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Yang Huang

Publications and source records attributed to Yang Huang.

At least 55 records · Page 3Linked to original sources
arXiv2026

Thin-Film-Engineered Self-Assembly of 3D Coaxial Microfluidics with a Tunable Polyimide Membrane for Bioelectronic Power

Thin-film self-assembly of three-dimensional (3D) microsystems presents a compelling route to integrate complex functionalities into ultra-compact volumes, yet strategies for incorporating tunable ion-conducting elements remain limited. Here, we introduce a strain-induced self assembly platform that transforms lithographically patterned multilayer thin films into functional 3D coaxial Swiss-roll microtubes with total active volumes below 1 uL. A key innovation is the monolithic integration of a chemically tunable polyimide proton-exchange membrane, enabling post-fabrication optimization of ionic transport that balances proton transport with mediator blocking. We further implement a dual-mode operational scheme that decouples microbial metabolism from electrochemical power generation, revealing biofouling, not chemical fouling or membrane degradation, as the dominant failure mechanism in conventional architectures. Critically, optimally treated polyimide membranes exhibit excellent recoverability after fouling, while cell-free mode operation maintains stable performance by physically excluding microorganisms from the microelectronic environment. This integrated bio-electronic microsystem achieves a volumetric power density of ~3.1 mW cm-3 within an ultra-compact footprint of 4.16 mm2. Our work establishes a scalable thin-film engineering approach to create tunable, 3D bioelectronic power sources for autonomous microsystems.

physics.app-ph↗
arXiv2026

The Fate of the Milky Way--Andromeda System: To Merge or Not?

It has long been predicted that the Milky Way (MW) will eventually merge with Andromeda (M31), a view reinforced by \textit{HST} measurements indicating a small M31 transverse velocity. However, using updated \textit{Gaia}-based proper motions (PMs) and including the dynamical influence of the Large Magellanic Cloud (LMC) and M33, Sawala et al. reported an MW--M31 merger probability of $\sim$50\% within 10 Gyr, leaving the fate of the Local Group (LG) uncertain. Adopting their semi-analytic framework, we revisit this problem with the latest and most precise \textit{Gaia}-based PMs for M31 and M33, corrected for systematic offsets in \textit{Gaia} astrometry. In our fiducial model, the MW--M31 merger probability rises to 90\%, with a median merger time of $6.5_{-1.5}^{+1.3}$ Gyr, broadly restoring the classical picture. A sensitivity analysis shows that the merger probability depends strongly on the adopted M31 PM through two channels: a direct effect via the radial-tangential balance of the MW-M31 orbit, and a satellite-mediated effect, where the M31 PM fixes the orbital plane and determines how satellite-induced barycentric reflex motions project onto it, either promoting or suppressing a merger. Given this sensitivity, current measurements, while favoring a high merger probability, remain inconclusive, spanning from 64.7\% to 100\% across the 2$σ$ PM region. Future PM measurements with uncertainty of $\lesssim2\,\upmu\mathrm{as\,yr^{-1}}$ will be required to reach a firm conclusion, i.e., to constrain the probability range within 10\% at the 2$σ$ level.

astro-ph.GA↗
arXiv2026

Three-dimensional reddening maps of the Magellanic Clouds constructed by RR Lyrae stars

We present the first three-dimensional reddening maps of the Large and Small Magellanic Clouds (LMC and SMC) constructed using fundamental-mode RR Lyrae stars from the OGLE-IV survey. By applying a period-amplitude-color relation and a period-luminosity-metallicity calibration in the OGLE photometric system, we derive intrinsic colors, color excess $E(V-I)$, and photometric distances for more than 20,000 RRab stars in the LMC and 3,000 in the SMC. Spatial variations in reddening are modeled using an adaptive quadtree scheme, where robust reddening-distance relations are fit within each partition and distances are iteratively updated to achieve self-consistency. The resulting maps reveal resolved dust structures across both galaxies, including steep reddening gradients in the central LMC and flatter profiles in the SMC. The construction of the three-dimensional reddening maps further reveals that high-extinction regions exhibit reddening behavior inconsistent with a uniform extinction law, implying localized variations in dust properties. The final maps comprise 205 partitions for the LMC and 67 partitions for the SMC, and are released together with a Python-based query tool and GeoJSON data products. These 3D maps provide a foundation for distance-dependent reddening corrections and for probing the structure and physical conditions of the Magellanic interstellar medium, and future high-precision and cadence RR Lyrae sample from Gaia DR4 will support higher-resolution mapping and deeper exploration of dust substructure.

