Fluid Dynamics
Wave-Assisted Propulsion in Bimodal Sea States: Hydrodynamic Performance and Hydroelastic Tuning
Avinash Kumar Pandey, Jung-Hee Seo and Rajat Mittal
Wave-assisted propulsion (WAP) systems harvest ocean wave energy to generate propulsive thrust, offering a promising approach for improving endurance and energy efficiency of marine vehicles. Previous studies have focused primarily on monochromatic or unimodal wave conditions, leaving WAP performance in realistic ocean environments largely unexplored. This study investigates the hydrodynamic and hydroelastic response of a submerged flapping hydrofoil operating in bimodal sea states generated by the coexistence of swell and wind-sea wave systems. High-fidelity fluid–structure interaction simulations are performed for representative calm, transitional, and storm conditions, with passive pitching provided through a torsional spring. Simulations show that, despite increased complexity of bimodal wave forcing, propulsion performance follows the same effective peak frequency scaling previously established for monochromatic and unimodal waves, demonstrating the robustness of this scaling framework across a broad range of sea states. The findings further reveal that while the optimal normalized tuning ratio remains within a narrow range, dimensional torsional spring stiffness varies with sea state characteristics, highlighting the need for adaptive hydroelastic tuning to maximize thrust. Overall, the results demonstrate that WAP systems provide a robust means of generating wave-powered thrust under realistic ocean conditions while providing practical guidance for improved design of wave-powered marine propulsion systems.
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Astrophysics of Galaxies
Ripples in the OCEANS: Broad Line Variability of Little Red Dots
Madisyn Brooks, Kelcey Davis, Jonathan R. Trump et al. (+16 more)
Little Red Dots (LRDs) are a unique class of compact, red sources discovered in the JWST extragalactic deep fields. Determining if they are indeed powered by accreting supermassive black holes (SMBHs) is one of the main drivers of the intense study of these objects. Evidence for variability in these objects provides a direct test for the active
galactic nucleus (AGN) nature of their central engine. In this study, we present a variability analysis of 6 LRDs observed by the $R \sim 2700$ OCEANS survey and leverage archival $R \sim 1000$ spectroscopic data from the CEERS and RUBIES surveys. We report marginal detections of $\rm H\alpha$ broad-line (BL) variability in the LRDs OCEANS-100424/RUBIES-42232 (27% variability at 2.1$\sigma$ significance) and OCEANS-35829/RUBIES-49140 (GlimmIr/Irony; 50% variability at 1.5$\sigma$ significance). The other 4 LRDs in our sample do not show evidence for BL variability, with a 1$\sigma$ upper limit of $4.8 \% - 30\%$ variability between their epochs of observations. We also find no evidence ($<1\sigma$) for continuum variability in our LRD sample. We compare our results to a sample of SDSS-RM
quasars to determine the probability of our broad $\rm H\alpha$ variability detections. We find that the probability of reproducing 2 variable and 4 nonvariable
quasars is $4.71\%$, corresponding to $\sim 2 \sigma$ departure from typical
quasar variability. The detection of BL $\rm H\alpha$ variability in 2 LRDs provides some evidence for the AGN nature of these objects as opposed to pure scattering models.
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All authors Madisyn Brooks, Kelcey Davis, Jonathan R. Trump, Raymond C. Simons, Erini Lambrides, Pablo Arrabal Haro, Bren E. Backhaus, Nikko J. Cleri, Steven L. Finkelstein, Mauro Giavalisco, Norman A. Grogin, Michaela Hirschmann, Dale D. Kocevski, Anton M. Koekemoer, Rebecca L. Larson, Ray A. Lucas, Stephen M. Wilkins, Stijn Wuyts, Jorge A. Zavala
Quantum Gases
Dual Gauge Theory for Two Dimensional Superfluid Turbulence
Tobias Helbig, Sayak Bhattacharjee and Srinivas Raghu
We describe turbulent hydrodynamics of superfluids in two spatial dimensions via the dynamics of point-like
vortices coupled to an emergent 2+1 dimensional $U(1)$ gauge field. The cascade of superfluid kinetic energy is equivalently described by a cascade of dual electric field energies. We study superfluid
turbulence using the equations of motion of the dual gauge theory in the presence of a drive and dissipation. In the limit that the
vortices are point-like, the dual equations of motion directly yield the hydrodynamical equations of the superfluid. We obtain a turbulent cascade consistent with Kolmogorov's scaling law for two dimensional fluid
turbulence. We observe clustering of like-signed
vortices and compute the kinetic energy flux to show that the turbulent regime exhibits an inverse energy cascade.
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High Energy Physics (Phenomenology)
Singlet-Doublet fermion origin of dark matter, neutrino mass and inverse first-order electroweak phase transition
Debasish Borah, Indrajit Saha, Sujit Kumar Sahoo et al. (+2 more)
We study the possibility of an inverse first-order electroweak phase transition (IFOEWPT) and observable gravitational waves (GW) in a radiative
neutrino mass model of scotogenic type where singlet-doublet (SD)
fermions, the lightest of whom is the dark matter (DM) candidate, generate the necessary seesaw at one-loop level. Considering the possibility of light
neutrinos being Dirac for simplicity and additional detection prospects, we extend the standard model (SM) with two generations of $SU(2)_L$ singlet and doublet
fermions, one singlet scalar, and three right-handed
neutrinos (RHNs). While RHNs provide the right
chiral parts of light Dirac
neutrinos, the SD
fermions and the scalar singlet facilitate the one-loop
neutrino mass diagram. The neutral component of the lighter SD
fermion, stabilized under a residual $Z_2$
symmetry plays the role of DM while the heavier SD
fermions strongly couple to the
Higgs leading to an IFOEWPT where the Universe undergoes two different first-order phase transition as it goes from the symmetric to the final broken
Higgs phase. We constrain the parameter space from the requirements of generating the correct
neutrino mass, DM relic as well as IFOEWPT while incorporating the existing constraints from different experiments. The final allowed parameter space of the model can be probed at
collider, direct-detection, GW and
cosmic microwave background (CMB) experiments in near future.
