arXiv subjects

Kohta Murase

Publications and source records attributed to Kohta Murase.

At least 19 recordsLinked to original sources

arXiv2026

Constraining high-energy neutrinos from tidal disruption events with IceCube high-energy starting events

Tidal disruption events (TDEs) have been proposed as candidate sources of high-energy neutrinos. Successful and choked jets, as well as the accretion disk, corona, wind, and outflow regions in a TDE have been examined and shown to produce TeV - PeV neutrinos. In this work, we use the IceCube 12.5 year high energy starting events (HESE) dataset and perform a maximum likelihood analysis to investigate the spatial and temporal correlations between HESE dataset and a selected sample of 89 TDEs. Our results indicate that the currently observed data do not show any significant correlation and hence is consistent with the background only hypothesis. Using this result, we place constraints on the fraction of TDEs harboring intrinsic jets ($f_{\rm jet}$) and the corresponding isotropic-equivalent cosmic ray (CR) energy ($\mathcal{E}_{\rm CR}$). We note that even with limited statistics, we can constrain the parameter space as $\mathcal{E}_{\rm CR} \lesssim 3 \times 10^{53}$ erg for $f_{\rm jet} \gtrsim 0.6$ at more than 90% C.L. Finally, we discuss the theoretical implications of our results and the limits on the all-sky diffuse neutrino flux from TDEs. With more observational data in the electromagnetic band for TDEs and neutrino observations from IceCube and KM3NeT, our analysis can be used to place stringent constraints on physical parameters associated with TDEs.

astro-ph.HE↗

arXiv2026

Enhanced Detectability of Very-High-Energy Gamma Rays from Off-Axis Short Gamma-Ray Bursts: Impacts of Structured Jets and External Inverse-Compton Scattering

The binary neutron star merger GW170817 established a direct link between gravitational waves and short gamma-ray bursts (sGRBs), whose afterglows are commonly interpreted as nonthermal emission from structured relativistic jets viewed off-axis. Some sGRBs exhibit extended or plateau X-ray emission, suggesting prolonged central-engine activity. These X-ray photons can serve as seed photons for external inverse-Compton (EIC) scattering by relativistic electrons in the jet, producing very-high-energy (VHE) gamma rays. However, how the angular structure of the jet affects the detectability of EIC emission remains insufficiently explored. Here, we investigate EIC emission from off-axis structured jets and assess its detectability with the Cherenkov Telescope Array Observatory (CTAO). We find that EIC emission powered by extended and/or plateau X-rays produces detectable VHE signals from nearby sGRBs, particularly during the early afterglow, significantly outshining synchrotron self-Compton emission. In our adopted models, Gaussian and power-law jets produce brighter off-axis EIC emission than a top-hat jet, extending the viewing-angle range over which VHE emission may be detectable. These results demonstrate that early VHE observations with CTAO can probe both prolonged central-engine activity and the angular structure of relativistic jets in sGRBs.

astro-ph.HE↗

arXiv2026

Hidden Neutrino Active Galaxy Candidates: Prospects for Catalog and Stacking Searches with IceCube, IceCube-Gen2, and KM3NeT

In high-energy neutrino astrophysics, the identification of high-energy neutrino sources is a central goal, and jet-quiet active galactic nuclei (AGNs) have emerged as promising candidates. For this purpose, we present a theory-guided, intrinsic X-ray selected sample of hidden neutrino AGN candidates consisting of $28$ X-ray bright AGNs (X-HiNAC), combining the {\em Swift}/BAT and BASS surveys with dedicated {\em NuSTAR} observations and spectral analyses. We compile their intrinsic X-ray fluxes, spectral properties, luminosity distances, and supermassive black hole masses, to provide a coherent sample for neutrino source searches. The sample is physically motivated but remains model independent given that the neutrino flux is proportional to the intrinsic X-ray flux. Using the magnetically powered corona model, we also demonstrate the prospects for individual-source and stacking searches with IceCube-Gen2 and KM3NeT. We identify promising individual targets and find that stacking the remaining sources, excluding NGC 1068, could yield a $5σ$ detection within $\sim 5-15$ years under favorable model assumptions at the current and upcoming neutrino observatories. We highlight systematic uncertainties in the adopted source parameters, particularly the black hole masses, for which different measurement techniques can yield estimates differing by up to an order of magnitude. Such uncertainties can significantly affect the predicted neutrino emission, motivating more precise black hole mass measurements and improved broadband X-ray observations. Our findings motivate improved multiwavelength characterization of nearby AGNs and provide a guide for investigating their role as high-energy neutrino sources.

