Astrophysics of Galaxies
Gaia DR3 Limits on Stellar Engine Technosignatures in Nearby Stars
Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang et al. (+1 more)
An operating
stellar engine that transfers momentum to its host
star could produce an approximately persistent transverse acceleration during the
Gaia Data Release 3 (DR3) observing epoch. We search for such accelerations among 406,984 quality-selected
Gaia DR3
stars with nominal distances below 200 pc (about 650 light-years), using 8,890 published Acceleration7 solutions. Because long-period binaries and astrometric systematics can produce similar sky-plane
curvature, we model these conventional explanations together with a broad component that can absorb any remaining persistent acceleration or model mismatch. At $a_0 = 2.60 \times 10^{-4}$ m s$^{-2}$, where essentially the entire parent sample is searchable, mapping the residual weights evaluated at the one-sided 95% profile-limit point gives a parent-population fraction limit of $1.21 \times 10^{-5}$. Multiplying this fraction by the parent-sample size gives a summed upper-limit weight of about five
star-equivalents above the threshold. Toward the lowest acceleration thresholds, the searchable fraction declines rapidly, so the corresponding bounds primarily describe the reach of the search. No individual source is interpreted as a technological signal.
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All authors Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang, Zhi-E Liu
Fluid Dynamics
Measuring Mean Spanwise Flow with a Rotating Single Hot-Wire Probe over a Wide Yawed Riblet-Textured Surface
Yu Xia, Sandesh Parajuli, Hafiz Aliffrananda et al. (+2 more)
This study investigates the spatial development and recovery of near-wall flow steering induced by yawed widely-spaced riblets. To accurately measure the mean spanwise velocity in the near-wall region, we developed a unique, customised rotating probe equipped with a single hot-wire. This novel technique demonstrates high sensitivity, reliably detecting small spanwise velocity components. We applied this probe to map the flow over straight-to-yawed and yawed-to-straight riblet configurations. For the straight-to-yawed transition, the downstream distribution of the mean spanwise velocity closely aligns with the step-forced spatial Stokes layer (SSL) solution, achieving an equivalent active wall motion of $V^+_\mathrm{equ} \approx 2.0$. This offers a simplified analytical pathway for future passive flow manipulation studies. Conversely, flow recovery over the yawed-to-straight configuration diverges from the SSL step-down phase prediction. Instead, a spatial lag was observed where crest-adjacent flow recovered quickly, but significant residual spanwise flow ($V^+ > 0.5$) persisted far downstream ($\widehat{x}{}^{+} > 1000$).
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All authors Yu Xia, Sandesh Parajuli, Hafiz Aliffrananda, Daniel Chung, Nicholas Hutchins
Mesoscale and Nanoscale Physics
Chiral Damping-Induced Chirality Switching and Control of Domain Walls in Antiferromagnets
Collins Ashu Akosa, Mu-Kun Lee, Aurélien Manchon et al. (+1 more)
We investigate the impact of
chiral damping (CD) on current-driven domain-wall (DW) dynamics in antiferromagnets (AFMs). Asymmetric CD between sublattices generates off-diagonal components in the DW mass tensor, thereby coupling translational and rotational modes. When CD is modulated by an ac gate voltage via the Rashba
spin-orbit interaction (RSOI), symmetric and asymmetric contributions induce oscillations in the DW velocity and tilt angle, respectively. A perturbative analysis yields explicit expressions for the oscillation amplitudes, in quantitative agreement with numerical simulations. Remarkably, even in the absence of Dzyaloshinskii-Moriya interaction (DMI), asymmetric CD enables chirality switching between Néel- and Bloch-type DWs. Finally, by exploiting the relativistic Lorentz contraction of the DW width at high driving currents, we propose an experimentally viable protocol to qualitatively and quantitatively extract the CD contribution. These results establish clear experimental signatures of CD in
antiferromagnetic DW dynamics and demonstrate its potential as a control parameter for
magnetic textures.