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All authors Debasish Borah, Indrajit Saha, Sujit Kumar Sahoo, Narendra Sahu, Shashwat Sharma
Astrophysics of Galaxies
CLASSY. XV. Kinematics and Spatial Distributions of Outflows in Local Highly Star-Forming Galaxies
Mason S. Huberty, Cody A. Carr, Claudia Scarlata et al. (+17 more)
Star-forming
galaxies drive massive
outflows that play an important role in
galaxy evolution by regulating feedback and influencing the dynamics of surrounding media. Measuring
galactic outflow rates is essential for quantifying feedback efficiency and the amount of mass, momentum, and energy deposited into the circumgalactic medium. In this paper, we examine 17
galactic outflows from the CLASSY survey with radiative transfer modeling of UV absorption lines presented in M. Huberty et al. (2024), to study their spatial distributions and kinematic properties. We study the SiII, SiIII, and SiIV ionization states that trace the cool and warm phases of the
outflows and find that SiII traced winds generally behave differently than the warmer SiIII and SiIV traced winds. We derive the mass, momentum, and energy loading factors, which we find scale inversely proportional to
stellar mass. We find that our measurements of the mass and momentum loading factors are in agreement with the hydrodynamic FIRE-2 simulations. We model the velocity profiles of the winds, with profiles reaching a maximum velocity of 620 km/s on average, in agreement with hydrodynamic simulations from CGOLS. We also investigate the relationship between
outflow properties and the age of the
stellar population from SED fitting. We find that
outflows associated with young
star forming regions are more likely to have a column density dominated by cooler gas and have mass
outflow rates which decrease with radius.
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All authors Mason S. Huberty, Cody A. Carr, Claudia Scarlata, Alaina Henry, Matthew Hayes, Xinfeng Xu, Timothy Heckman, Karla Z. Arellano-Cordova, Danielle A. Berg, R. Michael Jennings, Crystal L. Martin, Kaelee S. Parker, Stephane Charlot, John Chisholm, Simon Gazagnes, Weida Hu, Bethan L. James, Claus Leitherer, Matilde Mingozzi, Evan D. Skillman
High Energy Physics (Theory)
Constraints on the $O(n)$ model from a negative number of flavors
Daniele Artico and Jasper Roosmale Nepveu
Treating the number of
flavors $n$ as a variable in the $O(n)$ model leads to non-perturbative constraints on the spectrum of operators. Using the duality between $O(n)$ and $Sp(-n)$, we extend these relations to negative even values of $n$ and we make them explicit by decomposing operators with general
flavor structure into irreducible representations. In perturbation theory, we exploit this structure to reveal novel degeneracies in the scaling dimensions of different operators, which persist for arbitrary $n$. This allows us to derive the two-loop anomalous dimension of any $\phi^k$-type operator from existing results without additional loop calculations. The same mechanism dictates patterns in renormalization group mixing
matrices, yielding new non-renormalization results in a specific operator basis. We comment on extending this framework to relations between operator product expansion coefficients and to analogous constraints arising from evanescence under continuation in the number of spacetime dimensions.
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High Energy Physics (Phenomenology)
Singlet-doublet dark matter beyond freeze-out
Prudhvi N. Bhattiprolu, Aaron Pierce and Alexander Takla
The Singlet-Doublet
fermion model of dark matter is an economical weak-scale dark matter model that realizes the dark matter abundance through interactions with the electroweak
bosons of the Standard Model. Depending on the size of the Yukawa couplings in the model, the dark matter relic abundance can be produced via freeze-out (including co-annihilation), co-scattering, freeze-in, or the SuperWIMP mechanism. We analyze the ways this model can realize the dark matter density with emphasis on the small Yukawa coupling regime. In this limit, direct and indirect detection are difficult, but a rich
collider phenomenology is possible.
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Mesoscale and Nanoscale Physics
Emergent trans-moiré orbitals and topology in rhombohedral graphene
Yuqin Wang, Jian Xie, Yi-Jie Wang et al. (+13 more)
The fractional
quantum anomalous
Hall effect (FQAHE) exhibited in fractional Chern
insulators has recently been demonstrated in twisted MoTe2 and rhombohedral
graphene/hBN moiré superlattices, promising new routes toward topological
quantum computation. Central to realizing this promise is the understanding of the underlying microscopic mechanism. This, however, remains elusive in the case of rhombohedral
graphene, with the crux being its two seemingly paradoxical conditions: a pronounced small-twist-angle ({\theta}) moiré interface, yet only when electrons are kept distant from it. Here, by scanning tunnelling microscopic imaging with both conditions fulfilled, we capture dramatic electronic structure reshaping in rhombohedral hexalayer
graphene by unforeseen 'trans-moiré orbitals', which emerge on the other, distant side of the moiré interface but nevertheless enforce the moiré periodicity at all measured fillings. We visualize a hierarchy of spatially and energetically distinct trans-moiré orbitals which doped electrons must sequentially occupy–the lowest-energy orbital, expectedly responsible for the FQAHE at small fillings, carries a hollow-cage-like shape. Remarkably, these trans-moiré orbitals vanish at {\theta} {\gtrsim} 1{\deg}, and so do QAHE plateaus in similar devices. Simulations reveal an interaction-driven charge-redistribution mechanism which shapes the trans-moiré orbitals and corresponding Chern minibands. With our findings providing the missing microscopic link, the paradoxical conditions find a natural explanation: electrons are not simply kept distant from a small-{\theta} moiré interface; they are forced into topological trans-moiré orbitals, forged precisely under such conditions. Our microscopic diagnostics unlocks a wide range of possible 'synthetic' FQAHE platforms.