astro-ph.GA↗
arXiv2026

Absorption and scattering of massless scalar waves by Frolov black holes

We study the absorption and scattering of massless scalar waves by Frolov black holes, a regular deformation of the Reissner--Nordström geometry. A null-geodesic analysis provides the photon-sphere radius and the critical impact parameters governing capture and glory scattering. Using a partial-wave approach, we compute total/partial absorption cross sections and differential scattering cross sections over a broad frequency range. When the absorption spectrum is rescaled by photon-sphere scales, the high-frequency oscillations exhibit a pronounced data collapse in the variables $\hatσ=σ_{\rm abs}/σ_{\rm geo}$ and $x=ω/Ω_c$, highlighting photon-sphere control of the absorption fine structure. We clarify the parameter dependence under the horizon-radius normalization and relate the apparent trends to the variation of the dimensionless mass across parameter space. Finally, comparing Frolov, Reissner--Nordström, and Hayward black holes with matched critical or glory impact parameters, we find that their absorption and scattering patterns can become remarkably close, indicating that in the intermediate-to-high frequency regime the dominant signatures are largely governed by the unstable photon orbit, while core effects enter as subleading corrections.

gr-qc↗
arXiv2026

Mass Production of 2023 KMTNet Microlensing Planets I: Low Mass Ratio

We initiate the systematic search for planets in the 2023 data of the Korea Microlensing Telescope Network (KMTNet), focusing on those planets found by the KMTNet AnomalyFinder with low preliminary estimates of the mass-ratio, $q<2\times 10^{-4}$. The 2023 season is the first for which the photometry of all events was re-reduced prior to the AnomalyFinder search, potentially increasing its sensitivity to planets. We find three strong low-$q$ planet candidates, KMT-2023-BLG-0164 ($q\sim 1.3\times 10^{-4}$), KMT-2023-BLG-1286 ($q\sim 1.9\times 10^{-4}$), and KMT-2023-BLG-1746 ($q\sim 8\times 10^{-5}$). KMT-2023-BLG-0164 is notable in that the source is projected on a very bright ($I=16.0$) foreground star, which is either the planet's host or (more likely) a companion to the host. We obtain a spectrum, finding that its mass and distance are $M\sim 1.0\,M_\odot$ and $D\sim 1.5$ kpc, the latter being the distance of the lens ($D_L$) regardless of whether the spectroscopic target is the host or its companion. We also analyze two other candidates, KMT-2023-BLG-0614 and KMT-2023-BLG-1593, which are unlikely to enter the statistical sample due to their ambiguous interpretations as possible non-planetary events.

astro-ph.EP↗
arXiv2026

Homogenization of the Stetson Photometry with the BEST Database

As one of the most widely recognized high-quality standard stars, the Stetson standards have been extensively used as a photometric reference for calibrating other surveys. In this work, we present an independent validation and re-calibration of the Stetson standard star photometry using the BEST database. Based on typically 30,000-70,000 calibration stars per band, we find that the original Stetson photometry achieves field-to-field zero-point precisions of approximately 10--40\,mmag in the $UBVRI$-band. In addition, significant spatially dependent magnitude offsets are detected within individual Stetson fields for all bands, with magnitudes exceeding 1\%, probably caused by the calibration errors in the Stetson photometry. After correcting those systematic errors, the agreement between the Stetson and BEST photometry is improved to $\sim$5\,mmag for individual fields for $BVRI$-band. The re-calibrated photometry is further validated using the SCR standards, yielding agreement better than 10\,mmag for individual stars in the $BVRI$ bands and confirming zero-point precisions of 2--4\,mmag in the $BVI$ band. The precisions is further confirmed by checks using Gaia DR3 broad band colors. These results highlight the power of the BEST database for improving photometric calibration and suggest that, if feasible, it be incorporated into the calibration process of future releases of the Stetson standard catalog.

