Cosmology and Nongalactic Astrophysics
Expanding the scope of dark siren cosmology: Inferring the population properties of gravitational wave-hosting galaxies
Rachel Gray, Daniel Williams and Alexander Papadopoulos
The field of gravitational wave "dark siren" cosmology is facing a number of challenges surrounding the way in which
galaxy catalogue data is incorporated into the analysis. The three biggest challenges are adequately compensating for
galaxy catalogue incompleteness, robust treatment of
galaxy redshift and source properties, and the as-yet unknown host
galaxy weighting model. We present an updated methodology for inferring cosmological parameters using dark sirens and incomplete
galaxy catalogues. By switching to a sampled
redshift prior, rather than one which is pre-computed on a grid, we can jointly infer parameters which describe the population of gravitational-wave hosting
galaxies, alongside the gravitational wave population and cosmological model. Using the cosmological inference software gwcosmo, we reproduce a subset of GWTC-5.0 cosmology results, then extend the analysis to jointly infer the host
galaxy weighting model - the first measurement of its kind to do so - leading to an updated measurement of the Hubble constant with $H_0 = {71.9}_{-7.5}^{+9.1}$ km s$^{-1}$ Mpc$^{-1}$ (median and 68% symmetric credible interval). This innovative new method opens the door to solving several of the biggest challenges currently facing the field of dark siren cosmology.
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Cosmology and Nongalactic Astrophysics
Late-Time Emergence of Dark Energy and Its Interaction with Dark Matter
Sibo Zhang, Weiqiang Yang, Supriya Pan et al. (+3 more)
We present an interacting scenario between dark energy (DE) and dark matter (DM), where DE has an emergent nature, that means, DE was absent in the early universe but it becomes effective only at late times. We consider two specific emergent DE models, one with no free parameters and the other featuring two parameters describing the speed and epoch of the transition. We constrain both scenarios using the
cosmic microwave background (CMB) measurements from the Planck 2018 release,
baryon acoustic oscillations from DESI DR2, and three different compilations of Type Ia
supernovae (PantheonPlus, DES-Dovekie, and Union3). Our analysis indicates that current cosmological probes are not able to tightly constrain the speed of the transition. For both scenarios, the posterior distribution of the interaction parameter is shifted away from zero at more than 95% CL whenever the CMB data are combined with any of these additional probes, with the preferred direction corresponding to a transfer of energy from DE to DM. While CMB alone yields a high value of $H_0$, in agreement with local determinations, this effect is reduced when DESI is added and disappears once
supernova data are included. In contrast, the clustering parameter $S_8$ is consistently shifted toward lower values in the combined
datasets, and it is correlated with the preference for a negative interaction. However, according to the $\Delta \chi^2_{\rm min}$ and
Bayesian evidence, none of the interacting models is favored over $\Lambda$CDM or $w_0w_a$CDM, indicating that the interaction does not rescue these emergent DE models. Our results therefore highlight the limitations of these scenarios in addressing current cosmological tensions, while pointing to the crucial role of future data in further assessing their viability.
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All authors Sibo Zhang, Weiqiang Yang, Supriya Pan, Olga Mena, Eleonora Di Valentino, Subenoy Chakraborty
Optics
Sub-2-Cycle, Terawatt Pulses via Double-Stage Multi-Pass Cell Compression of an Yb Laser
Victor Koltalo, Jaismeen Kaur, Louis Daniault et al. (+8 more)
We report a terawatt-class, sub-2-cycle post-compressed Yb-based
laser system operating at kHz repetition rate. 18 mJ, 400 fs pulses delivered at 1 kHz by a commercial Yb:YAG
laser are spectrally broadened and temporally compressed in a double-stage multi-pass
cell setup featuring an argon-filled Herriott-type
cell followed by a helium-filled array-type
cell, achieving an overall compression factor of 65. The resulting compressed pulses are measured to have 6.2 fs duration (1.8 optical cycles at 1030 nm) and 12.5 mJ energy, corresponding to 1.4 TW effective peak power. To the best of our knowledge, this constitutes the highest peak power reported to date for a few-cycle, kHz-repetition-rate, post-compressed Yb
laser system. Focused intensity measurements yield a normalized vector potential of a0 = 3.0, confirming the applicability of this light source for
laser wakefield acceleration.