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All authors Yuqin Wang, Jian Xie, Yi-Jie Wang, Jiajun Zhang, Yiting Gao, Zaizhe Zhang, Da Yi, Yan Xie, Jingjing Shi, Guanqin Zhao, Chengyu Xiong, Kenji Watanabe, Takashi Taniguchi, Zhi-Da Song, Xiaobo Lu, Yi Chen
Mesoscale and Nanoscale Physics
Exceptional activated mode theory for generalized real-complex transitions
Mengjie Yang, Alexander N. Poddubny and Ching Hua Lee
Real-to-complex spectral transitions mark the onset of amplification in non-Hermitian systems, but their thresholds are often treated as model-specific quantities. Here we develop a general, non-perturbative activated-mode principle that governs the real-to-complex threshold across broad classes of non-Hermitian systems. A central insight is that only a small
Hilbert subspace is “activated" at the transition onset, which can be variationally determined through the competition between spectral detuning and mode-level projected non-Hermitian couplings. The result is a closed-form exceptional-activation condition for arbitrarily large “disturbances", rather than a perturbative estimate. We apply our framework to three contrasting illustrative problems, establishing (i) a closed-form threshold for critical non-Hermitian skin amplification at all system sizes; (ii) a new link between
impurity tunneling threshold and exceptional point switching; and (iii) activation channel switching without underlying topological phase transition. Overall, our findings recast real-to-complex transitions as generic mode-selection problems independent of any specific
symmetry.
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Solar and Stellar Astrophysics
Astronomical Cardiology II: A Search For Heartbeat Stars Using APOGEE and TESS
Jowen Callahan, D. M. Rowan, C. S. Kochanek et al. (+1 more)
Stellar binaries in short-period, highly eccentric systems with significant
tidal deformations near pericenter, also known as heartbeat
stars, are a laboratory for studying dynamical tides and oscillations in
stars. We identify 50 heartbeat
stars using TESS light curves of
stars identified as binaries using SDSS APOGEE. We fit their phase-folded TESS light curves with an analytic model to measure their orbital periods, eccentricities, inclinations, and arguments of periastron. We measure the mass function of targets with enough APOGEE radial velocity observations to obtain a constraint on the secondary mass. We confirm our previous results that the non-
giant heartbeat
stars have started to evolve off the main sequence and that the fraction of (near) main sequence binaries that are heartbeat
stars rises rapidly with effective temperature.
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All authors Jowen Callahan, D. M. Rowan, C. S. Kochanek, M. M. Fausnaugh
Astrophysics of Galaxies
Trace the Self-Gravitating Gas Using CO Isotopologues
Linjing Feng, Jingwen Wu, Sihan Jiao et al. (+12 more)
Recent studies have shown that the
star formation rate (SFR) correlates tightly and linearly with the mass of gravitationally bound gas, which can be delineated from the power-law tail of the column-density probability distribution function ($N$-PDF) derived from
dust emission observations. This relationship holds across four orders of magnitude within the Milky Way–spanning low-mass to high-mass
star-forming regions and encompassing the extreme environment of the Central Molecular Zone. Building on this framework, we present a new approach for estimating the mass of gravitationally bound gas in molecular clouds using multi-line CO isotopologue observations. Our sample includes 16 molecular clouds with robust detections in $^{12}$CO, $^{13}$CO, and C$^{18}$O $J$ = 1-0, spanning both massive inner
Galaxy clouds and nearby
star-forming regions. We find that the $N$-PDFs derived from combined CO isotopologue data recover the characteristic log-normal plus power-law profiles seen in
dust-based studies. The mass and spatial distribution of the self-gravitating structures estimated from both
dust-based and CO-based methods agree well throughout the sample. This indicates that the CO isotopologue combination can robustly trace the self-gravitating component via the $N$-PDF method and provides a reliable, scalable, and velocity-resolved alternative to
dust emission for identifying the
star-forming gas in molecular clouds.