astro-ph.HE↗

arXiv2026

Unveiling Multimessenger Emission from Hidden Cores of Microquasars

Microquasars are radio-emitting X-ray binaries with relativistic jets and are established sources of $\sim 100$~TeV gamma rays, making them promising candidates for cosmic-ray acceleration. Motivated by recent detections of $\sim 100~$TeV photons from Cygnus~X-1 and multi-PeV photons from Cygnus~X-3, we employ the Astrophysical Multimessenger Emission Simulator (AMES) to model their multimessenger emission from radio to ultrahigh-energy gamma rays. Our modeling suggests that particle acceleration is extremely efficient in the jet region. The observed $\gtrsim 0.1$~PeV gamma rays can originate from either $pγ$ or $pp$ interactions, depending on the location and physical conditions of the emission region, while also reproducing the lower-energy spectra. These configurations yield observationally testable predictions. In the poorly constrained $0.1$-$10$~TeV band, the models predict either a deep valley, a mild suppression, or a power-law spectrum. Additionally, models involving compact emission regions comparable to the orbital separation predict strong variability, while those invoking more extended and static external zones show more stable behavior. We also provide a possible qualitative explanation for the energy-dependent modulation patterns, relying primarily on changes in the Doppler factor and external $γγ$ absorption. In particular, explaining the PeV emission from Cygnus~X-3 favors a compact emission region, for which a magnetic field strength of order $10^2~\mathrm{G}$ is required. Finally, after accounting for pion and muon cooling, the predicted neutrino flux is suppressed, implying that detection is more challenging than previously thought.

astro-ph.HE↗

arXiv2026

Interpreting the diversity of afterglow emission from radio-detected tidal disruption events with instantaneous and delayed outflows

Tidal disruption events (TDEs) occur when a star is gravitationally disrupted by the tidal field of a supermassive black hole during a close encounter. Radio emission has recently been detected in TDEs and is commonly attributed to synchrotron radiation from both wind and jetted outflows. However, several TDEs exhibit bright radio flares at late times, which cannot be easily explained if the wind is launched promptly after the stellar disruption. The radio light curves of TDEs with delayed radio flares are modeled using three scenarios: an instantaneous wind, a delayed wind, and a delayed relativistic jet. We show that the instantaneous wind model struggles to reproduce delayed radio flare events, indicating the necessity of an additional delayed outflow component. In contrast, the delayed wind model provides a consistent explanation for the observed radio phenomenology, successfully reproducing events both with and without delayed radio flares. For some delayed radio flare events (e.g., ASASSN-15oi and AT 2019dsg), both the delayed wind and delayed jet models can reproduce the observed radio light curves, making it challenging to distinguish between these scenarios based on radio data alone. To break this degeneracy, we present calculations of detailed multiwavelength spectra from radio to x-ray and very-high-energy gamma-ray bands, including both synchrotron and inverse-Compton processes. Within this framework, the delayed jet model produces x-ray and optical emission detectable at typical TDE distances, in contrast to wind-driven scenarios. Our results highlight how multiwavelength campaigns offer effective means to distinguish between possible outflow mechanisms. We apply our model to AT 2025aarm, which is one of the closest TDEs that has been observed, and show the importance of x-ray observations.

astro-ph.HE↗

arXiv2026

Multimessenger Constraints on Production Sites of High-Energy Neutrinos from NGC 1068

The detection of high-energy neutrino signals from the nearby Seyfert galaxy NGC 1068 provides us with a unique opportunity to explore nonthermal processes near the center of supermassive black holes. Using the IceCube and Fermi-LAT data, we present general multimessenger constraints on the energetics of cosmic rays and the extent of the neutrino emission region, considering not only photohadronic (photomeson and photopair production) but also hadronuclear ($pp$) processes. Compared to the photohadronic scenario, the hadronuclear scenario can alleviate constraints on the emission region, yielding $R\lesssim30-70R_S$ for low-$β$ plasma, where the magnetic pressure dominates the gas pressure, and $R\lesssim5-50R_S$ for high-$β$ plasma. While our results support the previous conclusion that the photohadronic scenario favors a compact corona with $R\sim3-10R_S$, these suggest the relevance of further investigations into $pp$ neutrino contributions. When the the cosmic-ray spectrum is extended down to a minimum energy of 1 GeV, which is natural in light of particle acceleration mechanisms, we find that the required cosmic-ray luminosity exceeds the X-ray luminosity for a spectral index of $s_{\rm CR}\gtrsim2$, which challenges some shock acceleration models. We also show that the beta decay scenario is unlikely even if the magnetic field is as strong as the maximum allowed by the Eddington luminosity. Given that NGC 1068 can be established as a neutrino source, our results will provide evidence for the standard hadronic scenario, including magnetically powered corona models having hard spectra with $s_{\rm CR}\lesssim2$.

