Instrumentation and Methods for Astrophysics · Cross-listed from cs.AI
A Multi-Level Validation and Traceability Framework for AI-Generated Telescope Scheduling Decisions
Hengchu Xiao and Chuanjun Wang
With the gradual introduction of AI into
telescope scheduling, AI-based decision-making has shown advantages in handling complex multi-constraint problems. However, its outputs often suffer from inconsistent data references,
reasoning errors, and non-executable decisions, limiting applicability in high-reliability observational tasks. In this work, we propose a multi-level validation and traceable
reasoning framework that performs systematic reliability verification of AI-generated decisions prior to execution, and enables explicit representation of the
reasoning process to support traceable decision-making. The framework integrates data reference validation, logical consistency checks, and observational and instrumental constraint verification to filter and correct invalid decisions. It also introduces atomic
reasoning units and their dependency relationships, representing scheduling decisions as a sequence of interconnected
reasoning steps that support error localization and post hoc analysis. Experiments show that the framework improves executability and reliability of AI scheduling and reduces loss of transient opportunities. In particular, feedback correction and structured validation of
reasoning steps enhance the ability to repair and block erroneous decisions, especially in complex scenarios. Compared with pure AI methods, the framework-enhanced approach maintains flexibility while substantially improving reliability and executability. These results demonstrate a feasible and verifiable pathway for applying AI to high-reliability astronomical observation scheduling.
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Quantum Physics
Quantum Fast-Forwarding Beyond Reversibility: The $\alpha$-Perturbed $n$-Cycle
Avah Banerjee, Asim Sharma and Sooraj Soman
Quantum fast-forwarding (QFF) is usually formulated for reversible Markov chains, where the projected
quantum walk
evolution is exactly governed by Chebyshev
polynomials of a Hermitian discriminant
matrix. We study whether this framework can be extended to nonreversible dynamics for an $\alpha$-perturbed $n$-cycle Markov chain, which preserves circulant structure while introducing controlled irreversibility. We show that the nonreversible case has a fundamental obstruction: for $\alpha \neq 0$, the
eigenvalues of $P_\alpha$ leave the interval $[-1,1]$, so $T_m(P_\alpha)$ is not uniformly bounded and cannot arise as an exact
unitary compression for all times. Thus, exact Chebyshev-based QFF does not extend directly beyond reversibility. Nevertheless, we obtain a finite-time approximation result using truncated Chebyshev and LCU techniques. The
evolution $P_\alpha^t$ can be approximated with degree $\tau=O\left(|\alpha|t+\sqrt{t\log(t/\eta)}\right),$ which recovers the reversible $O(\sqrt t)$ behavior only in the perturbative regime $|\alpha|=O(t^{-1/2})$. This identifies a nearly reversible regime where QFF survives perturbatively and quantifies how irreversibility degrades the speedup.
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Mathematical Physics · Cross-listed from math.AP
Determining potentials from the scattering map of the time-dependent Schrödinger equation
Qiuye Jia
For a time dependent Schrödinger equation, the scattering map is the map sending the asymptotic profile of a solution as $t \to-\infty$ to its asymptotic profile as $t\to+\infty$. In this paper we show that, for a certain class of metrics, the scattering maps and Poisson operators associated to two Schrödinger operators on the same curved space only differ by a compact operator on a critical level if and only if the two potentials are equal.
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Materials Science
Shape-Constrained Bayesian Active Learning of Self-Limiting Saturation Curves
Pouyan Navabi and Christos G. Takoudis
Saturation curves, monotone responses that rise from zero to a plateau, recur across gas adsorption, enzyme kinetics, and self-limiting growth. Learning one from a few costly, noisy measurements is a common bottleneck. We present a
Bayesian active-learning platform built on a penalized monotone I-spline. Non-negative weights make every posterior draw rise from zero and never fall, a survey measurement anchors the plateau in place of a flatness prior, and the input reaching any saturation level is read from the posterior by level crossing, assuming no kinetic form. Each measurement is placed where the surrogate is least certain, which beats random designs and edges a log-spaced grid of the same budget. One fixed configuration recovers five kinetically distinct regimes from twenty measurements to a saturation error of 0.037 to 0.041, below the output noise, and averages 0.045 on 250 curves from an unseen distribution. Running unconstrained Gaussian processes (GPs) and two unpenalized monotone bases through the same loop separates each ingredient's contribution. Logarithmic resolution and the roughness penalty carry the accuracy, while monotonicity guarantees a level crossing unique on every draw. The penalty keeps the surrogate the most accurate model at every noise level, and its second-order form centers the recommended input for saturation where a first-order penalty reads late (a bias of +0.32 s with 94% coverage, against +0.44 s and 64% for the matched unconstrained GP). Because the recommended input lies where the curve is nearly flat, no method can pin it down precisely, and we report it as a cost-indexed
quantile with the probability of falling short.