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All authors Linjing Feng, Jingwen Wu, Sihan Jiao, Zhi-Yu Zhang, Junzhi Wang, Chao-Wei Tsai, Di Li, Hauyu Baobab Liu, Yan Sun, Neal J. Evans II, Yuxin Lin, Hao Ruan, Fangyuan Deng, Yuanzhen Xiong, Ruofei Zhang
High Energy Physics (Theory)
Stabilizer complexity and the Python's lunch
Abhirup Bhattacharya, Jatin Narde, Onkar Parrikar et al. (+1 more)
In this note, we study the stabilizer complexity of the reduced density
matrix corresponding to one side of a partially entangled thermal (PET) state with fixed energy boundary conditions in a
holographic CFT. In particular, we study Wigner negativity, an operationally meaningful magic monotone which can be interpreted as the complexity of classically simulating any
quantum circuit preparation of the reduced state on the subregion. Using assumptions on the pseudorandomness of the CFT spectrum and the heavy operator insertion, we observe that the Wigner negativity of the PET state relative to the microcanonical density
matrix at the given energy is given by $\exp\left[\frac{1}{8G_N}(A_{\text{out}} - A_{\text{min}})\right]$, where $A_{\text{out}}$ is the area of the outer extremal surface, while $A_{\text{min}}$ is the area of the minimal extremal surface. Thus, the stabilizer complexity of the reduced density
matrix on the boundary subregion is $O(1)$ in the absence of a python's lunch, but gets exponentially enhanced in the presence of a python's lunch in the bulk geometry.
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All authors Abhirup Bhattacharya, Jatin Narde, Onkar Parrikar, Suprakash Paul
Astrophysics of Galaxies
FLAGS II: Constraining Galaxy Formation Models with Dimensionality Reduction of Direct Observables
Jack C. Turner, Stephen M. Wilkins, William J. Roper et al. (+1 more)
Comparisons between observations of
galaxies and theoretical predictions are regularly performed using physical properties, which are inferred by the often slow and biased process of SED fitting. Forward modelling facilitates a reliable alternative, whereby models are evaluated using direct observables alone. However, these
datasets become high-dimensional when collating observations from multiple
telescopes, leading to sparse sampling,
memory intensity and visualisation difficulties. We show that 2D
embeddings of JWST and HST photometric fluxes, constructed using the non-linear dimensionality reduction
algorithm UMAP, preserve sufficient information to differentiate between five models. Using a simple $\chi^{2}$-like metric, we show that JAGUAR reproduces the population of bright
galaxies $(m_{\mathrm{AB}}<26)$ in GOODS-S six times as well as SC-SAM and twelve times as well as SAGE. By adjusting the hyperparameters, we quantify how well each model replicates the distribution of SED shapes. The template SED approach of SPRITZ and the lack of photoionisation in SAGE cause significant discrepancies, highlighting the importance of comprehensive forward modelling. The embedded position of each
galaxy can be identified $>100$ times faster than inferring its properties with
Bayesian SED fitting, making this approach an ideal alternative for deriving statistical model constraints from large surveys such as LSST and Euclid, and performing simulation-based inference with CAMELS.
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All authors Jack C. Turner, Stephen M. Wilkins, William J. Roper, Aswin P. Vijayan
Instrumentation and Methods for Astrophysics
Don't Cut Corners: How Training Outside the Prior Makes Simulation-Based Inference More Robust
Chaipat Tirapongprasert and Matthew Ho
Large astrophysical simulation campaigns often generate training data by sampling parameters across a Uniform prior box. Due to the proposal's sharp edge, neural posterior
estimators struggle to learn accurate approximations near the boundaries. We propose Tailed-Uniform, a family of hybrid proposal distributions for sampling training simulations for robust simulation-based inference. By padding the original hard-truncated training box with decaying tails, Tailed-Uniform-trained networks yield more accurate posteriors near and beyond the edges. We demonstrate these improvements on a family of tail shapes, including a widened Uniform box as a control. Our results suggest that additional simulations near the prior boundary better constrain the networks as it approaches the edge of the training box, even for Uniform assumed priors. We show these advantages on a toy problem and cosmological parameter inference from the matter power spectrum. These benefits increase in high dimensions, where boundaries dominate parameter space volume.
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General Relativity and Quantum Cosmology
Thermal false vacuum decay near black holes is aspherical
D. S. Gorbunov, D. G. Levkov and V. E. Maslov
We study decay of a scalar field false
vacuum near a (3+1)-dimensional Schwarzschild black hole equilibrated at Hawking temperature with the environment. Our scalar field model has negative quartic self-coupling and thereby resembles
Higgs sector of the Standard Model in the large-field limit. We demonstrate that if the black hole is not too small, the false
vacuum in this model decays aspherically with regard to the black hole center: via formation of expanding true
vacuum bubbles emerging on the outer side of the event horizon. More specifically, we identify three regimes of the decay. For the largest and coldest black holes, the main mechanism is
quantum tunneling described by an infinitesimally thin bounce sitting at some point of the horizon. In the intermediate-mass regime, the
vacuum is destroyed by thermal fluctuations creating aspherical critical bubbles in the horizon vicinity. Finally, near the smallest black holes thermal fluctuations still guide the decay but the dominant critical bubble is spherically symmetric and covers the entire horizon.
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High Energy Physics (Phenomenology)
Defect-Mediated Conversion: Dark Matter from Cosmological Domain-Wall Scattering
João Paulo Pinheiro and Mohamed Younes Sassi
We propose a new mechanism for dark matter genesis, Defect-Mediated Conversion (DMC). Cosmological domain walls can host a scalar condensate in their core acting as a mixing portal between the Standard Model and a dark sector: thermal-bath
fermions crossing the wall are partially and non-thermally converted into dark particles. The conversion probability is governed by a single dimensionless mixing area built from the wall profile, and the yield by the area density of the network. For a light dark particle the probability is independent of both the incident energy and the dark mass, and the relic abundance collapses onto a single mass–coupling relation running from the keV Lyman-$\alpha$ floor to the wall-formation scale. For a heavy one, conversion turns the energy of a single incident
fermion into the dark mass, populating dark sectors with masses exceeding both the bath temperature and the mediator mass. The same portal also sources ordinary freeze-in, but DMC, boosted by the coherent wall-area enhancement, dominates it by one to two orders of magnitude at fixed couplings and remains operative in the heavy regime, where freeze-in shuts off.
