim {7.3\times 10^{43}}$ erg s$^{-1}$. We utilize these upper limits to constrain the FRB progenitor and central engine. For the rotation-powered young magnetar model, the upper limits can pose constraints on the allowed parameter space for the initial rotational period and surface magnetic field of the magnetar. We also place significant constraints on the kinetic energy of a relativistic external shock wave, ruling out the possibility that there existed a gamma-ray burst (GRB) beaming towards Earth during the past ten years as the progenitor of the repeater. The case of an off-beam GRB is also constrained if the viewing angle is not much greater than the jet opening angle. All these constraints are more stringent if FRB 180814.J0422+73 is at a closer distance.

astro-ph.HE↗

arXiv2026

Multi-messenger View of White Dwarf Tidal Disruption Events by Intermediate-Mass Black Holes: I. Gravitational Waves and Disk Photon and Neutrino Emissions

White dwarf (WD) tidal disruption events (TDEs) provide a unique window onto intermediate-mass black holes (IMBHs). We present a multi-messenger view of these systems in two papers. In this paper, we develop an accretion-disk model for WD--TDEs in which the bound debris accretes at extremely super-Eddington rates, $\sim 10^5$--$10^9$ times higher than in typical (main-sequence) TDEs. The model includes magnetic pressure, nuclear-burning heating, wind mass loss, and neutrino production via $e^{\pm}$ pair annihilation. At such high accretion rates, the gas and radiation temperatures of the inner flow can reach $T\gtrsim 10^9\,\mathrm{K}$, enabling prolific pair production and MeV neutrino emission. We find that the disk is predominantly advection dominated over a broad range of accretion rates, while disk winds can partially cool the flow and reduce the inner temperature. The predicted thermal EM emission is nearly insensitive to the fallback rate in the super-Eddington regime: the luminosity only mildly exceeds the IMBH Eddington luminosity and the spectrum peaks at $\sim 0.1$--$1\,\mathrm{keV}$, implying detectability with current X-ray facilities such as Einstein Probe. For low-mass IMBHs ($\sim 10^3\,M_{\odot}$), the disk can also produce a burst of MeV neutrinos with luminosities up to $\sim 10^{47}\,\mathrm{erg\,s^{-1}}$ for ONeMg WD--TDEs, although detectability with current neutrino detectors (e.g., Super-Kamiokande and JUNO) is limited to Galactic distances. Finally, we estimate the GW burst produced during the final passage prior to disruption, which peaks at $\sim 0.1$--$1\,\mathrm{Hz}$, placing WD--TDEs in the target band of proposed decihertz detectors and motivating coordinated GW+EM+neutrino searches. We also present a first exploration of GWs from a precessing WD--TDE disk; this signal is much weaker, with a detection horizon $\lesssim 1\,\mathrm{Mpc}$ for these missions.

astro-ph.HE↗

arXiv2026

Cosmological Constraints from Gravitational Wave-Fast Radio Burst Associations without Redshift Measurements for LIGO-Virgo and Cosmic Explorer

The potential association between gravitational waves (GWs) and fast radio bursts (FRBs) offers a unique multi-messenger probe for cosmology. In this paper, we develop a redshift-independent framework to constrain cosmological parameters using the luminosity distance - dispersion measure relation, accounting for realistic astrophysical uncertainties. We perform a comprehensive comparative analysis across different GWs detector sensitivities and modeling assumptions. Specifically, we investigate the performance of the current LIGO-Virgo (LV) network (at $z < 0.2$) versus the future Cosmic Explorer (CE). Our study further evaluates the impact of different dispersion measure (DM) distributions---specifically the corrected Macquart's PDF (Zhuge+2025) and the log-normal distribution---and explores the influence of including or excluding host galaxy DM contributions. Using realistic simulated observations, we find that while the current LV network lacks the precision to provide meaningful constraints, CE will enable high-precision cosmology. Even without spectroscopic redshifts, CE observations can effectively break parameter degeneracies and robustly constrain both cosmology and host galaxy parameters. These results highlight the necessity of next-generation detectors.

astro-ph.CO↗

arXiv2026

Mass-Ratio Reversal as an Alternative to Hierarchical Mergers for GW241011

Recent gravitational-wave (GW) observations have revealed binary black hole (BBH) mergers with both extreme mass ratios and large effective spin parameters ($χ_{\rm{eff}}$). GW241011 is a notable example that shows these properties. Although hierarchical mergers (second-generation + first-generation BHs) can naturally produce high spins and become more prevalent than first-generation + first-generation mergers at mass ratios $q \lesssim 0.6$, they are negligible at the extreme mass ratio $\sim 0.3$ and are further limited by gravitational recoil kicks that can eject the second-generation BH from the host environment. Moreover, recent studies have argued against a dynamical origin for GW241011. Here, we investigate the formation of GW241011-like systems through the mass-ratio reversal (MRR) channel in isolated binary evolution. By quantifying the probability of producing such systems across a range of binary-evolution models, we identify the key dependencies on stellar-evolution and binary-interaction physics. Our results demonstrate the conditions under which the MRR channel can provide a viable alternative to hierarchical mergers for GW241011-like events, although its predicted merger rate density remains relatively low.