astro-ph.HE↗

arXiv2026

Mineral Detection of Neutrinos and Dark Matter 2026 Proceedings

The fourth "Mineral Detection of Neutrinos and Dark Matter" (MDvDM'26) meeting was held April 14-17, 2026 in Karlsruhe, Germany, hosted by the Institute for Astroparticle Physics (IAP) at Karlsruhe Institute of Technology (KIT). These proceedings detail the contributions that were presented during MDvDM'26, illustrating the unprecedented progress in theoretical, computational and experimental studies towards the realization of the concept of mineral detectors. Mineral detectors represent an emerging particle detection concept that has risen in prominence in recent years due to the advent of modern computational and high-resolution microscopy techniques. Natural and synthetic crystals are capable of retaining microscopic damage features induced by nuclear recoils, which could be then read out with a variety of micrometer and nanometer resolution microscopy techniques. On laboratory time scales mineral detectors could be employed for reactor neutrino monitoring and dark matter detection, with the potential to measure the directions as well as the energies of the induced nuclear recoils. Uniquely, ancient natural crystals (so-called paleo-detectors) that have been recording nuclear recoils over geological timescales could be used for studying astrophysical neutrinos, cosmic rays, dark matter and heavy exotic particles, as well as the variation of their fluxes over our Galaxy's lifetime. In recent years the international MDvDM community has been successfully tackling the challenges associated with realizing the concept of mineral detectors, opening the pathway towards a fully fledged experimental program and potential future discoveries.

physics.ins-det↗

arXiv2026

Survival of ultraheavy nuclei in astrophysical sources: applications to protomagnetar outflows

Outflows of rapidly rotating protomagnetars have been considered as attractive sites for the synthesis of nuclei heavier than iron, but the question remains whether these nuclei are able to survive against photodisintegration as they make their way out of their formation environments. In this work, we present new analytic fitting formulae for the photodisintegration cross sections applicable to heavy nuclei beyond iron. We confirm that the results from the TALYS simulations are consistent with the theory of the giant dipole resonance, and apply the obtained new formulae to investigate whether ultraheavy nuclei entrained in protomagnetar outflows can be disintegrated by thermal and nonthermal photons before leaving the stellar envelope. We explore two outflow models: a spherical wind model and a jetted outflow model. For nuclei accelerated to the bulk speed of these outflows, their survival depends on the model and engine properties. For spherical winds, nuclei may survive for the first $\sim100\,{\rm s}$ post-core collapse, but as the wind Lorentz factor increases, the photodisintegration optical depth sharply rises and nuclei may no longer survive. For the jetted outflows arising from progenitors surrounded with stellar envelopes, nuclei can only survive before the jet breakout time in cases where the central engine has high spin-down energy, that is, with a high magnetic field strength and shorter spin period. In progenitors with more extended envelopes, the jet break out time is much longer, allowing for nonthermal photons to readily photodisintegrate nuclei in high spin-down energy cases. These results also outline some of the necessary, but not yet sufficient, conditions to source ultrahigh-energy cosmic-ray nuclei.

astro-ph.HE↗

arXiv2026

GRANDlib: A simulation pipeline for the Giant Radio Array for Neutrino Detection (GRAND)

The operation of upcoming ultra-high-energy cosmic-ray, gamma-ray, and neutrino radio-detection experiments, like the Giant Radio Array for Neutrino Detection (GRAND), poses significant computational challenges involving the production of numerous simulations of particle showers and their detection, and a high data throughput. GRANDlib is an open-source software tool designed to meet these challenges. Its primary goal is to perform end-to-end simulations of the detector operation, from the interaction of ultra-high-energy particles, through -- by interfacing with external air-shower simulations -- the ensuing particle shower development and its radio emission, to its detection by antenna arrays and its processing by data-acquisition systems. Additionally, GRANDlib manages the visualization, storage, and retrieval of experimental and simulated data. We present an overview of GRANDlib to serve as the basis of future GRAND analyses.