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All authors Victor Koltalo, Jaismeen Kaur, Louis Daniault, Antoine Cavagna, Mickael Allemand, Florent Pallas, Antoine Courjaud, Emilien Gontier, Cédric Sire, François Sylla, Rodrigo Lopez-Martens
Physics and Society · Cross-listed from stat.ME
A Strictly Proper Scoring-Rule Theory for Calibrating Stochastic Car-Following Models
Shirui Zhou, Shiteng Zheng, Junzhe Ding et al. (+2 more)
Problem definition: Fixed parameters and inputs in a
stochastic simulator induce a distribution over complete trajectories, not one trajectory. Calibration must assess this distribution, including variability and temporal dependence, against observations. Yet
stochastic car-following models are commonly calibrated with trajectory-error objectives inherited from deterministic modelling. Methodology/results: We establish a scoring-rule theory of
stochastic calibration. Strict propriety requires the data-generating distribution to uniquely minimise expected score. MRMean-I, the average run-wise error, drives separable
stochastic spread to zero; MRMean-II, the error of the ensemble-mean trajectory, cannot identify a parameter that changes only spread; and MRMin, the error of the closest simulated run, has a population target that changes with ensemble size. These results are confirmed for
stochastic Intelligent Driver Model extensions with additive acceleration noise and random desired headway. We recommend exact maximum likelihood when the correct transition density is available; otherwise, an unbiased simulation-based
estimator of a strictly proper score. The energy score meets this requirement and gives the best held-out distributional prediction among the evaluated simulation-based objectives, although both models retain too-narrow bands and miss persistent disturbances. Implications:Strict propriety separates a valid calibration target from parameter identifiability and model adequacy. The theory applies to vector-valued outputs from
stochastic transportation simulators; the car-following experiments illustrate its scope.
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All authors Shirui Zhou, Shiteng Zheng, Junzhe Ding, Rui Jiang, Junfang Tian
Plasma Physics
Impact of ion-beam stopping power on proton-boron fusion yield in the pitcher-catcher scheme driven by ultra-intense laser
J. Y. Hua, X. F. Li, J. X. Wang et al. (+3 more)
The effect of stopping power on
proton-boron fusion is investigated for a
proton beam propagating through boron
plasma. Due to the stopping power, the electron temperature of the boron target rises as the
proton beam deposits energy. Consequently, a feedback mechanism becomes significant when the trailing part of the beam propagates into the preheated
plasma. By coupling this phenomenon with the
proton-boron fusion process, fusion yields are systematically investigated by varying the central energy of the
proton beam, as well as the thickness and density of the boron target. It is found that, under the influence of stopping power, the optimal central energy for fusion deviates from the intrinsic 672 keV resonance and shifts to approximately 900 keV. Moreover, the present results are substantiated by particle-in-
cell simulations, which provides a valuable reference for subsequent high-yield hydrogen-boron fusion.
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All authors J. Y. Hua, X. F. Li, J. X. Wang, Y. X. Leng, Y. Tian, R. X. Li
History and Philosophy of Physics
From the Light Quantum to the Photon: The Evolution of a Physical Concept
Aaron Collavini, Valentina Bologna, Francesco Longo et al. (+2 more)
This work examines the physical and conceptual
evolution of the light
quantum from Planck's blackbody theory to the theoretical and experimental developments that led to the quantization of the electromagnetic field. The present study shows that the decisive transition occurred in Einstein's
quantum theory of radiation (1916-1917). Absorption, stimulated emission, and spontaneous emission were formulated as elementary probabilistic mechanisms whose statistical balance alone reproduces the blackbody spectrum. In particular, spontaneous emission requires the emission of a light
quantum, thereby implicitly proving its physical necessity before its theoretical status was clarified. At the same time, the already existing term
photon began to acquire a stable usage following Lewis's 1926 proposal and became increasingly associated with Einstein's light
quantum. By the mid-1920s, the central problem had shifted from whether light quanta were physically required to how radiation could be incorporated into the emerging
quantum-mechanical formalism. This transition marks a key stage, illustrating how initial debates about the existence of light quanta gave way to their integration into a comprehensive theoretical structure. The resulting asymmetry between the novel
quantum description of matter and the still-classical description of radiation, called into question by the phenomenon of spontaneous emission, identifies the physical problem that led to the quantization of the electromagnetic field.