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All authors Collins Ashu Akosa, Mu-Kun Lee, Aurélien Manchon, Masahito Mochizuki
Optics
In-situ adjoint protocols for nonlinear PT-symmetric self-optimizing machines
Zheming Li, Lucas J. Fernández-Alcázar, Zin Lin et al. (+1 more)
Adjoint methods provide a powerful route for gradient-based optimization, but their physical implementation is obstructed in generic nonlinear systems because the adjoint dynamics requires backward-time
evolution, Jacobian transposition, and terminal-value constraints. Here we show that nonlinear parity-time ($\mathcal{PT}$)-symmetric systems overcome this obstruction. Using a class of nonlinear non-Hermitian resonator networks, we establish
symmetry relations that map the formal adjoint dynamics onto experimentally accessible forward-time evolutions supplemented by controlled injections. This construction enables exact in-situ evaluation of adjoint gradients without requiring explicit backward propagation or
matrix transposition. We demonstrate the approach in nonlinear $\mathcal{PT}$-symmetric resonator chains, where the resulting optimization protocol autonomously discovers parameter configurations that realize prescribed spatio-temporal functionalities, including uniform energy redistribution and targeted wave transport at predefined time windows. Our results identify $\mathcal{PT}$
symmetry as a resource for implementing computational sensitivities within physical systems and establish a route toward self-optimizing nonlinear machines.
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All authors Zheming Li, Lucas J. Fernández-Alcázar, Zin Lin, Tsampikos Kottos
Nuclear Theory
Deep-learning classification of physically admissible nuclear-matter equations of state
Ahmed Abuali, Micheal Kahangirwe, Francesco Di Clemente et al. (+3 more)
Thermodynamic stability and causality impose fundamental constraints on the equation of state (EoS) of
nuclear matter. Verifying these constraints conventionally requires calculating quantities such as the specific heat,
baryon-number susceptibility, and speed of sound, which can become computationally expensive when many candidate EoSs must be examined. We investigate whether the normalized pressure surface, $Q(T,\mu_B)=P(T,\mu_B)/T^4$, alone contains sufficient information to determine the physical admissibility of an EoS. We develop a supervised convolutional neural network (CNN) that uses only this pressure representation to classify EoSs as physically admissible or inadmissible. The network is provided with training labels obtained from direct thermodynmaic stability and causality check and its does not get any information about the parameters of the underlying EoS framework. For EoSs generated within an Ising-mapping framework, the model achieves $97.65%$ accuracy on unseen test data. Applied independently to EoSs from a distinct
holographic framework, it achieves perfect classification of the test set. These results show that pressure surfaces contain
geometric signatures of thermodynamic stability and causality violations that can be learned directly by a CNN. Because the classifier relies only on the pressure surface, it avoids evaluating higher-order thermodynamic observables during inference and is largely independent of the EoS-generation framework. When the pressure surface is supplied as a two-dimensional array, the machine-learning validation is approximately 20 times faster than direct validation. Our results establish a fast, framework-independent approach for identifying physically admissible EoSs directly from their pressure surfaces.
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All authors Ahmed Abuali, Micheal Kahangirwe, Francesco Di Clemente, Vianney E Diaz-Barraza, Jorge A Munoz, Claudia Ratti
Quantum Physics
zenDot: An LLM-integrated quantum TCAD platform for semiconductor quantum-device design and optimization automation
Zeheng Wang, Yan Liu, Yue Hao et al. (+1 more)
Semiconductor quantum-device design still lacks an integrated Technology Computer-Aided Design (TCAD)-like environment that connects material geometry,
quantum many-body simulation, and automated design. Here we introduce zenDot, a large-
language model (LLM)-integrated
quantum TCAD platform that links a material-labelled device state to a unified condensed-matter physics toolbox. The device and calculation components are integrated into a desktop workbench, Python API, and an embedded LLM
agent, allowing electrostatics, charge and transport characterization, correlated-state calculations, and
qubit modelling to be executed within one reproducible environment. We demonstrate zenDot on a Si/SiO2 double
quantum dot, where a single device state reproduces the characterization workflow and supports hybrid, tunnel-charge, and singlet-triplet
qubit analyses. A platform-level universal-control scan revises the singlet-triplet operating point and reduces the predicted worst-gate infidelity by nearly 30-fold. Beyond analysis, the LLM
agent directly operates the same physics environment as human users, proposing design changes, executing registered simulations, and iterating on solver-returned metrics under physics-aware validation. Across three demonstration tasks it completes 18 validated design iterations, including geometry modification followed by a full re-solve from the material stack. zenDot establishes a machine-operable
quantum TCAD workflow that connects device physics with LLM-driven design exploration.
