arXiv subjects

J. Wang

Publications and source records attributed to J. Wang.

At least 19 recordsLinked to original sources

arXiv2026

Towards constraining cosmology with HI--galaxy cross-correlations from MeerKLASS

We present an inference of cosmological parameters from the cross-correlation power spectrum between the MeerKLASS 2019 L-band HI intensity maps and the overlapping WiggleZ galaxies at $z \simeq 0.43$. The analysis is intended as a proof of concept to verify that the full pipeline, from the foreground cleaning of the maps to the likelihood analysis, can be applied end-to-end to real data and can return results consistent with the concordance cosmology. The model of the observed power spectrum includes observational effects that are relevant to a single-dish experiment. In the most optimistic scenario in which we hold the astrophysical nuisance parameters fixed, we obtain $H_0 = 65.3^{+5.8}_{-10}\text{ km s}^{-1}\text{ Mpc}^{-1}$ and $Ω_{\text{m}} = 0.44^{+0.12}_{-0.30}$ at the 68% confidence level. We find that sampling the HI amplitude with an informative prior retains most of the constraining power and changes these results by less than 1 sigma. Moreover, using synthetic data, we show that neglecting the observational effects in the model biases the inferred parameters by up to 2.5 sigma and also underestimates their uncertainties. Finally, we show that varying the number of foreground modes removed and the range of scales included changes the inferred parameters by less than 0.5 sigma. These results demonstrate the robustness of our pipeline in modelling HI intensity mapping data, and set the foundation for future cosmological inference with intensity mapping using MeerKLASS and SKAO.

astro-ph.CO↗

arXiv2026

Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-α Emitters

Context. Protoclusters at reionization are thought to host a significant fraction of the cosmic star formation rate density, making them crucial for the timing and topology of reionization. The gas-phase metallicity, a key tracer of galaxy evolutionary stage, can now be measured directly in the early Universe with JWST. Aims. We measure the gas-phase metallicity of Lyman-$α$ emitters (LAEs) in the LAGER-z7OD1 protocluster at $z\approx6.93$ via the direct ($T_e$-based) method using the [O III]$λ$4363 auroral line, and combine it with stellar masses to constrain the mass-metallicity relation (MZR) in dense environments. Methods. We use JWST/NIRSpec MSA G395H spectroscopy, derive metallicities with self-consistent analytic prescriptions, and propagate the dust-extinction uncertainty into an asymmetric error budget via Monte Carlo simulations based on the observed Balmer decrements. Stellar masses come from BEAGLE SED fitting of JWST/NIRCam and UltraVISTA photometry. Results. We obtain five secure [O III]$λ$4363 detections and one upper limit, with 12+log(O/H) $\approx$ 7.2-8.0. The weighted spectral stack yields 12+log(O/H) = $7.76^{+0.06}_{-0.05}$, ~0.26 dex higher than stacks of LAEs at similar redshifts from JWST surveys. However, the MZR fit gives a slope $γ$ = 0.232 +/- 0.214 and normalization $Z_0$ = 7.888 +/- 0.199, placing our sources below the established MZR of normal galaxies and recent protocluster baselines at $z\sim5-7$. Conclusions. The higher metallicity relative to general LAEs suggests accelerated assembly driven by the overdensity, while the offset below the MZR points to a complex interplay between mass build-up and gas accretion. Since we target actively star-forming LAEs, we are likely capturing a phase of pristine gas inflow from the intergalactic medium that fuels star formation but dilutes the interstellar media of these protocluster members.

astro-ph.GA↗

arXiv2026

Classical-to-Quantum Transition in Blackbody Radiation Thermodynamics: Planck's Law without Statistical Assumptions

Inspired by Fermi's model of radiation-matter interaction, we investigate the classical dynamics of a closed, finite-energy system, in which matter is coupled to an electromagnetic field. We find that energy is progressively transferred to increasingly high-frequency field modes, so that the effective temperature of both matter and radiation approaches zero in the long-time limit - in sharp contradiction with the finite-temperature equilibrium assumed by classical blackbody thermodynamics. Requiring consistency with the Stefan-Boltzmann and Wien laws identifies a characteristic time $t_L$, at which both laws are simultaneously satisfied. Strikingly, classical spectra obtained for different energies and cavity sizes collapse onto the universal Planck distribution at $t_L$. We conjecture that quantum dynamical localization arrests the classical energy cascade at $t_L$, and that the Planck distribution emerges as a dynamical consequence of this arrest - without invoking any a priori statistical assumption.