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All authors Aaron Collavini, Valentina Bologna, Francesco Longo, Stefano Ansoldi, Fulvio Parmigiani
Chemical Physics
Operando imaging of intercalation memory in MXenes
Franz Groebmeyer, Mohsen Beladi, Christoph G. Gruber et al. (+6 more)
Ion intercalation enables reversible control of charge, structure and function in layered solids. Yet layered materials contain nanosheets with different thicknesses and stacking, whose intercalation pathways are averaged out in ensemble measurements. This becomes critical under Angstrom-scale confinement, where ion transport couples to solvent reorganization and host deformation, leaving the origins of kinetics, reversibility and activation unresolved. Here we combine operando interferometric scattering and interference reflection microscopy to resolve
proton-driven dynamics in individual single- and multilayer Ti3C2Tx MXene flakes and show that even a few stacked layers introduce a significant kinetic barrier. Cycling then separates nanosheets into three persistent behaviors: reversible monolayers, restacked multilayers with incomplete recovery and delayed deintercalation, and coherently stacked multilayers that self-stabilize through reversible folding. Operando synchrotron X-ray diffraction shows this
memory at electrode scale, where the interlayer structure converges towards a reproducible state. Our findings reveal cycling-induced structural
memory that governs subsequent intercalation in layered MXenes.
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All authors Franz Groebmeyer, Mohsen Beladi, Christoph G. Gruber, Ruocun Wang, Pol Salles, Nhu Quynh Nguyen, Jakub Drnec, Yury Gogotsi, Emiliano Cortes
Earth and Planetary Astrophysics
Updated in-flight calibration of the Hayabusa2/NIRS3 spectrometer: new global near-infrared photometric properties of asteroid (162173) Ryugu
Antonin Wargnier, Eri Tatsumi, Koki Yumoto et al. (+10 more)
The Near InfraRed Spectrometer (NIRS3) onboard Hayabusa2 observed asteroid (162173) Ryugu, searching especially for signatures of water-bearing minerals. However, during the mission, absolute reflectance measured by the Telescopic Optical
Navigation Camera (ONC-T) and NIRS3 showed a systematic offset. Additionally, touchdown operations have modified the instrumental response, which has made post-second-touchdown data less reliable. Correction of these issues is crucial to interpret the subtle spectroscopic differences across the surface, better understand the origin and
evolution of carbonaceous asteroids, and support the Hayabusa2$\sharp$ mission's future observations of the asteroids (98943) Torifune and 1998 KY26. We used Ryugu observations at different mission phases for relative calibrations and lunar observations for the absolute calibration. Moon spectra acquired during the first Earth swing-by were compared to simulated ones from photometric models based on lunar orbiter and ground-based data. We then applied the updated calibration to the full Hayabusa2 proximity phase
dataset, enabling disk-resolved global and regional photometric analyses. We showed that the data obtained following the first and second touchdowns required downscaled corrections of $5.4 \pm 1.8 $% and $10.3 \pm 0.4 $% at 2 $\mu m$, respectively, while the absolute calibration revealed that NIRS3 reflectance was underestimated by about 8% compared with the original calibration. Our new photometric parameters are consistent with previous studies and indicate a weak east-west dichotomy in phase ratio and phase reddening, pointing to higher surface roughness and higher abundance of fine-grained regolith in Ryugu eastern hemisphere.
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All authors Antonin Wargnier, Eri Tatsumi, Koki Yumoto, Mayumi Ichikawa, Shin-ya Murakami, Yuichiro Nagai, Kazuhiro Honda, Yasuhiro Yokota, Toru Kouyama, Takahiro Iwata, Moe Matsuoka, Satoshi Tanaka, Kohei Kitazato
Mesoscale and Nanoscale Physics
Bias-field control of the Neel skyrmion nonlinearity in a confined nanostructure
A.V. Valkov, A.A. Matveev, O.Yu. Arkhipova et al. (+3 more)
We study the nonlinear dynamics of a cylindrical skyrmion-based oscillator within the framework of a generalized Thiele model. We demonstrate the influence of an bias
magnetic field applied perpendicular to the plane of the nanocylinder on the oscillation frequency and on the nonlinearity coefficient. It is shown that the field tunes the response frequency, while also producing a substantial change in the nonlinear frequency shift. We find that the nonlinearity coefficient reverses its sign as the field crosses a certain critical value. The variation of the nonlinearity coefficient with the field is clearly illustrated by the observed qualitative changes in nonlinear amplitude-frequency responses. Controlling the nonlinear properties of a skyrmion oscillator by changing the bias
magnetic field opens up prospects for creating tunable computational elements for neuromorphic applications.