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High Energy Physics (Phenomenology)
Soft Collinear Effective Theory for Heavy QCD Axions
Deepanshu Bisht, Sabyasachi Chakraborty, Siddhartha Karmakar et al. (+1 more)
We develop a soft-collinear effective theory (SCET) framework for heavy QCD
axion, considering two low-energy realizations and taking $B\to Ka$ as a
benchmark mode. In the first realization, $aG\widetilde G$ is assumed to be the only independent
axion interaction at the scale $\mu\sim m_b$. We show that eliminating the redundant
flavor-changing derivative-
gluon operator in the weak effective theory generates a new dimension-seven
axion operator identified as $\mathrm{O}_{\partial ag}$. We match this operator onto SCET and derive the corresponding leading-power soft and spectator-scattering contributions to $B\to Ka$. We obtain a factorized expression for the spectator contribution in terms of perturbative hard kernels and the $B$- and $K$-
meson light-cone distribution amplitudes. The spectator contribution arises at the same order in the power expansion as the soft-overlap term and amounts to approximately $25\%$ of the soft contribution. In the second realization, the Wilson coefficient of $aG\widetilde G$ is assumed to be present above the electroweak scale. Renormalization-group
evolution and matching then induce a direct $b\to sa$ operator, which subsequently results in a dominant soft form-factor contribution, whereas the gluonic spectator term turns out to be numerically subleading ($\sim 6-7\%$). We thus identify the conditions under which spectator scattering becomes relevant for heavy-
axion production in rare $B$-
meson decays. Finally, we derive the corresponding bounds on the
axion decay constant $f_a$ for both realizations and compare their phenomenological implications.
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All authors Deepanshu Bisht, Sabyasachi Chakraborty, Siddhartha Karmakar, Atanu Samanta
Astrophysics of Galaxies
Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics
Minami Nakane and Masami Ouchi
We investigate the UV spectrum of GN-z11, a luminous, compact
galaxy with strong nitrogen lines, at $z=10.60$, using deep JWST/NIRSpec high-resolution IFU and medium-resolution MSA spectra assembled from the JADES, SPURS, and GO programs. After optimized reduction and extraction of the IFU data including an evaluation of statistical and systematic uncertainties, we obtain mutually consistent spectra from the high- and medium-resolution observations. After carefully accounting for the data quality limitations, we identify prominent P-Cygni profiles in NV$\lambda\lambda1238,1243$, SiIV$\lambda\lambda1394,1403$, and CIV$\lambda\lambda1548,1550$, together with broad NIV]$\lambda\lambda1483,1486$ emission (FWHM $\sim1600$ km s$^{-1}$). The P-Cygni profiles resemble those of massive
stars such as O-type
stars and luminous blue variables (LBVs), while the broad NIV] emission resembles that of nitrogen-sequence Wolf-Rayet (WN)
stars. We fit
stellar and active
galactic nuclei (AGN) UV spectral models and find that the
stellar models are strongly preferred over the AGN models ($\Delta$WAIC $=-20$), with the preference driven primarily by the NV P-Cygni profile. These results indicate that the luminous, compact UV continuum of GN-z11 is dominated by massive
stars. We derive electron densities from CIII]$\lambda\lambda1907,1909$, NIII]$\lambda\lambda1747-1754$, and NIV], with the nitrogen diagnostics extending well beyond the CIII]-based limit and reaching densities of $\gtrsim10^{6.5}$ cm$^{-3}$ for NIV], indicating physically distinct carbon- and nitrogen-emitting nebular components. These findings suggest that the apparent nitrogen enhancement inferred for GN-z11 as a whole may arise when strong narrow nitrogen emission originates from dense gas locally enriched in nitrogen by WN
stellar winds and photoionized by nearby massive
stars within the same
star-forming region.
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Strongly Correlated Electrons
Superconductivity in the $t$-$t'$ Hubbard Model from Symmetry-Preserving Neural-Network Quantum States
Riccardo Rende, Luciano Loris Viteritti and Antoine Georges
Despite its fundamental importance in the theory of strongly correlated electrons, the nature of the ground state of the two-dimensional doped Hubbard model remains intensely debated. Variational approaches provide a powerful route to this problem, but their conclusions can depend sensitively on the chosen wave-function parameterization, the mean-field initialization, or the pinning fields used to guide the optimization, as well as on boundary conditions. This can favor one type of
symmetry breaking over another, making it difficult to distinguish the genuine interplay of intertwined or competing orders from biases induced by the variational parameterization. Here, we introduce the
Symmetry-Preserving Backflow Pairing (SBP) ansatz, a neural-network wave function that respects translational
symmetry by construction and thereby avoids these broken-
symmetry minima. The SBP ansatz reaches state-of-the-art variational energies for the $t$-$t'$ Hubbard model on
lattices up to $24\times24$ with $504$ electrons, below those of competing pure stripe solutions. By extrapolating to the thermodynamic limit, we find robust evidence for $d$-wave superconducting order, resolving a long-standing question about the $1/8$-doped model at $t'/t=-0.2$ and $U/t=8.0$. Built on general principles of
symmetry and locality, the SBP wave function provides a broadly applicable variational representation for challenging interacting fermionic systems.