astro-ph.SR↗
arXiv2026

A 3D Chemodynamical Census of Inner-Galaxy Metal-poor Giants to [Fe/H]~-3.5

The earliest assembly of the Milky Way remains poorly understood, yet the spatial, chemical, and kinematic properties of its most metal-poor stars provide a unique fossil record of its proto-Galaxy phase. Understanding how this ancient component formed is essential for linking near-field Galactic archaeology to high-redshift galaxy evolution. We construct the currently largest 3D map of inner-Galaxy metal-poor giants by combining several narrow/medium-band photometric surveys, reaching metallicities down to $\mathrm{[Fe/H]}\sim-3.5$. Our final sample contains 5,095,676 giants, including 1,717,610 stars with $\mathrm{[Fe/H]}<-1$. Across $-4\le \mathrm{[Fe/H]}<-1$, the density distribution reveals a centrally concentrated, flattened spheroidal component extending to $r_{\rm gc}\sim15$ kpc, together with a prominent overdensity near $X\sim-5$ kpc that is dominated by metal-poor stars on disklike orbits, with a kinematically hot background also present. The selection-function-corrected metallicity distribution function shows a distinct, very metal-poor component around $\mathrm{[Fe/H]}\sim-2.7$ that becomes most prominent at 1$<r_{\rm gc}<$3 kpc. Stars with $-3.5\lesssim\mathrm{[Fe/H]}\lesssim-1.4$ exhibit weak net rotation and low rotational support within $r_{\rm gc}<15$ kpc. Finally, we briefly note that the centrally enhanced very metal-poor component could be qualitatively consistent with one or more early dissipative build-up episodes (e.g., high-$z$ compaction/"blue-nugget" phases) as one possible interpretation.

astro-ph.GA↗
arXiv2026

Topological observables and domain wall tension from finite temperature chiral perturbation theory

Within the framework of SU(2) chiral perturbation theory, we derive the general solution of the QCD $θ$-vacuum for an arbitrary vacuum phase, explicitly incorporating isospin-breaking effects from the light quark mass difference, and compute the temperature dependence of the topological susceptibility, higher-order cumulants, and the domain wall tension up to next-to-leading order. We find that the topological susceptibility agrees with lattice data at low temperatures but deviates at higher temperatures as expected from the breakdown of the chiral expansion; moreover, we demonstrate that the normalized fourth-order cumulant and the domain wall tension decrease monotonically with increasing temperature, while the normalized sixth-order cumulant exhibits the opposite behavior. These results extend earlier analyses by showing how isospin breaking reshapes the full hierarchy of topological charge cumulants and the dynamics of $θ$-vacuum domain walls, thereby offering new theoretical input on the $θ$-vacuum properties, which are relevant for axion-related effective theories in hot QCD matter.

hep-ph↗
arXiv2026

The solar-like latitudinal distribution of flaring activities revealed by TESS, APOGEE and GALAH

Flare flux reflect contribution from active regions rather than the whole hemisphere of a star. Unlike the amplitude of light-curves caused by starspots, the flare detection is independent of inclination. The two valuable properties of flares can be used to reveal the latitudinal distribution of active regions (LaDAR) given that LaDAR is coupled with inclination and location information in spatially unresolved stars. We detected $\sim 27000$ flares of 1510 flaring stars in the TESS mission with the corresponding inclinations obtained. The detection rate of flaring stars shows that flares are hard to detect on stars with low inclination, indicating that flares occur mainly at low latitudes. Further investigation of the relationship between the apparent flaring activity and inclination along with the rotation period finds that as the rotation period increases from a solar-like rotation to an ultra-fast rotation, the mean latitude of active regions increases from $θ\approx 15^{\circ}$ to $θ\approx 27^{\circ}$, whose trend is in line with the rotation--activity relationship. The LaDAR indicates that flares are attributed to small-scale fields that are formed at low latitudes, while polar spots that are associated with large-scale fields are inactive and are difficult to trigger flares.

