Astrophysics of Galaxies
The Age-Thickness Relation as a Tracer of the Merger History of Disk Galaxies
Lekshmi Thulasidharan, Elena D'Onghia, Robert Benjamin et al. (+2 more)
In the hierarchical framework of
galaxy formation, disk
galaxies are shaped by a sequence of mergers and interactions, yet reconstructing this history from observations remains challenging. We show that the merger history of a
galaxy leaves measurable imprints in the vertical structure of its
stellar disk. Using Milky Way analogues from the TNG50 simulations, we demonstrate that the Age-thickness relation, quantified by the dispersion of vertical
stellar positions ($\Delta_z$), encodes both the dynamical heating of pre-existing
stars and the birth conditions of
stars formed during perturbed phases. Major mergers produce pronounced, step-like features in the Age$-\Delta_z$ relation, reflecting strong disk heating and subsequent re-formation of a thin disk, while flyby interactions generate weaker, localized enhancements associated primarily with disturbed
star formation. We show that this diagnostic is robust across different locations within the disk and largely insensitive to fractional distance uncertainties lower than 20%, though its temporal resolution is limited by uncertainties in
stellar ages. Because the Age$-\Delta_z$ relation relies only on
stellar positions and ages, it provides an observationally accessible alternative to traditional kinematic diagnostics. With current and upcoming surveys mapping the Milky Way with unprecedented precision, this framework offers a new avenue for reconstructing the merger history of our
Galaxy and probing the dynamical
evolution of disk
galaxies across
cosmic time.
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All authors Lekshmi Thulasidharan, Elena D'Onghia, Robert Benjamin, Ronald Drimmel, Eloisa Poggio
Chemical Physics
Momentum Rescaling for Collapse to a Block Ehrenfest Dynamics
Ari R. X. Pereira and Benjamin G. Levine
The Ehrenfest with collapse to a block (TAB)
algorithm has recently been demonstrated to efficiently and accurately simulate nonadiabatic molecular dynamics in dense
manifolds of electronic states. TAB employs an Ehrenfest force for the classical
nuclei, accompanied by
stochastic collapses of the electronic density
matrix to account for decoherence. Energy conservation dictates that the
nuclear momentum be adjusted during such a collapse. In this paper, we present a prescription for rescaling the component of the
nuclear momentum that projects into the branching plane between arbitrary superposition states. This prescription yields accurate branching ratios and phase-space distributions when compared to alternative methods in which scaling is performed in the nonadiabatic coupling direction or the momentum direction. We justify this direction by deriving an effective nonadiabatic coupling vector from the localized Pechukas force during a collapse step.
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Quantum Physics
High-purity entanglement mediated by magnons despite weak coupling
Sanchar Sharma
Entangling distant
spins via a shared magnonic bus typically faces a tradeoff: stronger
spin-
magnon coupling increases the
entanglement fidelity, but also the
spin decay rate. We propose a protocol that breaks this tradeoff. The
magnons couple only to a transition outside the computational basis, in which the Bell state is created. Our protocol is probabilistic, and weak coupling reduces the success probability but not the fidelity. We analyze a setup where the
spins are two nitrogen-vacancy (NV) centers near a
magnetic wire. In the absence of NV dephasing, the protocol reaches unit fidelity with a maximally entangled state, for arbitrarily weak coupling. In our simulations via the Monte-Carlo wavefunction approach, the NV-
magnon coupling is taken to be one-third of the
magnon linewidth. Considering finite NV dephasing, we predict a fidelity of >0.99 for a state-of-the-art rate, and an optimal fidelity of 0.91 for a moderate rate, both at 0.6% success probability.
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Astrophysics of Galaxies
Discovery of Optical Filaments in the North Polar Spur/eROSITA Bubble
Julian Shapiro
I report the discovery of optical filaments in H$\alpha$, [O III], and [S II], coincident with $144\,\mathrm{MHz}$ structure, associated with the North Polar Spur (NPS) region of the eROSITA bubbles. The optical emission is identified in the Northern Sky Narrowband Survey, and contains distinct structure and potentially elevated $\text{[S II]}/\mathrm{H}\alpha$ relative to typical high-$b$
outflows from the warm ionized medium (WIM). $\Delta$-variance and power spectrum analysis of the NPS H$\alpha$ shows a preference for filaments on the scale of lag $L\approx0.6^{\circ}$. The optical and $144\,\mathrm{MHz}$ emission peaks in intensity in an interior region of the NPS, aligned with surrounding
Galactic magnetized structures, and also shows fainter signal at the eROSITA bubble edge. The required power to produce the background-subtracted $I_{\mathrm{H}\alpha}=1.85\pm1.04\,\mathrm{R}$ emission is $P_\mathrm{req}\approx5\mathrm{-}12\times10^{41}\,\mathrm{erg\,s}^{-1}$, comfortably exceeded by AGN jet models, plausible for AGN hot
accretion flow and
star formation ring models, and disfavoring
star formation driven winds.
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Chemical Physics
Accounting for Nanofilm Contributions in Interfacial Free Energy Calculations Using Classical Density Functional Theory
Yafan Yang, Zufeng Zuo, Xingyu Zhao et al. (+2 more)
Fluid nanofilms play a fundamental role in nanoscale interfacial thermodynamics, yet their treatment in classical density functional theory (cDFT) remains incomplete. We investigate nanofilm interfacial properties using a cDFT framework built upon the perturbed-chain statistical associating fluid theory (PC-SAFT) for both fluid-fluid and fluid-solid interfacial systems. Comparison with molecular simulations shows that the long-standing numerical discrepancies regarding free-standing nanofilms persist in the PC-SAFT functional predictions, supporting the view that they stem from thermal capillary-wave fluctuations rather than deficiencies of the density functional itself, as such fluctuations are inherently neglected in the mean-field approximation adopted by standard cDFT. Importantly, we establish a thermodynamically consistent framework for interfacial free energy (IFE) calculation, which explicitly incorporates nanofilm thermodynamic contributions and redefines the effective fluid volume by excluding the solid-phase region. The proposed method exhibits excellent consistency with another method based on the relationship between IFE and disjoining pressure for fluid systems, while both fluid-fluid and fluid-solid IFEs differ substantially from those predicted by the conventional method. We find that neglecting nanofilm contributions induces prominent size-dependent variations in the IFE and contact angle of hemicylindrical droplets, which is inconsistent with the extensive literature. Different methods also lead to opposite signs of the line tension for a hemispherical argon nanodroplet on a strongly lyophobic surface. The proposed framework provides a unified molecular-level basis for understanding interfacial processes involving nanofilms, including wetting, nucleation, adsorption, and other phenomena that rely on the accurate evaluation of IFEs.