cond-mat.stat-mech↗

arXiv2026

XuYi Interferometer Observation Simulator

The XuYi Interferometer is the first Chinese long-baseline optical interferometer currently under development by the National Institute of Astronomical Optics and Technology (NIAOT) of the Chinese Academy of Sciences. In preparation for future scientific operations, we developed the XuYi Interferometer Observation Simulator (XIOS), a lightweight MATLAB-based software package designed to assist observers in planning interferometric observations. The simulator combines target observability calculations, interferometric baseline geometry, delay-line constraints, (u,v)-coverage prediction, and visibility estimation into a single graphical user interface. It incorporates astronomical routines from the MAAT toolbox and adopts visualization concepts inspired by ASPRO2. The software allows users to evaluate observing opportunities, predict interferometric performances, and generate realistic observing configurations before telescope operations. We present the architecture of the simulator, its principal modules, and representative simulation results obtained for the current three-telescope XuYi interferometric configuration operating in the near-infrared H band.

astro-ph.IM↗

arXiv2026

First Measurement of Compton Scattering on $^3\text{He}$ at HI$γ$S

The world's first Compton scattering measurements on a $^3$He target were performed to probe neutron electromagnetic polarizabilities. Differential cross sections were measured at laboratory angles of $40^\circ$, $55^\circ$, $90^\circ$, $115^\circ$, $150^\circ$, using circularly polarized, quasi-monoenergetic photon beams at weighted mean energy values of 61.5 and 97.1 MeV from the High Intensity $γ$-ray Source at the Triangle Universities Nuclear Laboratory. Comparisons with chiral effective field theory show good agreement at 97.1 MeV but over-prediction at 61.5 MeV, motivating further theoretical development.

nucl-ex↗

arXiv2026

Ultralow Mean Transverse Energy and High Quantum Efficiency Cryogenic Bialkali Photocathode for MHz-Repetition-Rate Electron Sources

Simultaneously achieving high quantum efficiency (QE), ultralow mean transverse energy (MTE), and robust long-term operation under conditions relevant to continuous-wave (CW) X-ray free-electron lasers (XFELs) remains a central challenge for semiconductor photocathodes. This challenge arises from the trade-off between QE and MTE, as well as the difficulty of maintaining stable operation in high-field CW electron guns. Here we demonstrate a cryogenic K2CsSb photocathode that simultaneously achieves high QE, ultralow MTE, and robust long-term operation in a CW gun under XFEL-relevant operating conditions. Under cryogenic operation, the photocathode achieves an MTE of 50 meV while sustaining a QE of 5.4%. Milliampere-level CW current, including operation at 5 mA, was demonstrated together with an approximately 20-day operational history. The observations are consistent with improved carrier survival and/or surface escape in photocathodes prepared using the optimized recipe. These results show that the practical QE-MTE trade-off can be substantially mitigated in cryogenic bialkali photocathodes and provide a practical pathway toward high-brightness electron sources for CW XFELs and energy-recovery linacs.

physics.acc-ph↗

arXiv2026

Reconstruction of neutrino events in the Accelerator Neutrino Neutron Interaction Experiment: Part I

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) was designed to reconstruct neutrino events from the Fermilab Booster Neutrino Beam (BNB) with the parallel goals of measuring neutron production in interactions with oxygen and serving as a testbed for new technology. The ANNIE detector consists of a 26-ton water Cherenkov target tank instrumented with conventional photomultiplier tubes (PMTs), a downstream tracking muon spectrometer, and an upstream double wall of plastic scintillator to serve to veto charged particles incoming from neutrino events that occur upstream of the experimental setup. ANNIE has also deployed multiple Large-Area Picosecond PhotoDetectors (LAPPDs) and a test vessel of water-based liquid scintillator (WbLS). This paper describes the event reconstruction performance of the detector before implementation of these novel technologies, which will serve as a baseline against which their impact can be measured. That said, even the techniques used for event reconstruction using only the conventional PMT array and muon spectrometer are significantly different than those used in other water Cherenkov detectors due to the small size of ANNIE (which makes nanosecond-scale timing not as useful as in a large detector) and the availability of reconstruction information from the tracking muon spectrometer. We demonstrate that combining the information from these two elements into a single fit using only pattern recognition yields a muon vertex uncertainty of 60 cm, a directional uncertainty of 13.2 degrees, and energy reconstruction uncertainty of about 10\% for BNB muon neutrino Charged Current Zero Pion (CC0pi) events.

hep-ex↗

arXiv2026

The Hill sphere transits of Beta Pictoris c and the search for another 1981-like event

