Materials Science
Multi-image Overlap Stitching and Automatic Image Construction for Coherent X-ray Imaging
Starr Boney, Umeshika Dissanayaka, Lillian Rutowski et al. (+2 more)
Direct-space and real-time coherent X-ray imaging (direct-CXI) enables visualization of
magnetic-domain structures and dynamics over length scales exceeding the field of view of a single image. However, large-area measurements typically require raster scanning, producing hundreds of partially overlapping images that must be accurately aligned and combined before quantitative analysis can be performed. Here, we present Multi-image Overlap Stitching and Automatic Image Construction for coherent X-ray imaging (MOSAICX), an automated stitching workflow for large-area direct-space coherent X-ray imaging. The workflow consists of image centering, masking, trimming, binarization, hierarchical stitching, and post-processing. To demonstrate the method, we apply it to a
dataset comprising 434 direct-CXI images of the
antiferromagnetic topological
insulator MnBi$_2$Te$_4$. The images are first combined into column reconstructions and subsequently stitched into a single large-area composite image. The resulting reconstruction reveals the complete
magnetic-domain and domain-wall landscape over the scanned region while suppressing imaging artifacts and detector defects. The presented workflow provides an efficient approach for processing large direct-CXI
datasets and enables visualization and analysis of
magnetic-domain structures beyond the field of view of individual measurements.
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All authors Starr Boney, Umeshika Dissanayaka, Lillian Rutowski, Aaron George, Min Gyu Kim
General Relativity and Quantum Cosmology
A Fast and Scalable Transformer Pipeline for Binary Black Hole Detection
Chayan Chatterjee, Abigail Petulante, Haowei Fu et al. (+3 more)
With the projected increase in the detection rate of compact-binary coalescences in the coming decade, there is critical need to develop fast, robust, and scalable alternatives to matched filtering for gravitational-wave searches.
Transformer models have revolutionized natural
language and audio processing but their application to gravitational-wave astronomy is still largely unexplored. In this work, we introduce \castor, a
transformer-based coincident search pipeline for detecting binary black hole gravitational-wave signals from Advanced LIGO detectors. One of the major features of our model is that it allows the false-alarm rate to be estimated via time slides cheaply without requiring repeated evaluations of the neural network. We evaluate \castor\ on
datasets from the Machine-Learning Gravitational-Wave Search Challenge (MLGWSC-1) and on approximately five months of real O3b observing strain. When tested on
benchmark datasets, \castor\ ranks among the most sensitive machine-learning pipelines and successfully recovers the majority of confident events from the GWTC-3 catalog that lie within its training range. We also
benchmark \castor\ against another
transformer architecture, GW-Whisper, a domain-adaptation of OpenAI's audio foundation model. We find that \castor\ substantially outperforms the repurposed audio model in sensitivity and also reduces the computational cost of background estimation by a factor of 20. Our results demonstrate a highly practical, scalable approach for deep-learning gravitational wave searches and empirical background estimation for future observing runs.
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All authors Chayan Chatterjee, Abigail Petulante, Haowei Fu, Yang Hu, Roy Lau, Karan Jani
Superconductivity
Simão S. Cardoso, A. Mesaros and P. Simon
In flat band
superconductors,
quantum geometry, rather than kinetic energy, governs pairing and transport. However, how this geometry manifests in the response to a local, individually addressable
impurity remains largely unexplored. Here, we study the Yu-Shiba-Rusinov (YSR) bound state induced by a
magnetic adatom that hybridizes with every orbital of a two-dimensional flat band
superconductor, and characterize its spatial profile using two quantities: the quadratic spread $Q_S$ and the localization length $\xi$. We show that $Q_S$ is not set by the
quantum metric alone, as
geometric corrections arising from inter-orbital interference and, more importantly, from the anisotropy of the adatom-
lattice hybridization contribute on equal footing, making $Q_S$ strongly
impurity dependent and tunable. On the other hand, $\xi$ emerges from the projection onto the flat band alone and is a universal property set by the overlap of compact localized states. All
impurity dependence is instead isolated in the prefactor of the wavefunction whose magnitude correlates directly with $Q_S$. We, therefore, report a clean separation between universal and
impurity-tunable physics from the induced YSR bound state in these systems, and confirm our results numerically via exact diagonalization.
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Mathematical Physics · Cross-listed from math.CA
Critical points of point charge potentials along lines
Goncalo Oliveira
We prove
Conjecture 1.9 of Gabrielov-Novikov-Shapiro. More precisely, for every $p>0$, every nonconstant restriction to a line of a potential generated by $n$ point charges has at most $2n-1$ critical points. The bound is sharp, even for positive charges. The proof uses a duality with an auxiliary planar potential generated by collinear charges and Morse theory.
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Soft Condensed Matter
Using microrheology to study dynamical heterogeneities
Antonio M. Puertas and Thomas Voigtmann
Dynamical heterogeneities are one of the hallmarks of supercooled
liquids, and their properties and relevance have been studied with theory, simulations and experiments. In this work, we propose to monitor the dynamics of tracer particles (passive microrheology) to analyze the dynamical heterogeneities in a system of hard colloids close to the glass transition density, using Langevin dynamics simulations and mode coupling theory. Different observables, typical in the study of the dynamical heterogeneities are adapted to be calculated from the trajectory of a single tracer particle. The tracer dynamics shows a transition from a regime where it is most decoupled from the bath for small tracer size to a strong coupling regime for large tracers. Both theory and simulations show that the non-Gaussian parameter of the tracer is maximal for tracer sizes at the crossover between both regimes, and is highly dependent on the bath density. The dynamic susceptibility is also studied, but this parameter shows a minor dependence on both the tracer size or the bath density. Finally, the existence of regions with different mobility is also studied with microrheology. Although the tracer trajectory indeed shows stages with increased mobility, the estimated size of the regions decreases with the bath density, contrary to the results from cluster analysis in the bulk.
