Astrophysics of Galaxies
Changing-Look AGNs from DESI. VI. Host Galaxies
Shengxiu Sun, Linhua Jiang, Wei-Jian Guo et al. (+2 more)
Changing-look (CL) AGNs trace rapid changes in
nuclear activity, but their connection to host
galaxy properties remains unclear. We present a study of the host
galaxies of 105 CL AGNs previously selected by comparing DESI and SDSS data. We apply a two-epoch spectrophotometric decomposition to the DESI and SDSS spectra of the 105 objects. Meanwhile, HSC images are used to constrain their varying AGN components and non-varying
stellar population components. We find that 79 of the 105 (75.2%) CL AGN hosts are quiescent
galaxies, and 31/105 (29.5%) also show post-starburst signatures. We focus on 82 CL AGNs with extended host emission in the HSC images and compare them with extended
quasars at similar
redshift and
stellar mass. Their
star formation activity, Balmer absorption, and quiescent fractions are broadly consistent with those of the comparison
quasars, although post-starburst hosts are more common among the CL AGNs. Our CL AGNs with extended host emission are more often quiescent than those with compact morphology, but this difference is not apparent after matching in
redshift and
stellar mass. The $\mathrm{O\, \small II}$ and $\mathrm{O\, \small III}$ narrow lines show no population-wide response to the continuum and broad line changes, consistent with the slower response expected from the narrow line region. Together, these results favor changes in the central supermassive black hole
accretion rate as the main origin of the CL transitions.
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All authors Shengxiu Sun, Linhua Jiang, Wei-Jian Guo, Sarah E. I. Bosman, Zhiwei Pan
Superconductivity
Meissner Effect and Josephson Radiation in Driven Dissipative Superconductors
Carl Philipp Zelle and Subir Sachdev
Photo-induced superconducting signatures have been observed in several materials at temperatures far above their
equilibrium critical temperatures, including
magnetic field expulsion as in the Meissner effect. We propose driven-dissipative condensation of the superconducting order parameter as a mechanism for this phenomenon. In such a theory, optical pumping generates an effective gain (possibly via a parametric resonance) that overcomes the intrinsic damping of the pairing field, and stabilizes a non-
equilibrium condensate whose phase rotates at an intrinsic frequency that is generally lower than, and incommensurate with, the drive frequency. We develop a phenomenological continuum theory that couples this slowly rotating order parameter to the conserved charge density and the electromagnetic gauge field. Despite its finite-frequency dynamics, the resulting state exhibits the conventional long-wavelength electromagnetic signatures of superconductivity. In three dimensions, it displays a static Meissner effect and a gapped plasmon generated by the Anderson–
Higgs mechanism. In a two-dimensional sheet, it exhibits Pearl screening and the characteristic square-root plasmon dispersion. We further propose a direct experimental test based on a Josephson junction between the driven-dissipative state and an
equilibrium superconductor. The junction supports an AC Josephson current at zero applied voltage and emits radiation at the intrinsic rotation frequency of the condensate. Its low, pump-dependent, and generally incommensurate frequency provides a clear signature distinguishing driven-dissipative superconductivity from
equilibrium and drive-locked pairing states.
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High Energy Physics (Theory) · Cross-listed from math.DG
A user's guide to PINNs in geometric analysis: lessons from the asymptotic Plateau problem
Tancredi Schettini Gherardini
This proceedings contribution elaborates on the findings of arXiv:2605.26234v2: a joint work with Marco Usula, where we introduced a machine learning framework based on physics-informed neural networks (PINNs), aimed at constructing near-minimal discs in
hyperbolic space asymptotic to a prescribed
knot at infinity. We used this method to provide numerical evidence for a
conjecture of Joel Fine relating minimal surfaces in $H^{4}$ to the coefficients of the HOMFLY
polynomial. This is a methodological companion to that paper, based on a presentation given at the 2026 edition of the workshop "DANGER: Data, Numbers, and Geometry". Rather than reviewing the results, which are presented extensively in the preprint above, we discuss the two aspects of the framework which, in our experience, determined whether the method worked at all. First, the geometry of the problem must be encoded in the architecture of the model, so that the boundary condition and asymptotics at infinity hold exactly for every value of the learnable parameters - leaving us with a single-component loss function; second, the evaluation of the PDE residual must be engineered with care to ensure that complete trainings can be performed in a reasonable time. On the latter point, we describe two implementation techniques which are not spelled out in detail in the original paper: replacing nested reverse-mode automatic differentiation with the forward propagation of second-order jets, and compiling the computational graph of the residual once instead of rebuilding it at every optimisation step. Together, on identical hardware, these two changes reduce the cost of a training step by a factor of roughly forty to fifty. We hope these methodological discussions can be useful for researchers in differential geometry and
geometric analysis who wish to deploy PINNs on problems of their own.
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Astrophysics of Galaxies
Quiescent Host Galaxies of Extended Quasars Revealed by Spectrophotometric Decomposition
Shengxiu Sun, Linhua Jiang, Zhiwei Pan et al. (+27 more)
Previous works of low-
redshift quasar host
galaxies have focused on compact
quasars and found that their host
galaxies are mainly
star-forming
galaxies. Here we present a study of host
galaxies for
quasars with extended morphologies in ground-based optical images. We select a sample of more than 1000 type 1
quasars at
redshift $0.1<z<1$ that are classified as extended objects by DESI. Combining high-resolution spectra from DESI and high-quality images from Subaru HSC, we develop a spectrophotometric decomposition technique to iteratively decompose each
quasar into an AGN component and its host
galaxy. The technique can effectively break the degeneracy between the AGN and host components and capture the host spectral features. Our results show that the host
galaxies of most
quasars have low
star-formation rates (SFRs) and low specific SFRs, indicating that they are quiescent
galaxies. Many of them exhibit prominent post-starburst features with the existence of significant old
stellar populations. These properties are quite different from the nature of compact
quasars with
star-forming host
galaxies. In addition, the relation between the black hole mass and
stellar mass for our sample is broadly consistent with the canonical local relations. This work is complementary to the previous studies and suggests that the host
galaxies of low-
redshift quasars are more diverse than what was thought.