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Instrumentation and Methods for Astrophysics
Detectors for CLASS-W2: The second 90 GHz telescope of the Cosmology Large Angular Scale Surveyor
John W. Appel, Kyuyoung Bae, Charles L. Bennett et al. (+26 more)
The Cosmology Large Angular Scale Surveyor (CLASS) is measuring the
Cosmic Microwave Background (CMB) polarization anisotropy on the largest angular scales (>1 degree) to probe the epochs of inflation and reionization. To enhance the CMB mapping speed, we have built, tested, and commissioned in August 2025 a second 90 GHz receiver (CLASS-W2) with a detector focal plane composed of feedhorn-coupled Transition Edge Sensor (TES) bolometers fabricated at NIST-Boulder. The focal plane consists of four modules, each containing 37 feedhorns coupling orthogonal polarizations onto two TES bolometers, for a total of 296 optically sensitive detectors. Laboratory tests show highly uniform TES properties with an array average critical temperature of 184+-3 mK, a thermal conductance of 460+-47 pW/K, and a normal resistance of 7.8+-0.3 mOhms. The detector array has an average band center frequency of 95.2 GHz with 28.3 GHz bandwidth, and achieves a detector yield of 94%. On-sky measurements indicate a mean detector optical load of 3.3 pW, corresponding to an
antenna temperature of ~23 K. The array's average beam solid angle is 124 $\mu$sr, with a full width at half maximum of 0.592 degrees, and the end-to-end average optical efficiency is 0.37. We find that high-frequency 'blue-leak' radiation couples directly to the TES bolometer islands; adding a metal-mesh low-pass filter with cutoff frequency of 157 GHz in front of the focal plane suppresses the 'blue-leak' power by 0.9 pW. The four-module array achieves a noise-equivalent temperature of NET= 16 uKrtS. Adding this array has boosted the CLASS 90 GHz mapping speed by 41%.
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All authors John W. Appel, Kyuyoung Bae, Charles L. Bennett, Michael K. Brewer, Sarah Marie Bruno, Carol Yan Yan Chan, Joseph Cleary, Sumit Dahal, Jullianna Denes Couto, Kevin L. Denis, Shannon M. Duff, Joseph R. Eimer, Thomas Essinger-Hileman, Naina Gupta, Johannes Hubmayr, Gregory Jaehnig, John Karakla, Matthew Koc, Jeff Van Lanen, Yunyang Li, Michael J. Link, Tammy Lucas, Tobias Marriage, Carolina Morales Perez, Matthew A. Petroff, Caleigh Ryan, Rui Shi, Deniz A. N. Valle, Edward J. Wollack
High Energy Astrophysical Phenomena
Long-Period Transients as a new frontier in time-domain astronomy
Manisha Caleb, Dougal Dobie, Natasha Hurley-Walker et al. (+8 more)
Long-period
radio transients (LPTs) are relatively new astrophysical objects occupying the observational gap between canonical
pulsars and slowly varying
radio variables. They emit coherent, highly polarised
radio bursts with periods from minutes to hours, often exhibiting millisecond- to minute-scale substructure, short duty cycles, and broadband emission. Their
radio luminosities typically exceed what rotational energy alone can power, necessitating alternative energy sources such as
magnetic field decay, magnetospheric reconnection, or binary interactions. As multiwavelength counterparts in X-ray, optical, and infrared bands provide key constraints on progenitors and emission mechanisms, observational evidence points to a diverse progenitor population including ultra-long period magnetars and
magnetic white
dwarf binaries. Fast imaging surveys with SKAO and its precursors are opening a new discovery space, enabling systematic detection, high-cadence monitoring, and detailed follow-up. Despite the challenges of high extinction, intermittent emission, and computational demands for discovery, the expanding LPT population provides a new laboratory for studying coherent
radio emission in a range of compact-object systems, from
pulsars to white
dwarf binaries. This diversity allows us to test how the emission processes depend on
magnetic field strength, rotation, and binary interaction.
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All authors Manisha Caleb, Dougal Dobie, Natasha Hurley-Walker, Yogesh Maan, Yuan Mao, Hao Qiu, Nanda Rea, Kovi Rose, Iris de Ruiter, Ben Stappers, Ziteng Wang
Earth and Planetary Astrophysics
Ring Spacing from a Fourth-Order Radial Feedback Green Function in a Keplerian Accretion Disk
Yiwei Bao and Can Cui
ALMA observations of protoplanetary disks reveal ubiquitous concentric ring structures whose origin remains debated. We present an exactly solvable local model for ring spacing in a Keplerian disk. The passive advection–
diffusion problem with a general vertical diffusivity profile separates into a vertical Sturm–Liouville spectrum and a radial modified-Bessel Green function. This passive kernel is smooth and does not by itself generate a periodic ring train. We therefore introduce a minimal fourth-order radial feedback closure for the ring-averaged surface density. For a localized steady ring source, the resulting Green function has a damped oscillatory exterior branch whenever the decaying spatial roots are complex. Under an observationally motivated AU scaling, the same dimensionless solution gives an illustrative spacing of order $12$~AU, distinct from the fastest-growing temporal wavelength. The model separates the passive transport kernel from the feedback mechanism that selects the observable radial scale. Because this mechanism is internal to the disk, it does not require pre-existing
planets. The vertical diffusivity profile affects the background kernel but is not the source of the Green-function oscillation.
