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2604.11420 2026-05-20 cond-mat.stat-mech quant-ph

Exact Criterion for Ground-State Overlap Dominance after Quantum Quenches

量子淬火后基态重叠主导的精确判据

Taisanul Haque

AI总结 该研究质疑了在相同平衡相内突然淬火后初始基态与最终基态最大重叠的猜想,推导出自由费米子系统中基态重叠主导的精确必要充分条件,并展示了Kitaev链中的反例以及动态量子相变的机制。

Comments 6 pages + 3 figures; comments are welcome

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AI中文摘要

最近有人猜想并验证了在横向场Ising模型中,突然淬火后初始基态与最终基态的最大重叠发生在相同平衡相内。我们证明这一基于相的判据在自由费米子系统中并不成立。对于可以分解为独立2×2动量子系统的哈密顿量,我们推导出基态重叠主导的精确必要充分条件:初始和最终子系统的Bloch矢量在每个动量下必须具有正的点积。该结果在某些相内淬火强制满足这一几何条件的类别中证明了猜想,但在Kitaev链中提供了明确的相同相反例,其中激发的最终本征态可以主导重叠分布。我们进一步表明,相同的障碍控制着实时Fisher零交叉,允许在不跨越平衡相边界的情况下发生动态量子相变。

英文摘要

It was recently conjectured and verified for the transverse-field Ising model [Phys. Rev. B 113, 165102 (2026)] that, after a sudden quench within the same equilibrium phase, the initial ground state has its largest overlap with the final ground state. We show that this phase-based criterion is generally false, even in translationally invariant free-fermion systems. For Hamiltonians that factorize into independent $2\times 2$ momentum sectors, we derive the exact necessary-and-sufficient condition for ground-state overlap dominance: the initial and final sector Bloch vectors must have positive dot product for every momentum. This result proves the conjecture in classes where same-phase quenches enforce this geometric condition, but gives explicit same-phase counterexamples in Kitaev chains, where excited final eigenstates can dominate the overlap distribution. We further show that the same obstruction controls real-time Fisher-zero crossings, allowing dynamical quantum phase transitions without crossing an equilibrium phase boundary.

2604.09901 2026-05-20 astro-ph.SR

Near-critical magnetic fields in Kepler red giants

开普勒红巨星中近临界磁场

S. Deheuvels, J. Ballot, F. Lignières, G. Li, M. Villate

AI总结 研究通过开普勒红巨星的地震检测揭示了核心磁场特征,探讨了磁场起源及其在内部角动量传输中的作用,发现强磁场对混合模式频率的影响需要非微扰方法进行分析。

Comments Accepted in A&A, 22 pages, 11 figures

详情
Journal ref
A&A 709, A224 (2026)
AI中文摘要

最近对红巨星核心磁场的地震检测提供了表征这些磁场的机会,可能提供关于其起源及其在内部角动量传输中的作用的信息。我们在八颗开普勒红巨星中检测到g模式周期的显著偏离,这些恒星显示l=1双峰。其中三颗恒星的模式显示出部分抑制。我们研究了这些特征的磁性起源,并确定了能够产生这些特征的核心磁场特性。我们需要引入强、近临界磁场。评估此类磁场对混合模式频率的影响需要非微扰方法。我们使用并改编了最近提出的方法,该方法类似于传统旋转近似(TAR)。然后我们计算了包括磁效应的混合模式频率渐近表达式,并尝试重现观测到的振荡光谱。我们表明,对于近临界磁场,可以获取关于径向磁场Br的径向分布的信息,而不是较弱磁场只能测量Br平方的加权平均。对于八颗目标恒星,我们发现l=1双峰不能识别为m=±1成分。相反,我们表明通过将两个成分识别为m=0和m=1可以很好地拟合所有观测结果。这些解对应于强度从100到700kG的磁场,这些磁场被限制在氢燃烧壳层以下。八颗恒星的最佳拟合模型具有低质量(1.1-1.2M⊙)且主序期间的对流核最大尺寸大约等于测量的磁场的径向范围。检测到的磁场可能由主序对流核中的发电机作用产生。

英文摘要

The recent seismic detection of magnetic fields in red giants cores has given the opportunity to characterize these fields, potentially giving information about their origin and their role in the internal transport of angular momentum. We detect strong deviations from the regular pattern of g-mode periods in eight Kepler red giants showing $l=1$ doublets. In three of these stars, the modes show partial suppression. We investigate the magnetic origin of these features and determine the characteristics of the core fields that can produce such signatures. We need to invoke strong, near-critical fields. Assessing the effects of such fields on the mixed mode frequencies requires a non-perturbative approach. We use and adapt a formalism that was recently proposed following a similar development as the traditional approximation for rotation (TAR). We then compute asymptotic expressions of mixed mode frequencies including magnetic effects and attempt to reproduce the observed oscillation spectra. We show that for near-critical fields, information can be obtained about the radial profile of the radial field $B_r$, as opposed to weaker fields for which only a weighted average of $B_r^2$ can be measured. For the eight targets, we find that the $l=1$ doublets cannot be identified as the $m=\pm1$ components. Instead, we show that very good fits to all the observations can be obtained by identifying the two components as $m=0$ and $m=1$. These solutions correspond to fields with intensities ranging from 100 to 700 kG that are confined well below the H-burning shell. Our best-fit models for the eight stars have low masses (1.1-1.2 $M_\odot$) and the maximal size of their convective core during the main sequence approximately corresponds to the radial extent of the measured magnetic fields. The detected fields could thus have been generated by dynamo action in the main-sequence convective core.

2604.07646 2026-05-20 cond-mat.mes-hall cond-mat.soft

Multiscale morphology and contact mechanics of physisorbed Al and Cu nanoparticles

吸附铝和铜纳米颗粒的多尺度形态与接触力学

Mykola Prodanov, Oleksii Khomenko

AI总结 通过大规模分子动力学模拟研究了吸附在悬空石墨烯上的铝和铜纳米颗粒的形态和接触力学性质的标度行为,发现小尺寸纳米颗粒的表面积与体积与线性尺寸的标度关系偏离二次和三次方依赖,而大尺寸纳米颗粒则趋近热力学极限。

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Journal ref
https://pubs.rsc.org/en/Content/ArticleLanding/2026/CP/D6CP00886K
AI中文摘要

利用大规模分子动力学模拟,我们研究了吸附在悬空石墨烯上的铝和铜纳米颗粒(NPs)的形态和接触力学性质的标度行为。NP的特征线性尺寸范围从1 nm到49 nm,覆盖了1.5个十倍的长度尺度。NP是通过模拟热退湿过程获得的。计算显示,表面面积与体积比超过约1.8 nm⁻¹或线性尺寸小于3-6 nm的NP行为不同于较大颗粒。对于这些较小的NP,其总表面积和体积与线性尺寸的标度可偏离二次和三次方依赖。它们的平均界面分离和相对接触面积随尺寸迅速变化,表现出显著变化。相比之下,对于较大NP,这些量接近热力学极限。所有粒子的高度分布都表现出一个窄峰和一个衰减尾部,对于较大的NP,这两个部分都可以用高斯函数拟合。相比之下,界面间隙分布接近单个高斯分布。较小NP的高度功率谱密度(PSD)热图是模糊的,不像较大NP的PSD表现出六重对称性。六边形2D PSD的最大空间频率大致对应于Al和Cu的最近邻原子距离。对于直径为20-25 nm的较大NP,各向同性高度PSD表现出幂律区域,可解释为自相似粗糙度,Hurst指数为0.1-0.56。我们还计算了表观接触面积与近似底层原子层面积的相对差异。我们的模拟展示了表面拓扑如何随NP尺寸演变,并表明较大NP可以具有随机表面粗糙度。

英文摘要

Using large-scale molecular dynamics simulations, we investigate the scaling of morphological and contact mechanics properties of Al and Cu nanoparticles (NPs) physisorbed on suspended graphene. The characteristic linear size of a NP ranges from 1 nm to 49 nm, covering a length scale of 1.5 decades. The NPs were obtained using a procedure mimicking thermal dewetting of thin films. Calculations show that NPs with a surface area-to-volume ratio above about 1.8 nm$^{-1}$, or with a linear size under 3-6 nm, behave differently from larger particles. For these smaller NPs, scaling of their total surface area and volume with the linear size can deviate from quadratic and cubic dependencies, respectively. Their mean interfacial separation and relative contact area change rapidly with size, exhibiting substantial variation. In contrast, for larger NPs, these quantities approach the thermodynamic limit. The height distributions of all particles exhibit a narrow spike and a decaying tail, both of which can be fit to Gaussians for larger NPs. In contrast, the interfacial gap distributions are close to a single Gaussian. The height power spectrum density (PSD) heatmaps of the smaller NPs are smeared and do not manifest a clear structure in contrast to the sixfold symmetry of the PSD of the larger ones. The maximum spatial frequency of the hexagonal 2D PSD roughly corresponds to the nearest-neighbor atomic distance of Al and Cu. For larger NPs with diameters of 20-25 nm, the isotropic height PSD exhibits power-law regions, which can be interpreted as self-affine roughness with Hurst exponents of 0.1-0.56. We also calculate the relative difference between the apparent contact area and the approximated area of the bottom atomic layer. Our simulations illustrate how surface topography evolves with NP size and suggest that larger NPs can have random surface roughness.

2604.06151 2026-05-20 astro-ph.SR

Testing the 3-equation Kuhfuss Convection Model using the Sun

用太阳测试3方程Kuhfuss对流模型

T. A. M. Braun, F. Ahlborn, F. Kupka, A. Weiss

AI总结 本文通过太阳作为基准,测试了更完整的3方程Kuhfuss湍流对流模型,发现该模型在内边界温度梯度建模上比混合长度理论和1方程模型更合理,但接近表面时会产生不物理的负温度梯度。

Comments 15 pages, 14 figures, accepted for publication in Astronomy & Astrophysics

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Journal ref
A&A 709, A228 (2026)
AI中文摘要

简化的一维模型对于恒星演化的对流建模是必要的。通过包括对流的非局部效应,湍流对流模型比通常用于一维恒星演化的混合长度理论在物理上更准确。我们最近表明,1方程Kuhfuss湍流对流模型不足以满意地建模太阳的对流包层。使用太阳作为基准,我们测试了更完整的3方程Kuhfuss湍流对流模型。我们使用一维恒星演进代码GARSTEC,用3方程Kuhfuss湍流对流模型计算了一个太阳校准的模型。我们将模型预测的内部结构与太阳的太阳震测量进行比较。此外,我们研究了3方程模型的自由参数和闭合关系如何影响结果。我们发现,与混合长度理论或1方程模型相比,3方程模型在对流包层内边界处的温度梯度建模更加合理。这也有助于改善模型与太阳之间的声速剖面的一致性,并减少恒星震观测表面效应。然而,接近表面时,3方程模型会产生一个具有不物理的负温度梯度的层。这个层与3方程模型中使用的闭合关系有关。我们的结果展示了湍流对流模型的能力,并可以作为改进和更真实建模恒星演进代码中对流的下一步。

英文摘要

Simplified, one-dimensional models are necessary to model convection in the context of stellar evolution. By including the non-local effects of convection, turbulent convection models describe convection in a more physical way compared to mixing length theory, which is typically used in one-dimensional stellar evolution models. We recently showed that the 1-equation Kuhfuss turbulent convection model is not sufficient to model the solar convective envelope satisfactorily. Using the Sun as a benchmark, we test the physically more complete 3-equation Kuhfuss turbulent convection model. We calculate a solar calibrated model with the 3-equation Kuhfuss turbulent convection model using the one-dimensional stellar evolution code GARSTEC. We compare the predicted interior structure of the model with helioseismic measurements of the Sun. Furthermore, we investigate how the free parameters and the closure relations of the 3-equation model influence the results. We find that, with the 3-equation model, the temperature gradient at the inner boundary of the convective envelope is modelled more realistically compared to the mixing length theory or the 1-equation model. This also improves the agreement for the sound speed profile between the model and the Sun, and reduces the asteroseismic surface effect. However, close to the surface, the 3-equation model results in a layer having an unphysical, negative temperature gradient. This layer is connected to the closure relations used in the 3-equation model. Our results demonstrate the capabilities of turbulent convection models, and can serve as a next step towards an improved and more realistic modelling of convection in stellar evolution codes.