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All authors Zeheng Wang, Yan Liu, Yue Hao, Genquan Han
Optics
Transport-defined photodetection through electrically selectable nonequilibrium carrier transport
Jiaxuan Cai, Yan Xie, Ning Yang et al. (+9 more)
Broadband optical fields can change in both intensity and spectral distribution, but a fixed-response detector maps this evolving information onto a single electrical signal. Here we demonstrate transport-defined photodetection, in which electrical bias selects how photoexcited carriers are redistributed, escape and are collected, creating complementary response functions within one shared active region. In a GaAs/AlGaAs
semiconductor ratchet, light-driven ratchet transport defines the response at 0 V, whereas the spectral
evolution at -2 V is consistent with field-assisted hot-carrier transport. The overlapping states span a measured spectral range of 0.4-94.5 {\mu}m at 5 K, provide state-dependent calculated detection floors and support joint infrared operation at 30 K. Direct optical beat notes at 7.432 GHz in the mid-infrared and 17.103 GHz in the terahertz demonstrate optical-to-electrical conversion. Their common-path outputs recover an imposed spatial temperature gradient and the transient field-of-view-integrated effective radiation temperature of
laser-excited graphite. These results establish post-photoexcitation transport as a function-defining design variable for
semiconductor photodetectors, complementing structure-defined, field-tuned and optically encoded approaches to reconfigurable photodetection.
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All authors Jiaxuan Cai, Yan Xie, Ning Yang, Weidong Chu, Peng Bai, Lianhe Li, Edmund H. Linfield, Hanbing Wang, Meng Chen, Guanchen Li, Yingxin Wang, Ziran Zhao
High Energy Physics (Theory)
Gravitational wave signatures from area metric gravity
Bianca Dittrich
Area metric theories have been proposed as effective descriptions in a number of
quantum gravity approaches: as continuum limit of effective
spin foams, as an effective description for string theory and in the context of holography. Area metric actions allow for non-topological parity violating terms, which opens the possibility of observationally determining the Barbero-Immirzi parameter. We consider the shift symmetric version of linearized area metric theory in Lorentzian signature, which arises in particular from
spin foams and modified Plebanski theory, and avoids ghost and tachyonic instabilities in the graviton sector. We discuss the gravitational wave like solutions of this theory and through an analysis of the coupling to electro-magnetism, deduce the signals in gravitational wave detectors. Using polarized light in such interferometers allows in principle to measure area metric induced birefringence. For the non-length excitations that accompany a gravitational wave this birefringence turns out to be independent of the Barbero-Immirzi parameter; the parameter is instead encoded in the polarization structure of the massive non-length waves, where it rotates the axes of the induced birefringence. Assuming Planck massive non-length excitations in the area metric the resulting signals are however extremely weak.
