Searcharxiv⌕ Search

arXiv subjects

Hong Wu

Publications and source records attributed to Hong Wu.

At least 19 recordsLinked to original sources
arXiv2026

Decomposing the Kinematics of SNR G180.0-01.7 with Medium-Resolution Spectra

The exceptionally large angular diameter and intrinsic optical faintness of the Galactic supernova remnant (SNR) G180.0-01.7 (S147) have historically hindered a comprehensive spectroscopic census of its filamentary structure. We present the first dedicated medium-resolution (R ~ 7500) spectroscopic study of S147 using the LAMOST Medium-Resolution Spectroscopic survey of Galactic Nebulae (MRS-N). By implementing multi-Gaussian decomposition on the H$α$, [NII], and [SII] emission complexes and applying combined spectroscopic and spatial criteria, we disentangle the shock-ionized filaments of the SNR from the pervasive foreground and background Diffuse Ionized Gas (DIG). Our analysis reveals a distinct bimodal radial velocity distribution for the SNR: a low-velocity population tracing the decelerated forward shock at a dense cavity wall, and a high-velocity population (with absolute radial velocities of ~ 70 $\pm$ 30 km/s) corresponding to ejecta within a low-density cavity. The co-existence of these populations provides kinematic evidence for the "supernova-in-a-cavity" scenario. Furthermore, we detect enhanced [SII]/H$α$ ratios in the DIG along the eastern and northern boundaries of the remnant, signaling shock compression of the ambient interstellar medium and highlighting remnant's multifaceted feedback.

astro-ph.GA↗
arXiv2026

The Silk Nebula: A Newly Discovered Giant [OIII] Emission Filament

We report [O\,\textsc{iii}] narrow-band imaging of an extremely large-scale nebula, the Silk Nebula, discovered by the SWONS (Super Wide-Field [O\,\textsc{iii}] Narrow-band Survey), together with multi-fiber medium-resolution spectroscopic data covering the H$α$, [N\,\textsc{ii}], [S\,\textsc{ii}], and [O\,\textsc{iii}] emission lines, acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) as part of the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N). Based on 2,684 high-quality spectra, we measured its physical parameters, including relative line intensities, radial velocities (RVs), and full widths at half-maximum (FWHMs). The [S\,\textsc{ii}]/H$α$ ratio of the nebula significantly exceeds the shock-excitation threshold of 0.4. Its location in BPT diagnostic diagrams and spatial morphology of [O\,\textsc{iii}] both support the optical emission is dominated by shock-heated gas. The oxygen abundance is near solar and spatially uniform, consistent with a shock propagating into the ambient interstellar medium. Because [O\,\textsc{iii}] is the only emission line that clearly traces the nebular morphology, we base our distance estimate exclusively on the [O\,\textsc{iii}] kinematics, obtaining a fiducial distance of $\sim$160 pc. At this distance, the nebula has a physical extent of $\sim$28 pc along the north-south direction. We suggest that the Silk Nebula is a large [O\,\textsc{iii}] filament possibly associated with a supernova remnant, although a diffuse-ionized-gas (DIG) or ionized-bubble origin cannot be ruled out with the present data, and one of the largest angular-scale [O\,\textsc{iii}] emission structures documented to date. Future deep X-ray observations and shock-modeling efforts are required to firmly establish its nature.

astro-ph.GA↗
arXiv2026

APCD: Adaptive Path-Contrastive Decoding for Reliable Large Language Model Generation

Reliable text generation is critical for deploying large language models (LLMs) in real-world applications, particularly in high-stakes domains such as medicine. To improve factual reliability, various inference-time methods have been proposed, including logit-level methods that modify token probability distributions and representation-level methods that manipulate intermediate model representations. However, most existing approaches operate on a single decoding trajectory, limiting their ability to explore alternative reasoning paths and making them susceptible to error accumulation. To address this limitation, we propose Adaptive Path-Contrastive Decoding (APCD), an adaptive multi-path contrastive decoding framework that improves factual reliability without model retraining or fine-tuning. APCD comprises two key components: Entropy-Driven Path Expansion, which adaptively expands the decoding process only at high-uncertainty decision points, and Divergence-Aware Path Contrast, which dynamically regulates contrastive interactions among parallel decoding paths based on their distributional divergence to balance diversity and coherence. We evaluate APCD on four LLM backbones across eight benchmarks spanning both general-domain and medical question answering tasks. Experimental results demonstrate that APCD consistently outperforms strong inference-time baselines in factual accuracy while maintaining competitive inference efficiency. These results demonstrate the robustness and generalizability of APCD across diverse models and tasks, highlighting its effectiveness as a practical multi-path decoding framework for reliable LLM deployment, particularly in high-stakes domains such as medicine. Code is available at https://github.com/zty-king/APCD.