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All authors Yafan Yang, Zufeng Zuo, Xingyu Zhao, Shuyu Sun, Denvid Lau
Physics and Society
Cultural Evolution of Perfumes since 1900
Vahid Satarifard, Fabian Baumann, Geetanjali Minsky et al. (+4 more)
Perfumes are cultural artifacts and works of sensory art, composed from a finite, recombinable palette of notes that together evoke a distinctive scent impression. Here, we assemble the largest perfume corpus compiled to date, spanning multiple independent databases from 1900 to 2024, and study its
evolution through a multidisciplinary computational framework. We first characterize perfumes by properties such as complexity and novelty using crowd-sourced data, finding that compositions have grown more minimalist in their scent profiles, yet more novel in their note combinations, a transition that began in the 1990s. Next, we construct copy-lineage networks and examine how notes are selected across successive time windows. We show that although imitation is pervasive, a growing share of notes drifts free of selection, and original creations retain a measurable quality premium, where they last longer, project further, and earn higher regard. Finally, we construct the collaboration network of master perfumers and show that a perfumer's creative style behaves as a social contagion, transmitted through collaboration and decaying with social distance. We discuss the principal forces shaping this
evolution, including regulatory restrictions, cultural change, and the consolidation in the industry. Our findings position perfume as a culturally evolving system, akin to music and fashion, through which societies express and communicate hedonic sensory experiences.
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All authors Vahid Satarifard, Fabian Baumann, Geetanjali Minsky, Laura Sisson, Lou M. Haux, Christophe Laudamiel, Nicholas A. Christakis
Astrophysics of Galaxies
Mid-Infrared Colors Vary with Galactic Environment: Contrasting Star-Forming Disks, Young Centers, and Quiescent Star-Formation Deserts
Debosmita Pathak, Karin M. Sandstrom, Adam K. Leroy et al. (+27 more)
We present $50{-}100\,$pc-resolution JWST/MIRI and NIRCam measurements of mid-infrared (mid-IR) color variations in the diffuse interstellar medium (ISM) of 71 nearby
star-forming
galaxies from the PHANGS-JWST survey. Mid-IR emission traces the
dust column density, intensity ($U$) and hardness of the interstellar radiation field, and the physical state (charge, size) and abundance of polycyclic aromatic hydrocarbons (PAHs). Mid-IR colors that trace PAH band-ratios remain fairly constant in the diffuse ISM of
star-forming disks. However, they show stark variations in extreme environments: highly
star-forming central molecular zones (CMZs) and
star-formation deserts/quiescent bulges. In CMZs, PAH-to-continuum ($3.3/21$, $7.7/21$, and $11.3/21\,\mu$m) and the $10/21\,\mu$m continuum colors are $0.2{-}0.4$ dex lower than in normal disks. We attribute this to higher $U$ based on the far-IR
dust colors and the high $21\,\mu{\rm m}/\Sigma_{\rm Mol}$, which we suggest to be a good tracer of $U$ outside
star-forming regions. Meanwhile,
star-formation deserts show low $7.7\,\mu$m PAH emission, resulting in low $7.7/21\,\mu$m and $7.7/11.3\,\mu$m, while all other mid-IR colors remain typical. This suggests the presence of more neutral PAHs in
star-formation deserts, where low $7.7\,\mu$m likely reflects ISM conditions similar to early-type and elliptical
galaxies. All environments form part of a continuous trend in $7.7/11.3\,\mu$m vs.\ specific
star-formation rate.
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All authors Debosmita Pathak, Karin M. Sandstrom, Adam K. Leroy, Ryan Chown, Daniel A. Dale, Hannah B. Koziol, Mansi Padave, Jessica Sutter, Thomas G. Williams, Dalya Baron, Alberto D. Bolatto, Mederic Boquien, Oleg V. Egorov, Eric Emsellem, Simon C. O. Glover, Ralf S. Klessen, Eva Schinnerer, Todd A. Thompson, Francesco Belfiore, Frank Bigiel, Enrico Congiu, Ivan Gerasimov, Jay Gonzalez Lobos, Annie Hughes, Laura A. Lopez, Justus Neumann, Elias K. Oakes, Hsi-An Pan, Erik Rosolowsky, Sumit K. Sarbadhicary
Quantum Physics
Hybrid LLM-Guided Search for Quantum Reservoir Architecture Design
Krishna Bhatia and Gautami Sanjay Naik
Quantum reservoir computing (QRC) uses fixed
quantum dynamics as a high-dimensional temporal feature map and trains only a lightweight classical readout. QRC is attractive for near-term
quantum machine learning, but its performance depends strongly on architecture choices such as input encoding, reservoir depth,
entanglement topology, measurement features, state-reset policy, feature construction, and readout regularization. We introduce \method, a simulator-based
benchmark that formulates QRC design as constrained black-box architecture search and evaluates whether large
language models can act as proposal controllers for this search problem. The
benchmark compares five policies under identical evaluation budgets: random search, evolutionary search,
Bayesian/TPE optimization, a feedback-based LLM
agent, and \hybrid, which combines LLM proposals with
memory, mutation, crossover, duplicate avoidance, and exploration. On NARMA10, Mackey-Glass
forecasting, and temporal parity, \hybrid{} is the most consistent policy: it ranks first on NARMA10 and temporal parity and second on Mackey-Glass, narrowly behind evolutionary search. Under a 25-evaluation budget and three seeds, \hybrid{} improves over random search on all tasks, including a 23.6% relative reduction in Mackey-Glass error. The results do not show that LLMs are universal QRC optimizers; rather, they show that generative models can be useful high-level controllers when embedded inside validated, reproducible hybrid search loops.