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High Energy Physics (Theory)
Accretion, mergers, and metastability of fuzzy spheres in a three-matrix model
M. Hrmo, S. Kováčik, K. Magdolenová et al. (+5 more)
A three-
matrix model that contains a plethora of fuzzy sphere solutions was defined twenty years ago. It has been shown that in a certain regime of the model, combinations of fuzzy spheres become classical solutions of the model. In the original paper and subsequent works, the stability of specific states has been discussed, showing that only a single largest fuzzy-sphere configuration is stable. Here, we focus on a complementary question: starting from some initial configuration, is the thermodynamically preferred state approached rapidly, or are there other long-lived, metastable configurations which may support interesting physics? We find that the answer in the large-
matrix limit depends on the dispersion of the initial configuration. We identify the elementary transition as an
accretion, in which one sphere absorbs a single unit from another, and show that it is driven by fluctuations of the sphere centers. By measuring these fluctuations in long simulations, we find quantitative agreement with the one-loop effective action, with no free parameters. For multi-sphere states, we find that the stiffness of an inner sphere grows logarithmically with the number of surrounding layers, so that concentric onion-like configurations – describing an emergent three-dimensional
quantum space – become increasingly long-lived.
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All authors M. Hrmo, S. Kováčik, K. Magdolenová, A. Manta, K. Nedeľková, P. Rusnák, H. C. Steinacker, J. Tekel
Physics and Society
Modeling of Mobility and Energy Policies in an Agent-Based Framework: Case Studies for Chicago Region in 2050
Md Rakibul Alam, Omer Verbas, Taner Cokyasar et al. (+10 more)
Metropolitan regions are simultaneously pursuing several interventions to improve mobility, accessibility, and energy efficiency, necessitating integrated tools to understand how these policies interact to affect travel behavior, energy use, and infrastructure needs. This paper evaluates the combined impacts of electrification, freight demand management, road pricing, parking reform, and transit expansion on the Chicago metropolitan transportation system in 2050, using a business-as-usual (BAU) scenario as the baseline. We employ POLARIS, a large-scale
agent-based modeling framework calibrated to 2019 conditions, to simulate nine policy scenarios for the seven-county northeastern Illinois region. The framework co-simulates activity-based passenger demand, endogenous freight generation,
multimodal traffic assignment, and transit operations, with charging infrastructure and freight operations optimized for each case. Our findings reveal that under the high electrification scenario, total fuel mass declines by 68% while total charging energy increases by approximately 4-8x from BAU, resulting in a peak power demand near 4 GW concentrated in the urban core. Furthermore, freight management policies reduce freight VMT by increasing trip frequency but shortening distances, smart road pricing most effectively reduces auto VMT, and transit expansion boosts ridership by 18% relative to BAU. By presenting the first integrated,
agent-based scenario framework for Chicago that jointly evaluates these interventions, this study provides actionable insights for regional transportation planning, grid infrastructure investment, and emissions reduction, highlighting the value of targeted charger upgrades and coordinated policy bundles.
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All authors Md Rakibul Alam, Omer Verbas, Taner Cokyasar, Hadi Bhidya, Jesse Altman, Nora Beck, Joshua Auld, Pedro Veiga de Camargo, Jamie Cook, Felipe de Souza, Gopindra Nair, Hyunseop Uhm, Jan Zill
Statistical Mechanics
A Human-AI Theorem Connecting Spontaneous and Field-Induced Mechanisms of Collective Behavior in One Dimension
Weiguo Yin
Can an artificial intelligence (AI) generate a scientific hypothesis outside a human collaborator's active hypothesis space (AHS), and can human-AI research be organized to make such breakthroughs more likely? We document such a case while proving a
theorem that connects two basic organizing mechanisms of statistical physics: collective behavior arising in zero field from competing interactions and that induced or controlled by an external field. A zero-field $O(n)$-vector open chain with arbitrary inhomogeneous nearest- and next-nearest-neighbor interaction functions $U_i(S_i\cdot{S}_{i+1})$ and $V_i(S_i\cdot{S}_{i+2})$ is microscopically, via a temperature-independent mapping at the
Hamiltonian level, equivalent to a simpler $O(n)$ open chain with nearest-neighbor interaction $V_i(\boldsymbol\sigma_i\cdot\boldsymbol\sigma_{i+1})$ and axial single-
spin potential $U_i(\sigma_i^z)$ for every integer $n\ge1$ and every system size $L\ge1$. The homogeneous linear specialization maps the foundational frustrated $J_1$-$J_2$ model onto the canonical $J$-$h$ field model—with $n=1,2,3$ being the Ising, XY, and Heisenberg classical
spin models, respectively; the
theorem resolved a longstanding challenge for $n=3$ published in 1990. Its proof was done with an AI-synthesized recursive Householder moving frame and understood via a human-recognized hidden reciprocity. An analogous
theorem holds when the continuous $O(n)$
spins are replaced by the $q$-state Potts
spins, implying a closed-form exact solution of the $J_1$-$J_2$ standard Potts open chain for every $q\ge2$ and every $L\ge1$. The emergence of these
theorems from a human-AI co-development framework suggests that sustained AI involvement throughout a systematic research program may incubate autonomous scientific breakthroughs and make aspects of the discovery process experimentally testable.
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Quantum Physics
Which Otto Engine Is the Fastest?