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All authors Shengxiu Sun, Linhua Jiang, Zhiwei Pan, Małgorzata Siudek, Mar Mezcua, Gaocheng Yin, Swayamtrupta Panda, Wei-Jian Guo, Steven Ahlen, David Brooks, Todd Claybaugh, Axel de la Macorra, Peter Doel, Enrique Gaztañaga, Gaston Gutierrez, Theodore Kisner, Andrew Lambert, Martin Landriau, Aaron Meisner, Ramon Miquel, John Moustakas, Ignasi Pérez-Ráfols, Eusebio Sanchez, David Schlegel, Michael Schubnell, Hee-Jong Seo, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Rongpu Zhou
Mesoscale and Nanoscale Physics
Enhancement of exciton radius near a band-gap closing through quantum geometry
Jin-Hyung Choi, Sang-Hoon Han, Young-Kwon Han et al. (+3 more)
Exciton engineering traditionally focuses on modifying semiclassical material properties, such as the effective mass and dielectric screening, while largely overlooking the
quantum geometry of the underlying electron and hole Bloch states. This approximation is adequate for many materials but breaks down near a topological band-gap closing, where the
quantum metric around the band extrema becomes strongly enhanced. In this regime, Bloch states at different momenta become less similar, reducing the projected electron–hole Coulomb
matrix elements and consequently weakening
exciton binding. We demonstrate this mechanism in a
spin–orbit-coupled Lieb-
lattice model tuned toward a topological phase transition. The suppressed Coulomb
matrix elements narrow the
exciton wavefunction in momentum space, leading to an enlarged
exciton radius in real space. This increase in
exciton size produces an experimentally accessible enhancement of the weak-field diamagnetic response. Our results show that
quantum geometry can fundamentally reshape
exciton properties near a topological phase transition, revealing a previously underexplored route for engineering excitonic states.
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All authors Jin-Hyung Choi, Sang-Hoon Han, Young-Kwon Han, Sun-Woo Kim, Jun-Won Rhim, Joshua J. P. Thompson
Quantum Physics
Quantum Resources in Disorder-Free Localization Dynamics of Gauge Theories
Devendra Singh Bhakuni, Giovanni Cataldi, Jad C. Halimeh et al. (+1 more)
Quantum-state complexity diagnostics provide valuable insight into many-body dynamics, information scrambling, and
quantum computation. Here, we investigate the real-time dynamics of
quantum complexity in $1+1$-dimensional Abelian U(1) and non-Abelian SU(2)
lattice gauge theories (LGTs), focusing on the disorder-free localization (DFL) regime. Using stabilizer Rényi
entropy, participation Rényi
entropy, and fermionic non-Gaussianity as measures of complexity, we observe, for both theories, two main behaviors as a function of the gauge coupling: at intermediate values, a power-law relaxation towards saturation, consistent with observations in many-body localization, and, at sufficiently large values, an ultraslow double-logarithmic growth, which we substantiate with a configuration-space bound verified by exact counting. Our results not only provide deeper insight into the dynamics of DFL but also highlight the role of gauge invariance in constraining
quantum resources and are relevant to recent
quantum simulations of LGTs.
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All authors Devendra Singh Bhakuni, Giovanni Cataldi, Jad C. Halimeh, Emanuele Tirrito
Solar and Stellar Astrophysics
The s-process at Subsolar Metallicity: Insights from High-Resolution Infrared Spectroscopy of Magellanic Cloud Planetary Nebulae
N. C. Sterling, M. G. Stephenson, Harriet L. Dinerstein et al. (+8 more)
We present observations of 12 Magellanic Cloud planetary nebulae (PNe) obtained with the high-resolution near-infrared spectrometer IGRINS on Gemini South. In 10 targets we detect multiple
neutron(n)-capture elements that can be synthesized by the s-process during the preceding asymptotic
giant branch (AGB) phase, including the widely-observed species Se and Kr, and first detections of Rb, Cd, and Te in extragalactic PNe. The derived abundances significantly expand the inventory of trans-iron element abundance determinations from PNe in subsolar
metallicity stellar populations. Seven targets exhibit s-process enrichments relative to the
metallicity references O and Ar, with abundances elevated by factors of up to ~40-50 for Te and Kr. We compare these results with AGB nucleosynthesis predictions, using a machine-learning
algorithm to find the best-fitting Monash, FRUITY, and NuGrid models. For five of the PNe, Monash and FRUITY models with 2-4
solar masses and
metallicities from 1/3
solar to near-
solar match the observations well, although the Monash models more successfully fit the largest Kr enhancements. NuGrid models predict smaller s-process enrichments than observed, but the limited number of available models makes it difficult to assess their ability to reproduce the observed abundances. We were unable to find models that provide good fits to three other enriched PNe, including the most metal-poor objects in our sample. These comparisons address uncertainties in mass loss, convection, and other mixing mechanisms during the late
evolution of low- and intermediate-mass
stars, and improve the accuracy of s-process yields of AGB
stars, which are key parameters for modeling
galactic chemical
evolution.