2604.00671 2026-05-20 stat.CO

Implementation and Workflows for INLA-Based Approximate Bayesian Structural Equation Modelling

基于INLA的近似贝叶斯结构方程建模的实现与工作流

Haziq Jamil, Håvard Rue

AI总结 本文提出INLAvaan包,通过集成嵌套拉普拉斯近似框架实现快速近似贝叶斯结构方程建模,展示了其在复杂模型中的高效性能。

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AI中文摘要

贝叶斯结构方程建模(BSEM)提供了许多优势,如原理化的不确定性量化、小样本正则化和灵活的模型规范。然而,其依赖的马尔可夫链蒙特卡洛(MCMC)方法在仔细的心理测量实践中所需的迭代规范、批评和细化循环中计算上是不可行的。我们提出了INLAvaan,这是一个基于Jamil & Rue(2026,arXiv:2603.25690 [stat.ME])开发的结构方程模型集成嵌套拉普拉斯近似(INLA)框架的R包,用于快速、近似的贝叶斯结构方程建模。本文作为配套论文,描述了该包的架构决策和计算策略。两个实质性应用——一个具有256个参数的双因子圆周模型和一个具有完整信息缺失数据处理的多层中介模型——展示了该方法在MCMC需要数小时运行时间和仔细收敛工作的规范中的高效性能。相比之下,INLAvaan在几秒钟内即可提供校准的后验总结。

英文摘要

Bayesian structural equation modelling (BSEM) offers many advantages such as principled uncertainty quantification, small-sample regularisation, and flexible model specification. However, the Markov chain Monte Carlo (MCMC) methods on which it relies are computationally prohibitive for the iterative cycle of specification, criticism, and refinement that careful psychometric practice demands. We present INLAvaan, an R package for fast, approximate Bayesian SEM built around the Integrated Nested Laplace Approximation (INLA) framework for structural equation models developed by Jamil & Rue (2026, arXiv:2603.25690 [stat.ME]). This paper serves as a companion manuscript that describes the architectural decisions and computational strategies underlying the package. Two substantive applications -- a 256-parameter bifactor circumplex model and a multilevel mediation model with full-information missing-data handling -- demonstrate the approach on specifications where MCMC would require hours of run time and careful convergence work. In constrast, INLAvaan delivers calibrated posterior summaries in seconds.

2604.00098 2026-05-20 astro-ph.GA astro-ph.SR

The multi-age stellar populations of Terzan 5 as revealed by JWST

Terzan 5的多年龄恒星群体:通过JWST揭示

G. Zullo, C. Pallanca, F. R. Ferraro, B. Lanzoni, L. Origlia, D. Massari, E. Dalessandro, C. Fanelli, M. Cadelano, E. Vesperini, C. Crociati, R. M. Rich, E. Valenti

AI总结 本文利用JWST的观测数据,揭示了Terzan 5中存在多个不同年龄的恒星群体,通过光度分析确定了其中两个主要成分的年龄,并发现可能还存在更年轻的恒星成分。

Comments Accepted for publication in A&A

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Journal ref
A&A 709, A212 (2026)
AI中文摘要

詹姆斯·韦伯空间望远镜为研究位于银河系晕中的恒星系统提供了新的机会。Terzan 5可能是其中最神秘的天体之一:长期以来被归类为球状星团,但现在已知其包含具有不同铁含量的恒星群体(铁丰度范围大约从[Fe/H]=-0.8到[Fe/H]=+0.3 dex)。目前收集到的化学和结构特性表明,它可能是早期构成晕的原始团块之一,被称为“晕化石碎片”。本文基于JWST/NIRCam在F115W和F200W滤光片下的观测,以及存档的HST/ACS光学数据(F606W和F814W),对Terzan 5进行了新的光度分析。数据集克服了视线方向上严重的、空间变化的消光,获得了Terzan 5迄今为止最深的颜色-光度图。通过自行运动选择和高分辨率的差分消光校正,我们能够识别真正的星团成员,并提供了主序星轨区域的前所未有的视角。我们清晰地识别出两个主要成分,并确定了它们各自的年龄:老的、亚太阳成分的年龄为12.5±0.5 Gyr,而超太阳成分显著年轻,年龄为4.7±0.5 Gyr。有趣的是,我们还发现了一种更年轻的主序星轨和次巨星分支的迹象,这与存在一个年龄为3.8±0.5 Gyr的进一步恒星成分一致。此外,还发现了一个由亮度高达m_F115W≈17.4的恒星组成的蓝色烟雾,表明恒星形成持续到2.5 Gyr之前。

英文摘要

The James Webb Space Telescope provides an exciting opportunity to investigate stellar systems located in heavily obscured regions like the Galactic bulge. Possibly, the most enigmatic among them is Terzan 5: long classified as a globular cluster, it is now known to host distinct stellar populations with different iron abundances (ranging approximately from [Fe/H]=-$0.8$ to [Fe/H]=$+0.3$ dex). Indeed the chemical and structural properties collected so far suggest that it is the remnant of one of the primordial clumps that contributed to the early assembly of the bulge, a so-called "Bulge Fossil Fragment". Here we present a new photometric analysis of Terzan 5 based on JWST/NIRCam observations in the F115W and F200W filters, as well as archival HST/ACS optical (F606W and F814W) data. The dataset overcomes the severe and spatially variable extinction along the line of sight and yields the deepest color-magnitude diagram ever obtained for Terzan 5. Proper motion selections and high-resolution differential reddening corrections allow us to isolate bona fide cluster members and to provide an unprecedented view of the main-sequence turn-off region. We clearly identify two main components and determine their respective ages: the old, sub-solar component has an age of 12.5 $\pm$ 0.5 Gyr, while the super-solar component is significantly younger with an age of 4.7 $\pm$ 0.5 Gyr. Interestingly, we also find hints of an even younger main sequence turn-off and sub-giant branch, consistent with the presence of a further stellar component with an age of 3.8 $\pm$ 0.5 Gyr. There is also evidence of a blue plume populated by stars as bright as $m_{\rm F115W}\sim 17.4$, suggesting a prolonged period of star formation extending up to 2.5 Gyr ago.

2604.00096 2026-05-20 astro-ph.GA astro-ph.SR

Revealing the stellar population of the ultra-obscured Galactic globular cluster Glimpse-C02

揭示超遮蔽银河系球状星团Glimpse-C02的恒星群体

M. Loriga, M. Cadelano, C. Pallanca, F. R. Ferraro, B. Lanzoni, L. Chiappino, C. Crociati, E. Dalessandro, C. Giusti, S. Leanza, D. Massari, L. Origlia, E. Vesperini

AI总结 本文通过详细的光度分析,确定了银河系中最暗淡的球状星团Glimpse-C02的主序星转折点,并提供了其距离、金属licity、年龄等关键参数,揭示其可能位于银河中心附近,属于晕星团。

Comments 9 pages, 8 figures. Accepted for publication in A&A

详情
Journal ref
A&A 709, A186 (2026)
AI中文摘要

在本文中,我们对银河系中最暗淡的球状星团Glimpse-C02进行了详细的光度分析。我们构建了一个跨度约为10个星等的深度颜色-光度图,首次确定了该星团的主序星转折点。由于极端的红化影响该区域,需要进行差分红化校正。所得到的红化图揭示了红化变化高达δE(B-V)≈2.5 mag。通过差分红化校正后的颜色-光度图的等时线拟合,我们得到了平均颜色过量E(B-V)=6.33±0.05,以及距离模(m-M)₀=14.00±0.26,对应于太阳距离6.3±0.8 kpc,以及银心距离2.6±0.7 kpc。这个距离值,在相关不确定性范围内,表明该星团可能比之前的估计更靠近银河中心,可能支持其作为晕星团的分类。我们还得到了光度金属licity估计值[Fe/H]=-0.30±0.10,并得到了Glimpse-C02的第一个绝对年龄,结果为t=11.9±0.7 Gyr,这与在该金属licity下的银河系球状星团通常测量的年龄一致。我们还推导了星团的重心新估计,并通过解析恒星计数确定了其投影密度分布,发现高King集中参数(c=1.97±0.67±0.51)和核心半径r_c=8.72±0.40±0.35角秒。最后,通过系统的表面亮度分布,我们得到了积分H波段视星等M_H=-7.9,对应质量M=3.57±0.22±0.19×10⁴ M_⊙。因此,我们的工作将Glimpse-C02分类为一个古老且金属丰富的球状星团,处于其动力学演化的晚期阶段。

英文摘要

In this paper, we present the results of a detailed photometric analysis of Glimpse-C02, one of the most extincted globular clusters of the Milky Way. We built a deep color magnitude diagram spanning $\approx$ 10 magnitudes, enabling the first identification of the cluster's main sequence turnoff. Due to the extreme reddening affecting the region, a differential reddening correction was necessary. The resulting reddening map reveals variations up to $δE(B-V) \approx 2.5$ mag. From isochrone-fitting of the differential reddening corrected color-magnitude diagram, we derived a mean color excess $E(B-V)=6.33^{+0.05}_{-0.04}$, and a distance modulus $(m-M)_0=14.00^{+0.26}_{-0.11}$, corresponding to a distance of $d=6.3^{+0.8}_{-0.3}$ kpc from the Sun, and a Galactocentric distance of $2.6^{+0.6}_{-0.7}$ kpc. This distance value, within the associated uncertainties, suggests that the cluster may be located closer to the Galactic Center compared to previous estimates, possibly supporting its classification as a bulge globular cluster. We obtained a photometric metallicity estimate of [Fe/H]$=-0.30^{+0.10}_{-0.08}$ and the first absolute age determination for Glimpse-C02, resulting in $t=11.9^{+0.7}_{-0.6}$ Gyr, as typically measured for Galactic globular clusters at this metallicity. We also derived a new estimate of the center of gravity of the cluster and determined its projected density profile from resolved star counts, finding a high King concentration parameter ($c = 1.97_{-0.67}^{+0.51}$) and a core radius $r_c =8.72^{+0.40}_{-0.35}$ arcsec. Finally, from the surface brightness profile of the system, we derived an integrated $H$-band magnitude $M_{\rm H}=-7.9$, corresponding to a mass of $M=3.57^{+0.22}_{-0.19}\times 10^4 M_{\odot}$. Thus, our work classifies Glimpse-C02 as an old and metal-rich globular cluster that is in an advanced stage of its dynamical evolution.