astro-ph.SR↗
arXiv2026

A Tale of Two Origins: In-Situ versus Accreted Nitrogen-Rich Field Stars in the MW

Spectroscopic surveys have identified significant numbers of metal-poor nitrogen-rich (N-rich) field stars. These stars are strong candidates for escapees from globular clusters (GCs), as their distinctive nitrogen enhancement mirrors the chemical patterns observed in some of the members of GCs. As part of the effort to characterize their chemodynamical properties, we derived abundances for up to 25 elements in a sample of 33 N-rich field giant stars (18 of them are studied for the first time) using high-resolution optical spectroscopy. We confirm their elevated abundances of N, Na, and Al, strongly supporting a GC origin. Given that Galactic GCs themselves formed within diverse progenitor galaxies, we sought to identify the ancestral systems of these N-rich field stars. By analyzing their dynamical parameters, we separated the sample into high-energy (HE) and low-energy (LE) groups. The HE group exhibits lower [α/Fe] and enhanced r-process abundances compared to the LE group. This indicates that the HE stars likely escaped from GCs accreted from massive dwarf galaxies (e.g., Gaia-Sausage-Enceladus), while the LE stars probably originated from in-situ GCs. We also find that the chemical pattern of these N-rich stars with [Fe/H] {\lessapprox} -1.0 are similar to the high-redshift ''N-emitters''. Furthermore, orbital integrations revealed a close encounter between one N-rich field star and the globular cluster NGC 6235. Our work demonstrates the potential of using chemodynamical analyses to trace Galactic assembly through chemical peculiar stars, while highlighting that larger samples and more precise data in the future are crucial to establish definitive origins.

astro-ph.GA↗
arXiv2026

In-Orbit GRB Identification Using LLM-based model for the CXPD CubeSat

To validate key technologies for wide field-of-view (FOV) X-ray polarization measurements, the Cosmic X-ray Polarization Detector (CXPD) CubeSat series has been developed as a prototype platform for the Low-Energy X-ray Polarization Detector (LPD) onboard the POLAR-2 mission. The wide-FOV design significantly increases the complexity of the background environment, posing notable challenges for real-time gamma-ray burst (GRB) identification. In this work, we propose an in-orbit GRB identification method based on machine learning, using simulated spectral data as input. A training dataset was constructed using a Geant4-based simulator, incorporating in-orbit background and GRB events modeled within the 2-10 keV energy range. To meet the computational constraints of onboard processing, we employ a multimodal large language model (MLLM), which is fine-tuned using low-rank adaptation (LoRA) based on miniCPM-V2.6 and quantized to 4-bit precision. The model achieves perfect classification accuracy on validation data and demonstrates strong regression performance in estimating GRB spectral indices, with an RMSE of 0.118. Furthermore, we validate the feasibility of onboard deployment through a simulated satellite data processing pipeline, highlighting the potential of our approach to enable future real-time GRB detection and spectral analysis in orbit.

astro-ph.IM↗
arXiv2026

What does a regular star look like?

Recently, astronomers discovered unusual Einstein cross images of the galaxy HerS-3, which feature a bright central spot. Motivated by studies of images produced by regular stars, it has been proposed that optical appearances caused by compact stars acting as gravitational lenses may account for this central bright spot. We further suggest that images produced by regular stars exhibit additional characteristics distinct from those of ordinary black holes, such as the possible partial or complete absence of secondary images. These phenomena may serve as favorable observational criteria for identifying regular stars in future searches.

gr-qc↗
arXiv2026

S-PLUS: Beyond Spectroscopy IV. Stellar Parameters and Elemental-abundance Ratios for Six Million Stars from DR4 and First Results for the Magellanic Clouds