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High Energy Astrophysical Phenomena
Interacting Supernovae: a Radio and X-ray Strategy to Constrain the Structure of the Circumstellar Medium
Shunke Ai, Irene Tamborra and Leonardo Dinoi
The interaction of
supernova (SN) ejecta with the dense circumstellar medium (CSM) converts shock kinetic energy into radiation across multiple wavebands. We investigate the dependence of the X-ray and
radio emission on the CSM geometry, considering spherical, hourglass, and disk shapes for the CSM. We find that the spectral and light-curve properties, both in X-ray and
radio, significantly differ for spherical and non-spherical CSM structures. For a non-spherical CSM, the
radio light curve flattens out near the peak frequency, due to efficient free-free absorption by the unshocked CSM. Moreover, the early rise of the
radio light curve is shallower when the CSM density along the observer line of sight is larger than that in other directions. If the CSM density is lower along the observer line of sight, the
radio light curve flattens near its peak, and the reverse-shock component is negligible in X-rays. Building on these features, we provide a method to constrain the CSM structure based on the rising part the
radio light curve in the proximity of its peak; we show that the decay part of the
radio light curve, after its peak, carries insight on whether the CSM density profile is wind-like or not. We further adopt the X-ray signal to corroborate the information extracted from
radio. We test our strategy on SN 1993j and SN 2023ixf. For both SNe, we find that an asymmetric CSM is in excellent agreement with
radio and X-ray observations and provides a viable alternative to non-wind scenarios suggested in the literature. Our findings highlight the crucial insight provided by
radio and X-ray signals into the mass-loss history of the SN progenitor.
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High Energy Physics (Phenomenology)
Probing CP-violating top-quark dipole moments with tomographic observables
Maxim Perelstein, Minal Shaik and Taewook Youn
Quantum tomography program reconstructs the full
spin density
matrix of top-
quark pairs from dilepton angular correlations at both electron-positron and
hadron colliders. We use
symmetry arguments to identify tomographic observables sensitive to CP violation in top
quark couplings. As a concrete example, we study the sensitivity of these observables to (chromo-)electric dipole moment operators at the LHC and the FCC-ee. We also construct the optimal observable, which combines tomographic and kinematic information to achieve statistically optimal sensitivity for each operator and production process. The analysis is based on fast detector simulation of top pair production and decay in the dilepton channel. We project a $95\%$ CL sensitivity to new-physics scales (the inverse dipole couplings) of $10-15$ TeV for the electroweak electric dipoles at the FCC-ee ($365$ GeV, $3~{\rm ab}^{-1}$) and of 40 (200) TeV for the top chromo-electric dipole moment at the LHC Run 2 (HL-LHC). This sensitivities exceed those of the traditional observables currently used by experiments to use for these operators, indicating the power of the tomographic approach to search for CP violation.
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Astrophysics of Galaxies
Recycled Gas Dominates the Metal-rich Fuel of Supermassive Black Holes
Dongyun Kwak, Ena Choi, Hannah Jhee et al. (+5 more)
Understanding the origin and chemical properties of gas accreted by supermassive black holes (SMBHs) is essential for linking black hole growth to
galaxy evolution. Using a suite of 30 high-resolution cosmological zoom-in simulations, we investigate the chemical properties of gas accreted onto SMBHs in massive
galaxies with
stellar masses of $10^{10.9-11.9}\,\rm M_\odot$ and black hole masses of $10^{8.5-9.7}\,\rm M_\odot$ at $z=0$. By tracing the full cosmological histories of individual gas particles, we identify their origins and enrichment pathways. The accreted gas is classified into four categories: “early” gas accreted during the early assembly phase of the main
halo, “external” gas originating from other
galaxies or subhalos, “recycled” gas enriched through
stellar evolution processes within the primary
galaxy, including asymptotic
giant branch (AGB) winds and
supernova ejecta, and “smooth” gas accreted from the intergalactic medium. We find that recycled gas dominates the
accretion budget and is already metal rich at early epochs. Gas from other origins typically undergoes gradual chemical enrichment within the
galactic environment prior to black hole
accretion. The mean abundance ratios show only weak
redshift evolution and are broadly compatible with the high
metallicities inferred for
quasar broad-line regions. Our results suggest that metal-rich gas supply to SMBHs arises naturally from cosmological
galaxy evolution and
stellar recycling.
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All authors Dongyun Kwak, Ena Choi, Hannah Jhee, Rachel S. Somerville, Thorsten Naab, Michaela Hirschmann, Jaejin Shin, Jong-Hak Woo
Superconductivity
Finite-momentum coupling of Higgs and Bardasis–Schrieffer modes in superconductors with competing pairing channels
Samuel Awelewa, Yafis Barlas and Maxim Dzero
In
superconductors with competing pairing channels, two well defined excitations exist below the pair-breaking edge: the
Higgs mode of the condensed $s$-wave channel and the Bardasis–Schrieffer (BS)
exciton of the subdominant $d$-wave channel. Their mixing is doubly forbidden — by point-group
symmetry at zero momentum and because the two reside in the amplitude and phase sectors of the order parameter respectively, by particle–hole
symmetry at every momentum. Working in a Nambu–Keldysh quasiclassical framework extended to leading $1/\varepsilon_F$ corrections and including the self-consistently screened Coulomb potential, we show that finite momentum combined with particle–hole asymmetry generates a direct coupling which we obtain in closed form. Whether this coupling produces an avoided crossing is decided, however, not by its magnitude but by kinematics. In the clean limit the
Higgs is not a sub-gap pole but a resonance pinned to the pair-breaking edge, which disperses with coefficient unity in $(v_Fq)^2$, while the bound BS mode disperses more slowly: the two branches therefore separate rather than converge and never become degenerate. The obstruction is specific to the clean limit: exact dirty-limit results show that disorder detaches the amplitude resonance from the edge and reverses its dispersion, which can result in an avoided crossing with the BS mode at intermediate scattering. In that regime, the coupling computed here would set the splitting between the hybridized branches. We discuss the experimental implications of these results.