2603.28855 2026-05-20 astro-ph.GA

The CAVITY project. The spatially resolved SFR of galaxies in voids

CAVITY 项目。星系空洞中的空间分辨恒星形成率

Ana M. Conrado, Rubén García-Benito, Rosa M. González Delgado, Bahar Bidaran, Hélène M. Courtois, Salvador Duarte Puertas, Daniel Espada, Andoni Jiménez, Ignacio del Moral-Castro, Isabel Pérez, Tomás Ruiz-Lara, Laura Sánchez-Menguiano, Gloria Torres-Ríos, Simon Verley, María Argudo-Fernández, Simon B. De Daniloff, Estrella Florido, Yllari K. González-Koda, Alejandra Z. Lugo-Aranda, Javier Román, Smitha Subramanian, Pedro Villalba-González, Manuel Alcázar-Laynez, Mónica Hernández-Sánchez, Mónica Rodríguez Martínez, Paulo Vásquez-Bustos, Martin Blazek

AI总结 研究空洞中星系的恒星形成率及其与密环境星系的差异,通过空间分辨的恒星形成率测量和比较,揭示空洞环境对星系演化的影响。

Comments 18 pages, 13 figures, 5 tables. Accepted for publication in A&A

详情
Journal ref
A&A 709, A227 (2026)
AI中文摘要

宇宙中的质量分布不均匀,形成了大尺度结构(LSS),其特征是星团、丝状物、墙和空洞。空洞中的星系更蓝,类型更晚,质量更小,其演化速度也更慢。空洞环境对恒星形成率(SFR)等性质的影响仍存在争议。我们通过估计220个空洞星系的空间分辨SFR,利用CAVITY调查的220个空洞星系的Halpha光度校正后的数据。这些观测包括来自加那利阿尔卑斯天文台PMAS/PPaK光谱仪的光学积分场单元数据立方体。我们测量连续基底减去的发射线以获得SFR、特定恒星形成率(sSFR)和消光的制图。我们评估了全局属性和半数光半径内的径向分布。我们使用相同的方法比较了来自CALIFA调查的丝状物和墙中的星系,构建了一个在形态和恒星质量上匹配的对照样本。我们发现SFR和sSFR没有显著差异,尽管空洞中的星系倾向于有更大的SFR,特别是对于早期螺旋星系。这种效应在Sa星系的所有银河心距离以及晚期螺旋星系的外围区域都存在,表明向休眠状态的过渡更慢,盘的演化也更少。空洞晚期型星系的消光较低。使用消光归一化为恒星质量表面密度作为气体质量分数的代理,我们发现空洞早期螺旋星系的该值更大,特别是在外围区域。这表明空洞环境对从恒星形成到被动状态的转变的影响。

英文摘要

The mass in the Universe is distributed non-uniformly, originating the Large Scale Structure (LSS), characterised by clusters, filaments, walls and voids. Galaxies in voids are bluer, later type, less massive, and have slower evolution than galaxies in denser environments. The effect of the void environment on properties such as star formation rate (SFR) is still under discussion. We tackle this by estimating spatially-resolved SFR from extinction-corrected Halpha luminosities of 220 void galaxies from the CAVITY survey. These observations consist of optical integral field unit data cubes from the PMAS/PPaK spectrograph at Calar Alto Observatory. We measure the continuum-subtracted emission lines to obtain maps of SFR, specific star formation rate (sSFR) and extinction. We assess global properties and radial profiles up to 2 half-light radii. We compare with galaxies in filaments and walls from the CALIFA survey using the same methodology, building a control sample matched in morphology and stellar mass. We find no significant differences in SFR and sSFR, although void galaxies tend to have larger SFR, especially for early spirals. This effect is present for Sa galaxies at all galactocentric distances, and in the outer parts of late-type spirals, evidencing slower transition to quiescence and less evolved discs. Void late-type galaxies have lower extinction. Using extinction normalised by stellar mass surface density as a proxy for gas mass fraction, we find it larger for void early spirals, especially in outer regions. This indicates the effect of the void environment on the transition from star forming to passive.

2603.25690 2026-05-20 stat.ME

Approximate Bayesian Inference for Structural Equation Models using Integrated Nested Laplace Approximations

使用集成嵌套拉普拉斯近似法对结构方程模型进行近似贝叶斯推断

Haziq Jamil, Håvard Rue

AI总结 本文提出了一种基于集成嵌套拉普拉斯近似法框架的近似贝叶斯方法,用于结构方程模型的推断,通过简化拉普拉斯近似和变分贝叶斯修正,提高了推断效率和准确性。

详情
AI中文摘要

马尔可夫链蒙特卡罗(MCMC)方法仍然是结构方程模型(SEM)贝叶斯估计的主要方法,尽管它们通常会产生较高的计算成本。我们提出了一种定制的近似贝叶斯方法用于SEM,借鉴了集成嵌套拉普拉斯近似法(INLA,Rue等人,2009,J. R. Stat. Soc. Series B Stat. Methodol.)框架的思想。我们实现了一种简化的拉普拉斯近似,能够高效地在每个参数方向上对后验密度进行轮廓化,并校正不对称性,从而实现参数化的偏斜正态估计。此外,我们应用变分贝叶斯修正来调整边际位置,从而更好地捕捉后验质量。基本量,包括因子得分和模型拟合指数,通过调整的高斯哥特采样方案获得。对于正常理论SEM,这种方法为基于采样的推断提供了一个高度准确的替代方案,实现了接近最大似然的速度,同时保留了完整贝叶斯推断的精度。

英文摘要

Markov chain Monte Carlo (MCMC) methods remain the mainstay of Bayesian estimation of structural equation models (SEM), though they often incur a high computational cost. We present a bespoke approximate Bayesian approach to SEM, drawing on ideas from the integrated nested Laplace approximation (INLA, Rue et al., 2009, J. R. Stat. Soc. Series B Stat. Methodol.) framework. We implement a simplified Laplace approximation that efficiently profiles the posterior density in each parameter direction while correcting for asymmetry, allowing for parametric skew-normal estimation of the marginals. Furthermore, we apply a variational Bayes correction to shift the marginal locations, thereby better capturing the posterior mass. Essential quantities, including factor scores and model-fit indices, are obtained via an adjusted Gaussian copula sampling scheme. For normal-theory SEM, this approach offers a highly accurate alternative to sampling-based inference, achieving near-'maximum likelihood' speeds while retaining the precision of full Bayesian inference.

2603.23674 2026-05-20 astro-ph.GA

MICONIC: JWST/MIRI-MRS reveals heavily reprocessed PAH emission in the circum-nuclear disc of Centaurus A

MICONIC:JWST/MIRI-MRS揭示Centaurus A核周边盘中强烈再加工的PAH发射

L. Pantoni, M. Baes, L. Decin, P. Guillard, A. Alonso Herrero, L. Evangelista, L. Hermosa Muñoz, I. García-Bernete, F. Donnan, V. Buiten, S. Garcia-Burillo, G. Wright, L. Colina, T. Böker, G. Östlin, D. Dicken, A. Labiano, D. Rouan, P. van der Werf, A. Eckart, M. García-Marín, M. Güdel, Th. Henning, P. -O. Lagage, F. Walter, M. J. Ward

AI总结 研究通过JWST/MIRI-MRS观测分析Centaurus A核周边盘中PAH的分布,发现PAH发射主要集中在环状结构中,同时发现一个PAH缺乏区域,该区域与增强的电离气体速度分散和流入的分子流体相关,表明PAH可能经历了更开放结构的加工过程。

Comments Accepted for publication in A&A. 14 pages, 10 figures; plus 5 pages and 4 figures in the appendices

详情
Journal ref
A&A 709, A237 (2026)
AI中文摘要

多环芳香烃(PAHs)是银河系中的关键尘埃成分,在星际介质(ISM)物理中起着基础作用,但其对活动星系核(AGN)反馈的响应仍存在争议。我们对Centaurus A中心$7^{\prime\prime} imes12^{\prime\prime}$($\sim100 imes200$ pc$^2$)区域的PAH进行了空间分辨分析。我们利用JWST/MIRI-MRS观测,其波长范围为5-28 $μ$m,来自MIRI欧洲 consortium GTO项目MICONIC,角分辨为$0.35^{\prime\prime}-1^{\prime\prime}$(约6-17 pc)。我们通过局部连续体减去法推导出PAH零阶矩图,并从五个感兴趣区域中提取一维光谱,包括核区、核周边盘和一个PAH缺乏区域。光谱被分解为连续体、发射线和PAHs,以测量特征强度和等效宽度(EWs)。PAH发射主要分布在环状结构中,局部增强位于核区约40 pc处。在西北方向发现一个明显的PAH缺乏区域,大致垂直于喷流轴,并与增强的电离气体速度分散和流入的分子流体相关。11.3/7.7 $μ$m和6.2/7.7 $μ$m比值超过对多环 condensed PAHs的模型预测,表明存在更开放结构的加工群体。11.3/12.7 $μ$m比值表明在PAH缺乏区域中氢单个位点占主导地位,并部分脱氢,尤其是由冲击波驱动的侵蚀。最大的EWs出现在环状结构中,而缺乏区域的减少值表明部分破坏;在核区,低EWs主要是由于连续体稀释。

英文摘要

Polycyclic aromatic hydrocarbons (PAHs) are key dust components in galaxies and play a fundamental role in the physics of the interstellar medium (ISM), yet their response to AGN feedback remains debated. We present a spatially resolved analysis of PAHs in the central $7^{\prime\prime}\times12^{\prime\prime}$ ($\sim100\times200$ pc$^2$) of Centaurus A. We use JWST/MIRI-MRS observations at 5-28 $μ$m from the MIRI European consortium GTO program MICONIC, with angular resolution of $0.35^{\prime\prime}-1^{\prime\prime}$ (about 6-17 pc). We derive PAH moment-0 maps via local continuum subtraction and extract one-dimensional spectra from five regions of interest, including the nucleus, the circumnuclear disc, and a PAH-deficient region. The spectra are decomposed into continuum, emission lines, and PAHs to measure feature intensities and equivalent widths (EWs). PAH emission is primarily distributed in a ring-like structure with localized enhancements at $\sim40$ pc from the nucleus. A distinct PAH-deficient region is observed to the north-west, roughly perpendicular to the jet axis, and coincident with enhanced ionized-gas velocity dispersion and inflowing molecular streamers. The 11.3/7.7 $μ$m and 6.2/7.7 $μ$m ratios exceed model predictions for pericondensed PAHs, indicating processed populations with more open structures. The 11.3/12.7 $μ$m ratio suggests a dominance of solo hydrogen sites and partial dehydrogenation, particularly in the PAH-deficient region, where shocks likely drive erosion. The largest EWs are found in the ring, while reduced values in the deficient region point to partial destruction; in the nucleus, low EWs are mainly due to continuum dilution.