cs.CL↗
arXiv2026

PrismPlan: A Shared GPU Substrate for Motion Planning Across Paradigms

GPU acceleration has made motion planning one to two orders of magnitude faster, but it has not made the three paradigms---sampling, search, and optimization---comparable to one another: every GPU-accelerated planner is built around a single paradigm, so comparing across libraries also compares their collision checkers. All three, however, bottleneck on the same GPU primitive: batched collision detection and the batched forward kinematics beneath it. PrismPlan builds that primitive once, as a shared substrate of per-sphere collision--kinematics device code that every planner consumes. Because they all execute the same device code, the backend is held fixed by construction and the paradigms can be compared head-to-head. We run six planners over 1800 MotionBenchMaker problems on three robots (7--14 DoF, one a dual-arm whole-body composite) at an equal 2s budget. On the 7-DoF Panda, sampling (pRRTC) is the most reliable paradigm at 98%, while parallel search (wPA*SE) follows within four points at a 3-4 times$ lower median latency, and the local optimizers trail well behind when made to solve from scratch. On the 14-DoF dual-arm composite, sampling still solves about 90% of feasible problems, while no search or optimization planner clears a third of them. Our open-source code is available at https://github.com/XiaoyubotMotionTeam/PrismPlan.

cs.RO↗
arXiv2026

Inside-out growth and the kiloparsec-scale star formation main sequence for low-surface-brightness disk galaxies in MaNGA

Low surface brightness galaxies (LSBGs) are very faint objects in the universe whose formation and evolution have long remained an unresolved problem. We selected a late-type, face-on, and disk-dominated galaxy sample from the MaNGA survey, composed of 38 LSBGs and 216 high surface brightness galaxies (HSBGs) by adopting a central surface brightness threshold $μ_{0}(g) = {\rm 22.0\ mag\ arcsec^{-2}}$. Based on maps derived from pipe3D products of star-forming areas in galaxies, we investigated the global and resolved star formation main sequence (SFMS and rSFMS) and radial profiles of the stellar mass density ($\mathrm{Σ_{*}}$), star formation rate density ($\mathrm{Σ_{SFR}}$), and specific star formation rate ($\mathrm{Σ_{sSFR}}$). The radial profiles of $\mathrm{Σ_{*}}$ and $\mathrm{Σ_{SFR}}$ present negative gradients, while those of $\mathrm{Σ_{sSFR}}$ present positive gradients. Compared to HSBGs, the LSBGs show similar, flatter, and steeper slopes in $\mathrm{Σ_{*}}$, $\mathrm{Σ_{SFR}}$, and $\mathrm{Σ_{sSFR}}$ gradients, respectively. The very flat $\mathrm{Σ_{SFR}}$ gradients of LSBGs, whose slopes range from -0.1 to -0.2, indicates uniform star formation throughout the whole galaxy, and the positive $\mathrm{Σ_{sSFR}}$ gradients reflects their ``inside-out'' growth. Our LSBGs and HSBGs follow the same global and resolved SFMS as the full sample, and $μ_{0}$ shows no influence on both SFMS and rSFMS. For our full sample and two subsamples (HSBGs and LSBGs), the slopes of global SFMS and rSFMS are consistent, which indicates that the SFMS still hold on a kiloparsec scale and the star formation activities are regulated by local events. The treatment of different excitation sources in galaxies affects the slope of the SFMS and rSFMS, and using star-forming areas only is more advisable.