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Strongly Correlated Electrons
Transport-Noise and Optical Witnesses of Electronic Multipartite Entanglement
Shuhan Ding, Prakash Sharma, Zecheng Shen et al. (+3 more)
Entanglement among particles distinguishes correlated
quantum materials from conventional metals and
semiconductors. Experimentally certifying intrinsic
entanglement among interacting electrons in materials is important not only for classifying states of matter, but also for developing material-based
quantum technologies. Here, we introduce a transport protocol for witnessing multipartite
entanglement from the
equilibrium current-noise spectrum, measured directly or reconstructed from optical conductivity. The appropriately integrated, symmetrized, and projected noise spectrum obeys an upper bound derived from microscopic model parameters. Unlike witnesses based on localized
spins, our framework applies to general electronic states without requiring
magnetic moments and remains invariant under single-particle basis transformations. We
benchmark it in twisted
bilayer graphene, twisted
bilayer MoTe$_2$, and Hubbard models, and demonstrate
entanglement certification in a fractional Chern
insulator. This approach extends recently developed scattering-based
entanglement witnesses to ultralow-temperature conditions, where many candidate entangled phases emerge.
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All authors Shuhan Ding, Prakash Sharma, Zecheng Shen, Jiang-Xiazi Lin, Sergei Urazhdin, Yao Wang
Quantum Physics
Sub-cycle metrology of bright quantum light
Shima Gholam-Mirzaei, Michael T. Weil, David N. Purschke et al. (+7 more)
In
quantum optics, quantization of the electromagnetic field typically occurs in a finite volume - a cavity - which results in discrete frequency modes where
photons are created, annihilated and exchanged between such modes. As a result,
evolution of
quantum optical states is periodic in the carrier wave of the field, measurement protocols return cycle-averaged information, and any sub-cycle
evolution that is foundational to many light-matter interactions, especially at high field strengths, remains hidden. Adapting an attosecond technique, here we capture the electric-field
evolution of a
quantum optical state, femtosecond bright squeezed
vacuum, with sub-cycle precision. We find that it consists of many
stochastic, time-localized bursts within each pump pulse whose phase randomly switches between two values. We exploit the random phase flips to generate
quantum random bit sequences with a generation rate that can reach petahertz frequencies. In addition, the sub-cycle resolution allows us to measure coherence functions of the waveforms between any two times, which we explain with a superposition of time-limited modes. These results bridge attosecond metrology and
quantum optics and pave the way to measuring
quantum light-matter interactions as they evolve on a few-femtosecond time scale, and integrate
quantum randomness in petahertz electronics.
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All authors Shima Gholam-Mirzaei, Michael T. Weil, David N. Purschke, Katarzyna M. Kowalczyk, André Staudte, David M. Villeneuve, Paul B. Corkum, Jeff S. Lundeen, T.J. Hammond, Giulio Vampa
Materials Science
Beyond Local Berry Geometry: A First-Principles Finite-Momentum Theory of Electronic Position
M. S. Si, Y. Q. Li and G. P. Zhang
Electronic position controls how a
crystal polarizes and responds to an external field. In
crystals, it is usually described through local changes of electronic states in momentum space. This Berry framework has reshaped modern solid-state physics, but strong fields drive electrons across a finite momentum range, where coherence between different momenta becomes part of the response. Here we establish a first-principles theory of electronic position at finite momentum that retains this missing information. We show that unequal-momentum coherence can cancel under spatial averaging and still produce polarization, forming a coherence dipole. We obtain the
matrix directly from material wave functions, without model bands or fitted transition elements. In Si, the finite-momentum geometry sets a material momentum scale. Comparing this scale with the momentum change driven by the field predicts when finite-momentum physics becomes active. Crossing the scale strongly reorganizes the fifth and higher harmonics, showing that momentum-space geometry, rather than emitted
photon energy alone, controls the nonlinear response. HHG is the first demonstration, but the theory applies whenever driven electrons explore a finite momentum range. It therefore extends
quantum geometry beyond the local Berry limit and provides a general basis for predicting field-driven phenomena in real materials.