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High Energy Physics (Theory)
A Lapse in the Cosmological Constant Problem with Bulk Dynamics
Justin Khoury, Benjamin Muntz and Antonio Padilla
We have previously proposed a new approach to the cosmological constant problem based on anisotropic scaling in a compact extra dimension. In the ultra-local $z=0$ limit, the interplay between a projectable lapse, foliation-preserving diffeomorphisms, and higher-form fluxes renders the gravitational field equations insensitive to radiative corrections to the matter
vacuum energy. Here we extend this framework beyond the ultra-local limit by introducing $z=1$ deformations that restore dynamics along the compact direction. We show that
vacuum-energy cancellation persists at the level of the background equations, while generic extrinsic-
curvature couplings propagate an additional scalar ghost. A healthy quadratic spectrum selects the Fierz-Pauli relation between these couplings. This motivates a particularly simple realization in terms of five-dimensional Einstein
gravity, a top-form flux, and a spacelike khoron scalar field that dynamically defines a preferred projectable foliation. In this covariant formulation, the global constraint arises from an auxiliary einbein on the space of khoron leaves, and constant shifts of the renormalized matter
vacuum energy cancel algebraically from the intrinsic Einstein equations. Finally, allowing matter to propagate around the compact dimension generates finite,
topology-sensitive Casimir contributions that are not automatically removed by the mechanism. Suppressing these contributions requires additional spectral conditions on the propagating bulk degrees of freedom.
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Strongly Correlated Electrons
Cesar A. Gallegos and A. L. Chernyshev
A comprehensive analysis of pairing and bound states of
magnons in the Heisenberg $S\!=\!1/2$ square-
lattice $J_1\!-\!J_2$ ferro-
antiferromagnetic model is presented. We highlight the similarities and differences between the bound states of
spin flips on a
lattice and those of particles in the continuum.
Magnon bound states at finite pair momentum are studied throughout the Brillouin zone and a convenient
lattice partial-wave nomenclature is advocated. The mechanisms of enhanced stability or fragility of these bound states for the high-
symmetry pair momenta are identified and quantified as relating to the effective dimensional reduction or enhancement, respectively. These effects are also shown to control the
evolution of the bound states with the model parameters, providing a transparent framework for understanding
magnon pairing in a more general setting. A method to determine the bound state phase boundaries is presented.
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Astrophysics of Galaxies
The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. V. When Galaxies Glow with Industry
Olivia Curtis, Aidan J. Rowland, Jason T. Wright et al. (+3 more)
We present the most robust
stellar population synthesis (SPS)-based search for
galaxy-spanning technological waste heat to date, applied to 129 nearby
galaxies spanning a wide range of spectral energy distribution (SED) types, including ultraluminous IR
galaxies and MIR-luminous active
galactic nuclei (AGN). We incorporate the
AGENT Dyson sphere formalism into the Flexible
Stellar Population Synthesis code at the
stellar population level, so nebular and
dust emission respond self-consistently to Dyson sphere reprocessing. With Prospector, we perform a suite of 1,419 injection recovery tests across a range of covering fractions, $\alpha$, where we successfully recover the injected covering fractions (best-fit slope $m = 0.92$) and detect them through
Bayesian model selection down to $\alpha \sim 4$–$5\%$ in quiescent
galaxies. None of our 129
galaxies prefer a Dyson sphere component, and we place the first per-
galaxy 95% upper limits on warm ($T_{\rm BB} \gtrsim 100$K) swarms, reaching a median $\alpha < 0.3\%$ across quiescent hosts without a dominant AGN. Our injection-calibrated detection rates convert these zero detections into a population bound of $<2.6\%$ of
galaxies hosting $\alpha = 25\%$ swarms ($95\%$ confidence). Because survey colors cannot separate waste heat from starbursts and AGN, we develop a scaffold for future searches, running from inexpensive archival screens such as the Balmer decrement and the
stellar-to-dynamical-mass offset a swarm leaves behind, through resolved fitting with
nuclear excision, to PRIMA FIR photometry that makes targeted JWST imaging decisive. We find that the outskirts of quiescent
galaxies are the best hunting grounds for future technosignature searches.