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All authors N. C. Sterling, M. G. Stephenson, Harriet L. Dinerstein, A. Yagüe-López, Kyle F. Kaplan, J. Beaumont, Maria Lugaro, Amanda I. Karakas, Umberto Battino, J. García-Rojas, Samuel M. H. Erben
Instrumentation and Methods for Astrophysics
End-to-end differentiable retrieval of molecular spectra using hydrodynamics, chemistry, and radiative transfer
T. Grassi, G. Vermariën, J.E. Pineda et al. (+3 more)
We aim to reproduce observed molecular line emission using a pipeline that couples hydrodynamics, chemistry, and radiative transfer, capable of simultaneously optimizing all relevant physical and chemical parameters. We developed an end-to-end differentiable Jax pipeline consisting of a custom hydrodynamical code, a modified version of the differentiable chemical code Carbox, and a custom radiative transfer code. We tested the framework using controlled synthetic data. We demonstrate that the framework can recover the parameters of hydrodynamical shock models directly from molecular line spectra and optimize selected chemical reaction rate coefficients through gradient-based optimization. The differentiable formulation enables efficient optimization of the coupled physical and chemical model while preserving the full time-dependent
evolution.
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All authors T. Grassi, G. Vermariën, J.E. Pineda, S. Spezzano, S. Bovino, P. Caselli
High Energy Physics (Theory)
Towers of Operators in CFTs and Convexity Bounds at Large Charge
Fedor K. Popov and Adar Sharon
In arXiv:2406.19441, it was shown that for 3d CFTs with a
moduli space along which a $U(1)$
symmetry is spontaneously broken, the minimum scaling dimension at large charge $Q$ scales as $\Delta_{\min}(Q)=\alpha_1 Q+\alpha_0+O(1/Q)$. Motivated by the
holographic swampland program, we study possible bounds on the coefficients $\alpha_i$. For $\alpha_0$, the weak
gravity conjecture motivates the CFT charge convexity
conjecture, which requires the bound $\alpha_0\leq 0$. Using the
moduli space EFT we prove this bound for the $\textit{projected}$ $\Delta_{\min}(Q)$, obtained by fixing a single charge $Q$ and minimizing the dimension while allowing all other charges to vary. This provides a WGC-motivated bound that is explicitly provable using CFT methods. On the other hand, we show that $\alpha_1$ admits no universal bound apart from the trivial bound $\alpha_1\geq 0$. We also compute $\alpha_1$ and $\alpha_0$ in several new 3d $\mathcal{N}=1$ theories via the $\epsilon$-expansion and large-$N$ methods.
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Cosmology and Nongalactic Astrophysics
A Simulation Based Inference Approach to Modelling of Type Ia Supernova Populations
B. Popovic, M. Grayling, M. O'Callaghan et al. (+8 more)
Type Ia
Supernovae (SNe Ia) are prominent cosmological probes, utilising a standardisation process to reduce their observed scatter to $\sim0.15$ mag. A growing number of models seek to explain this remaining intrinsic scatter, based on a diversity of
dust properties and possible connections to the progenitor systems. Inference of new models has been limited due to the cost of simulations and attendant complexity. Here, we present Stjörnumál, a simulation based inference pipeline to infer intrinsic and extrinsic parameters of SNe Ia, an upgrade to previous SN Ia modelling attempts with SALT, e.g.
Dust2
Dust. Stjörnumál provides fast and accurate posterior inference via Neural Posterior Estimation, integrated model comparison with Neural Ratio Estimation, and overall significant speed and quality-of-life upgrades. We fit the Dark Energy Survey (DES) 5-year SN sample, finding good agreement with previously-published
dust model parameters for DES5YR. We test 7 models of SN Ia behaviour, finding that more data is needed to break degeneracies between $R_V$ models, but sufficient to evidence ($\log(10)~\textrm{Bayes Factor} = +1.9$, $f_{\rm mix} = 0.8$) against two populations of SNe Ia at high-
redshift. We employ a combination of frequentist $\chi^2$ metrics and
Bayesian model comparison to make model determinations, finding neither are sufficient on their own to properly compare models. For our nominal model, we find a smaller $\Delta R_V = 0.8$ for our nominal model than previous SALT-based attempts. We test our model for consistency against our assumed cosmology, and find our results are robust to $|\Delta w| < 0.10$. The code is publicly available at https://github.com/bap37/Stjornumal, and presents an opportunity to flexibly and rapidly test potential models of SNe Ia scatter in a common framework.
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All authors B. Popovic, M. Grayling, M. O'Callaghan, B. M. Boyd, K. Mandel, P. Wiseman, B. Carreres, N. Shiamtanis, D. Scolnic, E. Charleton, Y. Murakami
High Energy Physics (Phenomenology)
Hadron Structure from the Hierarchy of Quantum Correlations in Deep-Inelastic Scattering
Henry Bloss, TJ Hobbs and Navin McGinnis
We show that the hierarchy of
quantum correlations produced in deep-inelastic scattering (DIS) can serve as a novel probe of the
proton's nonperturbative structure. Specifically, we show that
quantum entanglement, discord, steering, and magic provide nontrivial and complementary sensitivities to the nucleon's parton distribution functions (PDFs), particularly those encoding the transverse-
spin polarization of the interacting
quark. This connection leads to a unique probe of the
proton's parton-level tensor charges with implications for beyond Standard Model (BSM) physics searches. We propose how
quantum information measures can be utilized for precision studies of
hadron structure at DIS experiments like the upcoming Electron-Ion
Collider (EIC).