astro-ph.GA↗
arXiv2026

Point-gap topology in amorphous non-Hermitian quantum systems

Recent studies have revealed that not only does the correspondence between spectral winding numbers and skin modes break down in non-Hermitian systems, but the energy spectrum itself is highly sensitive to generic perturbations, system size, and boundary conditions. In amorphous non-Hermitian systems, where the positions of lattice sites are uncertain, the spectral instability becomes even more severe, making it difficult to identify stable topological edge states from the eigenvalue spectrum alone. To overcome this challenge, we introduce a correspondence between stable zero-mode singular states and mid-gap states of the energy spectrum in the thermodynamic limit. Because the singular value spectrum is highly robust against small perturbations and variation in size, topological edge states can be reliably probed via singular values even in finite-sized systems. Based on the singular-value decomposition of the Hamiltonian, we construct a topological invariant in real space to characterize the associated topologically protected edge states. Our approach provides a general strategy for exploring point-gap topology in real space and redefine the non-Hermitian skin effect from a new perspective.

quant-ph↗
arXiv2026

Galactic HII regions in LAMOST Medium-Resolution Spectroscopic Survey of Nebulae

Based on LAMOST Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) data and WISE Galactic HII region catalog, we construct a sample of 280 Galactic HII regions and candidates in the Outer Galaxy (80$^{\circ}$ $\lesssim$ l $\lesssim$ 220$^{\circ}$). Using MRS-N optical spectra, we measure four emission lines (H$α$, [NII]$λ$6584, [SII]$λλ$6717,6731) and use line-ratios to spectroscopically confirm 255 HII regions, including 90 previously "Known" HII regions and 165 newly classified ones. We measure their $T_{\rm e}$, $n_{\rm e}$ and oxygen abundance, and determine distances via associated OB stars and the kinematic method. The sample spans $R_{\rm gal}$ from 8.16 to 15.36 kpc, enabling investigation of radial gradients in physical properties. We find [NII]/H$α$ and [SII]/H$α$ decrease with increasing $R_{\rm gal}$, while [SII]/[NII] remains nearly flat; these trends are quite different from diffuse ionized gas (DIG). We derive the $T_{\rm e}$ gradient of 344.530 $\pm$ 78.083 K kpc$^{-1}$, and the $\log n_{\rm e}$ gradient of -0.143 $\pm$ 0.041 cm$^{-3}$ kpc$^{-1}$. Oxygen abundance shows a steep slope of -0.044 $\pm$ 0.010 dex kpc$^{-1}$ in the inner disk and a shallow slope of -0.016 $\pm$ 0.005 dex kpc$^{-1}$ in the outer disk, with a global slope of -0.014 $\pm$ 0.005 dex kpc$^{-1}$. We also examine the two-dimensional distributions of $T_{\rm e}$, $n_{\rm e}$, and oxygen abundance, and find the gradients vary with azimuth. There is no obvious difference between spiral arm and interarm regions, and no trend appears along individual arms. From [NII]/H$α$-[SII]$λ$6717/H$α$ diagram, HII regions have a S$^+$/S ratio (0.32), lower than DIG (0.43); however, heavy overlap prevents clear separation from this diagram alone.

astro-ph.GA↗
arXiv2026

Home3D 1.0: A High-Fidelity Image-to-3D Asset Generation System for Interior Design

We present Home3D 1.0, a modular image-to-3D generation system that produces high-quality 3D assets from a single reference image, targeting interior design and e-commerce applications. Given a photograph of a furniture or decor item, the system outputs a mesh with physically-based rendering (PBR) materials, and the mesh can be decomposed into material-specific components. The pipeline is organized into four tightly coupled modules: Geometry reconstructs a watertight mesh through latent SDF modelling with a geometry VAE and a coarse-to-fine flow-matching DiT; Texture predicts multiview albedo observations, reprojects them onto the mesh, and completes unseen surface regions with a 3D texture field; Material uses MatWeaver to obtain component masks through video-based segmentation and UV-space voting, then retrieves and bakes PBR maps from a curated material library through hierarchical multi-modal matching; and Parts generates material-editable semantic part meshes with a PartVAE and PartDiT, decoding multi-head part-specific SDF fields in one pass. Each module is evaluated independently with dedicated metrics, highlighting both the current system capability and the remaining gaps toward broader deployment.

cs.CV↗
arXiv2026

Floquet topological phases with time-reversal and space inversion symmetries and dynamical detection of topological charges