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Astrophysics of Galaxies
Local morphology and asymmetry of galactic rotation curves in a kinetic gas transport framework: NGC 3198
Anton A. Lipovka and Anna A. Lipovka
We investigate whether the observed fine structure and asymmetry of non-averaged
galactic rotation curves can be reconstructed directly from the observed HI distribution within the framework of a kinetic gas transport description. Using the observed HI density profiles separately for the approaching (north-eastern) side and the receding (south-western) side of the
galaxy NGC~3198, we reconstruct the corresponding rotation curves based on the equation previously derived in \citet{Lipovka2022}. It is shown that the reconstructed curves reproduce not only the approximately flat large-scale behaviour of the observed rotation curves, but also their detailed local morphology and asymmetry separately for the north-eastern and south-western sides of the
galactic disk. The obtained results indicate that the local structure of
galactic rotation curves is closely connected with the local HI distribution and arises naturally as a consequence of kinetic gas transport processes in
galactic disks.
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Astrophysics of Galaxies
Reading Between the Lines: Forward Modeling Dust, Continuum, and Spectral Cleaning for Multi-Line Intensity Mapping
Anirban Roy, Rachel S. Somerville and Anthony R. Pullen
Line intensity mapping (LIM) offers a tomographic view of
galaxy evolution by measuring the aggregate emission from unresolved
galaxies. In the optical and near-infrared, the line emission is accompanied by much brighter continuum emission that must be removed to recover line auto- and cross-power spectra. We develop a forward-modeling framework using a $\sim2$deg$^2$ lightcone drawn from a cosmological $N$-body simulation populated with
galaxies using a physics-based semi-analytic model (SAM). We construct intensity maps for the
stellar continuum and for the strongest optical lines, H$\alpha$, H$\beta$, [O III] $\lambda5007$, and [O II] $\lambda3727$, including nebular
dust attenuation tied to
galaxy properties. From these cubes, we measure cross-channel angular power spectra, $C_\ell(\lambda_i,\lambda_j)$, and the normalized correlation
matrix $r_{ij}$. In line-only maps, the correlation
matrices show same-
redshift ridges between emission lines, demonstrating how multi-line intensity mapping (MLIM) can isolate large-scale structure and probe
dust attenuation. We show that
dust suppresses the line cross-power by an amount that depends on
galaxy properties, wavelength, and line pair, so a single overall amplitude cannot capture its effect. In total maps, however, the continuum dominates the raw correlations and hides much of the line-ridge structure. We therefore apply principal component analysis (PCA)-based spectral cleaning and quantify the line-transfer function using the simulation truth. Removing 20 PCA modes gives the best trade-off between line recovery and continuum suppression in our mock maps. Our results demonstrate the promise and challenges of extracting
dust-sensitive LIM observables from SPHEREx-like observations, and highlight the need to model continuum cleaning and its transfer function in quantitative inference pipelines.
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Physics and Society
Tensor Network Machine Learning for Wildfire Susceptibility Mapping: from Grokking Dynamics to Quantum Mixedness of Class Representations
Domenico Pomarico, Alessandra Costantino, Gabriel Ramirez Sanchez et al. (+12 more)
A
quantum-inspired tensor network framework for wildfire susceptibility classification in the Gargano region is introduced, leveraging AlphaEarth
embeddings and
Matrix Product State models. The approach combines scalable geospatial representations with an interpretable
quantum mask, enabling both binary and multiclass classification of wildfire susceptibility. Beyond predictive performance, the study reveals a pronounced grokking transition in the binary case and provides a detailed analysis of inter-class confusion in the multiclass setting. By introducing level-resolved mixedness diagnostics based on reduced density
matrices, we show that the MPS classifier naturally encodes a hierarchy of class distinguishability, with non-adjacent categories becoming more separable than neighboring ones. These results demonstrate that tensor network models not only achieve competitive classification accuracy but also offer a physically grounded framework to quantify and interpret class separability in complex environmental
datasets.
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All authors Domenico Pomarico, Alessandra Costantino, Gabriel Ramirez Sanchez, Loredana Bellantuono, Davide D' Alò, Mario Elia, Alessandro Fania, Francesco Giordano, Niloofar Kheirkhahan, Raffaele Lafortezza, Ester Pantaleo, Sabina Tangaro, Roberto Bellotti, Alfonso Monaco, Nicola Amoroso
Solar and Stellar Astrophysics
A Probabilistic Framework for Population Studies of the Solar Neighborhood: Application to SDSS-V and Gaia
Ilija Medan, Keivan G. Stassun, Zachary Way et al. (+8 more)
Studies of the
Solar Neighborhood require spectroscopic follow-up of
stars identified in astrometric surveys to fully characterize their physical properties. The SDSS-V
Solar Neighborhood Census (SNC) is a dedicated program to observe
stars within 100~pc. However, due to competing observing programs and fiber assignment constraints, the resulting sample carries severe and complex selection effects. A framework is presented for characterizing the selection function of the SDSS-V SNC relative to the
Gaia Catalog of Nearby
Stars (GCNS), along with a forward modeling method to infer the properties of
stellar subpopulations across the GCNS-defined 100 pc sample. The selection function is based on a method that models the selection probability as a function of sky position,
Gaia G magnitude, and BP-RP. The resulting detection probabilities faithfully reproduce the known survey planning logic. This work further introduces the concept of a "subpopulation probability" – a grid of posterior estimates across the Hertzsprung-Russell (HR) diagram representing the likelihood that a GCNS member belongs to a given SDSS-V defined subpopulation. The framework is validated with a mock
dataset and its scientific utility is demonstrated through two applications using data from the Data Release 19: mapping H$\alpha$ emission across the HR diagram and measuring the variation of
stellar density with mass and
metallicity. These results illustrate how statistically robust population studies can be conducted with an incomplete spectroscopic survey when the selection function is well characterized. The code is made publicly available with this work, which will serve as an important tool for future studies.