We combine narrow/medium-band filter photometry from the Southern Photometric Local Universe Survey (S-PLUS) DR4 with ultra broad-band filter photometry from Gaia EDR3 to derive fundamental stellar parameters ($T_{\rm eff}$, $\log g$, [Fe/H], ages) and elemental-abundance ratios ([C/Fe] and [$α$/Fe]) for 5.4 million stars in the Galaxy (4.9 million dwarfs and 0.5 million giants), as well as for over 0.7 million red giant stars in the Large and Small Magellanic Clouds (LMC and SMC). The precisions of the abundance estimates range from 0.05-0.10 dex for metallicity in the relatively metal-rich range ([Fe/H] $> -1.0$) to 0.10-0.30 dex in the metal-poor regime ([Fe/H] $<-1.0$), 0.10-0.20\,dex for [C/Fe], and 0.05 dex for [$α$/Fe]. The stellar parameters for LMC and SMC member stars are somewhat less precise than those from the S-PLUS main survey, primarily because of the effect of high reddening. The use of both metallicity- and carbon-sensitive filters provides unbiased measurements of both [Fe/H] and [C/Fe], of particular importance for very low-metallicity ([Fe/H] $< -2.0$) stars, where carbon enhancement can lead to systematically high estimates of [Fe/H] when only a single metallicity-sensitive filter is employed. Furthermore, multiple narrow-band filters enable metallicity estimates down to [Fe/H] $\sim -4.0$ with an accuracy of around 0.3 dex, exceeding the precision typically achieved by low/medium-resolution spectroscopy. This extensive photometric dataset, combined with the other three datasets in this series, will serve as a valuable legacy resource for Milky Way and Magellanic Clouds studies.

astro-ph.SR↗
arXiv2026

Carbon-Enhanced Metal-Poor Star Candidates in the Milky Way from J-PLUS and S-PLUS

Recent large-scale multi-band photometric surveys now enable elemental-abundance estimates for millions of stars with accuracies approaching those of low- to medium-resolution spectroscopy. Using [Fe/H] and [C/Fe] estimates derived from the Javalambre Photometric Local Universe Survey (J-PLUS) DR3 and the Southern Photometric Local Universe Survey (S-PLUS) DR4, which together cover $\sim$6,200 deg$^2$ of the sky, we identify large numbers of carbon-enhanced metal-poor (CEMP) stars in the Milky Way. After applying data-quality cuts and evolutionary corrections to the carbon-abundance estimates, we construct a combined J/S-PLUS sample of $\sim$6.40 million stars and identify $\sim$104,900 CEMP candidates, roughly twice the number of CEMP candidates identified from Gaia XP spectra by Lucey et al. We photometrically confirm that the absolute carbon abundance $A$(C) separates CEMP stars into two primary groups, CEMP-no and CEMP-$s$ stars, consistent with previous spectroscopic studies. We also recover CEMP morphological Groups I-III in the Yoon-Beers diagram, as well as the recently proposed Group IV, and show that it is statistically distinct even in photometric data. A cumulative frequency analysis confirms that the CEMP fraction increases toward lower metallicity and that CEMP-no stars dominate in the most metal-poor regime. By comparing frequencies with and without Group IV stars, we assess their relation to CEMP-no and CEMP-$s$ stars, and examine CEMP distributions across different Galactic components. The resulting catalog provides a substantial sample for future spectroscopic follow-up, in particular to constrain the likely origin(s) of the Group IV stars.

astro-ph.GA↗
arXiv2026

A General Discussion on Photon Spheres in Different Categories of Spacetimes

Photon spheres have attracted considerable interest in the studies of black holes and other astrophysical objects. For different categories of spacetimes (or gravitational sources), the existence of photon spheres and their distributions are dramatically influenced by the geometric and topological properties of spacetimes and characteristics of the corresponding gravitational fields. In this work, we carry out a geometric analysis on photon spheres for different categories of spacetime (including black hole spacetime, ultra-compact object's spacetime, regular spacetime, and naked singularity spacetime). Some universal properties and conclusions are obtained for these spacetimes. We mostly focus on the existence of photon spheres, the total number of photon spheres $n = n_{\text{stable}} + n_{\text{unstable}}$, the subtraction of stable photon sphere and unstable photon sphere $w = n_{\text{stable}} - n_{\text{unstable}}$ in different categories of spacetimes. These conclusions are derived solely from geometric properties of optical geometry of spacetimes, irrelevant to the specific spacetime metric forms. Besides, our results successfully recover some important theorems on photon spheres proposed in recent years.