2603.23038 2026-05-20 econ.TH

Stable Matchings with Choice Correspondences Under Acyclicity

具有选择对应关系的稳定性匹配与循环性

Varun Bansal, Mihir Bhattacharya, Ojasvi Khare

AI总结 本文研究了当代理人具有选择对应关系而非偏好关系时稳定性匹配的存在性,提出了基于弱化路径独立性假设的框架,并在多对多市场中证明了在满足可替代性和一般循环性条件下稳定性匹配存在,同时提出了一种构造性算法来生成稳定性匹配。

详情
AI中文摘要

我们研究了当代理人具有选择对应关系而非偏好关系时稳定性匹配的存在性。我们通过弱化路径独立性假设扩展了Chambers(2017)的框架。对于多对多市场,我们证明当选择对应关系满足可替代性和一个新的一般循环性条件时,稳定性匹配存在。我们提供了一种构造性证明,使用“生长或剔除”算法迭代扩展或消除合同,直到达到一个强最大个体理性集。我们提供了一种算法来获得稳定性匹配,其中被拒绝的合同不会被永久剔除,这与标准DAA型算法有显著区别。对于一对一市场,我们引入了一种基于替换的稳定性概念,并提供了一种算法,当选择对应关系满足二元循环性时,可以构造稳定性匹配。二元循环性是比路径独立性弱的性质。

英文摘要

We study the existence of stable matchings when agents have choice correspondences instead of preference relations. We extend the framework of \cite{chambers2017choice} by weakening the path independence assumption. For many-to-many markets, we show that stable matchings exist when choice correspondences satisfy substitutability and a new general acyclicity condition. We provide a constructive proof using a Grow or Discard Algorithm that iteratively expands or eliminates contracts until a strongly maximal individually rational set is reached. We provide an algorithm to obtain stable matchings in which rejected contracts are not permanently discarded, distinguishing our approach significantly from standard DAA-type algorithms. For one-to-one markets, we introduce a replacement-based notion of stability and provide an algorithm that constructs stable matchings when choice correspondences satisfy binary acyclicity, a property weaker than path independence. JEL classification: C62, C78, D01, D47 Keywords: choice correspondences, substitutability, general acyclicity, many-to-many matching, matching with contracts, Grow or Discard algorithm, replacement stability, binary acyclicity.

2603.22007 2026-05-20 astro-ph.GA astro-ph.SR

JOYS: Linking the molecular ice and gas-phase composition towards the high-mass hot core IRAS 18089-1732

JOYS:连接分子冰和气相组成以研究高质量热核IRAS 18089-1732

C. Gieser, W. R. M. Rocha, Y. Chen, K. Slavicinska, E. F. van Dishoeck, P. Nazari, N. G. C. Brunken, L. Francis, H. Beuther, S. Reyes-Reyes, A. Caratti o Garatti, P. D. Klaassen, J. M. Vorster, M. G. Navarro

AI总结 研究通过JWST和ALMA数据确定IRAS 18089-1732区域内的分子冰和气相柱密度,发现某些分子在气相中更丰富,而其他分子在冰中更丰富,揭示了星际介质中分子形成和破坏的复杂过程。

Comments 13 pages, 7 figures, accepted for publication in A&A

详情
Journal ref
A&A 709, A235 (2026)
AI中文摘要

背景。星际介质中分子的形成和破坏是气相反应和颗粒表面及冰壳内过程之间的复杂相互作用。在数十年来,通过(亚)毫米波段设施可以很好地表征恒星形成区域的气相组成。在詹姆斯·韦伯太空望远镜(JWST)发射之前,除了主要成分(H2O,CO,CO2,NH3,CH4,CH3OH)以外,其他冰物种由于灵敏度不足以及角分辨率和/或光谱分辨率不足而难以检测。目标。我们确定年轻且嵌套的高质量热核IRAS 18089-1732区域(5000 au)内的分子冰和气相柱密度。方法。我们使用JWST在5-28微米范围内的光谱数据来推导H2O、SO2、OCN-、CH4、HCOO-、HCOOH、CH3CHO、CH3COOH、C2H5OH、CH3OCH3和CH3COCH3的冰柱密度。通过使用阿塔卡马大毫米波/亚毫米波望远镜(ALMA)在3毫米波长处进行敏感分子线观测,推断出总共38种分子的气相柱密度,包括含O、N、S和Si的物种以及较少的同位素。结果。我们发现C2H5OH、CH3OH和CH3OCH3在两种相中的相对丰度相当。SO2和CH3COCH3的丰度在气相中更高,表明存在额外的气相形成途径。CH3CHO的冰中丰度比气相高一个数量级。IRAS 18089热核的冰中丰度(相对于H2O冰)与之前研究的银河系低质量和高质量原恒星相似。OCN-、CH3OH和CH3CHO冰的丰度似乎随着银心距离的增加而减少。(摘要版)

英文摘要

Context. The formation and destruction of molecules in the interstellar medium is a complex interplay between gas-phase reactions as well as processes on grain surfaces and within icy mantles. For many decades, the gas-phase composition of the cold material towards star-forming regions could be well characterized using (sub)mm facilities. Prior to the launch of the James Webb Space Telescope (JWST), ice species other than the main constituents (H2O, CO, CO2, NH3, CH4, CH3OH) were challenging to detect due to insufficient sensitivity as well as angular and/or spectral resolution. Aims. We determine molecular ice and gas-phase column densities towards the young and embedded high-mass hot core IRAS 18089-1732 within a region of 5000 au. Methods. We use spectroscopic data from 5-28 micron obtained with JWST to derive ice column densities of H2O, SO2, OCN-, CH4, HCOO-, HCOOH, CH3CHO, CH3COOH, C2H5OH, CH3OCH3, and CH3COCH3. Gas-phase column densities of a total of 38 molecules, including, O-, N-, S-, and Si-bearing species as well as less abundant isotopologues, are inferred from sensitive molecular line observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA) at 3 mm wavelengths. Results. We find comparable abundances (relative to C2H5OH or CH3OH) in both phases for C2H5OH, CH3OH, and CH3OCH3. The abundances of SO2 and CH3COCH3 are higher in the gas-phase suggesting additional gas-phase formation routes. The abundance of CH3CHO is one order of magnitude higher in the ices compared to the gas-phase. The ice abundances (relative to H2O ice) towards the IRAS 18089 hot core are similar to previously studied Galactic low- and high-mass protostars. There are hints of a decreasing abundance with Galactocentric distance for OCN-, CH3OH, and CH3CHO ice. (abridged)

2603.17184 2026-05-20 astro-ph.CO

Reconstructing the Type Ia Supernova Absolute Magnitude with Two-Probe Physics-Informed Neural Networks

用双探针物理信息神经网络重构Ia型超新星绝对星等

Denitsa Staicova

AI总结 本文利用两种变种的物理信息神经网络,通过结合BAO和超新星数据,在四种宇宙模型下重构Ia型超新星绝对星等M_B(z),发现Etherington距离双关关系比宇宙模型先验更基本,且在所有模型中均恢复M_B≈-19.3 mag,揭示了红移分组分布的系统性分离。

Comments 16 pages, 6 figures, 4 tables, final published version

详情
Journal ref
Physics of the Dark Universe, Volume 52, 2026, 102342
AI中文摘要

我们应用两种变种的物理信息神经网络(PINNs)来从联合BAO和超新星数据中重构Ia型超新星绝对星等M_B(z),在四种宇宙模型(ΛCDM、CPL、GEDE、Λ_sCDM)和两个DESI DR2基准集下进行。一种异方差单网络方法在四个约束配置中测试表明,Etherington距离双关关系比宇宙模型先验更基本,可减少内部不一致性的数量级。在完全约束下,所有模型均恢复M_B≈-19.3 mag,偏差低于0.05 mag。一种基于Fisher信息加权的双网络变种在BAO和SN数据上训练独立网络,提供清晰的探测分离;发现z∈[0.3,1.5]内无显著的M_B演变,但揭示了红移分组M_B分布的系统性分离。异方差方法在z≈0.4-0.5处发现持续的2-3σ残差,所有四个模型和两个基准集均一致,暗示相同的潜在紧张。虽然该特征的起源仍不明确,但其模型无关性和跨方法一致性值得进一步研究。

英文摘要

We apply two variants of Physics-Informed Neural Networks (PINNs) to reconstruct the Type~Ia supernova absolute magnitude $M_B(z)$ from joint BAO and supernova data under four cosmological models ($Λ$CDM, CPL, GEDE, $Λ_s$CDM) and two DESI~DR2 fiducial sets. A heteroscedastic single-network method tested across four constraint configurations establishes that the Etherington distance duality relation is a more fundamental constraint than cosmological model priors, reducing internal inconsistencies by up to an order of magnitude. Under full constraints all models recover $M_B \approx -19.3$~mag with biases below 0.05~mag. A Fisher information-weighted two-network variant trains independent networks on BAO and SN data, providing clean probe separation; it finds no significant pointwise $M_B$ evolution in $z \in [0.3, 1.5]$, but reveals a systematic separation of redshift-binned $M_B$ distributions. The heteroscedastic method identifies a persistent $2$--$3σ$ residual at $z \sim 0.4$--$0.5$ that is consistent across all four models and both fiducials, implying the same underlying tension. While the origin of this feature remains ambiguous, its model-independence and cross-method consistency warrant further investigation with forthcoming data.

2603.15955 2026-05-20 astro-ph.EP

A chemical perspective on planet formation in reduced systems

从化学角度探讨简化系统中的行星形成

Urja Zaveri, Haiyang S. Wang, Paolo A. Sossi

AI总结 本文研究了恒星C/O比和盘压变化对凝结化学的影响,揭示了在简化环境中将恒星组成映射到行星构建块的可靠性问题,发现不同凝结区域导致行星esimal成分差异显著。

详情
Journal ref
A&A 709, A223 (2026)
AI中文摘要

行星中难熔元素的相对丰度通常被认为反映其宿主恒星的丰度。然而,由于元素根据其在太阳星云中的行为进行分类,这隐含假设凝结过程与星云化学无关,尽管在化学简化系统中高碳氧比(C/O)比提供了相反的证据。我们研究了恒星C/O比和盘压变化如何影响凝结化学,并评估了在简化环境中将恒星组成映射到行星构建块的可靠性。对于C/O比在0.65-0.95(太阳=0.50)范围内的FGK恒星样本,我们使用FactSage在1900-400 K温度范围内计算平衡相稳定性,总压力为1e-2、1e-4和1e-6 bar。通过随机吸积框架聚合温度依赖的喂养区凝结物,推导出整体行星esimal组成。我们识别出三种不同的凝结区域:(i)类太阳(C/O < 0.7),(ii)过渡(C/O ~ 0.7-0.91),(iii)简化(C/O > 0.92)。与太阳序列相比,在过渡和简化区域中,含氧硅酸盐在较低温度下凝结,同时出现碳化物、硅化物和硫化物。整体行星esimal的Fe/Mg、Fe/Si和Fe/O比值显著偏离宿主恒星值,产生更多样化的岩石构建块。凝结序列并不在所有恒星组成中都是普遍的。在简化盘中,通常被视为难熔的元素比值可能无法可靠地追踪行星整体组成,为金属富集的超水星类行星和富含碳和硫的岩石行星提供潜在的形成路径。

英文摘要

Relative abundances of refractory elements in planets are commonly assumed to reflect those of their host stars. However, because elements are classified according to their behaviour in the solar nebula, this implicitly assumes condensation is independent of nebular chemistry, despite evidence to the contrary in chemically reduced systems with high molar carbon-to-oxygen (C/O) ratios. We investigate how variations in stellar C/O ratio and disk pressure modify condensation chemistry and assess the reliability of mapping stellar compositions to planetary building blocks in reduced environments. For a sample of FGK stars with C/O ratios spanning 0.65-0.95 (solar = 0.50), we compute equilibrium phase stability using FactSage over 1900-400 K at total pressures of 1e-2, 1e-4, and 1e-6 bar. Bulk planetesimal compositions are derived using a stochastic accretion framework aggregating condensates from temperature-dependent feeding zones. We identify three distinct condensation regimes: (i) solar-like (C/O < 0.7), (ii) transitional (C/O ~0.7-0.91), and (iii) reduced (C/O > 0.92). Relative to solar sequences, oxygen-bearing silicates condense at lower temperatures in transitional and reduced regimes, while carbides, silicides, and sulfides appear. Bulk planetesimal Fe/Mg, Fe/Si, and Fe/O ratios deviate substantially from host stellar values, producing more diverse rocky building blocks within a single disk. Condensation sequences are not universal across stellar compositions. In reduced disks, elemental ratios commonly treated as refractory may not reliably trace planetary bulk composition, providing potential formation pathways for metal-enriched super-Mercury analogues and C- and S-rich rocky planets.