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All authors A.V. Valkov, A.A. Matveev, O.Yu. Arkhipova, R.V. Shcherbakov, A.R. Safin, S.A. Nikitov
Astrophysics of Galaxies
Rubin J122659.4+090236: An Extremely Low Surface Brightness Galaxy Candidate Discovered in the Rubin LSST Early Data Preview 2
Dipanjan Mitra, Kanak Saha, Sugata Kaviraj et al. (+28 more)
We report the serendipitous discovery of an exceptionally low surface brightness
galaxy (LSBG) candidate, Rubin J122659.4+090236, in Rubin Observatory imaging of the interacting NGC 4410 system, identified in the
Cosmic Treasure Chest public release. 2D Sérsic modelling of the Rubin g, r, and i images reveals a nearly round system with a shallow profile (n ~ 0.4), an effective radius of R_e ~ 6”, and central surface brightnesses of $\mu_{0,g}=27.52\pm0.04$, $\mu_{0,r}=27.62\pm0.07$, and $\mu_{0,i}=27.04\pm0.08$ mag arcsec$^{-2}$. EAZY photo-z fitting favours an intermediate-z solution at z~0.3, while a low-
redshift solution at z~0.028, consistent with the NGC 4410 system, is also permitted by a restricted EAZY fit over 0<z<0.1 without imposing a
redshift prior. These alternatives imply substantially different physical interpretations, ranging from a diffuse
dwarf-like system to an exceptionally extended background LSBG. This discovery demonstrates Rubin's sensitivity to extremely diffuse
galaxies and highlights the potential of the LSST survey to uncover large samples of such elusive systems across wide areas, enabling systematic studies of the LSBG population and its role in
galaxy evolution.
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All authors Dipanjan Mitra, Kanak Saha, Sugata Kaviraj, Alister W. Graham, Sandro Tacchella, Ricardo Demarco, Dieu D. Nguyen, Elham Saremi, hernandez toledo, hector., Jose Benavides, Natanael M. Cardoso, Samuel Boissier, Dan S. Taranu, Bililign Dullo, Patricia B. Tissera, Matias Blana, Hao Fu, Priyanka Chakraborty, Kevin A. Pimbblet, Tayyaba Zafar, Anirban Dutta, Aidan P Cotter, Darko Donevski, Katarzyna Malek, Rossella Ragusa, Agnieszka Pollo, Unnikrishnan Sureshkumar, Aritra Ghosh, Antonio Vanzanella, Hareesh Thuruthipilly
General Relativity and Quantum Cosmology
Static Spherically Symmetric Solutions in Modified Entropic Gravity
A. Rostami, M. Rostampour, A. Yarahmadi et al. (+1 more)
Within the entropic
gravity paradigm introduced by Verlinde, one assumes that the microscopic degrees of freedom residing on the
holographic screen obey the equipartition law of energy. Nevertheless, implications of statistical mechanics suggest that this energy sharing can acquire corrections that depend on temperature. Taking such modifications into account leads to altered gravitational field equations when derived from thermodynamic considerations. We solve the resulting modified Einstein equations in the case of a static, spherically symmetric spacetime and determine the general structure of the metric components. Our findings indicate that if the temperature correction function behaves as $f(T)\propto T^{2}$, the corresponding spacetime geometry reduces to the flat Minkowski metric. Therefore, to obtain small deviations from flatness, it is necessary to consider slight departures from this purely quadratic temperature dependence. Such deviations can be interpreted as encoding additional gravitational effects, potentially associated with matter contributions that are not entirely described by the
holographic screen. As a result of these effects, the effective gravitational potential acquires a logarithmic correction, which can give rise to deviations from Newtonian
gravity. This aspect is especially significant in the regime of very weak gravitational fields, where these corrections may affect particle motion and could carry implications for both astrophysical and cosmological contexts.