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All authors Ilija Medan, Keivan G. Stassun, Zachary Way, Guy S. Stringfellow, Alexandre Roman-Lopes, Jiadong Li, Madeline Lucey, Andrew R. Casey, Bárbara Rojas-Ayala, Ricardo López-Valdivia, José G. Fernández-Trincado
Computational Physics · Cross-listed from math.NA
Robust Hierarchical Matrix Compression of Acoustic Volume and Boundary Integral Operators
Alberto Almuna-Morales, Danilo Aballay, Ignacio Labarca-Figueroa et al. (+1 more)
Discretizing integral formulations of the Helmholtz equation yields dense linear systems. Hence, simulating acoustic models at larger scales or higher frequencies is typically constrained by
memory capacity. Fast
algorithms, such as hierarchical
matrix compression, reduce the
memory footprint substantially while controlling the approximation error in
matrix-vector multiplications. However, the commonly used Adaptive Cross Approximation suffers from early-convergence problems, where the iterative construction of low-rank decompositions stops before reaching the targeted error tolerance. This failure arises when the error
estimator does not capture significant components of the
matrix structure under partial pivoting. This manuscript proposes a new diagonal convergence criterion, additional
matrix elements for the pivoting strategy, an extended admissibility condition, and a sustained convergence check to improve the robustness of hierarchical
matrix compression. These modifications improve compression reliability without increasing
memory. We tested our compression strategy on various discretized volume and boundary integral operators. The computational results show that our approach successfully compresses all
benchmark matrices within predefined tolerances, thereby resolving the early-convergence issues encountered in standard
algorithms. This robust
matrix compression was achieved at the same
memory footprint as alternative compression strategies. Furthermore, a complexity analysis shows log-linear
memory scaling with mesh refinement at constant frequency. Finally, we successfully applied our robust
matrix compression
algorithm to a coupled system of volume and boundary integral operators that models transcranial ultrasound propagation. This confirms the feasibility of our robust
algorithm to accelerate large-scale simulations with high-resolution meshes in a biomedical application.
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All authors Alberto Almuna-Morales, Danilo Aballay, Ignacio Labarca-Figueroa, Elwin van 't Wout
Quantum Physics
A unified framework for anomalous boson bunching
Léo Pioge, Leonardo Novo and Nicolas J. Cerf
Anomalous bunching is a paradoxical
quantum interferometric phenomenon in which partially distinguishable
photons exhibit a higher probability of bunching into two or more modes than fully indistinguishable
photons [Nat. Photonics 17, 702 (2023)]. While this effect is directly linked to violations of certain
conjectures on
matrix permanents, the mechanism underlying the anomaly is not yet fully understood. Here, we show that
boson bunching is governed not by internal indistinguishability alone, but by the total indistinguishability of the postselected output state. Total indistinguishability combines the internal degrees of freedom, such as polarization or arrival time, with the spatial degrees of freedom of their wave functions restricted to the measured output modes of the interferometer. This reformulation preserves the expected connection between
boson bunching and total indistinguishability, while clarifying how anomalous bunching can arise. It also reveals several additional facets of the same phenomenon, which are captured within a unified framework. In particular, we exhibit situations in which adding an independent source of distinguishability, either internal or spatial, can enhance multimode or even single-mode bunching probabilities, offering new insights into the subtle role of distinguishability in multiphoton interference.
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Nuclear Experiment
Experimental determination of the Dalitz plot for positronium decay using the J-PET detection system
Magdalena Skurzok, Steven D. Bass, Kamila Kasperska et al. (+37 more)
We present the first measurements of the Dalitz plot for ortho-positronium annihilation to three
photons. Our measurements, accurate to about 3% statistical and 2-3% systematic uncertainty in angular representation over almost the entire available phase space, were performed using the Jagiellonian Positron Emission Tomograph (J-PET) based on organic scintillator strips. Until now, the Dalitz plot for the three-body positronium decay has been poorly explored. The new measurements presented here are consistent with both the leading-order and next-to-leading order QED predictions for the Dalitz plot.
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All authors Magdalena Skurzok, Steven D. Bass, Kamila Kasperska, Ermias Beyene, Neha Chug, Catalina Curceanu, Eryk Czerwinski, Manish Das, Marek Gorgol, Sharareh Jalali, Bozena Jasinska, Krzysztof Kacprzak, Tevfik Kaplanoglu, Łukasz Kapłon, Aleksander Khreptak, Tomasz Kozik, Deepak Kumar, Karol Kubat, Sumit Kumar Kundu, Edward Lisowski, Filip Lisowski, Bartłomiej Łach, Justyna Mędrala-Sowa, Wiktor Mryka, Simbarashe Moyo, Szymon Niedźwiecki, Anand Pandey, Piyush Pandey, Alessio Porcelli, Bartłomiej Rachwał, Martin Rädlera, Sushil Sharma, Ewa Stępień, Tomasz Szumlak, Pooja Tanty, Keyvan Tayefi Ardebili, Satyam Tiwari, Kavya Valsan Eliyan, Anoop K. Venadan, Paweł Moskal
Cosmology and Nongalactic Astrophysics
The silent dark sector: a field-theory approach to unified dark fluids with vanishing speed of sound
Javier de Cruz Pérez, Darío Jaramillo-Garrido, Antonio L. Maroto et al. (+1 more)
We introduce a novel class of field-theory models that provide a unified description of the dark sector as a single perfect fluid with vanishing sound speed. These models also admit the interpretation of cold dark matter interacting with
vacuum energy while avoiding any phantom behavior and including standard $\Lambda$CDM as a particular case. Built upon a single scalar field invariant under transverse diffeomorphisms, the framework naturally implements the constraints imposed in the so called mimetic models. We analyze a particular simple example exhibiting an effectively evolving dark energy and find that it can reproduce the DESI best-fit CPL
evolution with the same number of free parameters.