Beta Pictoris is a young and nearby planetary system hosting an edge-on debris disk and at least three gas-giant planets. Their circumplanetary environments could host exomoons and rings, a detection of which would be highly informative for moon and planet formation theories. A photometric fluctuation of about 4% was seen towards Beta Pictoris in 1981, indicating the transit of dust in the system, which could be associated with the Hill spheres of the two inner planets. We search for the origin of the 1981 event by searching for an analogous event in multi-epoch photometry from 2017 to 2023, and look for signs of circumplanetary material in transits of the Hill sphere of Beta Pictoris c. Observations from the BRITE satellite, and the bRing and ASTEP observatories are fitted to a model of the 1981 event to search for a similar event, and also search for a signal consistent with a circumplanetary disk transit using a simple flat disk model. No compelling evidence for a 1981 event during a Hill sphere primary transit is found, although we do find a candidate event around 2019 July 26. Due to the uncertainty in the time of closest projected separation of Beta Pictoris c, a search for a disk during the primary transit of 2018 could not be robustly determined, but bRing photometry for the second primary transit places an upper limit on the dust content of the Hill sphere of ~ $10^{22}$ grams of material. With no compelling detection of an event similar to that seen in 1981 during the transits of Beta Pictoris c in the photometric time series, we rule out the hypothesis that this event was related to the Hill spheres of Beta Pictoris c and Beta Pictoris b. Future observations of the next Hill sphere transit in 2028 can be realised with both ground-based observatories and with PLATO, whose first long duration science pointing will include Beta Pictoris.

astro-ph.EP↗

arXiv2026

XRF 241001A/SN 2024aiiq: A faint soft X-ray transient detected by SVOM with a broad-line type Ic supernova revealed by JWST

X-ray flashes (XRFs) are a type of gamma-ray burst (GRB) with prompt emission predominantly below 30 keV and have been poorly detected by previous missions. The advent of the SVOM mission, with its wide-field instrument ECLAIRs, provides a new way to detect soft X-ray transients. We present photometric and spectroscopic observations of XRF 241001A detected by SVOM, a soft, subluminous, and low-energetic burst located in a poorly populated region of the Amati relation. We investigated the origin of its faint, soft high-energy emission to assess its connection to the long GRB population. We analyzed the SVOM/ECLAIRs prompt emission and modeled its afterglow emission from X-ray to-radio. We present JWST/NIRSpec and SVOM/VT observations of the associated supernova (SN 2024aiiq), and we compared its properties with previously detected GRB/SNe. The event XRF 241001A is located at z = 0.573 and has a prompt emission dominated by photons below 20 keV with a duration of T90 = 3.14 seconds. Its spectrum is consistent with both thermal and nonthermal models, each implying a low Epeak < 10 keV and Eiso ~ 8x10^49 erg. The X-ray-to-radio afterglow modeling favors an origin from a relativistic jet viewed on-axis. In the optical, XRF 241001A exhibits an early blue emission, similar to that detected in some eFXTs and inconsistent with synchrotron emission. The JWST/NIRSpec observations firmly established its collapsar origin by revealing a SN Type Ic with broad lines, comparable to SN 1998bw and SN 2025kg-like events. The event XRF 241001A is a soft low-luminosity collapsar event produced by a weak relativistic jet observed on-axis, supporting the view that part of the XRF population forms the low-energy soft tail of the long GRB population. Its observation demonstrates the potential of SVOM/ECLAIRs to probe the soft regime of the high-energy transient population that remains largely unexplored.

astro-ph.HE↗

arXiv2026

Sustainable Air-Ground Integrated Coverage Networks: ISCC Architecture, Technologies, and Testbed

The rapid emergence of sixth-generation (6G) networks and the low-altitude economy has accelerated the evolution of wireless infrastructures toward air-ground integrated coverage networks (AGICNs), which seamlessly fuse terrestrial and aerial communication resources. However, existing AGICN studies primarily focus on coverage enhancement, while ignoring sustainability. Pursuing sustainable AGICNs introduces new challenges due to the multidimensional resource coupling across heterogeneous air-ground segments. In view of this, this paper presents a comprehensive survey and tutorial on sustainable AGICNs, aiming to balance coverage capacity with carbon efficiency in low-altitude economies. An integrated sensing, communication, and computation (ISCC)-driven architecture, which enables dynamic resource orchestration through closed-loop control, is proposed. We thus introduce a multi-dimensional sustainability metric system, which covers operational efficiency, task-oriented performance, and full lifecycle carbon emissions, to quantify energy and carbon footprints. We review enabling technologies, including artificial intelligence, hybrid precoding, integrated sensing and communication, and simultaneous wireless information and power transfer, and discuss their integration into the ISCC framework to minimize energy consumption while maintaining robust coverage. Experimental results on a real-world testbed demonstrate a 20% reduction in power consumption while achieving over 90% coverage probability, highlighting the feasibility of sustainable AGICNs for future green networks.