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All authors A. Rostami, M. Rostampour, A. Yarahmadi, K. Rezazadeh
High Energy Physics (Phenomenology)
Tracing Gluon Saturation through Hadronization at EIC
Weiyao Ke, Xu Liu, Yu Shi et al. (+2 more)
Gluon saturation provides a window into the nonlinear nature of the strong interaction in
nuclear matter. One direct consequence of saturation is the $\boldsymbol{k}_T$ broadening in the final state.We investigate how hadronization reshapes conventional signatures of
gluon saturation at EIC within a complete event-generator framework. To this end, we implement in eHIJING an initial-state-radiation
algorithm based on nonlinear small-$x$
evolution and complete the events with beam remnants, final-state radiation, and hadronization. In our simulations, the signal of parton-level
nuclear $\boldsymbol{k}_T$ broadening is strongly diluted in both the nucleon energy correlator and leading-dihadron azimuthal decorrelation after hadronization. Global hadronic
recoil, by contrast, remains sensitive to the underlying $\boldsymbol{k}_T$ broadening. We further demonstrate that
Bayesian unfolding of the global hadronic
recoil provides access to the underlying hard-scattering $\boldsymbol{k}_T$ distribution. These results establish the global hadronic
recoil as a promising saturation observable at the EIC.
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All authors Weiyao Ke, Xu Liu, Yu Shi, Xin-Nian Wang, Jian Zhou
Statistical Mechanics
Universal Thermodynamic Law Governing Stochastic Pendulum Clocks
Yuki Izumida
Clocks' performance, especially their precision, is fundamentally limited by thermodynamic laws as they are physical devices. Yet, it is known that the established thermodynamic uncertainty relation (TUR), which imposes an upper bound on the uncertainty product of the precision of oscillations and
entropy production, is violated for underdamped systems such as
stochastic pendulum clocks. Here, we show that for a general class of
stochastic pendulum clocks described as a weakly nonlinear oscillator the uncertainty product of the phase of a pendulum clock and
entropy production takes a universal and simple form that depends solely on the degree of nonlinearity. Its validity and limitations are examined using several representative models of pendulum clocks. Our framework reveals a universal thermodynamic principle governing
stochastic pendulum clocks beyond the conventional TUR and provides a foundation for designing optimal pendulum clocks that operate efficiently in
stochastic environments.
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Materials Science
Nuclear quantum effects in the thermal conductivity of solid hydrogen
Hengtai Zheng, Zezhu Zeng and David E. Manolopoulos
We use a combination of path integral and
lattice dynamics methods to calculate the thermal conductivity of solid parahydrogen. Path integral molecular dynamics is first used to calculate a centroid potential of mean force at each temperature, on which a harmonic
phonon basis is constructed using the finite displacement method. We then calculate anharmonic force constants on the centroid potential and solve the linearised
phonon Boltzmann transport equation for the thermal conductivity. The resulting renormalised
phonon dispersion curves, heat capacity, and thermal conductivity are all in remarkably good agreement with experimental measurements. We find that the heat transport is dominated by collective relaxon modes at low temperatures and cannot be captured by making the
phonon relaxation time approximation. Indeed, quantitative agreement with the experimental thermal conductivity is only achieved when the
nuclear quantum effects in the centroid potential of mean force,
phonon boundary scattering, and hydrodynamic transport are all explicitly considered. This is also likely to be the case for other
quantum crystals.
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Mesoscale and Nanoscale Physics
Nonreciprocal plasmonic response of drift-biased two-dimensional metals
Gonzalo Álvarez-Pérez and Joel D. Cox
We develop a nonlocal electrodynamic framework for drift-biased two-dimensional electron gases (2DEGs) with Dirac (linear) and
parabolic (quadratic) dispersions, deriving closed-form drift-dependent conductivity tensors from the Boltzmann transport equation. We obtain the plasmon dispersion and near-field emission of a point dipole, revealing nonreciprocal propagation in both systems. At equal drift parameter, the
parabolic 2DEG exhibits stronger nonreciprocity than the Dirac system, although we find that a larger drift parameter does not by itself produce stronger nonreciprocity: the response is set by the interplay of drift and plasmon nonlocality. As such, the combination of strong nonlocality and experimentally accessible drift velocities of
semiconductor 2DEGs identifies
parabolic systems as a promising platform for tunable, nonreciprocal plasmonics.