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Cosmology and Nongalactic Astrophysics
The SKA View of the Sunyaev-Zeldovich Effect from Massive Cosmic Halos
Yvette C. Perrott, Luca Di Mascolo, Rémi Adam et al. (+4 more)
The thermal intracluster medium (ICM) can be observed via its interaction with
Cosmic Microwave Background
photons, known as the Sunyaev-Zeldovich (SZ) effect. This effect produces an observable signal at
radio to sub-mm wavelengths which probes the pressure of the ICM. The SKA will be sensitive to the thermal SZ effect in its highest frequency band, 5b. In this Chapter, we show that the SKA will provide a high-resolution, high-sensitivity view of the thermal SZ effect, allowing detailed observations of pressure substructures in clusters while retaining sensitivity to the large-scale global ICM emission.
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All authors Yvette C. Perrott, Luca Di Mascolo, Rémi Adam, Chiara Ferrari, Keith J. B. Grainge, Matthias Hoeft, Mamta Pandey-Pommier
Quantum Physics
Graph Structures for Local Distinguishability of Quantum Product States
Sooyeong Kim, David W. Kribs, Michael Nathanson et al. (+2 more)
We consider the problem of distinguishing sets of
quantum product states with local operations and classical communication (LOCC). Recent work has used graph theory to identify sets of product states distinguishable with one-way LOCC. We extend these efforts to full two-way LOCC, with the first significant analysis of the set of graphs corresponding to bipartite product states that can be distinguished with two-way protocols after finitely many steps. We derive basic closure properties of the set of distinguishable graphs and identify some classes of graphs that guarantee local distinguishability and some graphs that do not. We also include several examples and forward-looking comments.
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All authors Sooyeong Kim, David W. Kribs, Michael Nathanson, Rajesh Pereira, Sarah Plosker
Mathematical Physics · Cross-listed from math.AP
Sharp endpoint multilinear estimates for oscillatory integrals and spectral clusters
Shengwen Gan, Cheng Zhang and Zhifei Zhu
We prove sharp $k$-linear $L^p$ estimates for Carleson–Sjölin oscillatory integral operators with arbitrary separated frequency scales for all $k\ge 2$ and $1\le p\le \infty$. The estimates are sharp, including the endpoint logarithmic behavior for general Carleson–Sjölin phases. Moreover, we obtain log-free endpoint bilinear spectral cluster estimates on every closed three-dimensional Riemannian
manifold, resolving a problem of Burq–Gérard–Tzvetkov. As a consequence, we establish sharp $k$-linear $L^p$ spectral cluster estimates for all $k\ge 2$ and $1\le p\le \infty$.
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Materials Science
Topological phase transition driven by in-plane spin rotation
Xinyue Zhu, Yu Xie, Yifei Hao et al. (+3 more)
The intrinsic coupling between magnetism and nontrivial band
topology in
magnetic topological
insulators makes external
magnetic fields a powerful tool for manipulating topological states. However, conventional
magnetic control mechanisms, such as driving
magnetic phase transitions or fully reversing magnetization, typically demand large
magnetic fields and lack continuous tunability. Here, we establish a
symmetry framework for the reversible switching of topological states via continuous in-plane
spin rotation, governed by
magnetic point group constraints on the Berry
curvature distribution. Using a two-dimensional kagome
ferromagnetic Chern
insulator as a prototype, we demonstrate that a 60{\deg}in-plane magnetization rotation reverses the sign of the Chern number, transitioning through a topologically trivial state. Crucially, micromagnetic simulations confirm that this
spin-reorientation-driven switching operates under exceptionally small
magnetic fields and on ultrafast timescales. This work provides a highly efficient, low-energy paradigm for the manipulation of topological states.
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All authors Xinyue Zhu, Yu Xie, Yifei Hao, Fei Gao, Yue Li, Junting Zhang
High Energy Physics (Theory)
Holographic $s$- and $p$-wave superconductors from the $4D$ regularization of Einstein-Lovelock theory
Soodeh Zarepour and Ali Dehghani
We investigate holographically dual descriptions of $(2+1)$-dimensional s-wave and p-wave
superconductors in the framework of regularized four-dimensional Einstein-Lovelock
gravity theories, incorporating higher
curvature corrections beyond the Gauss-Bonnet sector. We first implement the 4D regularization of Einstein-Lovelock
gravity with finely tuned coupling constants to include corrections up to any $K$th order in
curvature. The bulk geometry is constructed from exact black-brane solutions characterized by the fine-tuned Lovelock coupling $\alpha$ and the highest power of
curvature in the Lagrangian K. We then analyze the condensation of scalar and vector operators dual to minimally coupled matter fields, focusing on two bulk-field mass prescriptions, which significantly affect the superconducting phase. Our results demonstrate that higher
curvature terms significantly modify the phase structure of both s-wave and p-wave systems and enhance the sensitivity of the condensates and critical temperatures to the gravitational couplings. In both cases, the critical temperature generally increases with the maximal
curvature order K, leading to higher-$T_c$ phases compared to Einstein
gravity, particularly for negative $\alpha$. The coupling $\alpha$ effectively governs the strength of higher
curvature interactions in the bulk: positive $\alpha$ suppresses condensation and lowers $T_c$, whereas negative $\alpha$ enhances superconducting order and promotes higher-$T_c$ phases relative to Einstein
gravity. We further study the optical conductivity and find that both the gap frequency and the ratio $\omega_g/T_c$ exhibit a strong dependence on $\alpha$ and $K$, deviating from the universal Einstein-
gravity result. Higher
curvature effects enhance the superconducting gap scale. Notably, the p-wave system shows a stronger sensitivity to the mass-fixing prescription compared to the s-wave case.