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All authors Javier de Cruz Pérez, Darío Jaramillo-Garrido, Antonio L. Maroto, Prado Martín-Moruno
General Relativity and Quantum Cosmology
Schrödinger perturbation theory for black hole quasinormal modes
Jacopo Lestingi, Laura Sberna and Stephen R. Green
Deviations from
vacuum general relativity (such as modified theories or the presence of an environment) produce small shifts in black hole quasinormal mode (QNM) spectra. These effects are becoming increasingly relevant for gravitational wave astronomy as observations of ringdown spectra become more precise. To leading order in deviations from
vacuum general relativity, frequency shifts can be calculated using
eigenvalue perturbation theory. However, for Kerr, there is no systematic framework to compute higher order corrections. The major obstacle is that QNMs do not form a complete basis due to the non-self-adjointness of the system. Nevertheless, it was recently shown that QNMs are orthogonal with respect to an appropriate bilinear form. In this work, we use the bilinear form to systematically lift Schrödinger perturbation theory to the black hole setting. We obtain a formula for quasinormal frequency shifts to any order, in terms of lower order mode shifts. We also provide a spectral decomposition of the first-order mode shift, which involves projections onto unperturbed QNMs along with continuous-spectrum contributions—making incompleteness explicit. We illustrate the framework on slowly-spinning Kerr and Pöschl-Teller examples, where we find that the QNM sum itself diverges.
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Astrophysics of Galaxies
Rapid growth in a dual AGN during a gas-rich merger at z~4.5
Hyewon Suh, Roberto Decarli, Emanuele Paolo Farina et al. (+15 more)
The late stages of
galaxy mergers - when two supermassive black holes (SMBHs) reach kiloparsec-scale separations - represent a critical phase for understanding SMBH growth,
galaxy co-
evolution, and the progenitors of low-frequency gravitational waves. Yet confirmed close-separation (<3 kpc) dual active
galactic nuclei (AGNs) remain confined to the local Universe, despite predictions that such systems should be common in the merger-rich early Universe. Here we report the discovery of LID-1166, a dual AGN with a projected separation of ~1.5 kpc at z~4.5, representing the first such system known beyond the local Universe. Spatially resolved JWST/NIRSpec integral-field spectroscopy reveals two spatially and kinematically distinct narrow-line emission components with a line-of-sight velocity offset of ~ -164 km/s. Both components additionally exhibit broad Ha emission, including a compact off-
nuclei broad Ha component associated with the companion source, confirming two actively accreting SMBHs. Independent ALMA [CII] 158 um observations reveal corresponding spatially and kinematically distinct cold gas components associated with the same
nuclei, demonstrating that the system is a gas-rich merger. While undergoing super-Eddington
accretion during a late-stage merger, the SMBHs already lie on the local black hole-host mass relation for massive elliptical
galaxies within the uncertainties, suggesting that rapid, obscured growth may help establish this relation early in
cosmic history. LID-1166 reveals a previously hidden phase of SMBH growth and points to a missing population of heavily obscured, merger-driven dual AGNs at high
redshift.
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All authors Hyewon Suh, Roberto Decarli, Emanuele Paolo Farina, Julia Scharwächter, Mar Mezcua, Giorgio Lanzuisi, Federica Loiacono, Brian C. Lemaux, Sukyoung K. Yi, Stefano Marchesi, Marta Volonteri, Günther Hasinger, Francesca Civano, Anniek Gloudemans, Ena Choi, Yeonwoo Nam, Adi Foord, Silvia Onorato
Instrumentation and Methods for Astrophysics
A Scalable Fast Multipole Method Poisson Solver for the RAMSES code: II. Adaptive Mesh Refinement and Adaptive Time Stepping
Jun-Young Lee and Romain Teyssier
We present an extended implementation of a scalable, O(N) Poisson solver based on the fast multipole method (FMM), fully compatible with adaptive mesh refinement (AMR) and adaptive time stepping (ATS) within the RAMSES framework. Building on the unigrid
algorithm in Lee & Teyssier (2026), we introduce several novel elements, including the use of multiple FMM trees, one for each AMR level, a merged FMM tree for all active levels to optimize neighbor searches, and the introduction of the concept of "nearest-field" to enforce force
symmetry across refinement levels. Across a broad set of test problems, we find excellent, percent-level agreement with our reference traditional multigrid (MG) solver. We show, however, that FMM exhibits better momentum conservation properties across coarse-fine AMR interfaces. Finally, despite the overhead introduced by the spatio-temporal adaptivity, FMM shows better scalability than MG across various AMR configurations, with the largest gains obtained for the largest configurations.