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Lattice Field Theory
Operator subspace based method for the extraction of higher energy levels in Lattice field theoretic systems
Ken-Ichi Ishikawa and Siddharth Ramesh Pandey
Given the importance of spectral analysis of
lattice quantum field theory data, the advancement of techniques for the same remains critically important. Therefore, we propose an
algorithm that uses the first three time slices of the correlation function
matrix to construct the transfer
matrix and extract its energy
eigenvalues. Reduction of systematic error arising from truncating the operator basis is achieved by varying the operator subspace dimension and applying
eigenvalue-variance extrapolation. Since the correlation functions in early time slices typically exhibit small statistical errors and retain a strong signal of higher-excited states, we expect our proposed method to perform well in extracting higher-excited-state energies. In this paper, we conduct two
lattice Monte Carlo simulations for
quantum mechanical systems, harmonic and anharmonic oscillators, to evaluate the efficiency of our proposed method for higher-excited-state energies. We compare the energy levels obtained using the standard GEVP method and our proposed method. We find that our method consistently outperforms the standard GEVP method in extracting intermediate excited states for both systems. Because our method has access only to the first three time slices, it is not preferable to the GEVP method for extracting the ground-state energy in its current form.
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High Energy Astrophysical Phenomena
SN 2023gfo: A Peculiar Type IIP Supernova with High Luminosity and Normal Plateau Duration
Riko Namba, Masayuki Yamanaka, Keiichi Maeda et al. (+9 more)
We present near-infrared (NIR) and optical observations of the highly reddened Type IIP
supernova (SN) 2023gfo in the nearby
galaxy NGC 4995 ($d = 26.4 \pm 3.2$ Mpc), which reached a high peak luminosity of $M_V = -18.6$ mag. The SN was initially detected as a faint red event, with $B-V = 0.8$ mag at the beginning of the plateau phase. By comparison with template, we estimate a total extinction of $A_V = 2.1$ mag. After correcting for this extinction, we derive a peak quasi-bolometric luminosity of $(5.9 \pm 1.5)\times10^{42}$ erg s$^{-1}$, placing this event among the most luminous SNe IIP, while its plateau duration remains within the normal range. The early-phase optical spectrum exhibits a P-Cygni profile of H$\alpha$, with a broad absorption of $V$ = $13{,}800$ km s$^{-1}$, which is among the highest observed for SNe IIP at comparable epochs. The high luminosity and the normal plateau duration suggest that this event represents an outlier. Applying an analytical model, we infer an unusually large progenitor radius. This may indicate that the progenitor experienced an extreme energy injection from the core to the envelope shortly before explosion, resulting in a substantially inflated radius. While ejecta-circumstellar matter (CSM) interaction could in principle account for the high luminosity, we find no observational evidence supporting strong interaction.
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All authors Riko Namba, Masayuki Yamanaka, Keiichi Maeda, Avinash Singh, Kenta Taguchi, Takahiro Nagayama, Miho Kawabata, Koji S. Kawabata, Tatsuya Nakaoka, Devendra Sahu, Anjasha Gangopadhyay, G. C. Anupama
Astrophysics of Galaxies
The Koi Pond: A Strongly Lensed Protocluster Core hosting a Diverse Population of DSFGs
Nicholas Foo, Kevin C. Harrington, Brenda L. Frye et al. (+29 more)
We present James Webb Space
Telescope (JWST) and Atacama Large Millimeter Array (ALMA) observations of PJ0846+15, The Koi Pond, a strongly lensed protocluster core at
Cosmic Noon. This field offers a magnified view of 11 dusty
star-forming
galaxies (DSFGs) all at $z=2.67$ (within $\Delta V=800$ km s$^{-1}$) spanning a projected extent of $>300$ kpc lensed by a $z=0.77$ foreground cluster. NIRCam and ALMA Band 6 continuum measurements map the
stellar distribution and thermal
dust emission respectively at a spatial resolution of $\sim$0.15$^{\prime\prime}$. This analysis reveals a diverse population of DSFGs, with evidence of both interacting and non-interacting systems exhibiting a wide range of morphological features including spiral arms, bars, bulges, clumps/
stellar clusters,
tidal tails/debris and displaced molecular gas reservoirs. Comparing the rest-frame J- band continuum (F444W) vs (i-J) color (F277W$-$F444W), we find a wide range of values, suggesting a $>$1-dex spread in
stellar mass and a
dust attenuation reddening of $\Delta A_{\mathrm{V}} > 1$ mag. The DSFG members exhibit varying
dust sizes relative to the
stellar emission, ranging from compact dusty cores to
galaxy-wide emission. Resolved color maps of individual sources showing a spread as high as F277W$-$F444W$=2$ mag suggesting complex
stellar-to-
dust geometry. Although gas-rich mergers are identified in the core, the most red and
dust emitting members are disks exhibiting clumpy structure indicating secular growth can drive these starburst events. Such a remarkable range in properties within this sample suggest DSFGs in protocluster core environments follow diverse evolutionary pathways towards their transition into quiescent, elliptical cluster
galaxies.