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Quantum Physics
Scattering theory for cavity-assisted spin-motion-photon interactions
Seigo Kikura, Aruku Senoo, Akihisa Goban et al. (+1 more)
Cavity-assisted
photon scattering (CAPS) is a powerful mechanism for realizing strong interactions between the internal states of stationary
qubits and flying
photons, underpinning a broad range of hybrid atom-
photon protocols including remote
entanglement generation and heralded atom-
photon gates. Recently, the motional
quantum state has emerged as an important building block for
quantum information processing with atomic
qubits, both as a coherently controllable degree of freedom and as a fundamental error channel through undesired
spin-motion coupling. For the resonant-coupling regime of cavity
quantum electrodynamics relevant to CAPS operations, however, the analytical formulation of
spin-motion-
photon coupling has so far remained elusive. Here, we develop a complete analytical framework for CAPS that incorporates the coherent interaction between atomic motion and a reflected
photon by extending scattering theory to include the motional degree of freedom. The resulting compact operator-based input-output relation applies uniformly across various cavity geometries,
spin-dependent trapping potentials, and nonidentical multiple
spins. As an exemplary application, we use the framework to elucidate how atomic motion affects CAPS-based atom-
photon gates, identifying the parameter regimes that suppress motion-induced errors. Our framework provides a theoretical foundation both for mitigating motional errors in CAPS operations and for deliberately exploiting motion-
photon interaction at the atom-
photon interface.
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All authors Seigo Kikura, Aruku Senoo, Akihisa Goban, Shinichi Sunami
Nuclear Theory
Thermal Effects on the Moment of Inertia and Gravitational Redshift of PSR J1012+5307: Implications for Hyperonic Matter under SU(3) and SU(6) Symmetries
Y.Xu, X.L.Huang, Y.B.Wang et al. (+5 more)
The temperature dependence of
neutron star structure significantly alters the equation of state, thereby affecting observable properties such as the moment of inertia and gravitational
redshift. Utilizing the relativistic mean-field theory with hyperonic degrees of freedom under SU(3)
flavor and SU(6)
spin-
flavor symmetries, we investigate the thermal effects on the structural properties of protoneutron
stars and cold
neutron stars. Focusing on PSR J1012+5307, we analyze the drastic structural transformations occurring during the transition from a PNS to a CNS. For a 1.94 Msun hyperonic
star under SU(3)
flavor symmetry, decreasing the temperature from T =30 MeV to 0 MeV induces a radius contraction of approximately 50 percent, accompanied by a drop in the moment of inertia by nearly 26% and a significant increase in gravitational
redshift by approximately 154 percent. Furthermore, we examine the variations in the moment of inertia and gravitational
redshift arising from mass uncertainties of PSR J1012+5307.Taking SU(3)
flavor symmetry at T =20 MeV as an example, increasing the mass across the range 1.72 Msun to 1.94Msun results in a radius contraction of 2.749 km, an 8 percent increase in the moment of inertia, and a significant 40 percent increase in the gravitational
redshift.We find that in the cold regime and at a fixed mass, the radius, moment of inertia,and gravitational
redshift of hyperonic matter under SU(3)
flavor symmetry differ only marginally from those of purely nucleonic matter, rendering it difficult to observationally confirm the presence of hyperons in the core of PSR J1012+5307. Moreover, future observations capable of precisely constraining
pulsar masses,ideally through long-termonitoring from birth,hold the potential to determine more conclusively whether hyperons or other exotic matter reside in individual
pulsars.
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All authors Y.Xu, X.L.Huang, Y.B.Wang, Q.Yuan, W.B.Ding, N.An, Y.F.Shen, Z.Yu
Astrophysics of Galaxies
Predicted Capabilities of the SPRITE SmallSat for a Low-Redshift Lyman Continuum Emission Survey
Yi Hang Valerie Wong, Brian Fleming, Elena Carlson et al. (+13 more)
Ionizing Lyman continuum (LyC; $\lambda < 912~\rm{\mathring{A}}$) radiation from low-
redshift ($z \sim 0.3$)
galaxies provides crucial insight into the processes that contributed to
cosmic reionization. While the James Webb Space
Telescope has observed
galaxies at
redshifts as high as $z \sim 14$, detecting LyC beyond $z \sim 3$ is challenging due to absorption by neutral hydrogen in the intergalactic medium (IGM). Low-
redshift LyC emitters (LCEs), therefore, act as proxies for their high-
redshift counterparts, enabling direct measurements of LyC escape fractions with reduced IGM interference. These observations allow detailed ancillary studies of
galaxy properties and the mechanisms driving ionizing
photon escape, which cannot be directly observed at the Epoch of Reionization. This paper examines the capabilities of the
Supernova remnants and Proxies for Re-Ionization Testbed Experiment (SPRITE) SmallSat, designed to study LyC emission from
star-forming
galaxies at $0.16 < z < 0.4$. SPRITE uses advanced mirror coatings and a highly sensitive far-ultraviolet imaging spectrograph, enabling it to probe LyC from
galaxies that have been difficult to study with prior and existing instruments. To assess SPRITE's predicted performance in LyC studies, we select eight previously confirmed LCEs from the Low-
redshift Lyman Continuum Survey as commissioning targets. Observations of these commissioning LCEs will validate SPRITE's LyC sensitivity and characterize its detection limits. This will enable the broader SPRITE low-
redshift LCE survey, which will provide new constraints on the physics of LyC escape and help bridge the gap between low- and high-
redshift LyC studies. SPRITE will also inform the design and scientific potential of future Lyman-UV missions, including the Habitable Worlds Observatory.