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Materials Science
Electron-Induced Formation of C$_{2}$ on Si(100) from Acetylene and Ethylene
Oliver MacLean, Marc Savoie, Damian G. Allis et al. (+12 more)
Hydrogen Desorption Lithography on Si(100) demonstrates the ability of the Scanning Tunneling Microscope (STM) to create functional atomic-scale structures and devices. The dehydrogenation of adsorbed molecules represents a potential complementary technique that has received little
attention. For example, formation of C$_{2}$ could introduce local strain or act as centers for subsequent reactions and would inform positionally controlled mechanosynthesis, an approach with vast potential in surface patterning and functionalization. Here, we studied the electron-induced dehydrogenation of acetylene and ethylene on Si(100) at 4 K using STM. Excitation of acetylene at +3.2 V and above induces configurational switching, including to a new sublayer-bonded geometry previously predicted to be an adsorption precursor, as well as migration and desorption. Excitation also induces dehydrogenation to C$_{2}$. Switching between three observed C$_{2}$ configurations can be induced by excitation at +4.2 V and above. Simulations using density functional theory reproduced the experimental images based on choice of functional, dimer-buckling averaging, and inclusion of diffuse basis functions. In addition, dehydrogenation could be induced using field-emitted electrons on a scale ranging from a single molecule to a radius of >10 nm. These observations highlight the potential of carbon dehydrogenation as an additional tool in Atomically Precise Fabrication (APF).
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All authors Oliver MacLean, Marc Savoie, Damian G. Allis, Rafik Addou, Ryan Groome, Si Yue Guo, Aru Joy Hill, Alex Inayeh, Hadiya Ma, Cameron J. Mackie, Sheena Ou, Marco Taucer, Denis A. B. Therien, Finley Van Barr, Ryan Yamachika
High Energy Astrophysical Phenomena
Four, One, and None: Quantifying the Ultra-High-Energy Neutrino Anomaly Across ANITA-IV, KM3NeT, and IceCube
Dibya S. Chattopadhyay, Carlos A. Argüelles and Vedran Brdar
The four near-horizon
neutrino-like events reported by ANITA-IV and the ultra-high-energy track-like event KM3-230213A observed by KM3NeT imply
neutrino event rates that are in tension with the absence of corresponding events at IceCube. In this work, we perform a joint analysis of these events, taking into account the absence of any corresponding ones at IceCube. We construct semi-analytic, energy- and direction-dependent effective areas for the three detectors and account for the time-dependent ANITA-IV and KM3NeT exposures. For a diffuse all-sky power-law flux varying both the normalization and the spectral index, the measured event rates across the three detectors are not reproduced. The best-fit configuration, corresponding to a tension of $\sim7.5\sigma$, predicts approximately five IceCube events while strongly underpredicting the ANITA-IV and KM3NeT counts. In contrast to the diffuse scenario, the tension can be substantially alleviated if the events arise from short-duration transients that occur exactly along the observed directions during the ANITA-IV and KM3NeT detection windows. Such a realization, however, is highly fine-tuned. If rare transients are instead distributed randomly across the full sky over the $\sim15$-year IceCube observation period, additional sources inevitably contribute to the IceCube exposure. For
benchmark populations with a probability of approximately $10^{-4}$ to produce four favorable transients at ANITA-IV, the best-fit configuration of sources, out of $10^5$ Monte Carlo realizations, remains in $5.9\sigma$ tension. We conclude that, within the Standard Model, directional and temporal variations alone can not reconcile the ANITA-IV and KM3NeT observations with the IceCube null result, under both a diffuse all-sky flux and a rare-transient source hypothesis.
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Statistical Mechanics
Localization transitions of diffusion dynamics in physical networks
Jun Yamamoto, Ivan Bonamassa and Márton Pósfai
Network
diffusion underlies many transport phenomena, with
Laplacian modes setting how information spreads and relaxes. In physical networks, however, connectivity alone is not enough: node volumes introduce local dwell times that regulate how flow is stored before being propagated. Here we show that physical heterogeneity reshapes
topology-driven localization, with the degree-volume ratio emerging as the relevant disorder parameter. We solve an analytical model in which ratio detuning qualitatively reorganizes the
Laplacian spectrum, and demonstrate in empirical networks how degree-volume correlations shift extremal eigenmodes away from the nodes selected by
topology alone. Our results reveal a general feature-rich-driven mechanism for localization control, showing that physicality non-trivially reshapes the disorder landscape governing network dynamics.
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Astrophysics of Galaxies
Extreme Variability Reveals How the Eddington Ratio Regulates Coronal Power in Active Galactic Nuclei
Arghajit Jana, Claudio Ricci, Franz E. Bauer et al. (+13 more)
The bolometric luminosity ($L_{\rm bol}$) of active
galactic nuclei (AGNs) is a key tracer of
accretion physics, but its direct determination is often hindered by limited spectral coverage and contamination of the host
galaxy. Bolometric corrections ($\kappa_{\lambda} = L_{\rm bol}/L_{\lambda}$) offer a practical means of estimating $L_{\rm bol}$, with the X-ray bolometric correction ($\kappa_{\rm 2-10}$) being crucial for exploring the coupling between the
accretion disk and the X-ray corona. Here we present multi-epoch, multi-wavelength observations of five highly variable, changing-state AGNs that span more than three orders of magnitude in Eddington ratio ($-3.6\lesssim \log \lambda_{\rm Edd} \lesssim -0.5$). This unique data set reveals a remarkably tight relation between $\kappa_{\rm 2-10}$ and $\lambda_{\rm Edd}$, with an intrinsic scatter of only $\sim0.05$ dex. We find that while the sources show bolometric corrections following different tracks in luminosity space that depend on black hole mass, they all display the same $\kappa_{\rm 2-10}-\lambda_{\rm Edd}$ trend. This shows unambiguously that $\lambda_{\rm Edd}$ is the primary driver of X-ray bolometric corrections, and points to a tight underlying trend that can be used to obtain reliable estimates of bolometric output from X-ray luminosities. Our results highlight how time-domain, multi-wavelength observations of variable AGN offer unique insights into the
accretion flow structure and its radiative output.