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High Energy Astrophysical Phenomena
Deep Learning-Based Classification and Analysis of Pulsar Candidates in Fermi-LAT Unassociated Sources
C. Pozo González, R. López-Coto, J. Méndez-Gallego et al. (+1 more)
The Large Area
Telescope (LAT) has revolutionized our understanding of the high-energy sky, yet approximately one-third of the sources in the Fourth
Fermi-LAT Source Catalog (4FGL) remain unassociated. Conventional machine learning, such as Decision Trees, often treat spectral features as independent tabular entries, neglecting the sequential topological information inherent in the Spectral Energy Distribution (SED). We aim to classify unassociated
Fermi-LAT sources by exploiting the intrinsic shape of their spectra and variability features, avoiding the use of
galactic coordinates as training features. Our primary objective is to generate a high-confidence list of PSRs candidates, further distinguishing between Young
Pulsars (YPs) and Millisecond
Pulsars (MSPs). We developed a hierarchical deep learning framework based on a 1D Convolutional Neural Network (1D-CNN), named TabularResCNN. This architecture treats the spectral data from the 4FGL catalog, allowing the model spectral shape. The classification is performed in two stages: first discriminating between AGNs and PSRs, and subsequently categorizing PSRs into YPs and MSPs. We implemented a cost-sensitive learning strategy to handle class imbalance and utilized Grad-CAM techniques to ensure the physical interpretability of the model's decisions. Applying this framework to 2563 unassociated sources, we identified 1136 AGNs and 202 high-confidence PSR candidates (166 YPs, 36 MSPs), increasing the
pulsar population by more than 60%. They exhibit strong astrophysical consistency: YPs are confined to the
Galactic plane, MSPs show a broader vertical distribution, and AGNs are isotropic. Furthermore, we identified 5 out of 5 PSRs recently confirmed by FAST. The proposed 1D-CNN framework isolates PSRs candidates based on intrinsic spectral and temporal properties, minimizing spatial bias.
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All authors C. Pozo González, R. López-Coto, J. Méndez-Gallego, E. de Oña Wilhelm
High Energy Physics (Phenomenology)
Gravity Probe-DM: The Gravitational Laboratory for Dark Matter
Yu-Dai Tsai and Hayden R. Foote
Dark matter is inferred gravitationally across the Universe but has not been detected within the
Solar System. The Sun inevitably focuses incident unbound dark matter into an irreducible downstream wake. Its structure encodes the incoming density and velocity distribution and, for wave dark matter, the de Broglie scale. We propose
Gravity Probe-DM, a heliocentric search using precision ranging between spacecrafts. The exact two-spacecraft observable is the differential wake acceleration; for a short baseline, it becomes the wake
tidal tensor projected along the baseline. For a $2.5\times10^6\,\mathrm{km}$ baseline crossing a $0.1\,\mathrm{AU}$ coherent width at $30\,\mathrm{km\,s^{-1}}$, a one-percent excess gives a raw uniform-core range scale of $0.63\,\mathrm{pm}$ over $5.77\,\mathrm d$. While the projected tide remains coherent over an interval $T$, the free response grows as $T^2$, reaching $2.5\,\mathrm{nm}$ over one year. An illustrative low-lag dark-disk component carrying $20\%$ of the reference local density and reaching a $30\%$ focused contrast gives a one-year scale of about $15\,\mathrm{nm}$. These pre-fit response scales show that trajectory design can move the signal from sub-picometre to nanometre scales. A detection would provide a purely gravitational map of local dark matter and probe the flow that produced it, including particle versus wave focusing. The Sun supplies the lens, spacecraft sample the wake, and precision ranging reads out its gravitational imprint.
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High Energy Physics (Phenomenology)
Natural Phantom Crossing from Axion-WIMP Interactions
Cédric Delaunay, Seung J. Lee, Yuan Yin et al. (+1 more)
We construct a technically natural model in which thermal dark matter (DM) interacts with
axion dark energy (DE) and produces an apparent late-time crossing of the phantom divide. A direct
axion coupling to weakly-interacting massive particles (WIMPs) would ordinarily radiatively destabilize the ultralight
axion potential. We avoid this issue through $N$
fermion species related by a cyclic $\mathbb{Z}_N$
symmetry, which projects the leading Coleman-Weinberg potential onto the exponentially suppressed $N$th harmonic. Although the microscopic theory preserves $\mathbb{Z}_N$, the
axion-dependent WIMP masses generate unequal
equilibrium abundances that freeze-out imprints on the cosmological relic state, thereby breaking the
symmetry spontaneously. The resulting relic distribution retains a
memory of the initial
axion value and generates an unsuppressed finite-density potential that holds the field fixed at early times. As the WIMP density dilutes, the
axion rolls toward the minimum of its confining potential, transferring energy from DE to DM at late times. An observer assuming separately conserved components then infers an effective equation of state that crosses below $-1$, without ghosts or violation of the null-energy condition. We present an illustrative cosmological solution with a DESI-like phantom crossing and percent-level suppression of structure growth, and discuss the implications of the WIMP multiplicity and relic distribution for DM searches.
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All authors Cédric Delaunay, Seung J. Lee, Yuan Yin, Bingrong Yu
Solar and Stellar Astrophysics
A New Sirius-like System at Only 21 Parsecs: An Elusive White Dwarf Companion to the Nearby K-dwarf HD 38230
Alexander Venner, Logan A. Pearce, Qier An et al. (+6 more)
White
dwarfs are among the rarest and faintest
stars found in the
solar neighbourhood and are therefore persistently challenging to detect. Whereas the
Gaia mission has vastly expanded our knowledge of isolated white
dwarfs, limited contrast sensitivity means that white
dwarfs companions to much brighter
solar-type
stars are easily missed, leaving a subset of white
dwarfs in "Sirius-like systems" that can only be discovered via high-contrast imaging. Here we report the discovery of a white
dwarf companion to the nearby K0V
star HD 38230 (HIP 27207). The companion, HD 38230 B, was originally detected with Keck/NIRC2 observations taken as part of the TRENDS high-contrast imaging survey, was detected by
Gaia without an astrometric solution, and was independently observed using Lick/ShaneAO and Palomar/PHARO in the literature. Combining these multiple imaging detections spanning 6 years, we demonstrate that HD 38230 B is a gravitationally bound companion and has photometry consistent only with a white
dwarf. Our analysis of the binary orbit, combining relative astrometry with over 25 years of precise radial velocity observations and Hipparcos-
Gaia astrometry, results in strong constraints on the $P$ = $1390^{+310}_{-200}$ year orbit despite the short observational span, and provides a precise dynamical mass of $M_B$ = $0.71^{+0.06}_{-0.05}$ $M_\odot$ for the white
dwarf. At 21 pc, this is the 11th-nearest Sirius-like system known to date, highlighting residual incompleteness in the local white
dwarf census.