cs.IT↗

arXiv2026

Geometric origin of supercurrents in Berry phase: Formula for computing currents from wavefunctions with correlation and particle number variation

The complexity of itinerant and many-body nature in Bardeen-Cooper-Schrieffer (BCS) wavefunctions has traditionally led to the use of coarse-grained order parameters for describing currents in superconductors (SC), rather than directly utilizing wavefunctions. In this work, we introduce a phase-based formula that enables the direct computation of currents from microscopic wavefunctions, accounting for correlation and particle number variations. Interestingly, the formulation draws parallels with insulators, suggesting a unified framework for understanding (intra-band) charge transport across two extremes of conductivity. A group velocity current $J_{band}{\propto}\frac{1}{\hbar}{\partial}_kE(k)$ is derived from Berry phase, independent of wave package dynamics, robust against correlation. Additionally, we identify a correlation-driven contribution, $J_{corr}$, which reveals that the pairing correlations ${\langle}c_kc_{-k}{\rangle}$ among dancing partners provide a current component beyond the velocity operator.

cond-mat.supr-con↗

arXiv2026

In the Eye of the Storm: The Third Giant X-ray Outburst of the Extreme Changing-look AGN IC 3599

We report the discovery and multiwavelength follow-up observations of a giant (factor >100) X-ray outburst of the exceptional changing-look active galactic nucleus (AGN) IC 3599. This is the third such outburst after two previous ones serendipitously discovered in 1990 and 2010. Based on our dedicated long-term monitoring of IC 3599 with {\it Swift}, the third outburst was detected while it was happening, and we triggered multiple follow-up observations within days to weeks for the first time. The Swift outburst spectra are supersoft and almost no photons are detected beyond 2.5 keV. The XMM-Newton short-term light curve shows a remarkable apparent oscillatory pattern that is reminiscent of quasiperiodic oscillations (QPOs). The optical high-state spectra reveal a multitude of bright coronal emission lines that have dramatically brightened and were absent or much fainter in low-state spectra. The new results eliminate outburst scenarios that require a constant time interval of repetitions (like certain variants of repeat tidal stripping, or of an orbiting supermassive black hole impacting the inner accretion disk), but remain in excellent agreement with an accretion disk radiation-pressure instability when assuming that local conditions in the disk of this long-lived AGN affect the onset time of each new instability. The combination of recurrent, giant, supersoft outbursts on decadal timescales, the exceptional emission-line response, and the rapid, candidate quasiperiodic, short-term variability on an hours timescale makes IC 3599 unique among AGN, and establishes it as a key system for studying accretion physics under extreme conditions and at the Eddington limit.

astro-ph.GA↗

arXiv2026

Discovery of EP J175257.3-351923 as a Candidate Black Hole Low-Mass X-ray Binary

We report the discovery of a new X-ray transient, EP J175257.3-351923 (EP250916a), by the Einstein Probe (EP) near the Galactic plane. The outburst lasted for at least 250\,days, reached a peak 2--10 keV flux of $\sim 4 \times 10^{-10}$~erg~cm$^{-2}$~s$^{-1}$, and exhibited a fast-rise exponential-decay (FRED) profile typical of X-ray binary outbursts. The source remained in the hard state throughout the outburst, with only modest variations in the photon index ($\sim 1.6$--$2.2$) and no evidence for a spectral state transition. Broadband spectral modeling suggests a truncated disk, a weak reflection component, and a high-energy cutoff at $\sim 217$~keV, consistent with hard-state accretion in black-hole systems. No reliable optical or radio counterpart is detected within the Swift/XRT error circle. The inferred X-ray-to-optical and X-ray-to-radio flux ratios are consistent with a low-mass X-ray binary classification. Neither pulsations nor significant aperiodic variability are detected. Although the compact object cannot yet be firmly identified, the timing, spectral, and multiwavelength evidence favors EP~J175257.3--351923 as a black-hole low-mass X-ray binary candidate, highlighting EP's potential to uncover a faint, previously hidden population of X-ray binaries.