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All authors Arghajit Jana, Claudio Ricci, Franz E. Bauer, Kriti Kamal Gupta, Benny Trakhtenbrot, Alessia Tortosa, Ruancun Li, Luis C. Ho, Richard Mushotzky, Hsiang-Kuang Chang, Yaherlyn Diaz, Georgios Dimopoulos, Kristína Kallová, Michael J. Koss, Stéphane Paltani, Matthew J. Temple
Strongly Correlated Electrons
Optical Magnetic Switching in Odd-Parity Magnets with Spin-Orbit Coupling
SangEun Han and Qiang Li
$p$-wave magnets exhibit odd-parity
spin polarization in momentum space, with
spin splitting that reverses under $\vec{k}\rightarrow -\vec{k}$, while preserving zero net magnetization. Here we show that, in odd-parity magnets with
spin-orbit coupling, elliptically polarized light generates a momentum-independent
spin-dependent term that dynamically switches a zero-net-magnetization $p$-wave state into a finite
spin-polarized state. The Floquet-engineered bands also acquire a nonzero Chern number whose sign is controlled by the light polarization. For $f$-wave magnets, circularly polarized light induces a net out-of-plane magnetization, offering a direct experimental signature. Our results establish light as an efficient means of controlling
magnetic states, with potential applications in spintronics and
quantum information.
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Astrophysics of Galaxies
A pilot sample of Planck-selected strongly lensed sub-mm galaxies: NOEMA observations and physical characterisation
Leonardo Trobbiani, Matteo Bonato, Ivano Baronchelli et al. (+6 more)
The extreme brightness of high-$z$ strongly lensed
galaxies detected by Planck surveys, thanks to their exceptionally large gravitational magnifications, offers a unique opportunity to investigate in extraordinary detail their structure and kinematics during their active
star-formation phase. As a step in this direction, we present and analyse NOEMA imaging and spectroscopic data for four lensed high-z
galaxy candidates. We performed continuum and line imaging of the sources at 2 and 3 mm bands down to $1''.2$ spatial resolution and 40 $\rm{km}\,{\rm s}^{-1}$ spectral resolution, reconstructed and fitted the line profiles, and produced moment maps of the line emission to investigate the spatial distribution and kinematics of the molecular gas. We also carried out the gravitational lens modelling for one of the sources. The continuum images showed multiple components for at least two of the sources, strongly supporting the strong
lensing scenario. We detected with high S/N ratios two CO lines for all sources, at CO(3-2), CO(4-3) and CO(5-4) transitions; for one source, we also detected the [CI](1-0) line. We derived accurate spectroscopic
redshifts $2.3 \lesssim z \lesssim 3.3$, with $1\sigma$ uncertainties $\delta z \approx 10^{-4}$ in
redshift. All four sources lie well above the CO line luminosity-linewidth relation for unlensed
galaxies, providing independent confirmation of their strongly lensed nature. Three sources exhibit broad (FWHM$\gtrsim 400\,{\rm km}\,{\rm s}^{-1}$), double-peaked line profiles and substantial velocity gradients, while the last one shows relatively narrow, single-peaked lines and no detectable velocity gradients, possibly indicating a nearly face-on geometry or intrinsically simple kinematics.
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All authors Leonardo Trobbiani, Matteo Bonato, Ivano Baronchelli, Gianfranco De Zotti, Mattia Negrello, Marika Giulietti, Stefano Berta, Cristian Vignali, Marcella Massardi
Quantum Physics
Quantum resonance-enhanced performance of quantum battery
Ankita Mazumdar, Shashi C. L. Srivastava and Sanku Paul
Quantum resonance arising whenever the ratio of the intrinsic system frequency to the driving frequency becomes a rational number has been demonstrated to generate super-linear
entanglement, enhance transport,
quantum metrology performance and communication. Here, we demonstrate that
quantum resonance can also serve as a powerful resource for
quantum batteries. We model the batteries as free rotors charged via a kicked protocol. When the individual batteries are at resonance, we show both analytically and numerically that charging power increases linearly with time while efficiency (defined as the fraction of stored energy that can be extracted) remains near unity despite strong
entanglement generation. Furthermore, we demonstrate that this enhanced performance persists at higher-order resonances. Demonstrating the universality of this mechanism, we show that similar enhancements arise in the interacting kicked top model, and briefly note the feasibility of its experimental realization. In a broader context, resonant charging holds significant implications for energy storage,
quantum computational resources, and
quantum thermodynamics.
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Solar and Stellar Astrophysics
Large Magellanic Cloud Globular Clusters in the Near-infrared. I. RR Lyrae in Reticulum
Anupam Bhardwaj, Susmita Das, Prashant Nishad et al. (+10 more)
Reticulum is an old, metal-poor, and sparsely populated globular cluster in the outer regions of the Large Magellanic Cloud (LMC) and hosts a rich population of RR Lyrae
stars. Being as close as possible to a single
stellar population with negligible
metallicity spread and low reddening, Reticulum is an ideal laboratory for testing
stellar pulsation models and calibrating population II distance indicators. We present homogeneous multi-epoch near-infrared (NIR, JHKs) observations of RR Lyrae variables in Reticulum obtained with the Flamingos-2 imager on the 8.1-m Gemini South
Telescope. Using NIR light-curve templates, we derive accurate intensity-averaged magnitudes and peak-to-peak amplitudes for 32 RR Lyrae
stars, including 22 fundamental-mode (RRab), 4 first-overtone (RRc), and 6 mixed-mode (RRd) pulsators. The empirical JHKs period-luminosity (PL) relations of Reticulum RR Lyrae are very tight, exhibiting dispersions (~0.05 mag) comparable to those observed in
Galactic globular clusters. The derived PL slopes are shallower than those reported for
Galactic cluster variables. Adopting recent empirical and theoretical period-luminosity-
metallicity (PLZ) calibrations based on
Galactic globular clusters and pulsation models, we derive a true distance modulus of $\mu_0 = 18.472 \pm 0.035$ mag to Reticulum. This cluster distance is in excellent agreement with the precise
geometric distance to the LMC and places Reticulum close to the LMC barycentric distance. The well-characterized RR Lyrae population and a precise distance make Reticulum a potential anchor for calibrating Population II distance ladder.