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All authors Alexander Venner, Logan A. Pearce, Qier An, Clémence Fontanive, Elisabeth C. Matthews, Kyle Franson, Justin R. Crepp, Hai Fu, Timothy D. Brandt
Mesoscale and Nanoscale Physics
Anomalous Boundary Modes in a Floquet Hyperbolic System
Ali Fahimniya, Hossein Dehghani, Alicia J. Kollár et al. (+1 more)
We construct an anomalous Floquet topological phase on a negatively curved
hyperbolic lattice. The model is a tight-binding
Hamiltonian with a periodically repeated four-color edge-hopping sequence and a sublattice-staggered onsite potential step. The topological regime is reached near the limit in which a single hopping step transfers amplitude completely across an active edge, while the trivial regime is reached near the point where two full hops occur along an active edge during a single hopping step, returning the amplitude to its starting site. In finite open patches, the topological regime is characterized by bulk quasienergy gaps at $0$ and $\pi$ that are populated by in-gap states, in contrast to a trivial regime where these gaps remain empty. Using compact periodic
lattices, we map the bulk $0$ and $\pi$ quasienergy gaps and identify the gapped regions connected to the trivial and anomalous open-boundary spectra. We diagnose the in-gap states as
chiral boundary modes by their real-space dynamics. Finally, we introduce a small-boundary spectral-flow diagnostic based on punctured periodic
hyperbolic lattices, which avoids the ambiguity associated with the extensive outer boundary of finite
hyperbolic patches. This puncture-based diagnostic should be useful for studying other topological
hyperbolic systems.
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All authors Ali Fahimniya, Hossein Dehghani, Alicia J. Kollár, Alexey V. Gorshkov
High Energy Physics (Theory)
Infinite Symmetry Algebras in Four-Dimensional Conformal Field Theories
Elizabeth Himwich and Monica Pate
In generic interacting four-dimensional Lorentzian conformal field theories, an infinite set of universal light-ray operators constructed from the stress tensor is shown to generate the wedge subalgebra of the loop
algebra of ${\rm w}_{1+\infty}$. This
algebra was recently identified among the asymptotic
symmetries of asymptotically flat spacetimes. The one-point functions of the ${\rm w}_{1+\infty}$ generators in scalar states (also known as one-point event shapes) are explicitly demonstrated to be finite and are precisely related to universal soft factors in the infinite tower of soft graviton
theorems. A second universal class of light-ray operators that generates the ”$S$
algebra,” the gauge-theoretic analog of ${\rm w}_{1+\infty}$, is also constructed and shown to have finite one-point functions in four-dimensional conformal field theories with a
spin-one conserved current. Along with the details of these results, this paper presents a general classification of stress-tensor and conserved current light-ray operators by scaling dimension and Lorentz ${\rm SL}(2,\mathbb{C})$ weights, a general technique for computing commutators by Poincaré recursion, results for other light-ray operator
algebras including a local version of the four-dimensional conformal
symmetry algebra, and examples for free scalar fields.
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Earth and Planetary Astrophysics
Atmospheric Signatures of Common Envelope Evolution in White Dwarf Planets
Sydney Jenkins, Andrew Vanderburg, James Mang et al. (+4 more)
The majority of confirmed
exoplanets orbit within 1 au of a main-sequence (MS)
star. When their
stellar hosts evolve off the MS, many of these
planets will be engulfed and destroyed, creating empty "forbidden" zones around the
stars as they evolve to their final state as a white
dwarf (WD). However, several confirmed and candidate WD
planets have been found within this forbidden zone. Two formation scenarios have been proposed to explain the existence of these close-in
planets: high-eccentricity migration and common envelope
evolution (CEE). There are currently few observational tests to distinguish between these pathways. In this study, we investigate whether CEE could leave a detectable atmospheric signature. Using Modules for Experiments in
Stellar Astrophysics (MESA) models, we simulate an engulfed
planet inspiraling into an AGB
star, and allow the
planet to accrete mass via Bondi-Hoyle-Lyttleton
accretion. Assuming a range of
planet masses (1$-$13 M$_{\mathrm{Jup}}$) and
accretion efficiencies (0.01$-$1.0), we find that the
planet can accrete up to 48% of its initial mass in the most extreme Eddington-limited scenario. Because this accreted material is enriched in hydrogen and helium, we expect it to decrease the
planet's bulk
metallicity. Using simulated emission spectra, we find that CEE can increase thermal emission by up to 9.0% for a cool
planet such as WD 1856 b. For lower
accretion efficiencies (0.01$-$0.5), thermal emission increases between 0.1$-$3.6%. This signature may be observable in the most favorable cases, providing a potential new probe for investigating the dynamical history of close-in
planets around WDs.