For spinful systems with spin 1/2, it is generally believed that P and T invariant strong and second-order topologies exist in four band and eight band system, respectively. Here, by using periodic driving, we find it is possible to have strong topological insulator, second-order topological insulator and hybrid-order topological insulator in a single four band system. Furthermore, we established a direct connection between topology and dynamics. More convenient experimental detection for these topological phases has also been proposed. This study provides the theoretical basis for novel topological insulator that possess hybrid-order boundary states beyond the conventional regimes.

cond-mat.mes-hall↗
arXiv2026

Impact of Satellite Constellations on Observations with the 80-cm Telescope and the Mini-SiTian at the Xinglong Observatory, NAOC

The rapid development of mega-constellations in low Earth orbit (LEO) severely impacts ground-based optical astronomical observations. By combining WorldWide Telescope (WWT) simulations with 2019 and 2023 observational data from the Xinglong Observatory 80-cm telescope and 2023 data from the Mini-SiTian (MST), we find that satellite visibility increases with deployment, particularly during the summer. For the 80-cm telescope, the fraction of images containing satellite trails increased from an average of 0.34% in 2019 to 0.7% in 2023; meanwhile, for the MST in 2023, the fraction rose from 5% in January to 12% by December, peaking at 19% in the summer. Through stratified analysis of solar elevation and local time, we find that observations during twilight and summer are particularly susceptible to satellite trail interference. Photometric analysis reveals that the interference intensity increases for fainter sources and those closer to the trails. Furthermore, a comparative analysis across different seeing conditions shows that the deviation of median standardized residuals (σ) is significantly greater under poor seeing than under good seeing conditions.

astro-ph.IM↗
arXiv2026

ReST-KV: Robust KV Cache Eviction with Layer-wise Output Reconstruction and Spatial-Temporal Smoothing

Large language models (LLMs) face growing challenges in efficient generative inference due to the increasing memory demands of Key-Value (KV) caches, especially for long sequences. Existing eviction methods typically retain KV pairs with high attention weights but overlook the impact of attention redistribution caused by token removal, as well as the spatial-temporal dynamics in KV selection. In this paper, we propose ReST-KV, a robust KV eviction method that combines layer-wise output Reconstruction and Spatial-Temporal smoothing to provide a more comprehensive perspective for the KV cache eviction task. Specifically, ReST-KV formulates KV cache eviction as an optimization problem that minimizes output discrepancies through efficient layer-wise reconstruction. By directly modeling how each token's removal affects the model output, our method naturally captures attention redistribution effects, going beyond simplistic reliance on raw attention weights. To further enhance robustness, we design exponential moving average smoothing to handle temporal variations and an adaptive window-based mechanism to capture spatial patterns. Our method, ReST-KV, significantly advances performance on long-context benchmarks. It surpasses state-of-the-art baselines by 2.58% on LongBench and 15.2% on RULER. Additionally, ReST-KV consistently outperforms existing methods on Needle-in-a-Haystack and InfiniteBench, all while achieving a remarkable 10.61$\times$ reduction in decoding latency at 128k context length. The code is publicly available at https://github.com/an-yongqi/rest-kv to facilitate reproducibility and further research.

cs.CL↗
arXiv2026

SilverTorch: A Unified Model-based System to Democratize Large-Scale Recommendation on GPUs

Serving deep learning based recommendation models (DLRM) at scale is challenging. Existing approaches rely on dedicated ANN indexing and filtering services on CPUs, suffering from non-negligible costs and missing co-design opportunities. Such inefficiency makes them difficult to support complex model architectures, such as learned similarities and multi-task retrieval. In this paper, we present SilverTorch, a model-based serving system that brings all components into one unified model. It unifies model serving by replacing standalone indexing and filtering services with model layers. We propose a model-based GPU Bloom index for feature filtering and a fused Int8 ANN kernel for nearest neighbor search. Through co-design of the ANN search and feature filtering, we reduce GPU memory usage and eliminate computation. Benefiting from this design, we scale up retrieval by introducing an OverArch scoring layer and a multi-task retrieval with a Value Model to aggregate scores. These advancements improve the retrieval accuracy and enable future studies for serving more complex models. Our evaluation on industry-scale datasets show that SilverTorch achieves up to 23.7\times higher throughput compared to the state-of-the-art approaches. We also demonstrate that SilverTorch solution is 13.35\times more cost-efficient than CPU-based solution while improving accuracy via serving more complex models. SilverTorch is deployed at scale, serving hundreds of models online and supporting recommendation for diverse applications.