2603.14511 2026-05-20 astro-ph.CO gr-qc

Cosmological peculiar velocities in general relativity

广义相对论中的宇宙学异常速度

Chris Clarkson, Roy Maartens

AI总结 本文重新审视了在1+3协变方法中晚期时间银河系异常速度的演化,指出协变方法并不比标准度量方法预测更强的异常速度增长,且错误源于对协变系统的不一致处理。

Comments 11 pages. Now includes additional material in response to 2603.28377. To appear in the Open Journal of Astrophysics

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AI中文摘要

我们重新考虑了在1+3协变方法中晚期时间银河系异常速度的演化。最近有人声称该方法预测异常速度增长比标准度量方法更强,因为协变处理是完全相对论的,而标准处理本质上是牛顿力学的。我们证明并非如此。当协变方程被一致应用时,1+3方法精确地再现了标准扰动理论中异常速度增长的标准结果。最近工作中声称的更强增长定律源于对耦合协变系统的不一致处理,在这种处理中,受场方程约束的项被当作独立源来处理。进一步声称更强的总体流可以模仿尘埃宇宙中的加速膨胀。我们论证这些说法基于对任意选择的观察者共轭线的运动学与由银河系追踪的物质共轭线的物理膨胀之间的混淆。我们得出结论,标准处理异常速度的方法是正确且完全相对论的,并不导致异常总体流或看似加速膨胀。

英文摘要

We reconsider the late-time evolution of galaxy peculiar velocities in the 1+3 covariant approach to cosmological perturbation theory. It has recently been claimed that this approach predicts substantially stronger growth of peculiar velocities than standard metric-based perturbation theory -- on the grounds that the covariant treatment is fully relativistic whereas standard treatments are effectively Newtonian. We show that this is not the case. When the covariant equations are applied consistently, the $1+3$ approach reproduces exactly the standard perturbative result for peculiar-velocity growth. The stronger growth laws claimed in recent work arise from an inconsistent treatment of the coupled covariant system, in which terms constrained by the field equations are treated as if they were independent sources. Further claims are made that the stronger bulk flows can mimic accelerated expansion in a dust universe. We argue that these claims rest on a confusion between the kinematics of an arbitrarily chosen observer congruence and the physical expansion of the matter congruence traced by galaxies. We conclude that the standard treatment of peculiar velocities is correct and fully relativistic~-- and does not lead to anomalous bulk flows or to apparent accelerated expansion.

2603.13921 2026-05-20 astro-ph.SR physics.plasm-ph physics.space-ph

Formation and rising phase of a flux rope through data-constrained simulations

通过数据约束模拟研究磁通绳的形成与上升阶段

M. V. Sieyra, A. Strugarek, A. Prasad, A. Wagner, P. Démoulin, F. Moreno-Insertis, A. J. Finley, R. Joshi, A. Blaise, A. S. Brun, E. Buchlin

AI总结 本文通过数据约束模拟研究了太阳耀斑事件SOL2014-12-18T21:41的形成与上升阶段,探讨了放松初始无电流假设对磁通绳形成的影响。

Comments 17 pages, 14 figures

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Journal ref
A&A 709, A211 (2026)
AI中文摘要

背景。数据约束模型结合了观测到的光球磁层磁场。然而,由于日冕其他部分缺乏磁场信息,模型依赖于外推,大多数情况下忽略了洛伦兹力。然而,这种力存在于低大气层,并可能在破坏平衡配置和触发爆发中起关键作用。目标。本研究旨在理解和再现发生在活跃区域NOAA 12241的太阳爆发SOL2014-12-18T21:41,该爆发 preceded by 一个M6.9闪焰,并探讨放松初始无电流假设的影响。方法。通过非无电流磁流体动力学模拟,利用在闪焰前几分钟获取的光球向量磁图进行非无电流磁场外推作为初始条件。该模拟包括分层大气和非理想效应,如热传导和辐射冷却。结果。模拟中形成了并上升了磁通绳,携走了来自低日球层的致密物质。其形成源于初始扭曲拱形上非零洛伦兹力的作用,不假设预先存在的磁通绳或光球驱动运动。磁通绳随后被偏转向磁压较低的区域,以约350 km/s的速度逃离模拟域,具有近似恒定的加速度。结论。通过应用稳健的数值框架对NOAA AR12241爆发进行建模,作为案例研究,假设在闪焰开始时的现实非无电流磁场。它展示了初始洛伦兹力不平衡如何成功触发磁通绳的形成,该磁通绳后来逃离模拟域。它还通过添加从光球到日冕的分层大气层,使与真实观测的比较成为可能。

英文摘要

Context. Data-constrained models incorporate observed photospheric magnetic fields. However, due to the lack of magnetic field information in the rest of the solar atmosphere, models rely on extrapolations that, in most cases, neglect the Lorentz force. Nevertheless, this force is present in the lower atmosphere and may play a key role in destabilising the equilibrium configuration and triggering eruptions. Aims. This study seeks to understand and reproduce a solar eruption SOL2014-12-18T21:41 that occurred in active region NOAA 12241, preceded by an M6.9 flare, and to investigate the impact of relaxing the initial force-free assumption. Methods. The resistive and compressible magnetohydrodynamic simulation is initiated using a non-force-free magnetic field extrapolated from a photospheric vector magnetogram taken minutes before the flare. The simulation includes a stratified atmosphere and non-ideal effects such as thermal conduction and radiative cooling. Results. A flux rope forms and rises in the simulation, carrying away dense material from the lower solar atmosphere. Its formation results from the non-zero Lorentz force acting on the initial sheared arcade, without assuming pre-existing flux ropes or photospheric driving motions. The flux rope is then deflected toward regions of low magnetic pressure, escaping the domain at 350 km/s with approximately constant acceleration. Conclusions. A robust numerical framework for modelling flaring active regions was applied to the eruption of NOAA AR12241 as a case study, assuming a realistic non-force-free magnetic field near the flare onset. It exemplifies how an initial Lorentz force imbalance can successfully trigger a flux rope formation that later escapes the simulation domain. It also enables comparison with real observations through the addition of a stratified atmosphere spanning from the photosphere to the corona.

2603.13701 2026-05-20 astro-ph.SR astro-ph.GA

Asteroseismology of red giants in the globular cluster 47 Tuc using the HST

利用哈勃空间望远镜对球状星团47 Tuc中的红巨星进行恒星内部结构研究

Dennis Stello, Timothy R. Bedding, Ronald L. Gilliland

AI总结 本文通过哈勃空间望远镜的数据,对47 Tuc球状星团中的红巨星进行太阳型振荡搜索,确定了两颗恒星的质量,并推断出上红巨星分支的总质量损失,为未来的观测任务提供了依据。

Comments 5 pages + references, 6 figures, accepted by MNRAS

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Journal ref
Mon Not R Astron Soc (2026)
AI中文摘要

球状星团为研究恒星演化提供了独特的机会——作为第二亮的星团,47 Tuc是一个主要目标。通过恒星内部结构研究可以精确测量恒星质量,最近已应用于球状星团中的红巨星,但尚未应用于47 Tuc。本文利用8.3天的高采样率哈勃空间望远镜数据,对47 Tuc中的红巨星进行太阳型振荡搜索。我们检测到其中两颗红巨星的振荡,一颗位于水平分支(HB),另一颗位于红巨星分支(RGB)且亮度相似。从地震信号中,我们测得恒星质量为$0.78\pm0.13\,$M$_\odot$(HB)和$0.94\pm0.15\,$M$_\odot$(RGB),从而推断出上RGB的总质量损失为$0.16\pm0.20\,$M$_\odot$。要获得有用的总质量损失估计,需要质量不确定性小于0.05M$_\odot$,而要测量星团多个化学群体之间的质量差异,需要不确定性低于0.01M$_\odot$。前者可通过观测约100倍更多的恒星以形成群体平均值,或通过更长的观测任务观测更少的恒星来实现。检测化学亚群体之间的质量差异可通过20天的观测任务观测数百颗恒星来实现。我们对振荡的清晰检测以及本文提出的前景表明,有必要进行专门的高采样率任务对47 Tuc进行观测,这可能通过NASA的罗马任务和未来如HAYDN任务实现。

英文摘要

Globular clusters provide unique opportunities to study stellar evolution -- as the second brightest cluster, 47 Tuc is a prime target. Asteroseismology can be used to measure precise masses of stars and has recently been applied to red giants in globular clusters, but so far not for 47 Tuc. Here, we present a search for solar-like oscillations in red giants of 47 Tuc using 8.3 days of high-cadence Hubble Space Telescope data. We detect oscillations in two out of the five giants falling in the field of view. One is on the horizontal branch (HB) while the other is on the red giant branch (RGB) at a similar brightness. From the seismic signal, we measure the stellar masses to be $0.78\pm0.13\,$M$_\odot$ (HB) and $0.94\pm0.15\,$M$_\odot$ (RGB), and hence an inferred integrated mass loss along the upper RGB of $0.16\pm0.20\,$M$_\odot$. A mass uncertainty of less than 0.05M$_\odot$ would be required to obtain a useful estimate of the mass loss, while an uncertainty below 0.01M$_\odot$ would be required to measure the mass difference between the cluster's multiple chemical populations. The former would be attainable with observations of about 100 times more stars to form ensemble-averaged values, or alternatively a longer campaign observing fewer stars. Detecting mass differences between the chemical sub-populations, could be obtained with a 20-day campaign observing several hundreds of stars. Our clear detection of oscillations and the prospects presented here warrant dedicated high-cadence campaigns of 47 Tuc, which are possible with NASA's Roman mission and future missions like HAYDN.