astro-ph.IM↗

arXiv2026

TeV Gamma Rays and Neutrinos from Winds Driven by Radiatively Inefficient Accretion Flows of Low-Luminosity Active Galactic Nuclei

Recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the first TeV gamma-ray detection from a low-luminosity active galactic nucleus (LLAGN) lacking a strong jet. This source, NGC 4278, is one of the nearest LLAGNs that can be studied in detail as a template for more distant objects. Most previous studies have focused on the month-scale-variable gamma-ray activities, seeking to explain them with weak jets. We focus instead on NGC 4278's quiet-period emission, proposing a different mechanism based on a wind launched from a radiatively inefficient accretion flow (RIAF). In particular, we model particle acceleration at a wind-driven shock and calculate the resulting multimessenger emission. To match the TeV gamma-ray fluxes reported by LHAASO in the quiet period, our model requires a wind power of $\lesssim2\times10^{43}~\mathrm{erg~s^{-1}}$ with a spectral index of injected cosmic rays of 2.0. We show that this is achievable through Bondi accretion of the ionized gas observed on the 100-pc scale, for a shallow accretion profile. We discuss the testability of our wind-driven shock scenario with multimessenger observations. As another important application, we extend our model to Sgr A*, the nearest LLAGN, and show that its TeV gamma-ray emission is reproduced with reasonable parameters. Our results suggest that RIAF-driven winds may be a generic emission mechanism in LLAGNs, making this class a potentially important population of both gamma-ray emitters and cosmic-ray accelerators.

astro-ph.HE↗

arXiv2026

High-energy neutrino emission associated with gravitational-wave signals: effects of cocoon photons and constraints on late-time emission

We investigate prospects for the detection of high-energy neutrinos produced in the prolonged jets of short gamma-ray bursts (sGRBs). The X-ray lightcurves of sGRBs show extended emission components lasting for 100-1000 seconds, which are considered to be produced by prolonged engine activity. Jets by prolonged engine activity should interact with photons in the cocoon formed by the jet propagation inside the ejecta of neutron star mergers. We calculate neutrino emission from jets by prolonged engine activity, taking account of the interaction between photons provided from the cocoon and cosmic rays accelerated in the jets. We find that IceCube-Gen2, a future neutrino telescope, with the second-generation gravitational wave detectors will probably be able to observe neutrino signals associated with gravitational waves with around 10 years of operation, regardless of the assumed value of the Lorentz factor of the jets. Neutrino observations may enable us to constrain the dissipation region of the jets. We apply this model to GRB 211211A, a peculiar long GRB whose origin may be a binary neutron-star merger. Our model predicts that IceCube is unlikely to detect any associated neutrino, but a few similar events will be able to put a meaningful constraint on the physical quantities of the prolonged engine activities.

astro-ph.HE↗

arXiv2026

High-Energy Neutrinos from Supernova Shock Breakouts in Circumstellar Media: Light Curves, Spectra, and Contribution to the Extragalactic Neutrino Background

Enhanced mass loss from core-collapse supernova (SN) progenitors shortly before explosion appears to be common, creating a compact, optically thick circumstellar medium (CSM) at $\sim10^{14}-10^{15}$ cm. We derive an analytic description of the light curves and spectra of high-energy neutrinos emitted by nonrelativistic SN shock breakouts through such CSM, as a function of shock velocity and CSM parameters, accounting for the evolution of the hydrodynamic structure and the electromagnetic (EM) spectrum as the shock transitions from being radiation-mediated to collisionless. This evolution determines the time-dependent neutrino production efficiency, the maximum proton/neutrino energy, and the pair-production optical depth. A significant fraction of the neutrino energy is typically emitted within a few days of explosion, during breakout and before the EM light curve peak, with $1-100$ TeV neutrinos carrying $\approx10\%$ of the energy of shock-accelerated protons. The escape of high-energy photons ($>1$~GeV) is suppressed by pair-production for compact CSM configurations. If enhanced mass losses are common, and assuming that shock-accelerated protons carry $\approx10\%$ of the collisionless shock energy, CSM SN breakouts may significantly contribute to the observed high-energy neutrino background, without overproducing a corresponding high-energy gamma-ray background. SNe producing $>1$ neutrino events in a $1\left(10\right){\rm km^2}$ detector are expected at a rate of $\sim0.05\left(1\right){\rm yr^{-1}}$.