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All authors Yi Hang Valerie Wong, Brian Fleming, Elena Carlson, Briana Indahl, Dmitry Vorobiev, Sebastian Escobar, Kevin France, Maitland Bowen, Dónal O'Sullivan, Anne E. Jaskot, Jason Tumlinson, Sanchayeeta Borthakur, Michael J. Rutkowski, Stephan McCandliss, Ravi Sankrit, John O'Meara
General Relativity and Quantum Cosmology
Primordial black hole formation in bulk-viscous cosmology
Zi-Yan Yuwen, Cristian Joana, Shao-Jiang Wang et al. (+1 more)
We investigate
primordial black hole (PBH) formation in a cosmological background with bulk viscosity. Using numerical simulations, we determine the collapse threshold and the resulting PBH mass. We find that the critical threshold $\mu_c$ retains a dependence on the equation-of-state parameter $w$ similar to that in the inviscid case, but is enhanced by an amount comparable to the bulk-viscosity strength $\epsilon$. For fixed $w$, the increase in $\mu_c$ is approximately linear in $\epsilon$. By fitting the standard critical-scaling law for near-threshold collapse, we find that the bulk viscosity leads to an enhancement in the resulting PBH mass. These results indicate that bulk viscosity can systematically modify both the PBH threshold and PBH mass scaling law in the early Universe.
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All authors Zi-Yan Yuwen, Cristian Joana, Shao-Jiang Wang, Rong-Gen Cai
Astrophysics of Galaxies
UV Star-Formation Rates of the SHIELD Dwarf Galaxies
David G. Gormanous, Anjali S. Dziarski, John J. Salzer et al. (+11 more)
The Survey of HI in Extremely Low-mass
Dwarfs (SHIELD) is a multi-wavelength observational project targeting gas-rich,
star-forming
dwarf galaxies at the faint end of the HI mass function. We present near-ultraviolet (NUV) and far-ultraviolet (FUV) flux measurements obtained from GALEX survey images and use these fluxes to derive FUV
star-formation rates (SFRs) for all 75 SHIELD
galaxies with GALEX data. This paper represents the first published analysis that makes use of the full SHIELD sample. We compare the FUV SFRs to a variety of physical quantities to better understand the nature of SHIELD
galaxies. When comparing the H$\alpha$ SFRs to the FUV SFRs for SHIELD and other local
galaxy surveys, we confirm and solidify previous results that show that H$\alpha$-based SFRs for
dwarf galaxies can grossly underestimate the true rate of
star formation, emphasizing the highly
stochastic nature of
star formation in extremely low-mass
galaxies. We further show that FUV SFRs appear to be robust tracers of
star formation down to the very lowest
galaxy masses included in this study. We show that baryonic mass is the best mass-related tracer for the prediction of the FUV SFR of the
galaxies in our sample. Not surprisingly, the SHIELD
dwarf galaxies exhibit long gas-depletion timescales and large gas mass fractions: fully 68% of the SHIELD
galaxies have gas masses that are larger than their
stellar masses.
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All authors David G. Gormanous, Anjali S. Dziarski, John J. Salzer, John M. Cannon, Steven Janowiecki, Nathalie Haurberg, April Horton, Elizabeth A. K. Adams, Martha P. Haynes, Myles J. Klapkowski, Joshua R. Marine, Kristen B. W. McQuinn, Katherine L. Rhode, Evan D. Skillman
Exactly Solvable and Integrable Systems
Integrable pentagram-type maps on polyhedra via partial difference operators
Bao Wang
This paper introduces a family of natural generalizations of the pentagram map from polygons to (twisted) polyhedra and proves their integrability through the partial difference operators. A canonical special case, which corresponds to the discrete Laplace transformation of discrete conjugate nets, is investigated in detail. We first establish a canonical bijection between the projective equivalence classes of these polyhedra in $\mathbb{RP}^3$ and the spectral data of doubly periodic partial difference operators modulo the gauge actions. Furthermore, we prove the complete integrability of these pentagram-type maps by explicitly identifying them with the refactorization maps on the Poisson-Lie group of pseudo partial difference operators. This algebraic identification naturally yields an explicit Lax representation and an $r$-
matrix induced Poisson bracket for the
geometric dynamics.