Idriss Hank Nkouatchoua Ngueya and Marcin Łobejko
A general thermal machine is characterized by distinct time or energy scales: temperature, coupling to the heat baths, internal free dynamics and interactions, and external driving. We address the question: what parameters determine the speed of a given engine, and how can they be used to reliably compare different types of engine? Specifically, we consider four realizations of the Otto engine, each operating with the same Otto efficiency, and aim to characterize and compare their power outputs. The main insight of this paper is that, irrespective of their very different dynamical implementations, the power of each engine can be factorized into a common characteristic work and an implementation-specific characteristic time. The characteristic work depends only on the internal frequencies of the machine and the temperatures, whereas the characteristic time depends on the coupling strength to the baths and on the implementation-specific driving. This observation allows us to compare the power of different engines through their characteristic times and thereby reduce the relevant parameter space to parameters that capture the dynamical aspects of engine performance. Despite different dynamical implementations, this framework reveals simple common features. In all cases, the maximum operating speed is limited by a common timescale given by the sum of the characteristic thermalization times of the hot and cold baths. Moreover, the four engines fall into two distinct asymptotic classes: implementations in which driving and thermalization occur simultaneously exhibit quadratic scaling, whereas those in which work extraction and thermalization alternate exhibit linear scaling. These results expose general dynamical features that determine the operational speed of
quantum Otto engines.
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Physics and Society
Modeling microbiome dynamics on social networks: how between-host transmission shapes within-host evolution
Longmei Shu and Feng Fu
A social network perspective on the human microbiome is crucial for understanding how the interplay between within-host microbial dynamics and between-host transmission influences microbial community stability, host metabolism, and population health and nutrition. Here, we provide a mathematical and numerical analysis of human-associated microbial communities in dyadic social ties and within a small network. By utilizing a generalized Lotka-Volterra model, we simulate within-host dynamics while incorporating inter-host microbial sharing driven by social interactions. Furthermore, the study accounts for individual variability in microbial behavior across different hosts. Our work identifies the conditions under which microbial sharing can have long-lasting effects, offering insights into how social networks shape the human microbiome.
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Solar and Stellar Astrophysics
Direct Measurement of Polar Coronal Hole-like Solar Wind in its Acceleration Phase
Samuel T. Badman, Yeimy J. Rivera, Michael L. Stevens et al. (+38 more)
The early
evolution of fast polar coronal hole (PCH)
solar wind remains largely unconstrained by in situ measurements. In March 2025, Parker
Solar Probe (Parker) at its closest approach of 9.86
Solar Radii ($R_\odot$) measured
outflow from a large equatorial coronal hole (ECH) which was also measured at 1\,au and at intermediate distances by
Solar Orbiter (also near its perihelion). At 1\,au the stream properties are consistent with PCH properties established by Ulysses. The stream was measured by Parker substantially below the Alfvén surface, with
proton temperatures in excess of 2\,MK and a speed at $\sim$10\,$R_\odot$ which was only $\sim$60% of its asymptotic value. The
Solar Orbiter data indicates that the acceleration is largely complete by 60~$R_{\odot}$. Spherically-polarized fluctuations in the stream are observed to develop from near-transverse and small-angle at Parker to full reversal “switchbacks” at
Solar Orbiter. Comparison of the implied acceleration profile to historical doppler-dimming measurements suggests that the stream's low coronal acceleration is similar to that of PCH flows. Consistent with previous work, this acceleration requires significantly more energy than can be provided by the observed thermal pressure gradients, with a significant contribution likely from the abundant Alfvénic fluctuation energy observed at Parker. These observations provide unique constraints on models of the radial
evolution of the fastest
solar wind, and indicate that these wind streams experience gradual, steady acceleration over their first few tens of
solar radii of
evolution.
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All authors Samuel T. Badman, Yeimy J. Rivera, Michael L. Stevens, Mari Paz Miralles, Steven R. Cranmer, Andrea Verdini, Lynn B. Wilson III, Xiangyu Wu, Georgios Nicolaou, Jean-Baptiste Dakeyo, Kai Jaffarove, Tamar Ervin, Dominic S. Payne, Michael Terres, Kristopher G. Klein, Jasper S. Halekas, Sujan Prasad Gautam, William H. Matthaeus, Riddhi Bandyopadhyay, Srijan Bharati Das, Tatiana Niembro, Christopher J. Owen, Rungployphan Kieokaew, Ali Rahmati, Orlando M. Romeo, Federico Fraschetti, Marco Velli, Lorenzo Matteini, Kristoff W. Paulson, Lidiya Ahmed, Stuart D. Bale, Phyllis Whittlesey, Marc Pulupa, Nour E. Raouafi, Timothy S. Horbury, Jean Morris, Helen O'Brien, Roberto Livi, Davin E. Larson, Adam J. Finley, Philippe Louarn
General Relativity and Quantum Cosmology
Ghost-free higher-gradient Newtonian gravity from the Second Law of Thermodynamics
M. Pszota and P. Ván
Higher-gradient modifications of Newtonian
gravity remove the point-mass singularity, but their Lagrangian dynamics is haunted by the Ostrogradsky instability. We show that the same field equations follow from the Second Law of thermodynamics applied to a self-gravitating fluid with a weakly nonlocal state space, and that on this route the instability is absent by construction: the potential obeys a first-order relaxation equation that is a gradient flow, whose Lyapunov function is the
entropy density, and whose relaxation spectrum is negative definite at every wavenumber precisely when the
entropy is concave. The derivation also yields the pressure tensor and the energy current, an exact identity that reproduces Newton's force law without further input, and a dissipation-free cross-coupling to the bulk viscous pressure that no variational principle can produce. Regularity constrains the Yukawa-type corrections by an amplitude sum rule, $\sum_i\alpha_i=-1$, so that laboratory tests of the inverse-square law bound the largest internal length below $4\times10^{-5}$~m, and identify the complex-root regime as a classically consistent Lee–Wick-like sector.