astro-ph.HE↗

arXiv2026

BRF-GS: Hyperspectral Bidirectional Reflectance Factor Modeling and Image Generation Based on 3D Gaussian Splatting

The bidirectional reflectance factor (BRF) characterizes the directional radiative properties of terrestrial surfaces. However, existing three-dimensional (3D) radiative transfer models require complex scene construction and computationally intensive radiative transfer solvers, limiting efficient generation of multi-angle hyperspectral reflectance imagery. 3D Gaussian Splatting (3DGS) offers an efficient framework for neural scene representation and novel view synthesis, but its low-order spherical harmonics representation is insufficient for complex directional reflectance, while the high dimensionality and inter-band quality differences of hyperspectral data introduce additional challenges. To address these challenges, we propose BRF-GS, a 3DGS-based framework for BRF modeling and hyperspectral reflectance image generation. BRF-GS introduces a hybrid BRDF-driven kernel to represent complex directional reflectance, selects geometry-reliable spectral bands for robust 3D scene initialization, and adopts a two-stage training strategy that decouples geometry optimization from spectral modeling. We further construct the AIR-BRF dataset, a multi-angle hyperspectral directional reflectance dataset comprising three scenes with diverse natural and artificial targets. Experiments demonstrate that BRF-GS achieves superior spatial and spectral fidelity and accurately reproduces characteristic view-dependent BRF responses. The proposed framework provides an efficient data-driven approach for BRF modeling and multi-angle hyperspectral reflectance image generation in remote sensing scenes.

cs.CV↗

arXiv2026

Minutes-long soft X-ray prompt emission from a compact object merger

Compact object mergers are multi-messenger sources and known progenitors of some gamma-ray bursts, bright flashes of high-energy radiation powered by a central engine, either an accreting black hole or a neutron star. Our understanding of these events has so far been shaped primarily by observations in the gamma-ray band, leaving their prompt phase poorly constrained at lower energies. A long-lasting ($\approx$100 s) engine-driven X-ray emission was discussed to explain rapidly fading X-ray afterglows following several ($\approx$30%) bursts of short ($\lesssim$2 s) duration. However, this prompt X-ray component was not directly observed and past candidates were not confirmed. Here we report the discovery of EP250704a containing a minutes-long ($\sim$560 s) flash of soft (0.5--4 keV) X-rays immediately following the short ($\sim$0.4 s) GRB 250704B. The variability and spectral shape of this emission are inconsistent with the canonical picture of a hard, accretion-powered spike followed by a standard external-shock afterglow. Instead, the long-soft bump points to a distinct phase of prompt emission in X-rays, which would not have been detected without the soft X-ray coverage of Einstein Probe. The detection of a prompt soft X-ray counterpart in an otherwise ordinary short GRB shows that long-lasting X-ray emission is likely a common feature of merger-driven bursts and a promising electromagnetic counterpart to gravitational wave sources.

astro-ph.HE↗

arXiv2026

DynaPPI: A Large-scale Dynamic Protein Dataset for AI-driven Advances in Protein Interactomics

Diffusion models have been widely explored in protein backbone generation due to their powerful generation capabilities.However, in today's AI-driven biological research, predicting the structure of unknown multi-chain protein aggregates (called "complexes" in biology) remains an unsolved challenge.This is because existing static or dynamic protein datasets focus solely on static snapshots or single-entity trajectories, neglecting the dynamic process of multiple monomers forming complexes.To alleviate this dilemma, we present DynaPPI, a dynamic protein dataset comprising molecular dynamics (MD) trajectories of protein complex formation from dissociated chains to the bound state, as a pivotal resource to bridge the gap between static structural biology and the inherently temporal nature of dynamic molecular interactions.Benefiting from this dataset, diffusion models can explicitly learn the dynamic binding trajectories of known complexes and accurately predict the structures of unknown complexes based on their diverse generative properties, thereby further catalyzing AI-driven structural biology and protein interactomics.

cs.CV↗

arXiv2026

On the Physical Origins of Long Period Radio Transients

Long-period radio transients (LPRTs) are a rapidly growing class of coherent radio sources with periods ranging from minutes to hours, whose central engines and emission mechanisms remain unclear. Motivated by the detection of red dwarf (RD) companions in several LPRTs and by generic period constraints from the Roche limit and the mass transfer limit, we argue that LPRTs naturally separate into two broad classes: shorter-period sources that are likely isolated compact objects and longer-period sources that are compact objects in binary systems that are likely detached. For isolated objects, we find that isolated white dwarfs (WDs) generally have difficulty sustaining pair production and coherent radio emission unless the surface temperature is extremely high, while slow rotating neutron stars (NSs) can remain marginally active through inverse-Compton-driven pair cascades. For binary systems, asynchronous WD / NS + RD systems can power coherent radio emission through unipolar induction when the WD / NS magnetic field dominates the companion surface field, with relativistic electron cyclotron maser emission as the radiation mechanism, while at larger separations the system enters the magnetospheric interaction regime, possibly powered by magnetic reconnection. Bright X-ray counterparts favor magnetar-related systems and undetected X-ray emission is expected from WD-related channels. We propose a diagnostic flow chart that uses observational criteria to classify LPRTs and identify their central engines. These criteria lead to a physically motivated classification framework for LPRTs.

astro-ph.HE↗