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Mesoscale and Nanoscale Physics
Cascade spin dynamics of excitons localized in indirect-band-gap (In,Al)As/AlAs quantum dots with type-I band alignment
S. V. Nekrasov, I. V. Kalitukha, A. A. Golovatenko et al. (+5 more)
We investigate the
spin dynamics of
excitons localized in type I (In,Al)As/AlAs
quantum dots with an indirect in momentum space band structure. Polarized selective photoluminescence spectroscopy, i.e. fluorescence line narrowing, under
magnetic fields up to 5 T applied in the Faraday geometry is employed. The experiment reveals a cascade
spin evolution process of
excitons in the indirect band-gap
quantum dots: an initial short term
spin dynamics associated with excited direct
exciton states possessing a large oscillator strength is followed by electron relaxation into the X valley of the Brillouin zone and subsequent long term
spin dynamics of indirect
excitons. The two step mechanism manifests itself in the distinct features of the
magnetic field dependences of photoluminescence: two component recovery of optical orientation, two component linear to circular polarization conversion and the presence of the linear polarization plane rotation. At the same time, suppression of the optical
alignment shows one-component behavior governed by the
spin dynamics of the indirect
exciton states. Within the pseudospin formalism, we derive analytical expressions that quantitatively describe the observed dependences and yield estimates for the anisotropic exchange splitting: 210 {\mu}eV for direct
excitons and 1.3 {\mu}eV for indirect
excitons. Further analysis using the density
matrix formalism agrees well with the pseudospin model calculations and shows that the finite optical orientation at zero
magnetic field is due to comparable magnitudes of the anisotropic splitting of the indirect
exciton states and the splitting of the X-valley electron states caused by the hyperfine interaction with
nuclei.
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All authors S. V. Nekrasov, I. V. Kalitukha, A. A. Golovatenko, Ya. A. Kuznetsova, N. O. Mikhailenko, M. D. Ragoza, T. S. Shamirzaev, Yu. G. Kusrayev
Applied Physics
Noise-Resilient Detection of Neuronal Spikes by a Hopf-Bifurcation Device
Jitendra Kumar, Roberto Fenollosa, Gonzalo Rivera-Sierra et al. (+4 more)
Detecting weak transient signals in noise is a persistent challenge in sensing, communication, and electrophysiology. Here, we demonstrate a physical weak-signal detector based on a
semiconductor negative differential resistance (NDR) device operated near a
Hopf bifurcation. A coherent input that persists over the response time of the dynamical system can drive a transition between quiescent and oscillatory states, whereas faster
stochastic fluctuations are largely suppressed. This nonlinear transformation converts a weak analog threshold crossing into all-or-none voltage spikes and therefore provides asynchronous signal detection without a reference clock. Using a modulated photovoltaic signal, we detect a weak frequency component of 100 Hz as a demonstration, at an input signal-to-noise amplitude ratio as low as 1/500, and reliably recover it in the output spectrum. We then apply the same principle to neuronal multisite extracellular recordings. After standard band-pass filtering, the raw microelectrode signal is transformed by the NDR dynamics, enhancing the distinction between neuronal spikes and background fluctuations. The resulting detected spike times agree closely with those obtained using a traditional spike-detection pipeline. These results establish bifurcation-engineered NDR dynamics as a compact hardware approach to noise-resilient signal discrimination and event-based analog-to-digital conversion that will be useful for neuroprosthetic devices.
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All authors Jitendra Kumar, Roberto Fenollosa, Gonzalo Rivera-Sierra, So-Yeon Kim, Adam Armada-Moreira, Juan Bisquert, Michele Giugliano
Earth and Planetary Astrophysics
Mapping the WISPIT2 Planet-Hosting Cavity at Sub-Hill-Radius scales
Myriam Benisty, Stefano Facchini, Richard Teague et al. (+6 more)
We present new deep, very high angular resolution observations of the sub-mm continuum (19x13 mas) and 12CO (67x52 mas) emission from the disk surrounding the
planet host WISPIT2. Our analysis reveals a clear gas gap carved by WISPIT 2b and an empty cavity within the orbit of WISPIT 2c. We also find a gaseous and optically thin dusty ring located between the orbits of the two
planets. Channel maps show a pronounced change in the emission surface height of the disk, which transitions from flat within the cavity to strongly flared beyond the orbit of
planet b, producing clear breaks in the velocity channels. A pronounced thunderbolt-shaped feature, identified as a kinematic planetary signature (KPS), is detected at the location of WISPIT 2b, in agreement with predictions from
planet-disk interaction simulations. This constitutes the first system with a confirmed kinematic signature associated with a directly imaged
planet. By mirroring opposite velocity-channel maps about the systemic velocity, we further investigate the KPS and identify spatially resolved excess emission in the vicinity of WISPIT 2b. We find that this emission is resolved across the full Hill sphere of the
planet, significantly exceeding the expected extent of a circumplanetary disk. We therefore suggest that the observed emission arises from a combination of processes, including prominent
planet-driven spiral wakes, localized heating induced by the
planet and a circumplanetary disk. Although higher spectral resolution is required to disentangle these contributions, our observations demonstrate the potential to directly characterize the birth environment of forming massive
planets at scales down to sub-Hill radius.