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Mathematical Physics
Robin Laplacians with point interactions on unbounded domains: discrete spectrum and coupling asymptotics
Diego Noja and Francesco Raso Stoia
We investigate the discrete spectrum of finitely many point interactions for Neumann and Robin
Laplacians on special unbounded and exterior $C^{1,1}$ domains in dimensions two and three. The operators are realized as self-adjoint extensions through an ordinary boundary triple whose gamma field and Weyl
matrix are constructed from the Robin Green kernel.
Eigenvalues below the background spectrum are characterized by the Weyl
matrix, yielding an exact finite-dimensional counting formula. If the background operator is non-negative, this also gives the number of negative
eigenvalues without assuming a finite zero-energy limit of the Weyl
matrix. In the one-centre case we identify the critical coupling and prove that the unique
eigenvalue branch is real analytic, strictly increasing, and strictly concave. For scalar multicentre couplings $\Theta=\alpha I_N$, sufficiently strong attraction produces exactly $N$
eigenvalues below the background spectrum, and all of them have universal leading asymptotics coinciding with the whole-space laws. If the bottom of the background spectrum is an isolated
eigenvalue, the branch exists for every finite coupling and we determine its leading decoupling asymptotics as the coupling tends to $+\infty$. Explicit exterior-sphere and exterior-disk models illustrate the critical couplings and their threshold behaviour.
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Chemical Physics
Use of Cholesky decomposition in the CFOUR program package
Jürgen Gauss, Simon Blaschke, Sophia Burger et al. (+10 more)
An overview is given about our efforts to speed up high-level computations of molec- ular energies and properties using Cholesky decomposition (CD). We describe the cor- responding developments in the CFOUR
quantum-chemical package with a focus on (a) the use of CD in complete-active space self-consistent-field (CASSCF) and coupled- cluster (CC) computations, (b) the implementation of analytic CC gradients using CD, (c) the efficient calculation of
magnetic properties (NMR shieldings and magnetizabili- ties) using CD when carried out with explicit
magnetic-field dependent basis functions, i.e., the so-called gauge-including atomic orbitals (GIAOs), (d) the efficient computa- tion of CASSCF response properties using CD, (e) the use of CD in relativistic two- and four-component computations, as well as (f) computations for molecules in finite
magnetic fields using GIAOs together with CD. An outlook on future developments concerning the CFOUR package is given.
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All authors Jürgen Gauss, Simon Blaschke, Sophia Burger, Davide Cianchino, Marios-Petros Kitsaras, Luca Melega, Tommaso Nottoli, Jeremias Oswald, Tereza Uhlířová, Chaoqun Zhang, Lan Cheng, Stella Stopkowicz, Filippo Lipparini
Solar and Stellar Astrophysics
A Data-Driven Model for $r$-Process Production Patterns
Chen-Qi Li, Yong-Zhong Qian, Axel Gross et al. (+1 more)
Using the elemental abundances in 68 metal-poor (MP)
stars, we present a data-driven model for $r$-process production patterns covering Sr to U. We show that essentially all the $r$-process patterns in those and other test
stars can be adequately explained as mixtures of Patterns 1 and 2, which provides theoretical insights into the empirical categories of limited-$r$, $r$-I, and $r$-II
stars. We carry out an extensive survey of the yield templates produced by parametric $r$-process calculations. We propose that Pattern 2 may be dominated by a single template and points to regularity in $r$-process production by a subset of
neutron star mergers (NSMs), while Pattern 1 is the average superposition of multiple templates and reflects production by other NSMs and perhaps also some magneto-rotational
supernovae. We raise possible systematic issues with abundance ratios for elements measured in different ionization states, and highlight the need for examining the Os, Ir, and Pt measurements for HD~122563, which is dominated by Pattern 1 with a prominent Pt peak in our model. If this result is confirmed, the meaning of the limited-$r$ category requires drastic revision. Further measurements of a wider range of $r$-process elements in a larger sample of MP
stars are critical to test and improve our model.
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All authors Chen-Qi Li, Yong-Zhong Qian, Axel Gross, Zewei Xiong
Solar and Stellar Astrophysics
TESS Observations of Seven Newly Identified High-amplitude $\delta$ Scuti Stars
Chenglong Lv, Ali Esamdin, Amir Hasanzadeh et al. (+3 more)
We report seven newly identified high-amplitude $\delta$ Scuti (HADS)
stars. Among them, two
stars (TIC 30977864 and TIC 387379145) exhibit pure radial pulsation without the excitation of non-radial modes. TIC 30977864 is classified as a double-mode HADS
star, while the other four
stars potentially show triple-mode HADS behavior. TIC 112682462 and TIC 255603395 closely resemble RR Lyrae
stars based on their light curves, position in the period-luminosity diagram, and the period-ratio diagram. However, without spectral observations, it is challenging to ascertain whether these two
stars are HADS or RR Lyrae
stars. TIC 281695001 exhibits a fundamental frequency amplitude smaller than that of the first overtone, suggesting the presence of intriguing phenomena that necessitate further analysis. We analyzed the relationship between
metallicity and period using data provided by Netzel & Smolec. The
metallicities of the 176
stars display a broad distribution ranging from -2.0 dex to 0.5 dex, with periods spanning 0.05 to 0.20 days. This random distribution of
metallicities may contribute to the dispersion observed in the $P_1/P_0$ ratio. To derive more accurate conclusions, future spectroscopic observations of a larger sample of HADS
stars are crucial. These observations will provide precise rotational velocities and more accurate determinations of
metallicities.