2603.13671 2026-05-20 cs.DC cs.MA cs.PL

Grassroots Bonds as a Foundation for Market Liquidity

基层债券作为市场流动性的基础

Ehud Shapiro

AI总结 本文提出基层债券,通过引入到期日扩展基层加密货币,将现金重新定义为成熟的基层债券,从而允许通过利息-bearing信用实现流动性,使本地数字经济能够在没有初始资本或外部信用的情况下形成和成长。

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AI中文摘要

全球加密货币未被背书且具有高交易成本,而基层加密货币由发行者提供的商品和服务背书,且仅需操作智能手机即可完成交易。基层加密货币的流动性源于发行者之间的相互信用通过硬币交换产生。然而,由于基层硬币可按1:1兑换任何其他基层硬币,信用形成交换也必须为1:1,否则在兑换后可能使各方产生不当利润或损失。因此,基层硬币与通过利息-bearing信用实现的流动性不一致。本文引入基层债券,通过引入到期日扩展基层硬币,将现金重新定义为成熟的基层债券。债券赎回扩展了硬币赎回,允许用流动的硬币交换利息-bearing未来到期的债券。我们展示数字社会合同——人们之间的自愿协议,通过数字方式指定、履行和执行——可以表达所有金融工具作为自愿的基层债券交换,包括贷款、债务出售、远期合约、期权和基于托管的工具,并且经典流动性比率同样适用于基层债券。基层债券可能因此使本地数字经济在没有初始资本或外部信用的情况下形成和成长,利用社区内的相互信任产生流动性。本文所呈现的形式化规范是在GLP中实现的,GLP是一种在Dart上运行的并发逻辑编程语言,用于智能手机部署。该实现通过GLP中的运行多智能体村庄市场场景进行说明。

英文摘要

Global cryptocurrencies are unbacked and have high transaction cost incurred by global consensus. In contrast, grassroots cryptocurrencies are backed by the goods and services of their issuers -- any person, natural or legal -- and have no transaction cost beyond operating a smartphone. Liquidity in grassroots cryptocurrencies arises from mutual credit via coin exchange among issuers. However, as grassroots coins are redeemable 1-for-1 against any other grassroots coin, the credit-forming exchange must also be 1-for-1, lest prompt redemption after exchange would leave the parties with undue profit or loss. Thus, grassroots coins are incongruent with liquidity through interest-bearing credit. Here we introduce grassroots bonds, which extend grassroots coins with a maturity date, reframing grassroots coins -- cash -- as mature grassroots bonds. Bond redemption generalises coin redemption, allowing the lending of liquid coins in exchange for interest-bearing future-maturity bonds. We show that digital social contracts -- voluntary agreements among persons, specified, fulfilled, and enforced digitally -- can express the full gamut of financial instruments as the voluntary swap of grassroots bonds, including loans, sale of debt, forward contracts, options, and escrow-based instruments, and that classical liquidity ratios are applicable just as well to grassroots bonds. Grassroots bonds may thus allow local digital economies to form and grow without initial capital or external credit, harnessing mutual trust within communities into liquidity. The formal specification presented here was implemented in GLP, a concurrent logic programming language running on Dart for smartphone deployment. The implementation is illustrated by a running multiagent village market scenario in GLP.

2603.11202 2026-05-20 astro-ph.EP astro-ph.IM

Cold giant discoveries from a joint radial-velocity and astrometry framework

从联合径向速度和视差测量框架发现冷型巨行星

Pablo A. Peña, James S. Jenkins, Fabo Feng, Douglas R. Alves, Florence de Almeida, Frédéric Dux, Guang-Yao Xiao, Joanne M. Rojas M., Jose I. Vines, Rafael I. Rubenstein, R. Ramírez Reyes, Suman Saha, Connor J. Cheverall, Matías R. Díaz

AI总结 本文通过结合径向速度和视差测量数据,发现并表征了围绕金属丰度高的FGK型恒星的冷型巨行星,展示了视差测量在提高检测信心和确定真实质量方面的有效性。

Comments Submitted and refereed in A&A

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Journal ref
A&A 709, A213 (2026)
AI中文摘要

长周期巨行星种群塑造了行星系统架构和形成路径,但这些冷型巨行星仍相对未被探索。径向速度(RV)调查在多天文单位距离上灵敏度下降,而凌星调查在长周期时难以检测。从Hipparcos和Gaia任务获得的绝对视差测量提供了额外的恒星运动数据,可以打破轨道倾角退化并增强检测信心。这尤其及时,因为Gaia DR4/DR5预计将使长周期RV行星的常规视差检查和真实质量测量成为可能。通过将跨度达16年的RV数据与绝对视差测量相结合,扩展了智利-赫尔福德郡系外行星调查(CHEPS),我们搜索并表征了围绕金属丰富的FGK型恒星的冷型巨行星。我们升级了EMPEROR框架,纳入视差差分以联合拟合RV和视差数据,对五个CHEPS目标进行了贝叶斯模型比较,并量化了视差贡献。我们的分析表征了HIP 21850中两个已知行星的轨道参数,并检测到五个新行星:一个暖巨行星——HIP 10090c,轨道周期P=321.8±0.5天,质量M=0.85±0.08M_J,以及四个巨行星类比——HIP 8923b,轨道周期P=14.1±0.06年,质量M=9.98±0.47M_J,HIP 10090b,轨道周期P=8.1±0.3年,质量M=3.87±0.63M_J,HIP 39330b,轨道周期P=12.7±0.7年,质量M=1.68±0.15M_J,以及HIP 98599b,轨道周期P=7.3±0.1年,质量M=6.85±0.16M_J。加入视差测量将周期和质量的不确定性降低了3到10倍,并将贝叶斯因子提高了最高60倍。长基线RV和绝对视差测量的协同作用为发现和表征冷型巨行星提供了稳健的途径。我们的结果表明,视差测量在提高检测信心和将最小质量转化为真实质量方面具有重要意义。

英文摘要

The population of long-period giant planets shapes planetary system architectures and formation pathways, but these cold Jupiters remain relatively unexplored. Radial velocity (RV) surveys lose sensitivity at multi-AU separations, while transit surveys have poor detection probability at long periods. Absolute astrometry from the Hipparcos and Gaia missions offer an additional source for stellar motion that can break the orbital inclination degeneracy and strengthen detection confidence. This is especially timely ahead Gaia DR4/DR5, expected to enable routine astrometric vetting and true-mass measurements for long-period RV planets. Extending the Chile-Hertfordshire ExoPlanet Survey (CHEPS) by combining RVs spanning up to 16 years with absolute astrometry, we search for and characterise cold giants around metal-rich FGK stars. We upgrade the EMPEROR framework, incorporating astrometric differencing to jointly fit RVs and astrometry for five CHEPS targets, performing Bayesian model comparison and quantify the astrometric contribution. Our analysis characterises orbital parameters for two known planets in HIP 21850 and detects five new: a warm Jupiter--HIP 10090c, orbital period $P=321.8 \pm 0.5$ d and mass $M=0.85 \pm 0.08$ $M_J$, and four Jupiter analogues--HIP 8923b, with $P=14.1 \pm 0.06$ yr and $M=9.98\pm 0.47 M_J$, HIP 10090b with $P=8.1\pm 0.3$ yr and $M=3.87\pm 0.63$ $M_J$, HIP 39330b with $P=12.7\pm 0.7$ yr and $M=1.68\pm 0.15$ $M_J$, and HIP 98599b with $P=7.3\pm 0.1$ yr and $M=6.85\pm 0.16$ $M_J$. Adding astrometry reduces period and mass uncertainties by factors between 3 and 10 and increases the Bayes factor by up to 60. The synergy of long-baseline RVs and absolute astrometry provides a robust pathway to discover and characterise cold giant planets. Our results demonstrate that astrometry meaningfully improves detection confidence and converts minimum masses into true masses.

2603.10109 2026-05-20 astro-ph.GA astro-ph.SR

Right round: onset and long-term evolution of rotation in star clusters

Right round: 星团旋转起始及长期演化的研究

E. Dalessandro, A. Della Croce, E. Vesperini, M. Cadelano, S. Leanza, G. Ettorre, M. Hughes

AI总结 本文通过详细的动力学分析,研究银河系中大量恒星团的旋转现象,揭示了恒星团在任何年龄都可能存在旋转,且约25%-30%的系统显示出显著的旋转证据,这一发现将已知的旋转恒星团数量提高了约5倍,并首次使旋转作为时间函数进行观测。年轻恒星团的旋转速度范围更大,且在年轻时旋转系统的比例更高,而随着年龄增长这一比例显著下降。

Comments 13 pages, 9 figures; accepted for publication in A&A

详情
Journal ref
A&A 709, A200 (2026)
AI中文摘要

我们对银河系中大量已知恒星团的详细动力学分析结果表明,首次揭示了恒星团在任何年龄都可能存在旋转,样本中有约25%-30%的系统显示出显著的旋转证据。这一发现将已知的旋转恒星团数量提高了约5倍,最终使旋转作为时间函数进行观测成为可能。年轻(<500 Myr)的恒星团显示出更大的旋转速度范围,而在年轻时,旋转系统的比例显著更高(50%-60%),而较老的系统则较低(约15%)。这些纯经验性的结果与旋转在恒星团形成和早期演化阶段被印刻,随后被长期的动力学演化效应逐渐抹去相一致。对于能够进行完整三维分析的子样本,我们计算了内部旋转轴与恒星团轨道运动轴之间的角度。有趣的是,对于年龄小于轨道周期的恒星团,我们观察到顺行和逆行系统的比例相似,而更成熟的恒星团则倾向于顺行。我们认为这种行为与由母分子云或后续的分层恒星团组装过程所印刻的原始旋转,以及内部恒星团动力学和与银河系场的相互作用所引起的扭矩驱动的旋转与轨道运动轴对齐相一致。

英文摘要

We present the results of a detailed kinematic analysis of a significant fraction of the known population of Galactic star clusters aimed at constraining the physical mechanisms driving the onset and evolution of cluster rotation. Our study reveals for the very first time the presence of rotation in clusters at any age, with about $25\%-30\%$ of systems in the sample showing significant evidence of rotation. This result increases by a factor of $\sim5$ the number of clusters identified as rotators so far and it finally enables an observational reading of cluster rotation as a function of time. Young ($<500$ Myr) clusters show a larger range of rotation velocities than older systems. In addition, at young ages we observe a significantly larger fraction ($50\%-60\%$) of rotating systems than at older ones ($\sim 15\%$). These purely empirical results are compatible with rotation being imprinted during the very early stages of cluster formation and early evolution and then being progressively erased by the long-term effects of dynamical evolution. For the sub-sample of clusters for which we were able to perform a full 3D analysis, we calculated the angle between the internal rotation axis and that of the cluster orbital motion. Interestingly, while for clusters with an age smaller than their orbital period we observe similar fractions of prograde and retrograde systems, more evolved clusters appear to be preferentially prograde. We argue that such a behavior is in qualitative agreement with the expectations for the evolution of systems in which primordial rotation was imprinted by the parent molecular cloud and/or by the following hierarchical cluster assembly processes, and in which internal cluster dynamics and interactions with the Galactic field have induced a torque-driven alignment between cluster rotation and orbital motion.

2603.09861 2026-05-20 math.AP

A fast dynamo on the three-torus

三重 тор 上的快速 dynamo

Michele Coti Zelati, Massimo Sorella, David Villringer

AI总结 本文研究了三重 тор 上的动力学 dynamo 方程,通过构造一个均匀超双曲流,证明了在时间周期性、无散、Lipschitz 连续速度场下快速 dynamo 作用的严格性。

Comments 64 pages. Added sections 7 and 8 to treat diffusion in continuous time

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AI中文摘要

我们研究了三重 тор 上的动力学 dynamo 方程,并为时间周期性、无散、Lipschitz 速度场提供了快速 dynamo 作用的严格证明。我们的构造基于生成均匀超双曲流的拉伸-折叠-剪切机制。为了分析相关的动力学,我们开发了适应于底层超双曲结构的各向异性 Banach 空间,使我们能够恢复理想 dynamo 操作符的离散谱图。在强混沌 regime 中,我们显示该操作符具有模长严格大于一的特征值。然后我们证明这种不稳定性在由扩散引起的奇异摄动下持续存在,导致磁感应强度在电阻率趋于零的极限下均匀指数增长。

英文摘要

We study the kinematic dynamo equation on the three-torus and provide a rigorous proof of fast dynamo action for a time-periodic, divergence-free, Lipschitz velocity field. Our construction is based on a stretch-fold-shear mechanism generating a uniformly hyperbolic flow. To analyze the associated dynamics, we develop anisotropic Banach spaces adapted to the underlying hyperbolic structure, allowing us to recover a discrete spectral picture for the ideal dynamo operator. In the strong-chaos regime, we show that this operator admits an eigenvalue with modulus strictly larger than one. We then prove that this instability persists under the singular perturbation induced by diffusion, yielding exponential growth of the magnetic field uniformly in the vanishing resistivity limit.