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All authors Sydney Jenkins, Andrew Vanderburg, James Mang, Juliette Becker, Caroline V. Morley, Melinda Soares-Furtado, Ricardo Yarza
Quantum Physics
Cascading amplifiers can create exponentially large coherence
Lucas A. Ostrowski, Giacomo Pantaleoni, Howard M. Wiseman et al. (+1 more)
A standard
laser beam has
photon degeneracy, or coherence, $\mathfrak{C}$, of at most $8\mu^2$, where $\mu$ is the number of
photons in the
laser itself. Even
quantum-engineered
lasers, if required to produce a beam with the standard statistical properties, have limited coherence, scaling as $\mu^4$. Moreover, such
lasers (still unrealised) require very unconventional gain and output-coupling mechanisms. Here, we propose a different path to increasing $\mathfrak{C}$: cascaded linear amplifiers, with conventional couplings. By dropping the requirement on the beam's properties, this approach can, in theory, achieve $\mathfrak{C}$ scaling exponentially in $\mu$. Here $\mu$ is the total source excitation number, across all the amplifiers. Two amplifiers suffice to surpass the standard $\mu^2$ scaling.
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All authors Lucas A. Ostrowski, Giacomo Pantaleoni, Howard M. Wiseman, Dominic W. Berry
Astrophysics of Galaxies
Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry
Francesco D'Eugenio, Gabriele Pezzulli, Roberto Maiolino et al. (+18 more)
Little Red Dots (LRDs) are compact active
galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-H$\alpha$ emission, probably tracing the host
galaxy. We measure a nearly grey continuum polarisation $p_{\rm cont}=1.53\pm0.04$(rand.)$\pm$0.20(syst.) per cent, while broad H$\alpha$ is less polarised, $p_{\rm H\alpha}=0.58-0.84$ per cent. We rule out polarisation by Milky Way
dust and dilution by an unpolarised line. The polarised continuum with a depolarised line resembles local Seyfert-1
nuclei and favours a single dominant source over multi-source explanations. After Stokes-continuum subtraction, broad H$\alpha$ shows no blue-to-red swing, but there is a significant (48$\pm$4)$^\circ$ continuum-to-line offset in polarisation angle. This implies a break of axial
symmetry inside this object, posing interesting geometrical challenges to all existing LRD models and frameworks. We discuss different possible origins of this
symmetry break and possible paths to discriminate between them with future observations.
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All authors Francesco D'Eugenio, Gabriele Pezzulli, Roberto Maiolino, Alessandro Marconi, Xihan Ji, Cristina Ramos Almeida, Andrea Ferrara, Piero Madau, Xiaojing Lin, José A. Acosta-Pulido, Fuyan Bian, Matilde Brazzini, Zheng Cai, Stefano Carniani, Xiaohui Fan, Ignas Juodžbalis, Robert G. Pascalau, Jan Scholtz, Charlotte Simmonds, Fengwu Sun, Sandro Tacchella
High Energy Astrophysical Phenomena
Peering through the dip: IXPE unveils the extended scattering environment of GX 13+1
Alessandro Di Marco, Fabio La Monaca, Luigi Stella et al. (+17 more)
Neutron star low-mass X-ray binaries feature complex
accretion geometries, often including an
accretion disk corona or disk winds. Here, a study of the highly inclined dipping source GX 13+1, using coordinated observations from the IXPE, NuSTAR, and Swift-XRT, is presented; this is the first time that such a campaign was conducted to monitor its periodic dip. Our analysis reveals significant variations in polarimetric properties tracking the dip. At the center of the dip, the polarization degree reaches a maximum of ${\sim}$9% (at more than $8\sigma$ confidence level). This is accompanied by a highly significant polarization angle rotation of roughly 60$^\circ$ when passing from the dip to the subsequent off-dip state. Furthermore, the dip state exhibits energy-dependent polarization. By modeling the polarization during the periodic dip, we constrain the geometry of the scattering medium. In the scenario of an oblate extended
accretion disk corona (ADC), an equatorial radius at least 1.5 times its polar radius is needed with $\tau{\sim}0.3$. Alternatively, the results can be modeled as scattering in a disk wind with a most probable electron density of $1.3\times10^{14}$ cm$^{-3}$ and an opening angle near 40$^\circ$, corresponding to an optical depth of ${\sim}0.2$. The obtained results highlight the crucial role of X-ray polarimetric data to unveil the geometry of the extended scattering environment surrounding the
accretion disks, advancing our understanding of
neutron star low-mass X-ray binaries.
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All authors Alessandro Di Marco, Fabio La Monaca, Luigi Stella, Anagha P. Nitindala, Alexandra Veledina, Anna Bobrikova, Eleonora Veronica Lai, Alessandro Papitto, Maura Pilia, Juri Poutanen, Daniele Rogantini, Matteo Bachetti, Maria Cristina Baglio, Caterina Ballocco, Ettore Del Monte, Wei Deng, Giulia Illiano, Vladislav Loktev, Sara Motta, Fei Xie
Astrophysics of Galaxies
Searching for Population III stars with line intensity mapping cross-correlations
Sahil Hegde, Guochao Sun, Julian B. Muñoz et al. (+1 more)
Decades of searches for Population III
stars in individual
galaxies have yielded a few potential candidates, but a statistically robust characterization of the demographics of the first
stars in the lowest-mass systems remains elusive. Line intensity mapping (LIM), an observational technique that measures fluctuations in the aggregate emission from the entire
galaxy population — including the faintest sources — offers an alternative strategy that is especially well-suited for the Pop III era. With the recent launch of SPHEREx and the rapid development of a number of complementary LIM studies, we are poised to place some of the first LIM constraints on sites of
star formation at high-
redshift. In this work, we expand an analytical model for LIM power spectra, Zeus21/oLIMpus, to include Pop III
stars and the emission lines identified as diagnostic signatures of
star formation with a low-
metallicity, top-heavy IMF, such as H$\alpha$ and HeII. We introduce a flexible framework to estimate the measurement uncertainties associated with instrument and survey configurations, and apply these to study LIM signatures of the first
stars in mock surveys carried out with SPHEREx and potential next-generation instruments. We quantify the sensitivity of the LIM signal to variations in Pop II and III parameters and forecast joint limits that can be placed on the Pop III
star formation efficiency (SFE) and IMF shape with SPHEREx. We find that next-generation instruments will be necessary to comprehensively survey the Pop III theoretical landscape — both with respect to `classical' and `exotic' Pop III models — and identify design improvements that will enable such studies. Finally, we carry out a Fisher analysis to characterize synergies between SPHEREx and JWST, suggesting that joint constraints on the Pop III SFE and extensions to conventional Pop III models may be within reach.