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All authors Chenglong Lv, Ali Esamdin, Amir Hasanzadeh, Shuguo Ma, TaoZhi Yang, Rivkat Karimov
Solar and Stellar Astrophysics
Statistical analysis of asteroseismic indices and stellar parameters of TESS-observed $\delta$ Scuti stars
C. Lv, A. Esamdin, A. Hasanzadeh et al. (+4 more)
We analyze the statistical properties and asteroseismic indices of delta Scuti
stars observed during TESS Cycle 4. Using 2 minute cadence photometry and
Fourier analysis, we identified 765 delta Scuti
stars in Sectors 40-55, including 179 objects with low-resolution
stellar parameters from LAMOST. We examined the distributions of their pulsation and
stellar parameters using values from the TESS Input Catalog and LAMOST. Most targets lie within the classical instability strip, follow the period-luminosity relation, and show periods, amplitudes, temperatures, surface gravities, and luminosities consistent with delta Scuti
stars. For the LAMOST subsample, we estimated the large frequency separation ($\Delta\nu$), $\nu_{\rm max}$, and $\nu({\rm Amax})$ using an empirical relation and a two-dimensional autocorrelation method. We also derived relations among these asteroseismic indices. This catalog provides a useful sample for future studies of the internal structure and
evolution of delta Scuti
stars.
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All authors C. Lv, A. Esamdin, A. Hasanzadeh, M. Ghazinejad, J. Pascual-Granado, G. M. Mirouh, R. Karimov
Accelerator Physics
A particle-in-cell model of beam dynamics in a dielectric wall accelerator
Christopher M. Lund, Paul M. Jung, Jamiel Nasser et al. (+6 more)
Dielectric wall accelerator (DWA) technology has been proposed as a compact, cost-effective alternative to rf accelerators for
proton therapy, but its beam dynamics and practical feasibility remain relatively unexplored. In this work, we derive a three-dimensional, time-dependent axisymmetric electromagnetic field model from a prescribed on-wall excitation and implement it as stacked external field elements in the particle-in-
cell code Warp. In the absence of experimental DWA beam-transport data, the implementation is cross-checked against a previously developed linear optics model in TRANSOPTR using deliberately idealized beam conditions. Strong agreement is observed between the two models in this regime. The models are then compared for larger transverse and longitudinal emittances, bunch charges up to 1x10^8e, and beam parameters representative of a low-energy
proton source. The PIC simulations remain consistent with the linear predictions over much of the investigated range, while also identifying wall interactions, longitudinal phase-space distortions, and space-charge induced aberrations. The PIC model represents an intermediate step between linear optics and combined, geometry-specific electromagnetic and particle-transport simulations. It resolves particle-level transport and beam self-fields while retaining an analytical field description that can be varied without committing to a particular DWA structure. More detailed effects may be introduced through externally generated field data or empirical corrections, including models of
cell-to-
cell coupling, providing a practical basis for increasingly realistic DWA field and beamline studies.
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All authors Christopher M. Lund, Paul M. Jung, Jamiel Nasser, Morgan J. Maher, Julien Bancheri, Chau Giang Bui, Thomas Planche, Rick Baartman, Jan Seuntjens
Solar and Stellar Astrophysics
Discovery and Characterization of Three New High-amplitude delta Scuti Stars from TESS Observations
Chenglong Lv, Ali Esamdin, J. Pascual-Granado et al. (+5 more)
We report the discovery and detailed analysis of three new high-amplitude {\delta} Scuti (HADS)
stars, TIC 408074920, TIC 189714989, and TIC 34137913, identified from Transiting
Exoplanet Survey Satellite short-cadence observations.
Fourier analysis reveals dominant radial modes accompanied by rich harmonic structures in all three
stars, confirming their HADS classification. In addition, TIC 189714989 exhibits clear symmetric side peaks around the radial harmonics, indicative of amplitude and/or phase modulation. Broadband spectral energy distribution (SED) fitting constrained by
Gaia DR3 parallaxes provides independent estimates of the
stellar effective temperatures and radii. These are compared with results from
stellar evolutionary and seismic modeling based on MESA and GYRE. For two targets, the SED-derived and seismic radii are mutually consistent, while TIC 408074920 displays a significant discrepancy, plausibly attributable to the different sensitivities of the two methods and additional systematic effects. These findings highlight the diversity of amplitude variability among classical HADS and emphasize the importance of the long-term monitoring that future missions such as PLATO will allow in order to explore the underlying physical mechanisms of this variability.