astro-ph.HE↗

arXiv2026

First Gamma-Ray Burst Observations with SVOM

Following its launch on 22 June 2024, the Space-based multi-band astronomical Variable Objects Monitor (SVOM) successfully completed its flight acceptance, commissioning, and scientific validation phases in early 2025, during which several tens of gamma-ray bursts (GRBs) were detected onboard. Three quarters of these events have also been detected by other satellites, and a quarter are SVOM-only GRBs. In this article, we describe these early GRB observations, with a first description of the SVOM GRB sample that is emerging, and of the level of characterisation already achieved, and with a focus on a few events of particular interest. These early results are very encouraging regarding SVOM's ability to detect and fully characterise (including prompt emission, afterglow and distance) a wide range of GRBs (classical long GRBs, short GRBs, X-Ray Flashes, etc.) and to enable the use of these extreme high-energy transients as probes of the distant Universe.

astro-ph.HE↗

arXiv2026

Early results from the SVOM Observatory Science program

We present the organisation and early results from the Observatory Science program of the Space-based multi-band astronomical Variable Objects Monitor (SVOM), based on data collected between July 2024 and December 2025. Although primarily designed for gamma-ray burst studies, SVOM's wide-field, multi-wavelength instruments enable a broad range of high-energy astrophysical investigations. We summarize the execution and performance of the General Program and Target-of-Opportunity observations, and we describe the frameworks used for serendipitous source detection and monitoring with the ECLAIRs coded-mask instrument. Over this period, SVOM carried out more than a thousand pointed observations and detected several hundred non-GRB high-energy sources, mainly X-ray binaries, as well as blazars, stellar flares, magnetars, and unidentified events. We highlight some key results, including the monitoring of the microquasar Cygnus X-1, the detection of burst oscillations from the Low-Mass X-ray Binary 4U 0614+091, the spectral-state monitoring of Aql X-1, the first SVOM detection of an X-ray blazar flare from 1ES 1959+650, and observations of a stellar flare from HD 22468. These results demonstrate SVOM's strong capabilities for time-domain astrophysics beyond its core GRB program.

astro-ph.HE↗

arXiv2026

Deep HI observations of cold gas inflow and outflow

A major question in galaxy evolution is how galaxies acquire sufficient gas to sustain their star formation rates. HI observations with high angular resolution and sensitivity to very low column densities are some of the important observational ingredients that are currently still missing. Answers to these questions are necessary for a correct interpretation of observations of galaxy evolution in the high-redshift universe and will provide crucial input for the sub-grid physics in hydrodynamical simulations of galaxy evolutions. In this chapter we discuss the progress that has been made over the past years, describe the various processes that lead to inflow and outflow of gas, and discuss how SKA-Mid AA4 observations can contribute to further understanding these important aspects of galaxy evolution using deep observations of nearby individual disk and dwarf galaxies.

astro-ph.GA↗

arXiv2026

High Multiplicity Trigger for Long-Lived Particles in CMS detector

Searches for long-lived particles (LLPs) at the CMS experiment often involve unconventional event topologies that are difficult to efficiently select using standard trigger strategies. To improve sensitivity to such signatures during LHC Run~3 operation, a dedicated High Multiplicity Trigger (HMT) has been developed and deployed in the CMS trigger system. The trigger targets events containing unusually large numbers of hits in the CMS cathode strip chamber (CSC) muon detectors, a characteristic signature of several LLP scenarios involving displaced decays in the muon system. The HMT implementation, trigger logic, rate dependence with pileup, and operational stability are described. Optimized hit multiplicity thresholds are used to maintain acceptable trigger rates under high-luminosity and high-pileup conditions while preserving high efficiency across a broad range of LLP lifetimes and kinematic regimes. The trigger performance is evaluated using both simulated event samples and proton-proton collision data collected during Run~3 of the LHC. The HMT substantially extends the CMS sensitivity to non-standard signatures associated with LLP decays and provides a flexible platform for future searches for physics beyond the Standard Model.

hep-ex↗

arXiv2026

Influence of chemical ordering on magnetocrystalline anisotropy and magnetoelastic properties in Weyl magnetic semimetal Co2MnGa thin films

The magnetic anisotropy and magnetoelastic properties of the magnetic Weyl semimetal Co2MnGa were investigated in the Co2MnGa thin films with different chemical orderings. Their properties change, in line with the increase in the contents of the highly-ordered B2 and L21 phases. The most significant changes of both the magnetic anisotropy and the magnetoelastic properties were correlated with the appearance of the L21 ordered phase of Heusler alloy, which is also responsible for topological properties of these compounds. The magnetoelastic properties of L21 ordered Co2MnGa are discussed in comparison with the Co2FexMn1-xSi system with a similar degree of ordering, which has similar crystallographic structure but it is not Weyl semimetal. In particular, significant differences between the magnetoelastic properties of ordered Co2MnGa and Co2MnSi were found. In the case of L21-ordered Co2MnGa, the giant anisotropy of the magnetoelastic properties was observed.

cond-mat.mtrl-sci↗