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All authors Sahil Hegde, Guochao Sun, Julian B. Muñoz, Steven R. Furlanetto
Instrumentation and Methods for Astrophysics
Single Frequency CMB Foreground Removal with Inter-scale Machine Learning
Helen Shao, Fiona McCarthy, Blake D. Sherwin et al. (+2 more)
Accurate measurements of
Cosmic Microwave Background (CMB) B-mode polarization, a key probe of inflationary physics, are hindered by complex
Galactic dust foregrounds. Traditional foreground removal with Internal Linear Combination (ILC) fully preserves the
primordial signal but requires multi-frequency data and is limited to two-point statistics. We present a novel way to estimate and remove foregrounds at single frequency using signal-preserving machine learning that leverages inter-scale correlations. Using the DustFilaments simulations, we train CNNs to reconstruct large-scale foregrounds ($\ell < 200$) from small-scales ($\ell > 200$). We quantify the effectiveness of foreground removal with the residual foreground power, $f_{\rm{resid}}$, which gives the fraction of foreground power remaining after removal. Predictions using only small-scale $B$-modes achieve $f_{\rm{resid}}\simeq 0.704$, while adding temperature and $E$-modes decreases it to $f_{\rm{resid}} \simeq 0.376$. These results are still higher than the spatial ILC, which leverages multi-frequency data at Simons-Observatory-like frequencies. However, a hybrid network that uses both multi-frequency and inter-scale correlations attains $f_{\rm{resid}}=4.71\times10^{-4}$ when using $B$-mode inputs alone, and $3.62\times10^{-4}$ when using temperature and $E/B$-mode inputs. This network achieves a residual power of $\sim 7\times$ lower than ILC, while inheriting ILC's signal-preserving property. This is $\sim 2$–$3\times$ lower than a network that only uses multi-frequency inputs, demonstrating that correlations across scale are not redundant with correlations across frequency and that our techniques are complementary to multi-frequency foreground removal. However, this is achieved only for DustFilments and network generalization across simulations remains a key challenge for robust ML-based foreground removal. (abridged)
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All authors Helen Shao, Fiona McCarthy, Blake D. Sherwin, Miles Cranmer, Carlos Hervias-Caimapo
Mathematical Physics · Cross-listed from math.AP
Nontrivial solutions for a class of semilinear elliptic equations with a nonlinear Goldstein-Wentzell boundary condition
Enzo Vitillaro
The paper deals with the existence and multiplicity of nontrivial solutions for the doubly
elliptic problem $$\begin{cases} -\Delta u=f(u) \qquad &\text{in $\Omega$,}\\ \phantom{-}u=0 &\text{on $\Gamma_0$,}\\ -\Delta_\Gamma u +\partial_\nu u =g(u)\qquad &\text{on $\Gamma_1$,} \end{cases} $$ where $\Omega$ is a bounded open domain of $\mathbb{R}^N$ ($N\ge 2$) with $C^1$ boundary $\Gamma=\partial\Omega$, with $\Gamma=\Gamma_0\cup\Gamma_1$, $\Gamma_0\cap\Gamma_1=\emptyset$, $\Gamma_1$ being nonempty and relatively open on $\Gamma$, $\mathcal{H}^{N-1}(\Gamma_0)>0$. The terms $f$ and $g$ are subcritical with respect to Sobolev
embeddings, respectively in $\Omega$ and on $\partial\Omega$. We prove that, under suitable assumptions, the problem admits nontrivial solutions at the depth of the potential well energy level, which is the minimum energy level for nontrivial solutions. We also prove that the problem has infinitely many solutions at higher energy levels.
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Cosmology and Nongalactic Astrophysics
Understanding constraints on primordial mass black holes made of dark matter using fast radio bursts
Surajit Kalita, Shruti Bhatporia and Amanda Weltman
In recent decades, a multitude of modified
gravity theories have been proposed to address a variety of cosmological and astrophysical problems. While many of these theories remain viable, observational constraints on their parameters are increasingly stringent. Fast
Radio Bursts (FRBs), in particular, have emerged as powerful probes of cosmology and fundamental physics. This study investigates the implications of a generic modified
gravity theory for gravitational
lensing by FRBs. By analyzing the
dataset of CHIME/FRBs, we constrain the fraction of dark matter composed of
primordial black holes within this theoretical framework. Furthermore, we demonstrate that modified
gravity introduces a screening effect on gravitational
lensing, analogous to the scattering effect of
plasma on light rays.
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Quantum Physics
Experimental Demonstration of a Measurement-Feedback Quantum Information Engine
Jinfeng Wei, Yingying Hong, Dehua Liu et al. (+8 more)
Harnessing finite-time nonadiabatic transitions that are conventionally associated with
quantum inner friction for useful work extraction remains an open experimental challenge. Here we address this issue by introducing and experimentally realizing an innovative measurement-feedback
quantum information engine model in the trapped 40Ca+ ion system, in which the projective measurement replaces the hot reservoir as a nonthermal energy source and the feedback control conditionally steers the system through either
unitary compression-expansion strokes or thermalization. We experimentally show that the repeated feedback cycle converges to a stable operating regime with a resolved energetic balance, and, by controlling the measurement angle and stroke duration, measurement-induced coherence and the finite-time nonadiabatic contribution can enhance work extraction and raise the efficiency above the corresponding Otto
benchmark. The experimental results further show that, over finite ranges of stroke durations, the efficiency and intrinsic cycle power can increase simultaneously. Our experiment establishes a route toward information-to-work
quantum engines that convert finite-time irreversibility into performance-enhancing resources.