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All authors Chenglong Lv, Ali Esamdin, J. Pascual-Granado, Guojie Feng, Haozhi Wang, Rivkat Karimov, Bolkin Juraev, Shuhrat A. Ehgamberdiev
Astrophysics of Galaxies
ELVES-Dwarf. II. A Systematic Search for Satellite Systems of Dwarf Galaxies in the Local Volume
Jiaxuan Li, Jenny E. Greene, Shany Danieli et al. (+7 more)
We present the Exploration of Local VolumE Satellites of
Dwarf Galaxies (ELVES-
Dwarf) survey, a systematic census of satellite systems around
dwarf hosts in the Local Volume. Our final sample comprises 39 predominantly isolated hosts with
stellar masses $10^{7}<M_\star<10^{10}\,M_\odot$, including 32 hosts searched uniformly in this work and 7 drawn from the literature. We search for satellite candidates within the projected virial radius of each host using $155~\mathrm{deg}^2$ of Legacy Surveys imaging data. We determine satellite membership using surface brightness fluctuation distances from Subaru/HSC, Magellan/IMACS, and Gemini/GMOS imaging, supplemented by literature TRGB distances and radial velocities. From 207 candidates, we confirm 39 satellites with $M_\star>10^5\,M_\odot$ around the 39 hosts. Above our fiducial completeness threshold of $M_\star\gtrsim10^{5.7}\,M_\odot$ and within the projected virial radius, 21 hosts have no confirmed satellites, 10 have one, six have two, and two have four, revealing substantial host-to-host scatter in satellite abundance. Overall, the observed satellite abundances and
stellar mass functions are broadly consistent with predictions from the cosmological simulation TNG50 and
galaxy formation models calibrated using Milky Way satellites. The projected radial distribution of the satellites is also consistent with theoretical expectations and with satellite populations around Milky Way-mass hosts. In contrast, the quenched fraction of satellites around
dwarf hosts is substantially lower than around Milky Way-mass hosts, suggesting that environmental quenching is less efficient in
dwarf halos. ELVES-
Dwarf provides the first large, homogeneous, distance-confirmed sample of satellites around
dwarf hosts and establishes a foundation for understanding
galaxy formation and
evolution in less-dense environments.
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All authors Jiaxuan Li, Jenny E. Greene, Shany Danieli, Scott G. Carlsten, John Moustakas, Marla Geha, Masayuki Tanaka, Fangzhou Jiang, Ping Chen, Sufia Birmingham
Earth and Planetary Astrophysics
Three-dimensional circumplanetary flows in a PDS 70c-inspired system: hydrodynamic simulations with FARGO3D and analysis with FARGOpy
Alejandro Murillo-Gonzalez, Jorge I. Zuluaga and Matias Montesinos
The detection of circumplanetary material around the forming
planet PDS~70c provides a valuable setting for studying three-dimensional gas
accretion during
giant-
planet formation. We present three-dimensional hydrodynamic simulations with FARGO3D for a locally isothermal protoplanetary disk, adopting system-motivated
stellar, orbital, and disk parameters and planetary masses of $2$, $4$, and $8,M_{\rm Jup}$, all above the local thermal mass. The locally isothermal prescription provides a controlled prescribed-temperature limit that isolates the hydrodynamic organization of the flow, without modeling self-consistent thermal
evolution or radiative observables. Gas enters the planetary environment through meridional flows from the upper disk layers and streams near the midplane. With increasing planetary mass, the flow changes from a vertically extended, envelope-like configuration to a more compact and stratified circumplanetary structure. The inferred CPD radius increases from $R_{\rm CPD}\simeq0.31$ to $0.40,R_{\rm Hill}$, while the flow remains sub-Keplerian, reaching $v_\phi/V_{K,p}\sim0.79$–$0.85$. Most enclosed gas mass lies within a few tenths of the Hill radius, whereas the outer Hill sphere is dominated by anisotropic inflow,
outflow, and recirculation. The analysis was performed with FARGOpy, a Python post-processing framework developed in this work to reconstruct three-dimensional fields, compute integrated fluxes, and characterize circumplanetary kinematics from FARGO3D outputs. This study therefore provides both a hydrodynamic baseline for a PDS~70c-like environment and a reproducible framework for analyzing three-dimensional FARGO3D simulations.
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Astrophysics of Galaxies
Accretion-disk sizes in two quasars with interferometrically resolved broad-line regions at $z=2.3$ and $z=4.0$
Francisco Pozo Nuñez, Eduardo Bañados, Swayamtrupta Panda et al. (+3 more)
We present the first direct comparison between
accretion-disk (AD) and broad-line region (BLR) sizes in
quasars at z > 2, combining continuum reverberation mapping with interferometric BLR constraints from
GRAVITY and
GRAVITY+. Using medium-band photometric monitoring with the MPG/ESO 2.2 m
telescope, we measure inter-band continuum lags in SDSS J092034.17+065718.0 at z = 2.33 (J0920) and SMSS J052915.80-435152.0 at z = 3.96 (J0529), among the most luminous
quasars known (Lbol ~ 10^48 erg s^-1). These are currently the only two
quasars at z > 2 with spatially resolved BLRs and dynamical black-hole masses from interferometry. We detect significant continuum lags in both
quasars, increasing monotonically with wavelength. The inferred UV disk sizes are RAD = 4.35 +0.78/-0.91 light-days for J0529 and RAD = 3.15 +0.50/-0.48 light-days for J0920. For J0920, accreting at lambda_Edd ~ 7-20, the disk size is consistent with standard thin-disk expectations despite its super-Eddington regime. For J0529, the disk size agrees with thin-disk predictions using the single-epoch black-hole mass, but implies disk inflation by a factor of a few if the
GRAVITY+ dynamical mass, an order of magnitude lower, is adopted. UV continuum disk sizes therefore provide an independent physical scale constraining black-hole mass and
accretion-rate models, particularly where BLR kinematics are dominated by
outflows. The interferometric BLR sizes reveal pronounced radial hierarchies, with RBLR/RAD ~ 270 for J0529 (Hbeta) and ~115 for J0920 (Halpha). The successful lag detections at Lbol ~ 10^48 erg s^-1 show that continuum reverberation mapping remains feasible for the most luminous systems, opening a path to larger samples with surveys such as the Vera C. Rubin Observatory's LSST.