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Accelerator Physics
Systematic Derivation of Reliable Wake Functions for Complex Structures from Mesh-Based Wakefield Simulations
Chih-Kai Liu, Wai-Keung Lau, Shih-Hung Chen et al. (+1 more)
Wakefield calculations are essential for analyzing beam-driven electromagnetic structures in accelerators. Although analytical wake functions are available for simple symmetric structures, complex geometries generally require mesh-based electromagnetic simulations, which provide finite-bunch wake potentials rather than point-charge wake functions directly. In this study, we present a systematic deconvolution-based method for extracting reliable wake functions from numerically calculated wake potentials using the prescribed drive-bunch distribution. The method is validated with a rectangular dielectric-lined waveguide (DLW), where the extracted longitudinal wake functions agree well with analytical solutions in both the short- and long-range regimes when the drive bunch is sufficiently short. The extracted wake function is further implemented in particle-tracking simulations, producing phase-space distributions consistent with those obtained using a built-in analytical wake-function model. The method is also applied to a modified rectangular DLW with a non-uniform horizontal dielectric distribution. The extracted longitudinal and transverse wake functions and corresponding beam impedances show that the dominant deflecting wakefield can be substantially reduced without significantly degrading the longitudinal wakefield. These results demonstrate the reliability and applicability of the proposed method for complex dielectric-loaded structures.
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All authors Chih-Kai Liu, Wai-Keung Lau, Shih-Hung Chen, Wei-Yuan Chiang
Plasma Physics
The Negative Triangularity Tokamak Path for Fusion Pilot Plants: Experimental Progress and Future Prospects
K. E. Thome, M. E. Austin, S. Coda et al. (+8 more)
This paper reviews the experimental progress of negative triangularity (NT), a tokamak configuration where the poloidal cross-section is a reversed-D shape compared to the conventional positive triangularity (PT) shape. NT is a promising reactor scenario that addresses the fundamental tension between performance, exhaust, and robustness. NT studies have accelerated globally across these three pillars over the past several years. While tokamak pilot plants are typically designed for the standard PT H-mode regime, this approach faces significant challenges in balancing high core performance with manageable heat and particle exhaust as well as reliable robustness. In contrast, NT
plasmas have achieved H-mode-level confinement while remaining robustly free of the deleterious edge localized mode (ELM) instability. Regarding exhaust, NT offers a larger divertor wetted area on the outboard side and demonstrates compatibility with detachment and operation at high core radiation fraction without the constraints of the L-H power threshold, while also exhibiting low core
impurity retention. NT operates with high reproducibility over a wide operating space, demonstrated by robust discharge-to-discharge consistency, and has access to
plasmas with very high Greenwald fractions and/or low edge safety factors compared to PT H-mode
plasmas. Further research is required to answer outstanding questions related to reactor confinement extrapolation, the optimal triangularity for a reactor, and core-edge integration. NT studies in existing and planned tokamaks are increasing, as is interest in possible reactor concepts. The unique physics and engineering advantages of NT offer a robust and simplified foundation for a viable fusion power plant.
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All authors K. E. Thome, M. E. Austin, S. Coda, A. Marinoni, A. Hyatt, A. O. Nelson, T. Odstrčil, C. A. Paz-Soldan, O. Sauter, F. Scotti, B. Vanovac
Exactly Solvable and Integrable Systems
Symmetries of the Generalized Yang–Baxter Equations
Pramod Padmanabhan, Somnath Maity, Akash Sinha et al. (+1 more)
The generalized Yang-Baxter equations are multi-site versions of the standard Yang-Baxter equation. When spectral parameters are included, such equations are expected to lead to integrable
Hamiltonians with local interactions involving multiple degrees of freedom. In this work we characterize both the continuous and discrete
symmetries of these equations required to establish an equivalence class of solutions. We find that the set of such
symmetries depends on the number of sites on which the equation is supported. In several cases there are more
symmetries than the standard Yang-Baxter equation, thus placing heavy constraints on the number of inequivalent solutions and the associated integrable models. As an application we show how to restrict the generic $16\times16$ ansatz to the 30-dimensional subspace invariant under a chosen discrete
symmetry subgroup. An explicit $16\times 16$ solution is also written down.
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All authors Pramod Padmanabhan, Somnath Maity, Akash Sinha, Vladimir Korepin
High Energy Physics (Theory)
Duality-covariant particles and exotic branes
Josh O'Connor and David Osten
In this paper we construct duality-covariant worldvolume dynamics of particles and branes. We extend known actions and phase space formulations to include the hidden $E_8$
symmetry of 11D supergravity, analogous to the Ehlers
symmetry of 4D
gravity. Making the worldvolume theory manifestly duality-covariant requires the ancillary structure of $E_8$ exceptional field theory to be taken into account. For zero-branes, we propose an enlarged worldline model with a coadjoint orbit term to encode this. More generally, we propose worldvolume theories for arbitrary exotic branes in a way that generalises the known gauged sigma model of the Kaluza-Klein monopole. These are natural in the duality-covariant
Hamiltonian formulation employed here. We discuss the case of zero-branes in eleven dimensions as an illustrative example.