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All authors Jinfeng Wei, Yingying Hong, Dehua Liu, Xi Wang, Zhe Wang, Yiling Zhan, Kaifeng Cui, Jintao Bu, Jianhui Wang, Leilei Yan, Gang Chen
General Physics
Metric–Measure Geometry and Geometric Analogues of Holographic Extremal Surfaces
Rohit Dhormare
We develop a
geometric framework based on metric–measure spaces $(M,g,f)$, where the function $f$ defines a deformation of the Riemannian measure motivated by Perelman's formulation of
Ricci flow. Within this setting, we introduce measure-weighted hypersurfaces and associated
geometric functionals, and derive modified extremality conditions for codimension-one and codimension-two submanifolds. These conditions provide intrinsic
geometric analogues of extremal surface equations, arising solely from the metric–measure structure and independent of
holographic duality or
quantum field theoretic input. We further define a generalized functional combining a measure-weighted
geometric term with an effective bulk contribution and analyze its variational properties. The resulting Euler–Lagrange equation exhibits a structural correspondence with semiclassical generalized
entropy functionals, while maintaining a purely
geometric interpretation distinct from thermodynamic
entropy in the sense of Perelman's $W$-functional. Applications to Schwarzschild and Anti-de Sitter geometries illustrate the emergence of preferred
geometric scales and the modification of ultraviolet scaling behavior induced by the function $f$. These results suggest that metric–measure geometry provides a minimal framework in which key structural features of extremal surface constructions can arise from intrinsic
geometric principles.
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High Energy Physics (Theory)
Learning to Trace Seiberg Dualities
Jonathan J. Heckman, Shani Meynet, Alessandro Mininno et al. (+1 more)
Dualities play an important role in establishing both microscopic and emergent phenomena in a wide range of physical systems. In practice, though, it can often be computationally challenging to establish when two systems are dual, even when all of the "rules of the game" are well-known. Said differently, when confronted with two systems, how can one efficiently establish that they are in fact dual? In this paper we use machine learning methods to address this question for Seiberg dualities of supersymmetric quiver gauge theories. Mathematically, this involves establishing mutations of quivers, which is in turn a variation on the theme of "learning to unknot". On the one hand, this leads us to a practical tool for establishing the computational complexity of different dualities. On the other hand, it also allows us to study how different network architectures learn how to trace Seiberg dualities. We find that for quivers with a modest number of quiver nodes (of order $10$), different network architectures consisting of
transformers and multi-layer perceptrons tend to outperform deterministic
algorithms. Supplementing the network by well-established pathfinder
algorithms (essentially "Google Maps for quivers") leads to an additional improvement in the efficiency and accuracy of the search strategy. We anticipate that this class of questions can serve as a useful
benchmark for frontier AI models applied to theoretical physics.
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All authors Jonathan J. Heckman, Shani Meynet, Alessandro Mininno, Gary Shiu
High Energy Astrophysical Phenomena
A Four-dimensional Model-agnostic Probe into the Astrophysical Origins of Binary Black Hole Subpopulations
Anarya Ray and Vicky Kalogera
There is strong evidence of multiple binary black hole~(BBH) subpopulations in the cumulative gravitational wave catalog by the LIGO-Virgo-KAGRA collaboration that likely originate through distinct evolutionary channels. The astrophysical interpretation of this complex underlying population is subject to theoretical uncertainties in treatments of binary
stellar evolution, core collapse, and host environments. Due to a lack of robust predictions and the sheer diversity of plausible features, strongly modelled population analyses often lead to prior-driven conclusions. On the other hand, flexible alternatives are often difficult to scale in higher dimensions, which can lead to a loss of critical information on astrophysically meaningful correlations. In this Letter, we present the first data-driven reconstruction of the joint four-dimensional distribution of BBH primary masses, mass ratios, effective inspiral and effective precessing
spin parameters, which yields novel model-agnostic constraints on the astrophysical origins of BBH subpopulations. We characterize four distinct subpopulations spanning different ranges of BBH masses and report new correlations in these specific mass ranges that are beyond the reach of strongly modeled parametrizations and lower-dimensional data-driven frameworks. Our results unveil novel insights into the abundances of specific subchannels of isolated binary
evolution, dynamical assembly, and hierarchical mergers across various mass ranges in the astrophysical BBH population.
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Quantum Physics
Lifting Lifted Product Codes
Yuta Hirasaki and Jong Yeon Lee
Lifted product (LP) codes form an important class of
quantum error correcting codes with favorable code parameters. We introduce a systematic construction of LP code families based on group extensions and graph lifts. The construction increases the code size while preserving the local structure of the Tanner graph, and relates code parameters, logical operators, and fault-tolerant logical-operation gadgets within the families through chain and cochain maps. As a first application, we obtain LP codes with better code parameters than previously reported ones. We then demonstrate that code-surgery gadgets can be transferred across the selected finite lifts through chain maps and, in several cases, implemented with lower space overhead. We also develop parallel product surgery for lifted clustered cyclic codes. Finally, we propose lifting as a systematic first step toward defining thermodynamic families for algebraically defined qLDPC codes without an underlying Euclidean
lattice. For several base codes and selected lifts, coherent information exhibits finite-size crossings, while our results also indicate that additional conditions are needed to determine a unique family.
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