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All authors Anupam Bhardwaj, Susmita Das, Prashant Nishad, Marina Rejkuba, Giulia De Somma, Marcella Marconi, Chow-Choong Ngeow, Vincenzo Ripepi, Sarang Shah, Subhajit Kar, Shashi Kanbur, Matteo Monelli, Massimo Dall'Ora
General Relativity and Quantum Cosmology
Tachyonic modes as a resonant system in weakly curved stellar spacetimes
Bruno S. Felipe and Maurício Richartz
A real scalar field nonminimally coupled to the
curvature of an astrophysical object can develop an effective potential that supports, alongside stable oscillatory solutions, a set of tachyonic modes with purely imaginary frequencies. Focusing on constant-density Newtonian
stars, we show that the tachyonic sector behaves as a collection of decoupled inverted harmonic oscillators, whose quantization is naturally addressed within the rigged
Hilbert space formalism. At the
quantum level, this sector is described by resonant states, with mean lifetimes determined by the associated imaginary frequencies. To probe the physical implications of this framework, we compute the transition probability of an Unruh-DeWitt detector in a circular orbit. In the presence of tachyonic modes, the detector response acquires an additional finite Lorentzian profile that modifies the standard circular Unruh-like background.
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Astrophysics of Galaxies
The GOLIATH Survey: OVI Absorption Reveals CGM Evolution through the Starburst-to-Quiescent Transition in Massive Galaxies
Derick Flores, Rongmon Bordoloi, Jason Tumlinson et al. (+12 more)
We present the GOLIATH survey (
Galaxies,
Outflows, and the Lifecycle of Immense, Active, Transforming
Halos), a study of the multiphase circumgalactic medium (CGM) of massive ($\langle\log M_\star/M_\odot\rangle \approx 11$), blue ($u-r < 1.65$) starburst and post-starburst
galaxies at $\langle z\rangle \approx$ 0.43. This work characterizes the warm-hot CGM through OVI absorption in the inner
halo ($R/R_{\rm vir} \leq 0.6$) of these rare systems. Across the
star-forming population, OVI column density rises by nearly 1~dex from $\log M_\star/M_{\odot} \sim 8$ to $\sim 11.5$ and increases with specific
star-formation rate (sSFR). Two GOLIATH
galaxies with the highest sSFR show the strongest CGM OVI absorption ($\log N_{\rm O\,VI}[\rm cm^{-2}] \gtrsim 15$). In the $\log M_\star/M_{\odot} = [11,12)$ inner-CGM region, massive
star-forming
galaxies exceed quiescent
galaxies on average by a factor of $\sim 3$ in OVI column density and $\sim 1.5$~dex in CGM OVI mass ($\log(M_{\rm O\, VI}/M_\odot) \approx 7.3$ versus $\approx 5.8$), with covering fractions roughly three times higher (62.5% versus 24% at $\log N_{\rm O\,VI}[\rm cm^{-2}] \geq 14$). The OVI line widths and column densities are consistent with feedback-driven radiative cooling, in which
outflow shocks heat the CGM and the gas cools back through the OVI window; the short cooling time, $t_{\rm cool} \sim 10$-$100$~Myr, requires continuous replenishment by active feedback to sustain this reservoir. The residual OVI in quiescent systems may arise from ambient gas at the high-temperature end of the cooling curve. OVI thus traces feedback on short timescales and probes the
star-forming–quiescent transition at $\log M_\star/M_{\odot} \gtrsim 11$.
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All authors Derick Flores, Rongmon Bordoloi, Jason Tumlinson, J. Christopher Howk, Nicolas Lehner, Mary Rickel, Benjamin Oppenheimer, Joseph Burchett, Ahmed Shaban, John O'Meara, Andrew Fox, J. Xavier Prochaska, Simon Xinlin Wu, Jack Higginson, Robert A. Simcoe
Cosmology and Nongalactic Astrophysics
Cosmic CORALS: Timing the Universe with high-z star clusters
Elena Tomasetti, Martin Millon, Licia Verde et al. (+5 more)
In this work, we explore the potential of anchoring the age-
redshift relation across
cosmic time by probing the oldest
star clusters at high
redshift, now observed thanks to the James Webb Space
Telescope in strongly lensed fields. As a case study, we consider one of the highest-
redshift systems observed, the
Cosmic Gems arc at $z=9.625$. We perform image deconvolution of multi-band JWST imaging, identifying a total of 20 point sources along the arc. We derive the
stellar ages through a cosmology-independent spectral energy distribution (SED) fitting framework, ensuring that these measurements can be used as unbiased cosmological anchors. By combining these high-z systems with state-of-the-art local globular cluster ages, we perform a joint
Bayesian fit to the age-
redshift relation in a flat $\Lambda$CDM model, measuring $H_0=70^{+27}_{-16}\ \rm{km\ s^{-1}\ Mpc^{-1}}$ and $\Omega_m=0.33^{+0.37}_{-0.21}$. While these constraints are still loose, we show that the slope of the degeneracy, a power-law in the $\Omega_m - H_0$ plane, is highly dependent on the
redshift of the sources, becoming shallower as
redshift increases. Leveraging this
geometric rotation, we present forecasts showing that a future sample of $\sim 300$ lensed proto-globular clusters well-distributed up to $z \approx 10$ could tighten the statistical precision to $4\%$ on $H_0$ and $11\%$ on $\Omega_m$, competitive with and independent of methods currently in use. The present work, therefore, represents a new avenue in cosmology and comes at a timely moment, when JWST observes high-
redshift lensed
star clusters routinely, Euclid and the Nancy Grace Roman Space
Telescope uncover new strong
lensing fields, and close to the start of operation of the ESO Extremely Large
Telescope.
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All authors Elena Tomasetti, Martin Millon, Licia Verde, Frédéric Courbin, Raul Jimenez, Michele Moresco, Carmela Lardo, Andrea Cimatti