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All authors Nicholas Foo, Kevin C. Harrington, Brenda L. Frye, Patrick S. Kamieneski, Melanie Kaasinen, Rafael Ortiz III, Alex Pigarelli, Gibson B. Bowling, Belén Alcalde Pampliega, Joe Bhangal, Timothy Carleton, Jianhang Chen, Seth H. Cohen, Camila de Sá-Freitas, Jose Diego, Román Fernández Aranda, Carlos Garcia Diaz, Nikhil Garuda, Eric F. Jiménez-Andrade, Daizhong Liu, James D. Lowenthal, Allison Man, Allison Noble, Massimo Pascale, Francesca Rizzo, Hannah R. Stacey, Amit Vishwas, Q. Daniel Wang, Rogier A. Windhorst, Ilsang Yoon, Min S. Yun, Dazhi Zhou
Quantum Physics
Resolving and resetting the charge environment of single T-centers in silicon p-i-n waveguides
Chaoshen Zhang, Hanbin Song, Lukasz Komza et al. (+6 more)
The silicon T-center is a telecom-band
spin-
photon interface in a manufacturable photonics platform. In nanophotonic devices, however, its optical linewidth is broadened by a fluctuating charge environment, limiting
photon indistinguishability for
quantum networking. Here, we address this challenge through characterization and suppression of the local charge-noise of single T-centers in lateral p-i-n waveguides, demonstrating an unheralded method of T-center optical linewidth narrowing. Above-band illumination resets the charge environment, neutralizing the local field and suppressing spectral
diffusion. Across 46 emitters this reset narrows the median linewidth 3.5-fold to 0.57(11) GHz, and an optimized emitter reaches 128(22) MHz, the narrowest unheralded linewidth reported for an integrated T-center. The narrowed transition supports coherent optical Rabi oscillations with a coherence time of 20(2) ns. Finally, we perform Stark-shift tuning using the p-i-n junction, and read out the local electric field and the charge-noise width at 15 mK. An analytical model of proximal surfaces, bulk, and junction field effects provides good agreement with our findings. Our multi-pronged characterization of the nanophotonic-integrated T-center charge environment enables future device optimization toward scalable
quantum interconnects.
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All authors Chaoshen Zhang, Hanbin Song, Lukasz Komza, Aaron M. Day, Enrique Garcia, Donald Witt, Mihir K. Bhaskar, Alp Sipahigil, Evelyn L. Hu
Instrumentation and Methods for Astrophysics
Exact spherical-wave forward model for radio reflection from stratified media and implications for the anomalous-polarity events observed by ANITA
Paramita Dasgupta
Radio detection of ultra-high energy particles relies on the propagation and reflection of broadband
radio pulses at boundaries between natural media. In the Sommerfeld–Weyl treatment, a spherical wave is decomposed into plane-wave components and their reflection from a single homogeneous interface is calculated exactly. We extend that treatment to an arbitrary number of laterally uniform spherical layers. Both the spherical-wave decomposition of the source and the spherical geometry of the boundary are retained, while the reflection and transmission coefficients of the plane-wave components are replaced by the exact characteristic-
matrix coefficients of the layered medium, evaluated at the local incidence angle on the spherical boundary. When the layer contrast is removed, the formalism recovers the single-boundary result to machine precision, and it reproduces the published spherical-surface reflectivity calculation to better than $1.1\%$ at ten HiCal-2 elevation angles, with a mean deviation of $0.6\%$. We reproduce the measured HiCal-1 reflected pulses from their measured direct partners, with a best signed correlation of $0.83$ and a median of $0.70$ across $106$ pairs, of which $101$ show the expected polarity inversion. Applied to the six reported ANITA anomalous-polarity event geometries, the buried-layer refractive index required for a sign change of the reflection coefficient ranges from $1.68$ at the steepest event to $3.8$–$5.4$ at the four near-horizon events. The full waveform calculation gives no non-inverted reflected pulse at any of these angles, showing that shallow, laterally uniform firn layering does not account for the polarity of the anomalous ANITA events. Because the formalism depends only on the complex refractive index of the medium, it applies more generally to isotropic, nonmagnetic stratified media, including ice, lunar regolith, and conducting layers.