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Materials Science
Ductility Design Rules for Tungsten based Refractory High Entropy Alloys from Sparse Experimental Datasets
Avik Mahata and Nick Beaver
Tungsten-based refractory high-
entropy alloys (RHEAs) are promising materials for fusion applications but often remain brittle at room temperature because of tungsten's high ductile-to-brittle transition temperature (DBTT). To identify alloying strategies that improve ductility, we compiled a curated
dataset of experimentally reported tungsten-containing
alloys and developed composition-based, physics-informed descriptors for machine learning. Three classifiers were evaluated using nested cross-validation, and a support vector classifier (SVC) showed the best generalization for this sparse
dataset. Shapley additive explanations identified the exchange-correlation parameter, valence electron concentration, pressure field, and electronegativity mismatch as the most influential features governing ductile-brittle behavior. Synthetic compositions generated within the convex interpolation domain of the training data were evaluated and visualized on pseudo-ternary diagrams to map predicted ductility trends. The model predicts that moderate additions of Ti, Ni, and Co increase the likelihood of room-temperature ductility, whereas high Cr contents promote brittle behavior. These predictions agree with published experimental observations, including Ti-assisted ductility through solid-solution and electronic effects and embrittlement in Cr-rich refractory
alloys. Agreement between DFT-derived elastic descriptors and SVC decision-function margins further supports the physical relevance of the learned classification boundary. Although the available mechanical
dataset remains limited and heterogeneous, the model captures experimentally consistent trends and provides an interpretable, physics-informed framework for screening tungsten-based RHEAs for targeted simulation and experimental validation in fusion environments.
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Mesoscale and Nanoscale Physics
Photo-thermal origin of pulse laser induced orientation of crystallographic c axis in Tellurium thin films
Arata Mitsuzuka, Yuta Kobayashi, Takuto Hiraoka et al. (+2 more)
Recent studies have shown that the orientation of crystallographic c axis of Tellurium thin films can be controlled using picosecond long
laser pulses. This method provides spatially programmable control of the
crystal orientation and is therefore highly attractive for practical applications in functional optical and electronic devices. Previously, it was suggested that
laser-induced selective melting and recrystallization can cause the
laser-induced reorientation. However, this interpretation remains inconclusive due to limited data. To clarify the mechanism, here we systematically study Te samples under different irradiation conditions. We find that the threshold fluence for inducing optical reorientation depends on the number of
laser pulses. The results agrees well with a minimal kinetic model based on the Arrhenius law. Using the model developed, we investigate the condition required to control the optic axis in other two-dimensional materials, such as black phosphorus, WTe2, and SnSe. These findings provide a guide for developing functional electro-optical devices based on anisotropic materials.
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All authors Arata Mitsuzuka, Yuta Kobayashi, Takuto Hiraoka, Masashi Kawaguchi, Masamitsu Hayashi
Solar and Stellar Astrophysics
Dust Formation in Common Envelope Binary Interactions – III. Lightcurves
Chunliang Mu, Orsola De Marco, Luis C. Bermúdez-Bustamante et al. (+6 more)
Luminous red novae are transient events thought to arise from common envelope binary interactions. In this paper, we perform post-processing light-curve calculations for two, 3D hydrodynamic simulations of common envelope events. These simulations model interactions between 1.7 $M_\odot$ and 3.7 $M_\odot$ asymptotic
giant branch
stars and a 0.6 $M_\odot$ compact companion, including
dust nucleation. In both our simulations, which are carried out for 44 years under adiabatic conditions, we observe a bright, hot peak lasting $3-5$ years, primarily due to the expansion of the photosphere before and during inspiral. Additional peaks can be seen appearing at different times and for different viewing angles, due to the asymmetry of the interaction.
Dust forms about $1-3$ years after the beginning of the simulated interaction and shortly afterwards we witness a sharp decline in the bolometric luminosity, followed by a partial recovery and a plateau with an effective temperature of $\sim$400 K. The
dust photosphere reaches a size of $\sim$250 au by the end of the simulations, but we predict that between 100 and 200 years, the
dust will become optically thin at visible wavelengths, revealing an inner, warmer photosphere. The lightcurves obtained have two, well-quantified, but large uncertainties: insufficient surface resolution primarily affecting the first 1-2 years of the simulated lightcurves and the adiabatic assumption that affects primarily the later years. We finally contextualise our simulations within a group of observed luminous red nova transients, drawing particular
attention to the outburst of OGLE-2002-BLG-360 and AT 2025abao, which are the closest match to our simulation.
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All authors Chunliang Mu, Orsola De Marco, Luis C. Bermúdez-Bustamante, Ryosuke Hirai, Daniel J. Price, Lionel Siess, Miguel González-Bolívar, Mike Y. M. Lau, Nadejda Blagorodnova
Earth and Planetary Astrophysics
A semi-analytic model of the bouncing barrier for protoplanetary dust aggregates
Sota Arakawa, Haruto Oshiro, Yuki Yoshida et al. (+1 more)
Collisional bouncing limits the growth of
dust aggregates in protoplanetary disks, but its dependence on aggregate size, collision velocity, and filling factor remains poorly understood. Here we develop a semi-analytic model for the sticking probability of colliding
dust aggregates. We divide each aggregate collision into two phases: a compression phase and a separation phase. The compression phase is described with an elastoplastic contact model, which determines the maximum contact radius and repulsive energy after compression. The separation phase is treated as fracture of a
stochastic network of interparticle bonds, whose fracture energy is evaluated using weakest-link statistics. The model naturally predicts that larger aggregates bounce more readily because larger contact regions are more likely to contain weak bonds. Comparison with distinct element method simulations shows that the model reproduces the simulated sticking–bouncing boundary. Furthermore, applying the calibrated model to moderately porous aggregates inferred from ALMA observations of protoplanetary disks, we find that the predicted bouncing barrier passes through the observationally inferred size–velocity range. Thus, our semi-analytic model provides a useful framework for predicting the collisional
evolution of protoplanetary
dust aggregates.