cs.IR↗
arXiv2026

Spectral Dataset of Stripped-Envelope Supernovae from the Tsinghua Supernova Group

The extent of envelope stripping in the progenitor stars is directly reflected in the diversity of spectral features observed in stripped-envelope supernovae (SESNe). Through extensive spectral observation and analysis, we aim to clarify the statistical differences between the subclasses of SESNe. The Tsinghua Supernova group obtained 249 optical spectra of 62 SESNe during the years from 2010 to 2020, covering phases from $-$16 to over 190 days relative to maximum light. Most spectra were obtained during the photospheric phases after the supernova explosion. For each spectrum, the pseudo-equivalent widths (pEWs) and blueshift velocities of principal lines were measured. We further investigated the common spectral features by analysing their velocity and strength correlations across all subtypes. We identify the feature near 6200~Å in SNe Ib as H$\mathrmα$ through comparison with SNe IIb and Ic, which resolves inconsistent literature interpretations. Our finding reveals prevalent residual hydrogen in SNe Ib, further supporting a continuous stripping sequence from SNe IIb to Ib. We observe a trend in increasing velocity among different subtypes of stripped-envelope SNe, with SNe IIb exhibiting the lowest line velocities, followed by Ib, Ic, and Ic-BL. Typically, the O~I lines in SNe Ic/Ic-BL are stronger than those seen in SNe IIb/Ib. In nebular phases, the [Ca II] emission dominates over [O I] in SNe IIb/Ib while [O I] is stronger in SNe Ic, including the He-rich SN 2016coi. This spectral dichotomy implies that progenitors of SNe Ic (BL) have more massive CO cores and hence higher initial masses.

astro-ph.HE↗
arXiv2026

The size-velocity dispersion relationship of Galactic HII regions

The size-velocity dispersion ($σ$) relation, while well established for giant HII regions, remains uncertain for their smaller counterparts (physical radii R < 20 pc). Thanks to the LAMOST MRS-N dataset's large sky coverage and high spatial/spectral resolution, we examined this relationship using 10 isolated Galactic HII regions with R < 20 pc. Our results reveal two key findings: (1) these small-size HII regions remarkably follow the same size-$σ$ relation as giant HII regions, suggesting this correlation could serve as a novel distance indicator for Galactic HII regions; and (2) we find distinct dynamical behaviors between younger and older HII regions. Specifically, in younger (< 0.5 Myr), ionization-bounded HII regions, the velocity dispersion shows no correlation with expansion velocity, indicating that turbulence is driven primarily by stellar winds and ionization processes. In contrast, in older (> 0.5 Myr), matter-bounded HII regions, a clear correlation emerges, implying that expansion-driven processes begin to play a significant role in generating turbulence. We therefore propose an evolutionary transition in the primary turbulence mechanisms, from being dominated by stellar winds and radiation to being increasingly influenced by expansion-driven dynamics, during the evolution of HII regions. Considering the small sample size used in this work, particularly the inclusion of only two young HII regions, which also have large uncertainties in their expansion velocities, further confirmation of this interpretation will require higher-resolution 2D spectroscopy to resolve blended kinematic components along the line of sight for more accurate estimation of expansion velocities, along with an expanded sample that specifically includes more young HII regions.

astro-ph.GA↗
arXiv2026

SN 2024abfl: A Low-Luminosity Type IIP Supernova in NGC 2146 from a Low-Mass Red Supergiant Progenitor