2603.09622 2026-05-20 hep-ph hep-ex nucl-ex nucl-th

JLab and J-PARC for the J/{\ensuremathψ} Production at the Threshold

JLab和J-PARC在J/ψ产生阈值处的研究

Igor I. Strakovsky, Jung Keun Ahn, William J. Briscoe, Misha G. Ryskin, Axel Schmidt

AI总结 通过JLab的007和CLAS12实验的新阈值测量,扩展了之前基于GlueX数据的J/ψ-质子散射长度α_{J/ψp}的现象学确定,同时探讨了质子形变因子F_N的作用,并计算了可能的修正。

Comments 21 pages, 3 figures, 4 tables. Text was revised, including the nucleon form factor effect

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AI中文摘要

新的阈值测量通过007和CLAS12实验,允许我们扩展之前基于GlueX数据的J/ψ-质子散射长度α_{J/ψp}的现象学确定。三种J/ψ数据集之间的一致性表明方法学上没有系统性差异。此外,扰动QCD预测支持重矢量介子-核子散射长度的现象学确定。讨论了质子形变因子F_N的作用,并使用F_N的极点形式计算了可能的修正。即将进行的J-PARC阈值测量将有助于评估低能J/ψ产生中重五夸克态P_c的可能作用以及质子形变因子的影响。

英文摘要

New threshold measurements for $γ~p\to p~J/ψ\to p~(μ^+μ^-)$ by 007 and $γ^\ast~p\to p~J/ψ\to p~(e^+e^-)$ by CLAS12 allow us to extend the previous phenomenological determination of the J/\ensuremathψ-proton scattering length, $α_{J/ψp}$, using GlueX threshold data for $γ~p\to p~J/ψ\to p~(e^+e^-)$. The agreement between all three J/\ensuremathψ data sets shows no indication of systematic differences between methodologies. Furthermore, perturbative QCD predictions support the phenomenological determination of heavy vector meson-nucleon scattering lengths. The role of the nucleon form factor, $F_N$, is discussed, and a possible correction to the phenomenological scattering length for heavy vector meson photoproduction is calculated using the pole form of $F_N$. Upcoming J-PARC threshold measurements of the reaction $π^-~p\to n~J/ψ\to n~(l^+l^-)$ will help to evaluate the possible role of heavy pentaquark, $P_c$, states in low-energy $J/ψ$ production and the effects caused by the nucleon form factors.

2603.02456 2026-05-20 econ.TH econ.EM econ.GN q-fin.EC

When Does Static Willingness to Pay Mislead? A Framework for Dynamic Hedonic Valuation

当静态支付意愿误导何时?动态享乐估值的框架

Josephine Auer

AI总结 本文研究了静态支付意愿何时会误导,提出了一种动态享乐估值框架,通过家庭扫描数据展示了享乐表示对价格的现实限制,并说明习惯性形成如何在该表示条件下提高行为一致性。

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AI中文摘要

许多政策反事实依赖于消费者对产品属性(如糖、钠、咖啡因、酒精或排放)的价值评估。标准的享乐和差异化产品模型将这些评估静态化。当属性具有习惯性时,这种解释是受限的:观察到的价格反映了同时期边际价值和当前消费产生的持续价值。我开发了一个非参数揭示偏好框架用于动态享乐估值,推导出合理化观察价格和选择的必要和充分条件。利用家庭扫描数据对谷物购买的分析,我表明享乐表示对价格施加了现实限制,而习惯性形成在该表示条件下提高了行为一致性。结果提供了一个诊断工具,用于判断静态属性估值何时是合理的,以及价格如何揭示超过同时期边际价值。

英文摘要

Many policy counterfactuals depend on how consumers value product attributes such as sugar, sodium, caffeine, alcohol, or emissions. Standard hedonic and differentiated-products models interpret these valuations statically. That interpretation is restrictive when attributes are habit forming: observed prices then reflect both contemporaneous marginal value and the continuation value generated by current consumption. I develop a nonparametric revealed-preference framework for dynamic hedonic valuation, deriving necessary and sufficient conditions for rationalising observed prices and choices. Using household scanner data on cereal purchases, I show that the hedonic representation places real restrictions on prices, while habit formation improves behavioural coherence conditional on that representation. The results provide a diagnostic for when static attribute valuation is justified and when prices reveal more than contemporaneous marginal values.

2603.01633 2026-05-20 astro-ph.HE

Episode-wise spectro-polarimetry of GRB 220107A: Testing the hypothesis of evolving radiation mechanisms

GRB 220107A的事件式光谱偏振学:检验辐射机制演化的假说

Rahul Gupta, Rushikesh Sonawane, Shabnam Iyyani, D. Frederiks, Judith Racusin, Tanmoy Chattopadhayay, A. J. Castro-Tirado, A. F. Valeev, Soumya Gupta, Mayuresh Tembhurnikar, A. Ridnaia, D. Svinkin, S. B. Pandey, Dipankar Bhattacharya, Vidushi Sharma, Varun Bhalerao, G. C. Dewangan, Santosh Vadawale, R. Sánchez-Ramírez, Anastasia Tsvetkova

AI总结 通过分析GRB 220107A的光谱偏振学特性,研究其两个不同发射事件之间的辐射机制演化,发现光谱软化可能源于亚日冕耗散或薄磁层同步辐射,偏振约束展示了时间分辨光谱偏振学在约束GRB喷流物理中的潜力。

Comments 16 pages, 10 figures, 6 tables, accepted for the publication in Astronomy and Astrophysics

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Journal ref
A&A 709, A222 (2026)
AI中文摘要

我们研究了长持续时间GRB 220107A的光谱偏振学特性,该爆发表现出两个不同的发射事件,间隔40秒的静默期。我们分析了AstroSat/CZTI、Fermi/GBM和Konus-Wind的即时发射数据,对每个发射事件进行光谱偏振学分析。时间积分偏振分析显示无显著检测(PF < 38%,2σ)。时间分辨分析显示两个事件之间有明显的光谱演变,第一事件具有硬低能光子指数,第二事件表现出显著的光谱软化(α≈-0.72)。偏振方面:第一事件显示低偏振上限(<52%),与由准热Compton化主导的富含物质喷流的预期一致。第二事件也显示总体低偏振(PF <55%,2σ),尽管滑动窗口分析显示在T0+76到T0+88秒之间有略微增强的信号(PF=70±30%,BF=2.8)。两个事件之间稳健的光谱软化可能源于亚日冕耗散、薄磁层同步辐射或如果试探性的偏振增强是固有的,则可能支持大尺度有序磁场中的同步辐射。GRB 220107A的光谱演变结合我们的偏振约束,展示了时间分辨光谱偏振学在约束GRB喷流物理中的潜力。我们提出GRB 220107A作为测试案例,展示了未来更高灵敏度观测如何区分多事件爆发的竞品发射模型。我们的结果强调了即时阶段偏振学的潜力和当前的局限性。

英文摘要

We investigate the spectro-polarimetric properties of the long-duration GRB~220107A, which exhibited two distinct emission episodes separated by a 40 s quiescent gap, to test whether such multi-episode bursts show evidence for evolution in their underlying radiation mechanisms. We analyzed prompt emission data from AstroSat/CZTI, Fermi/GBM, and Konus-Wind, performing spectro-polarimetric analysis for each emission episode. The time-integrated polarization analysis shows no significant detection (PF$ < 38 \%$, $2σ$). Time-resolved analysis reveals clear spectral evolution between the two episodes, with episode 1 exhibiting a hard low-energy photon index and episode 2 showing substantial spectral softening ($α\sim -0.72$). Regarding polarization: Episode 1 shows a low polarization upper limit (< 52\%), consistent with expectations for photospheric emission dominated by quasi-thermal Comptonization in a baryon-rich outflow. Episode 2 also shows overall low polarization (PF$ < 55 \%$, $2σ$), though sliding-window analysis yields a marginally elevated signal (PF$= 70 \pm 30\%$, BF = 2.8) between T0+76 to T0+88 s. The robust spectral softening between episodes could arise from sub-photospheric dissipation, optically thin synchrotron radiation in small-scale magnetic fields, or if the tentative polarization enhancement proves intrinsic, it would favor synchrotron emission in large-scale ordered magnetic fields. The spectral evolution of GRB 220107A, combined with our polarimetric constraints, demonstrates the diagnostic potential of time-resolved spectro-polarimetry for constraining GRB prompt emission physics. We present GRB 220107A as a test case illustrating how future higher sensitivity observations could discriminate between competing emission models for multi-episode bursts. Our results emphasize both the promise and current limitations of prompt phase polarimetry.

2602.23272 2026-05-20 nlin.CD

Interplay of Nonsmoothness, Time Delay, and Stochasticity in Turning Dynamics

非光滑性、时间延迟和随机性在转向动力学中的相互作用

Meiyazhagan Jaganathan, Vikram Pakrashi, Aasifa Rounak

AI总结 本文研究了正交金属切削过程中再生和非光滑摩擦效应的随机动力学,指出忽略摩擦和随机效应中的非光滑性会导致建模缺陷,通过分析工具运动的动力学现象,发现随机扰动导致随机P和D分岔,并通过熵度量量化动力学转变,进一步通过考虑随机性和时间延迟的盆地稳定性分析,系统研究了切削工具在多个工件表面粗糙度剖面下的动力学行为,表明通过限制初始工具位移和控制初始工件表面粗糙度可控制颤振,为精密制造提供实用策略。

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AI中文摘要

本文通过数值方法研究了正交金属切削过程中再生和非光滑摩擦效应的随机动力学。本文展示了在建模此类切削过程的动力学时忽略摩擦和随机效应中的非光滑性所带来的不足。工具运动的动力学表现出丰富的非线性现象,如切削颤振中的粘滞滑动,随机扰动的切削力进一步增加了复杂性,导致随机P和D分岔的发生。熵度量被发现有效用于量化工具动力学中的动态转变。随后,考虑随机性和时间延迟的盆地稳定性分析被进行,以系统地研究切削工具在多个工件表面粗糙度剖面下的动力学行为。盆地稳定性分析表明,通过限制初始工具位移和控制初始工件表面粗糙度可以控制颤振,这为提高精密制造的加工效果提供了实用策略。

英文摘要

The stochastic dynamics of orthogonal metal cutting with both regenerative and nonsmooth frictional effects are investigated numerically in this paper. The shortcomings of neglecting nonsmoothness in frictional and stochastic effects in modeling the dynamics of such a machining process are demonstrated. Dynamics of the tool motion is observed to exhibit rich nonlinear phenomena such as stick-slip during chatter, with stochastic perturbations in cutting forces adding further complexity, leading to the occurrence of stochastic P and D bifurcations. Measures of entropy are found to be effective in quantifying the dynamical transitions occurring in the dynamics of the tool. Subsequently, basin stability analyses, modified to account for stochasticity and time-delays, are carried out to systematically investigate the dynamics of the cutting tool across multiple surface roughness profiles of the workpiece. Basin stability analyses indicate that chatter can be controlled by restricting initial tool displacement and controlling initial workpiece surface roughness, suggesting practical strategies to improve machining outcomes for precision manufacturing.