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All authors Francisco Pozo Nuñez, Eduardo Bañados, Swayamtrupta Panda, Amit Kumar Mandal, Bozena Czerny, Jochen Heidt
Strongly Correlated Electrons
Yu-Han Lin, Jin-Wei Dong, Ziqiang Wang et al. (+1 more)
We propose a
symmetry-guided route to engineer tunable $p$-wave magnetism in a
bilayer system composed of two AB-stacked
antiferromagnetic square
lattices with their collinear moments nonparallel to each other. We show that an in-plane relative shift between the two layers selectively breaks the
symmetries protecting
spin degeneracy while preserving time-reversal-related constraints, thereby generating odd-parity
spin splitting in a fully compensated
magnetic state without
spin-orbit coupling. The direction and the magnitude of the resulting $p$-wave
spin-splitting, together with the associated
spin responses, can be continuously tuned by the in-plane displacement, providing a potential knob for control. We further map the
bilayer system onto an effective bond-modulated square
lattice and investigate the corresponding Hubbard model within a mean-field framework. The calculated phase diagram reveals extended regions where $p$-wave magnetism with coplanar or
chiral spin textures emerges spontaneously. Our results establish a minimal
equilibrium platform for realizing and manipulating $p$-wave magnetism in two-dimensional systems.
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All authors Yu-Han Lin, Jin-Wei Dong, Ziqiang Wang, Sen Zhou
Applied Physics
A fully coupled electromagnetic-thermal-mechanical model for metal-insulated HTS high field magnets
Anang Dadhich, Nikola Jerance, Tara Benkel et al. (+2 more)
Ultra high field REBCO magnets operate under strongly coupled electromagnetic, thermal and mechanical conditions, where screening currents, localized heating, thermal expansion and Lorentz forces can modify both the structural state and the critical current density of the conductor. In this work, a coupled electromagnetic, thermal and mechanical model is developed for a metal-insulated nested REBCO insert designed for a 40 T class SuperEMFL magnet. The existing electromagnetic formulation resolves the non-uniform screening currents in the REBCO tapes. The thermal model is extended from an explicit Finite Difference Method (FDM) to an implicit Backward Euler scheme with Picard iteration, while a new axisymmetric mechanical FDM solver based on BiCGSTAB is introduced to calculate displacements, strains and stresses in the coil windings and G10 spacer regions. Thermal expansion and Lorentz force contributions are included, and the calculated longitudinal mechanical strain is coupled back to the electromagnetic model through a strain dependent critical current density, which also depends on temperature,
magnetic field, and its orientation. A literature-informed
Parabolic-Weibull model is used to model reversible and irreversible strain degradation of the REBCO conductor. The numerical methods are benchmarked, and the resulting framework provides a computationally efficient approach for investigating temperature gradients, thermo-mechanical stresses, strain-dependent critical current degradation and quench behaviour in full scale nested high field REBCO magnets.
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All authors Anang Dadhich, Nikola Jerance, Tara Benkel, Philippe Fazilleau, Enric Pardo
High Energy Physics (Phenomenology)
Two-Stage Machine Learning Strategy for Scalar and Vector Leptoquark Discrimination at the LHC
Ernesto Arganda, Martín de los Rios, Andres D. Perez et al. (+2 more)
We present a machine learning framework for the characterization of leptoquark (LQ) signals at the Large
Hadron Collider, focusing on the discrimination between scalar (SLQ) and vector (VLQ) hypotheses. The method is based on a two-stage inference pipeline that combines a classifier trained to separate Standard Model backgrounds from a mixed LQ signal with a second classifier designed to distinguish between SLQ and VLQ scenarios, using the signal yield inferred from the first-stage classifier to guide the corresponding scalar and vector mass hypotheses. A test statistic is constructed from the classifier outputs and interpreted using reference probability density functions. The approach is applied to realistic LHC final states with hadronically decaying tau
leptons, multiple jets, and missing transverse momentum, and its performance is assessed using simulated pseudo-experiments. We show that the proposed strategy provides a robust and statistically consistent procedure to discriminate between SLQ and VLQ signals across a wide range of masses and signal stregths. We find that the
spin identification power closely follows the discovery potential, demonstrating that determining the
spin nature of a newly discovered LQ does not require substantially larger
datasets than those needed for discovery itself.
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All authors Ernesto Arganda, Martín de los Rios, Andres D. Perez, Rosa M. Sandá Seoane, Alejandro Szynkman
Lattice Field Theory
Long-distance hybrid spin-dependent and hybrid-quarkonium mixing potentials from lattice gauge theory
Vilija de Jonge, Paul Pütz, Antonio Vairo et al. (+1 more)
We present $SU(3)$
lattice gauge theory results for the $\mathcal{O}(1/m_Q)$ hybrid
spin-dependent and hybrid-quarkonium mixing potentials. The only existing
lattice computation of these potentials is limited to
quark-antiquark separations smaller than approximately $0.5\,\text{fm}$. In this work, we extend the
lattice results up to around $1.25 \, \text{fm}$ using large-volume, high-statistics simulations at several
lattice spacings and gradient flow times, providing the first
lattice data in this previously unexplored regime.
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All authors Vilija de Jonge, Paul Pütz, Antonio Vairo, Marc Wagner
Instrumentation and Methods for Astrophysics
The Hopkins Ultraviolet Telescope: A Historical and Personal Retrospective
William P. Blair
This manuscript documents the inception and development of the Hopkins Ultraviolet
Telescope (HUT) project, which was a component of the Astro Observatory payload that flew on two Spacelab shuttle missions in the 1990s. The discussion places the HUT project in the context of the times and highlights the importance of its acceptance by NASA in 1980 to the growth and development of astrophysics at the Johns Hopkins University. Personal recollections from the author, including a detailed description of the real time flight operations during each mission, provides an insiders view. The document includes a link to an online historical archive of supporting materials compiled in support of this effort.