astro-ph.HE↗

arXiv2026

NASA ASTRA Initiative White Paper: Space-Based Mission for Ultrahigh Energy Particles

Ultra-high-energy cosmic rays ($E_{\rm CR} \gtrsim 1$ EeV) are the highest-energy particles known, signaling extreme particle processes at work in the universe. However, many aspects of their nature remain largely unknown, even after more than a century of study. Very-high-energy ($E_ν\gtrsim 1$ PeV neutrinos associated with cosmic-ray interactions, both during the acceleration process and propagation, would provide new insight into these extreme particles, as we have seen at lower energies with the dawn of TeV neutrino astronomy. Nevertheless, only a handful of such neutrinos have been observed thus far. A space-based observatory dedicated to studying cosmic rays, neutrinos, and photons would provide an unprecedented platform for observations of these extreme-energy messengers.

astro-ph.IM↗

arXiv2026

Modeling the imprints of large-scale magnetized structures on $γ$-rays from extragalactic transients

In the multimessenger era, the association of high-energy transients with their $γ$-ray counterparts can be obscured by magnetized large-scale structure surrounding the source. We analyze models for delayed off-axis $γ$-rays, arising from the injection of ultrahigh-energy cosmic rays ($E\gtrsim 10^{18}$ eV) and $γ$-rays ($\varepsilon_γ\gtrsim10^{18}$ eV), and very-high-energy $γ$-rays ($\varepsilon_γ\gtrsim 100$ GeV) from the transient. As a representative case, we consider the brightest gamma-ray burst, GRB~221009A, embedded in a magnetized structure. We examine charged-particle deflection in electromagnetic cascades, followed by propagation of secondaries through the intergalactic medium, and derive the time delays and angular offsets of the resulting $γ$-rays. To test the models, we analyze 1.25 years of post-event \textit{Fermi} Large Area Telescope (LAT) data and construct a 1 GeV -- 1 TeV test statistic (TS) map within $10^\circ$ of the burst localization. We find two sub-threshold peaks with TS$\geq9$. The more significant peak, J1911.8+2044, shows $γ$-ray emission in pre-burst LAT data, while J1913.2+1901 coincides with a 664.6 GeV $γ$-ray recorded $\sim191.9$ days after the trigger at $\approx 0^{\circ}.75$ from the GRB. The corresponding flux upper limit provides a fiducial value for constraining the parameter space in our models and estimating the source energy requirement for delayed off-axis signals. Although a magnetized structure can reproduce the angular offset of this sub-threshold feature, the resulting time delay disfavors an origin in this GRB.

astro-ph.HE↗

arXiv2026

Physical origin of very-high-energy gamma rays from the low-luminosity active galactic nucleus NGC 4278 and implications for neutrino observations

Relativistic jets in active galactic nuclei (AGNs) are known to accelerate particles to extreme energies, yet the physical origin of very-high-energy (VHE) emission from low-luminosity (LL) AGNs remains unclear. NGC 4278, a nearby LL AGN, has recently been identified as a VHE source following detections by LHAASO. In this work, we present a multiwavelength and multimessenger analysis to investigate the origin of this emission. Swift X-Ray Telescope monitoring reveals a quasi-quiescent state characterized by the low X-ray flux. Modeling the broadband spectral energy distribution with the leptohadronic code AMES, we find that a standard one-zone synchrotron self-Compton model underpredicts the VHE flux, unless a relatively high Doppler factor ($δ\gtrsim 6$) is invoked. Alternatively, an external inverse-Compton (EIC) scenario-scattering seed photons from a radiatively inefficient accretion flow-provides a good description of the broadband emission with modest jet power and Doppler factor. We further explore neutrino production within a leptohadronic framework. The EIC model in the quasi-quiescent state yields the largest predicted number of muon neutrinos, reaching $N_{ν_μ} \sim 0.001$ over 15 yr of IceCube observations (assuming that 0.1\% of the Eddington luminosity is converted into high-energy protons). Future multimessenger observations are essential to unveil the details of the high-energy processes of NGC 4278.