2602.23127 2026-05-20 astro-ph.GA

Distribution functions for spheroids

spheroids的分布函数

James Binney

AI总结 本文研究了通过作用积分J的解析函数构造包含多个组件(包括暗物质)的银河系模型,探讨了在J_ϕ->0时DFs需满足的条件以避免非物理的速度分布,并展示了如何构造各向同性、径向偏置球状系统及扁平系统的速度分布函数,指出径向偏置球状系统易受四极扰动影响,混沌可能在恒星盘生长中起关键作用。

Comments 11 pages 10 figures submitted to MNRAS

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Journal ref
Mon Not R Astron Soc (2026)
AI中文摘要

由自洽生成的引力场束缚的银河系模型,可通过作用积分J的解析函数形式的分布函数(DFs)轻易构造。我们解释了为何此类模型除非热组件的DFs在J_ϕ->0时满足特定条件,否则具有非物理的速度分布。我们展示了如何通过指定f(J)构造各向同性和径向偏置球状系统的DFs,以及如何构造具有显著速度各向异性扁平系统的DFs。构造自洽模型而非受外部势能约束的群体,导致结论:径向偏置球状系统普遍易受四极扰动影响。混沌很可能在恒星盘渐进增长过程中维持这些约束中起关键作用。

英文摘要

Galaxy models comprising several components (including dark matter) that are bound by the self-consistently generated gravitational field are readily constructed from distribution functions (DFs) that are analytic functions of the action integrals J. We explain why such models have unphysical velocity distributions unless the DFs of hot components satisfy certain conditions as J_ϕ-> 0. We show how DFs for both isotropic and radially biased spherical systems can be constructed with specified f(J). We show how to construct DFs for flattened systems with significant velocity anisotropy. Construction of self-consistent models rather than populations that are confined by an external potential leads to the conclusion that radially-biased spherical systems are generically unstable to quadrupolar perturbations. Chaos is likely key to maintenance of these constraints during adiabatic disc growth.

2602.18815 2026-05-20 math-ph math.MP physics.class-ph

On the adiabatic invariance of the action of a trapped wave

关于受困波作用的绝热不变性

Ekaterina V. Shishkina, Serge N. Gavrilov

AI总结 本文研究了受困波在离散-连续系统中的绝热不变性,提出通过总能量与频率的比值定义新的绝热不变量,并将其应用于连续系统中局部振荡问题的求解。

Comments 18 pages

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AI中文摘要

最近,Gavrilov等人(Nonlinear Dyn, 112, 2024)证明,在具有多个缓慢时间变化参数的线性离散-连续系统中,强局域化模式(受困波)的振幅可由当前参数值计算得出,且不依赖于参数变化的历史。这一结果使我们能够根据绝热不变量的一般定义引入该量,即参数缓慢变化时保持近似恒定的量。本文表明,以这种方式定义的绝热不变量可由受困波的总能量与频率的比值计算得出。这为解决一类连续系统中带有离散包含物的局部振荡问题提供了显著简化的途径,尽管波能量的定义可能具有歧义。因此,我们可以将新引入的绝热不变量视为哈密顿系统中已知概念的直接推广。最后,我们引入了一个具有相同绝热不变量的有效哈密顿系统,这为推导振幅演化定律提供了另一种高度直接的方法,尽管需要进一步研究。

英文摘要

Recently, it has been shown (Gavrilov et al., Nonlinear Dyn, 112, 2024) that in a linear solid discrete-continuous system with several slowly time-varying parameters, the amplitude of a strongly localized mode (a trapped wave) can be calculated as a function of current parameter values and does not depend on the history of the parameter change. This result allows us to introduce the adiabatic invariant for such a system according to the general definition as a quantity that remains approximately constant if the parameters vary slowly. In this paper, we show that, defined in this manner, the adiabatic invariant can be calculated as the ratio of the total energy of the trapped wave to its frequency. This yields a significantly simplified approach to solving a class of problems concerning localized oscillation of continuous systems with discrete inclusions, although the definition of the wave energy can be ambiguous. Thus, we can consider the newly introduced adiabatic invariant as a straightforward generalization of the concept known to Hamiltonian systems. Finally, we introduce an effective Hamiltonian system, which is characterized by the same adiabatic invariant as the trapped wave. This yields another highly straightforward approach to deriving the amplitude evolution law, although further investigation is required.

2602.17657 2026-05-20 cond-mat.quant-gas cond-mat.stat-mech physics.atom-ph

Realization of fractional Fermi seas

分数费米海的实现

Yi Zeng, Alvise Bastianello, Sudipta Dhar, Zekui Wang, Xudong Yu, Milena Horvath, Grigori E. Astrakharchik, Yanliang Guo, Hanns-Christoph Nägerl, Manuele Landini

AI总结 该研究通过调节一维玻色气体的相互作用强度,实现了分数费米海的实验验证,展示了其在量子热力学中的应用潜力。

Comments 16 pages, 12 figures; new version incorporated minor changes to references and email address

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AI中文摘要

泡利不相容原理是量子物理的基石:它决定了物质的结构。这一原理的扩展,如哈达玛的广义排斥统计,预测了具有分数费米海(FFS)的 exotic 量子态的存在,即具有均匀但分数占据的动量分布。在这里,我们报告了通过在相互作用强度上进行斜坡循环来实现一维激发玻色气体中分数费米海的实验。所得到的激发但稳定的玻色气体态表现出弗里德尔振荡,这是底层 FFS 的特征性证据。这些状态的稳定化为深入理解具有 exotic 统计的量子热力学提供了机会,并为量子信息和传感的应用铺平了道路。

英文摘要

The Pauli exclusion principle is a cornerstone of quantum physics: it governs the structure of matter. Extensions of this principle, such as Haldane's generalized exclusion statistics, predict the existence of exotic quantum states characterized by fractional Fermi seas (FFS), i.e. momentum distributions with uniform but fractional occupancies. Here, we report the experimental realization of fractional Fermi seas in an excited one-dimensional Bose gas prepared through ramping cycles in the interaction strength. The resulting excited yet stable Bose-gas states exhibit Friedel oscillations, smoking-gun signatures of the underlying FFS. The stabilization of these states offers an opportunity to deepen our understanding of quantum thermodynamics in the presence of exotic statistics and paves the way for applications in quantum information and sensing.

2602.14816 2026-05-20 econ.TH cs.GT cs.MA

Majoritarian Assignment Rules

多数派分配规则

Felix Brandt, Haoyuan Chen, Chris Dong, Patrick Lederer, Alexander Schlenga

AI总结 本文研究了多智能体系统中对象公平分配问题,通过分析经典多数派社会选择函数在分配领域的特性,发现偏好配置与多数派图之间存在近似一一对应关系,从而揭示了帕累托最优、最小不受欢迎和混合受欢迎等属性可通过多数派图确定,并进一步证明了所有帕累托最优分配都属于顶级循环,且顶级循环可通过串行独裁制轻易找到。

Comments Appears in the 25th International Conference on Autonomous Agents and Multiagent Systems (AAMAS), 2026

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AI中文摘要

多智能体系统中的核心问题是在代理之间公平分配物品。在本文中,我们开始分析经典多数派社会选择函数在分配领域的分析。利用分配领域的特殊结构,我们展示了一系列在一般社会选择中没有对应结果的令人惊讶的结果。特别是,我们建立了偏好配置与多数派图之间的近似一一对应关系。这种对应关系意味着分配的关键属性--如帕累托最优、最小不受欢迎和混合受欢迎--可以仅通过关联的多数派图确定。我们进一步证明,所有帕累托最优分配都是半受欢迎的,并且属于顶级循环。顶级循环中的元素因此可以通过串行独裁制轻易找到。我们的主要结果是对顶级循环的完全表征,这表明顶级循环只能由一个、两个、除了两个之外的所有、除了一个之外的所有或所有分配组成。相比之下,我们发现未覆盖集只包含非常少的分配。

英文摘要

A central problem in multiagent systems is the fair assignment of objects to agents. In this paper, we initiate the analysis of classic majoritarian social choice functions in assignment. Exploiting the special structure of the assignment domain, we show a number of surprising results with no counterparts in general social choice. In particular, we establish a near one-to-one correspondence between preference profiles and majority graphs. This correspondence implies that key properties of assignments -- such as Pareto-optimality, least unpopularity, and mixed popularity -- can be determined solely by the associated majority graph. We further show that all Pareto-optimal assignments are semi-popular and belong to the top cycle. Elements of the top cycle can thus easily be found via serial dictatorships. Our main result is a complete characterization of the top cycle, which implies the top cycle can only consist of one, two, all but two, all but one, or all assignments. By contrast, we find that the uncovered set contains only very few assignments.

2602.14217 2026-05-20 hep-ph physics.geo-ph

Limits on the Carroll-Field-Jackiw electrodynamics from geomagnetic data

从地磁数据对Carroll-Field-Jackiw电动力学的限制

G. F. de Carvalho, M. Fillion, P. C. Malta, C. A. D. Zarro

AI总结 本文基于地磁数据,通过求解静态点状磁偶极子的场方程,利用Green方法研究了Carroll-Field-Jackiw项对标准磁偶极场的修正,从而对太阳参考系中Carroll-Field-Jackiw向量的分量给出了更严格的限制,比之前基于其他地质现象的限制提高了约四个数量级。

Comments 58 pages, 16 figures. Constructive comments are welcome

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Journal ref
J. High Energ. Phys. 2026, 163 (2026)
AI中文摘要

洛伦兹对称性破坏可能通过CPT奇、三维的Carroll-Field-Jackiw项来描述,该项将电磁场与一个常数四向量k_{AF}耦合,从而在时空中选择一个优先方向。我们通过Green方法求解静态点状磁偶极子的场方程,发现k_{AF}依赖的修正对近地磁场均具有主导作用。鉴于当前模型与地面和卫星地磁数据之间有很好的一致性,我们在太阳参考系中对k_{AF}的分量的最严格限制为:对于k_{AF}的Z分量,| (k_{AF})_Z | ≲ 4 × 10^{-25} GeV,对于X和Y分量,| (k_{AF})_X |, | (k_{AF})_Y | ≲ 10^{-24} GeV,在两西格玛水平上。这比基于其他地质现象的先前限制提高了约四个数量级。

英文摘要

Lorentz-symmetry violation may be described via the CPT-odd, dimension-3, Carroll-Field-Jackiw term, which couples the electromagnetic fields to a constant 4-vector $k_{\rm AF}$ selecting a preferred direction in spacetime. We solve the field equations using the Green's method for a static point-like magnetic dipole and find the $k_{\rm AF}$-dependent corrections to the standard dipolar magnetic field that strongly dominates the near-Earth magnetic field. Given the very good agreement between current models and ground- and satellite-based geomagnetic data, our strongest constraints on the components of $k_{\rm AF}$ in the Sun-centered frame read $|(k_{\rm AF})_Z| \lesssim 4 \times 10^{-25} \, {\rm GeV}$ for $|(k_{\rm AF})_X|, |(k_{\rm AF})_Y| \lesssim 10^{-24} \, {\rm GeV}$ at the two-sigma level. This represents an improvement of about four orders of magnitude over earlier bounds based on other geophysical phenomena.