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Earth and Planetary Astrophysics
A JWST transiting survey of FGK stellar limb darkening: empirical evidence for quadratic laws and atmospheric model comparisons
David K. Sing, Joshua D. Lothringer, Jeff A. Valenti et al. (+11 more)
We present a study of
stellar limb-darkening using JWST transit observations of seven
exoplanets orbiting FGK host
stars, spanning 4200-6800 K. The wide wavelength coverage and high S/N of NIRISS/SOSS and NIRSpec/PRISM enable precise constraints on the wavelength-dependent limb-darkening. Using
Bayesian model selection, we find that the quadratic limb-darkening law is statistically preferred over higher-order laws for most FGK
stars, recovers consistent intensity profiles for $>$95% of the
stellar disk area, and introduces a minimal bias in the derived transit depths of only $\sim$14 ppm (1$\sigma$) for 6/7 targets. This contrasts with previous studies relying on
stellar models. We compare the empirically derived quadratic coefficients to predictions from the PHOENIX, MPS-ATLAS, MURaM, and Stagger
stellar atmosphere grids. We introduce a quadratic limb-darkening parameterization in terms of limb intensity ($\ell$) and
curvature at mid-$\mu$ ($\delta$), finding that empirical FGK limb darkening is generally more linear than models predict ($\delta \lesssim 0.1$). We identify wavelength-independent offsets between data and model quadratic coefficients, minimized by adopting $\mu_{\rm min} = 0.2$ in intensity calculations; we attribute this in part to models overpredicting limb-darkening near the limb where the plane-parallel approximation breaks down. For spherical PHOENIX models, we derive a $\mu$ rescaling method using a $\tau = 1$ photospheric radius. With these corrections, residual offsets are minimized and all
stellar models achieve statistically acceptable fits. We provide recommended limb-darkening offset priors for use in JWST transit analyses, enabling more accurate constraints on
exoplanet transmission spectra while accounting for residual
stellar model uncertainties.
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All authors David K. Sing, Joshua D. Lothringer, Jeff A. Valenti, Natalie H. Allen, Katherine A. Bennett, Carlos Gascón, Mei Ting Mak, Patrick McCreery, Sagnick Mukherjee, Lakeisha M. Ramos Rosado, Stephen P. Schmidt, Kevin B. Stevenson, Daniel P. Thorngren, Le-Chris Wang
Fluid Dynamics
Creeping flows through confined arrays of cylinders
Sean Bohling, Sri Savya Tanikella, J.P. Raimondi et al. (+2 more)
Hair-covered appendages serve a variety of purposes in Nature, from chemical sensing and particle capture on the
antennae of a crustacean to drag generation on bristled wings. At low to intermediate Reynolds numbers, these finite porous media experience three flow regimes. At low Reynolds numbers, the flow goes around the porous structure; this is the paddle or rake regime. As the Reynolds number increases, so does the relative flow rate through the array. If the fluid exits the structure mostly laterally, the flow is in the deflection regime. If the fluid exits downstream, the flow is in the sieve regime. Confining structures, such as the animal body or larger hairs, have been hypothesized to focus the flow on the hair-covered region. We investigate the influence of confinement on the flow through and around an array of cylinders, using a combination of experiments and numerical simulations. Experimentally, we vary the cylinder spacing, channel dimension, and flow rate and measure the velocity field using Particle Image Velocimetry. After comparing the results of finite element analysis with the experimental data, we numerically investigate a broader range of system geometries and flow parameters. Our results show that the confinement focuses the flow in the array and shifts the domains of existence of the three regimes. We present an analytical model that relies on the permeability of rectangular slits to predict the relative flow rate through and around the array. The model is in quantitative agreement with the numerical results, demonstrating that the flow through the array increases with increasing confinement, while the flow angle decreases. These results should provide insight into the morphology of hairy surfaces and have implications in the design of bio-inspired flow sensors and filters.
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All authors Sean Bohling, Sri Savya Tanikella, J.P. Raimondi, Nathan Jones, Emilie Dressaire
Instrumentation and Methods for Astrophysics
Simulation and development of astrophotonic H-band nulling beam combiner for the CHARA Array
Samantha G. Morrison, Pradip Gatkine and Michael P. Fitzgerald
Nulling interferometry is a promising method for direct detection and characterization of faint
stellar companions such as
exoplanets and faint binary sources. The dominant constraint on instrument performance is instability noise from vibrations, thermal expansions, and other systematic sources. Photonic instruments have footprints of a few centimeters and enable advanced light control architectures. Astrophotonic implementations can include active phase control via Mach-Zehnder interferometers (MZIs) to actively minimize residual optical path errors at the location of beam combination. The compact size of photonic chips also makes them a promising solution for space-based applications such as the upcoming Habitable Worlds Observatory. The Center for High Angular Resolution Astronomy (CHARA) Array is equipped with the world's longest baseline in the near-infrared at 330 meters long. CHARA therefore has the most sensitive angular resolution in the near-infrared. A nuller at CHARA would have access to a novel parameter space essential for
exoplanet discovery and characterization. The first step in preparing a nulling beam combiner for CHARA is to develop compelling, realistic, and well-defined science cases. Simulation suites quantify the technical requirements to reach such science goals in their respective complex systems. The CHARA Array Response Model (CHARM) is the first-ever simulator built specifically for CHARA, opening up new pathways for instrument simulation. CHARM is a flexible simulation tool of an H-band, self-calibrated astrophotonic nulling beam combiner with active phase control for the CHARA Array. In this paper, we present an update on the development of our photonic nulling beam combiner for CHARA. We include early results from CHARM, demonstrating that the photonic nuller has the potential to detect and characterize a wide range of bright
stellar companion systems.
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