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General Relativity and Quantum Cosmology
Perturbative solutions for the bumblebee field in a Schwarzschild background
Demetre Seturidze and Don Colladay
In this paper, we investigate the behavior of a vector field subject to a Lorentz-violating quartic potential on a fixed Schwarzschild background. We analyze the
equilibrium configuration of the field and its linear perturbations. We show that the
equilibrium solution and spherically symmetric perturbations are governed by a quadratic function whose properties determine their qualitative behavior. By requiring the background field to be real and finite, we derive bounds on the allowed parameters and identify critical cases in which the monopole perturbations become enhanced. We further derive asymptotic expressions for multipole perturbations near the event horizon and at spatial infinity.
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General Relativity and Quantum Cosmology
Constraint on environments with eccentric extreme-mass-ratio inspirals: Bayesian inference and Fisher-matrix for dark-matter spikes
Genliang Li and Tieguang Zi
Extreme-mass-ratio inspirals (EMRIs) provide sensitive probes of the astrophysical environments surrounding massive black holes. We investigate the inference of dark-matter (DM) spikes with eccentric EMRI gravitational waves within the analytic-kludge waveform framework, including DM-induced dynamical friction and
accretion in the secular orbital
evolution. We perform
Bayesian parameter estimation using Markov-chain Monte Carlo sampling, complemented by Fisher-
matrix analyses. We find that steeper DM spikes produce stronger accumulated waveform modifications and substantially improve the measurement of the spike slope $\alpha_{\rm DM}$. More importantly, the constraints exhibit a nonmonotonic dependence on orbital eccentricity. At moderate eccentricity, higher harmonics help break the degeneracy between $e_{\rm LSO}$ and $\alpha_{\rm DM}$, whereas this correlation can persist or the parameter recovery can deteriorate for highly eccentric systems. These results demonstrate that the harmonic structure of eccentric EMRIs can provide valuable information for probing DM distributions around massive black holes with future LISA observations.
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Cosmology and Nongalactic Astrophysics
Cosmology without the cosmological principle: A study of the large-scale structure effects in the background universe
Erick Pastén
Recent studies strongly suggest that the $\Lambda$CDM model may no longer serve as the definitive standard model in cosmology, given the increasing tensions between different cosmological observables. Some researchers have described this situation as a "crisis in cosmology." The $\Lambda$CDM model relies on two fundamental assumptions: the isotropy of the universe (supported by observational evidence) and the Copernican principle (a philosophical postulate). Together, these assumptions lead to the well-known Cosmological Principle, with the homogeneity of the universe emerging as a direct consequence. In this thesis, I review the cosmological consequences of relaxing some of these assumptions, exploring inhomogeneous and anisotropic universe models, as well as tilted cosmologies, which consider observers in motion relative to the Hubble flow. We examine methods to study these effects using existing cosmological data. First, we explore a variety of models that describe inhomogeneous and anisotropic universes, including different metric theories, perturbative analyses, averaging effects, tilted scenarios, and cosmographic approaches. We then apply this theoretical framework to analyze SNIA data and the local peculiar velocity field, aiming to constrain key parameters.
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