astro-ph.HE↗

arXiv2026

Interpreting Swift and NuSTAR Observations of the Low-Luminosity Active Galactic Nucleus NGC 4278 with Radiatively Inefficient Accretion Flows and Implications for Neutrino Emission

We report the first NuSTAR hard X-ray observations of the low-luminosity active galactic nucleus NGC 4278. The source is clearly detected beyond 10 keV with a hard X-ray spectrum consistent with a power law of photon index between 2.2 and 2.5 without evidence for a high-energy cutoff. The X-ray flux is low compared to the active state in 2021, but exhibits variability by a factor of ~2 on a timescale of a month. We discuss the origin of the hard X-ray emission and explore its connection to gamma rays and high-energy neutrinos. We explain the X-ray data, including both quiescent and active states, using a radiatively inefficient accretion flow (RIAF) model with a variable accretion rate. We also show that TeV gamma rays cannot escape from the RIAF disk, and very high-energy gamma rays observed in LHAASO are likely to originate from outer regions such as jets and winds, which is consistent with our results favoring a magnetically arrested disk. We also discuss hidden neutrino emission from RIAFs together with possible connections to coronae of active galactic nuclei with standard, radiatively efficient disks.

astro-ph.HE↗

arXiv2026

Old and Bright: The Remarkable Radio Brightening of the Engine-driven SN 2012au Several Years After Explosion Signals the Birth of a PWN

We present the results from an extensive broad-band (radio to X-rays) observing campaign of the engine-driven Type Ib SN 2012au in the first 13 years of evolution. The early-time ($δt\leq{190}$ d) radio and X-ray evolution is well-described by conventional models of a forward shock interacting with a wind-like circumstellar medium ($ρ_{\rm{CSM}}\propto{r}^{-2}$). However, starting at $δ{t}\approx{6.7}$ yr, we detect a significant radio re-brightening. This late-time emission is dominated by a luminous component characterized by a broad and rapidly evolving spectral peak and a shallow optically thin spectral slope, $F_ν\proptoν^{-0.31\pm0.02}$. These properties imply a compact emitting region ($R\lesssim{10}^{16}$ cm) expanding at a remarkably slow velocity ($\lesssim{500}$ km/s) into a high-density environment ($\geq{10}^4 \rm{cm}^{-3}$), accompanied by a hard electron power-law index $p\approx{1.6}$. No soft or hard X-ray emission is detected at any epoch, indicating that high-energy radiation is either strongly absorbed or intrinsically absent. In the context of aspherical shock-CSM interaction models, these observations imply extreme properties of the CSM (geometry, density, total mass) that lack clear astrophysical motivation. Instead, we show that the emergence of radiation from a newborn Pulsar Wind Nebula (PWN) naturally explains the radio spectral evolution and high-energy limits, where the emission is governed by the adiabatic expansion of a relic pair plasma. We conclude that SN 2012au represents the most compelling candidate for a young, newborn PWN discovered to date, a scenario that can be directly tested with pending Very Long Baseline Interferometry (VLBI) observations.

astro-ph.HE↗

arXiv2026

Predicting Multiwavelength Emission Associated with X-Ray Flares and Extended Emission of Gamma-Ray Bursts

Gamma-ray bursts (GRBs) are one of the most extreme transients in the universe, but their explosion and emission mechanism remains unclear. To investigate the nature of GRB jets, here we focus on X-ray flares (XFs) and extended emissions (EEs), which are X-ray emissions that occur 100 to 1000 seconds after the main burst. They can be observed by recently developed multi-wavelength facilities. In this paper, we calculate emissions across multi-wavelengths associated with XFs and EEs under the hypothesis that XFs and EEs are optically-thin synchrotron emissions from nonthermal electrons in relativistic jets. Considering ranges of the dissipation radius $r_{\rm diss}$ and the Lorentz factor $Γ$ of the jet, we determine the parameter space in which a detectable emission can be produced at each wavelength. We found that simultaneous ultraviolet and very-high-energy gamma-ray emission associated with XFs or EEs can be detected by Swift/UVOT, SVOM/VT, and CTAO approximately every three years. The detection and non-detection rates for each detector are key to determining the uncertain yet essential values necessary for understanding the physics of GRB jets.

astro-ph.HE↗