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All authors Sota Arakawa, Haruto Oshiro, Yuki Yoshida, Kiwamu Yoshii
Accelerator Physics
Two-and-a-half dimensional symplectic space-charge solver
Ji Qiang
The nonlinear space-charge effect plays a significant role in high-intensity accelerators and has been extensively studied using multi-particle tracking methods. In this paper, we present a novel 2.5-dimensional
symplectic space-charge solver specifically designed for long beam bunches. We begin by detailing its application to a transverse Gaussian density distribution under open boundary conditions in a straight system, where a semi-analytical expression is derived. We then demonstrate the solver's adaptation to arbitrary distributions in open space, as well as within rectangular and round conducting pipes. Finally, we discuss the extension of this solver to circular accelerator systems. This study shows that the fast 2.5-dimensional solver can be a good approximation to the fully three-dimensional solver for long bunches in large circular accelerators.
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Quantum Physics
Nonsmooth Bloch Oscillations in Non-Hermitian Systems
Yanyan He and Tomoki Ozawa
Bloch oscillations (BOs) represent a paradigmatic manifestation of force-driven band dynamics in
lattices, conventionally characterized by continuous quasimomentum
evolution and smooth periodic trajectories. Here we show that non-Hermiticity qualitatively changes this paradigm, introducing nonsmooth BOs characterized by cusp-like real-space trajectories and abrupt momentum jumps. Reversing the force switches the dynamics between smooth and nonsmooth BOs, enabling strongly nonreciprocal dynamics. We derive a universal relation for the critical force that governs the nonsmooth-to-smooth dynamical transition in general one-dimensional
lattices, which is induced by a pitchfork bifurcation in momentum space. Our work establishes a unified framework for non-Hermitian BOs and uncovers a fundamental bifurcation mechanism that can generate nonsmooth wave transport in entirely linear systems.
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Quantum Physics
Algebraic structures of the Lindblad equation
Leonel Bixano, Guillermo López-Alvarez, Victor Alberto Cruz-Barriguete et al. (+4 more)
We investigate the algebraic structure underlying the Lindblad equation for finite-dimensional open
quantum systems. By introducing a suitable operator representation of the Liouville superoperator, we show that the dynamics can be formulated in terms of a closed
algebra of Hermitian operators that is independent of the particular physical model. This formulation reveals that dissipative dynamics requires a substantially richer algebraic structure than purely
unitary evolution, thereby providing a clear characterization of the additional complexity introduced by the Lindbladian. The resulting framework naturally leads to parametrizations of the dynamical map and to differential equations governing its
evolution. We further derive recursion relations that enable the efficient construction of the
algebra for systems of increasing dimension. Because the algebraic basis is universal, while all model-dependent information enters through a single set of coefficients, the proposed approach significantly reduces the computational cost of constructing the Liouville superoperator compared with direct methods. To facilitate the implementation of the method, we provide a Mathematica notebook containing a one-
qubit example that can be systematically extended to an arbitrary number of
qubits. The proposed framework therefore provides both a general mathematical description of finite-dimensional Lindblad dynamics and a practical foundation for efficient analytical and numerical implementations.
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All authors Leonel Bixano, Guillermo López-Alvarez, Victor Alberto Cruz-Barriguete, V. G. Ibarra-Sierra, José Luis Cardoso, Juan Carlos Sandoval-Santana, Alejandro Kunold
High Energy Astrophysical Phenomena
Hunting for extreme high-energy-peaked BL Lacs: Rare to find and difficult to classify
Loredana Bassani, Raffaella Landi and Nicola Masetti
We explore the possible existence of a new population of BL Lacs, called ultra extreme high-energy-peaked BL Lacs (UEHBLs), whose synchrotron emission component peaks in the MeV band. In particular, we analysed Swift/XRT follow-up observations of a set of 10 hard X-ray sources from the Swift/BAT catalogues which were suggested to represent the first observational hints of this new blazar population on the basis of their spectral properties. We find that 6 of these candidate UEHBLs can be classified as line-emitting active
galactic nuclei (AGNs), 4 of which are of type 2 and X-ray absorbed objects, while 2 are type 1 AGN and X-ray unabsorbed sources. In one more case, we find that the hard X-ray emission is probably the contribution of two line-emitting AGN, i.e. a Seyfert of type 1.9 and another of type 2. All these 7 classifications exclude the possibility that these hard X-ray sources are extreme BL Lacs. Of the remaining 3 UEHBL candidates, only 2 objects are found to have a spectral energy distribution (SED) compatible with those expected by MeV-peaked BL Lacs: however, in one of these 2 cases, an alternative
Galactic association is also possible. The third source is instead likely associated with a more classical quasi-
stellar object. Overall, we find that UEHBLs are extremely rare to find and probably very difficult to classify. Nevertheless, they represent a viable alternative classification for hard X-ray sources displaying no obvious or very weak counterparts.
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