Type IIP supernovae (SNe IIP) exhibit a significant diversity in their explosion properties, yet the physical mechanisms driving this diversity remain unknown. In this work, we present photometric and spectroscopic observations of SN 2024abfl, a SN IIP in NGC 2146 with a directly detected red supergiant (RSG) progenitor. We find it has a low plateau luminosity ($M_V \sim -15$ mag) and a relatively long plateau length ($\sim 126.5$ days). By fitting a semi-analytical model, we estimated a $^{56}$Ni mass of $\sim 0.009 M_\odot$, an initial kinetic energy of $\sim 0.42$ foe, an initial thermal energy of $\sim 0.03$ foe and an ejecta mass of $\sim 8.3 M_\odot$. The spectral evolution of SN 2024abfl is similar to those of other SNe IIP, except for much lower ejecta velocities at similar epochs. At later epochs, we find a relatively high-velocity H$α$ absorption feature at $\sim -4000$ km s$^{-1}$, possibly due to a fast-moving plume of matter in the inner ejecta, and two emission features at $\pm 2000$ km s$^{-1}$, possibly caused by CSM interaction. We estimate the progenitor mass to be $\le 15 M_\odot$ based on nebular spectra. We conclude that SN 2024abfl is a low-luminosity SN IIP originating from a low-mass RSG progenitor.

astro-ph.HE↗
arXiv2026

Non-Hermitian second-order topological insulator with point gap

The zero-mode corner states in the gap of two-dimensional non-Hermitian Su-Schrieffer-Heeger model are robust to infinitesimal perturbations that preserve chiral symmetry. However, we demonstrate that this general belief is no longer valid in large-sized systems. To reveal the higher-order topology of non-Hermitian systems, we establish a correspondence between the stable zero-mode singular states and the topologically protected corner states of energy spectrum in the thermodynamic limit. Within this framework, the number of zero-mode singular values is directly linked to the number of mid-gap corner states. The winding numbers in real space can be defined to count the number of stable zero-mode singular states. Our results formulate a bulk-boundary correspondence for both static and Floquet non-Hermitian systems, where topology arises intrinsically from the non-Hermiticity, even without symmetries.

quant-ph↗
arXiv2025

StarWhisper Telescope: An AI framework for automating end-to-end astronomical observations

The exponential growth of large-scale telescope arrays has boosted time-domain astronomy development but introduced operational bottlenecks, including labor-intensive observation planning, data processing, and real-time decision-making. Here we present the StarWhisper Telescope system, an AI agent framework automating end-to-end astronomical observations for surveys like the Nearby Galaxy Supernovae Survey. By integrating large language models with specialized function calls and modular workflows, StarWhisper Telescope autonomously generates site-specific observation lists, executes real-time image analysis via pipelines, and dynamically triggers follow-up proposals upon transient detection. The system reduces human intervention through automated observation planning, telescope controlling and data processing, while enabling seamless collaboration between amateur and professional astronomers. Deployed across Nearby Galaxy Supernovae Survey's network of 10 amateur telescopes, the StarWhisper Telescope has detected transients with promising response times relative to existing surveys. Furthermore, StarWhisper Telescope's scalable agent architecture provides a blueprint for future facilities like the Global Open Transient Telescope Array, where AI-driven autonomy will be critical for managing 60 telescopes.

astro-ph.IM↗
arXiv2025

LAMOST Medium-resolution Spectroscopic Survey of the Rosette Nebula

We report multi-fiber, medium-resolution spectroscopy of the Rosette Nebula with full spatial coverages, and present a table of the nebular parameters based on the spatially-resolved measurements of emission lines. These new observations were conducted through the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N) on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Comprehensive analyses were performed on a total of 3854 high-quality nebular spectra, so far the most extensive spectral dataset available for this nebula that encompasses an area of 4.52 square degrees. Various physical parameters, including relative line intensities, radial velocities (RVs), and full widths at half maximum (FWHMs), were derived through measurements of the H-alpha, [N II] 6548,6584 and [S II] 6716,6731 emission lines detected in the LAMOST MRS-N spectra. For the first time, we found a bow-shaped feature in the spatial distribution of RVs of the Rosette Nebula. Moreover, the spatial distributions of RVs and FWHMs, as well as additional parameters such as gas temperature and turbulent velocity in the vicinity of the nebula, indicate possible interaction between Rosette and the nearby supernova remnant (SNR), Monoceros Loop. Our new observations provide indispensable measurements of the Rosette Nebula. The parameter table in particular can be used as valuable constraint on the chemo-dynamical modeling of the nebula, which will enable deeper understanding of the characteristics of this H II region.

astro-ph.GA↗