gr-qc↗
arXiv2026

Applying the Gibbons-Werner method to bound orbits of massive particles in stationary spacetimes

The Gibbons-Werner (GW) method provides a geometric framework for calculating the deflection angle of particles in curved spacetimes, and numerous extensions based on the original version have been developed in recent years to expand its applicability. Most existing studies, however, are restricted to unbound orbits. The finite-distance deflection angle, which assumes both the source and observer to be located at finite distances, motivates us to investigate the bending of bound orbits. In this work, we broaden the GW method to bound orbits of massive particles in stationary axisymmetric (SAS) spacetimes, following our previous extension in static spherically symmetric (SSS) backgrounds [Huang et al., Phys. Rev. D 107, 104046 (2023)]. By employing our generalized GW method for SAS spacetimes [Huang et al., J. Cosmol. Astropart. Phys. 01(2024)013], (a) We obtain a formula for the deflection angle of bound massive particles in SAS spacetimes by dividing bound orbits that azimuthally overlap with themselves into multiple non-overlapping segments. This division enables the application of the GW method -- originally developed for unbound orbits -- to each segment in a consistent manner. (b) We overcome the limitation associated with the loss of positive definiteness of the Jacobi-Maupertuis Randers-Finsler (JMRF) metric, which occurs because bound massive particles have energies below unity. To show the practical implementation of our approach, we carry out the calculation in Kerr spacetime and obtain the deflection angle between two arbitrary points along the bound orbit of massive particles.

gr-qc↗
arXiv2026

A Tale of Two Dust Disks in Our Milky Way

Cosmic dust plays a vital role in stellar and galactic formation and evolution, but its three-dimensional structure in the Milky Way has remained unclear due to insufficient precise reddening and distance measurements. Although early studies typically adopted a single-disk model, we detect two distinct components at Galactocentric distances of 5-14 kpc, enabled by photometric, spectroscopic, and astrometric measurements of over 5 million stars. The thin dust disk's scale height increases radially from 60 to 200 pc, while the thick disk grows from 300 to 800 pc. For the first time, we find the thin and thick dust disk correlates spatially with molecular and atomic hydrogen disk, respectively. The thin, thick, and combined disks have scale lengths of 9.6+1.2-1.1 kpc, 4.2+0.4-0.3 kpc, and 6.6+0.3-0.3 kpc, respectively. The gas-to-dust ratio shows an exponential radial gradient, increasing from around 60 at 5 kpc to around 470 at 14 kpc. These findings provide new insights into dust morphology in the Galaxy and raise fundamental questions that require further investigation.

astro-ph.GA↗
arXiv2026

A Large and Precise All-Sky Photometric Standard Star Dataset Across More Than 200 Passbands

High-precision photometric standard stars play a key role in enabling accurate photometric calibration and advancing various fields of astronomy. However, due to limitations in calibration methods and the limited availability and underuse of high-precision reference data, existing photometric standard stars may suffer from insufficient numbers, systematic errors exceeding 10 milli-magnitude (mmag), limited photometric band coverage, or incomplete sky coverage, among other issues. To overcome these limitations, we have constructed the largest (over 200 million stars, 1000 times the widely recognized Landolt standards in the same magnitude range), most precise (better than 10 mmag), and most comprehensive (over 200 bands, nearly 40 times the coverage of traditional standards) all-sky standard stars. Based on standards, we have calibrated multiple survey datasets to mmag precision, and subsequently developed a complete sky distribution of stars for the Pan-STARRS system. This database, the BEst STars Database (BEST), is expected to pave the way for achieving mmag-level - or even higher - photometric precision in large-scale surveys, and to play a central role in shaping a high-precision astronomical measurement framework.

astro-ph.IM↗