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All authors Olivia Curtis, Aidan J. Rowland, Jason T. Wright, Caryl Gronwall, Jakob M. Helton, Joel Leja
Earth and Planetary Astrophysics
Climates of Gl 514 b
Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick et al. (+2 more)
The continuous discovery of
exoplanets, each with distinctive
stellar and planetary properties, along with the development of higher resolution ground and space
telescopes has positioned
climate evolution as a fundamental component of the study of habitability. In particular, the
planet Gl 514 b, located within the habitable zone of an M0.5
dwarf star 7.62 pc from Earth, is a candidate for direct observations with future ground and space-based
telescopes and therefore worthy of
climate modeling. One notable aspect of this
planet is its eccentricity of $e = 0.45^{+0.15}_{-0.14}$, which could affect the seasonal
climate by inducing large swings in instellation over the course of an orbit. Hence, we simulate a plausible range of climates on this
planet to assess the likelihood that its surface is habitable as well as estimate the surface ice coverage, which could affect the photometric signal. To perform these simulations, we use an energy balance model to explore the parameter space permitted by the observations and the allowed ranges of the obliquity, eccentricity, atmospheric CO$_2$, precession angle, land fraction, and land distribution. We find the
planet is most likely to be in either a snowball or ice free state, but about 1.27% of our simulations contain polar ice caps or an ice belt. A partial pressure of CO$_2$ in the range of 7.25-9.5 bar permits the
planet's surface to be habitable. These results constrain the orbital, rotational, and physical conditions required for surface habitability of Gl 514 b and will help guide future direct-imaging surveys of this and similar
planets.
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All authors Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick, Mario Damasso, Nathaniel Brown
High Energy Physics (Phenomenology)
Dark matter in scale-invariant gravity with hidden-sector condensation
Juan P. Garcés, Jisuke Kubo, Manfred Lindner et al. (+1 more)
The origin of the electroweak scale,
cosmic inflation, and dark matter are often treated as independent problems beyond the Standard Models of particle physics and cosmology. In this work, we explore the possibility that they instead arise from a common underlying framework based on classically scale-invariant quadratic
gravity coupled to a strongly interacting hidden sector. The $R^2$ term naturally realizes Starobinsky inflation, while confinement in the hidden sector dynamically generates the Planck scale and triggers electroweak
symmetry breaking through a gravitationally induced
Higgs mass generation mechanism. The scalar degree of freedom associated with the $R^2$ term subsequently reheats both the visible and hidden sectors through universal couplings to the energy-momentum tensor, leading to the gravitational freeze-in production of hidden-sector states. We investigate three representative realizations of the hidden sector in which the dark matter candidate is either a hidden $\eta'$
meson, a hidden vector
boson, or charged hidden pions, and derive the corresponding dark matter and dark radiation relic abundances.
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All authors Juan P. Garcés, Jisuke Kubo, Manfred Lindner, Markus Reinig
Strongly Correlated Electrons
Ameya Chavda and Ryohei Kobayashi
We develop a
lattice characterization of fermionic 't Hooft anomalies of finite internal
symmetries in one and two spatial dimensions, formulated in terms of obstructions to symmetric short-range-entangled (SRE) states. We consider
lattice systems formed by tensor product of onsite fermionic and bosonic local degrees of freedom, and finite internal
symmetry given by a central extension $\mathbb Z_2^F\to G_f\to G_b$. We extract a hierarchy of fermionic anomaly indices for a given
symmetry operator in both (1+1)D and (2+1)D. In (1+1)D, an exact
lattice symmetry is characterized by a pair of cohomological data $(n_2,\nu_3)$. For $G_f=G_b\times\mathbb Z_2^F$, we further show that a
symmetry with trivial
lattice anomaly indices $(n_2,\nu_3)$ is onsiteable and hence admits a symmetric SRE state, establishing that these indices faithfully detect the
lattice anomaly. Comparing with continuum fermionic QFT, we find that exact
lattice symmetries do not realize the additional $H^1(BG_b,\mathbb Z_2)$ anomaly layer in continuum QFT. In particular, for $G_b=\mathbb Z_2$, exact
lattice symmetries realize only the even $\mathbb Z_4$ subgroup of the continuum $\mathbb Z_8$ classification. In (2+1)D, we identify three successive anomaly layers of cohomological data $(n_2,n_3,\nu_4)$. We show that a nontrivial value of any layer obstructs a symmetric SRE state. For $G_f=G_b\times\mathbb Z_2^F$, it also forbids a symmetric invertible state. We also construct a non-onsite $\mathbb Z_4^F$
lattice symmetry in (2+1)D with nontrivial
lattice anomaly index that forbids any symmetric invertible states with $c_-\in\mathbb{Z}$, therefore forbids any invertible states compatible with onsite $\mathbb{Z}_4^F$
symmetry. Our results motivate a systematic study of which continuum anomalies admit exact microscopic
lattice realizations.
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Superconductivity
Floquet Quasiparticle Poisoning of Frozonium
Haoyu Guo and Debanjan Chowdhury
Periodic driving can suppress the Josephson nonlinearity of a fluxonium superconducting
circuit, producing a nearly harmonic Floquet spectrum at isolated freezing points [K. Lewellen et al., Newton 2, 100434 (2026)]. Here we show that this dynamically frozen behavior does not generically suppress quasiparticle-induced dissipation in the resulting frozonium
circuit. We formulate quasiparticle processes in the frozonium using a Floquet framework and analyze both drive-assisted Cooper-pair breaking and tunneling of pre-existing quasiparticles. Pair generation is controlled by gap-breaking thresholds at high drive frequencies, while multiphoton resonances produce pronounced rate enhancements at lower frequencies. Quasiparticle tunneling exhibits connected resonance structures organized by the harmonic Floquet-Magnus spectrum near the freezing point, with resonant hybridization generating characteristic avoided crossings. Our results show that suitable operating regimes must balance dynamical freezing against quasiparticle loss and provide a framework for identifying experimental drive parameters away from harmful resonances.
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