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All authors Myriam Benisty, Stefano Facchini, Richard Teague, Francesco Zagaria, Pietro Curone, Viviana Pezzotta, Jaehan Bae, Gabriele Cugno, Daniel J. Price
Earth and Planetary Astrophysics
Ravit Helled, Sho Shibata, Shubham Kanodia et al. (+1 more)
Giant planets orbiting low-mass
stars represent a unique population of
giant planets that can be studied to constrain
planet formation theory. Surveys of transiting
giant exoplanets around M-
dwarfs (GEMS) allow for measurement of their masses and radii, which in turn can be used to estimate their bulk densities. Coupling these observations to interior structure and
evolution models can yield the bulk
metallicity of these
planets, however there are degeneracies to this that are improved by measurements of atmospheric
metallicity. Estimates of bulk
metallicity can be crucial to our understanding of
planet formation timescales and mass budgets, particularly in these extreme (
planet-to-
star) mass ratio systems. Here we show that GEMS are expected to have a low bulk
metallicity as a natural result of the
planet formation process, and the low efficiency of planetesimal capture post-formation. To test this empirically, we need a larger sample of GEMS with atmospheric measurements, which can reduce some of the degeneracies with the interior modelling of
planets. Measuring the atmospheric composition of GEMS with JWST and Ariel will be crucial for better understanding this unique planetary type, which sits at the tail of standard
planet formation conditions.
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All authors Ravit Helled, Sho Shibata, Shubham Kanodia, Billy Edwards
Plasma Physics
Revisiting kinetic electrostatic electron non-linear (KEEN) waves in the presence of dynamical ions
Rostislav-Paul Wilhelm, Philipp Krah, Kai Schneider et al. (+2 more)
We revisit the kinetic electrostatic electron nonlinear (KEEN) waves studied by Afeyan et. al in 2014 using a hybrid flow-mapping strategy that combines the characteristic mapping method (CMM) with numerical flow iteration (NuFi). The study extends the classical setup to dynamical ions, comparing their impact on the long-time KEEN dynamics with the static-ion case. To this end, we extend the CMM-NuFI framework with a multi-map strategy, assigning one map to the ion and one to the electron characteristic flow. The resulting problem exhibits a wide separation of spatial and temporal scales, driven by the fine structures generated by the ponderomotive force and by the large ion-to-electron mass ratio, which renders it computationally prohibitive for conventional grid-based methods. Our multi-map CMM-NuFI method efficiently resolves these disparate scales, enabling long-time simulations of KEEN dynamics with fully dynamical ions.
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All authors Rostislav-Paul Wilhelm, Philipp Krah, Kai Schneider, Fabio Bacchini, Virginie Grandgirard
High Energy Physics (Phenomenology)
Global Fixed Point Potentials in the Abelian Higgs Model with $N$ flavors
Gergely Fejős and Shunsuke Yabunaka
Existence of charged fixed points in the Abelian
Higgs model with $N$
flavors in $d$ dimensions is studied using the functional renormalization group. We numerically solve the coupled fixed point equations for the scale dependent charge and the non-perturbative effective potential for the scalar field. We show that the $\epsilon=4-d$ expansion, famously successful in theories with $O(N)$
symmetry, fails to produce reliable results when taking the $\epsilon \rightarrow 1$ limit. By determining global fixed point potentials, it is shown that the critical
flavor number at which charged fixed points appear, modifies significantly compared to the perturbative treatment. In $d=3$, signs of a richer fixed point structure with presumably multicritical fixed points are also found. Discussions include subtleties of the gauge fixing and the corresponding modified Ward-Takahashi identities, including the possibility of a nonzero dimensionless
photon mass at the infrared fixed point.
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Geophysics
Bayesian inversion of multilayer $\mathrm{CO}_2$ migration from seismic plume observations using a graph-based finite-rate invasion-percolation model
Elling Svee, Jo Eidsvik, Kasper Hunnestad et al. (+1 more)
Vertical migration of $\mathrm{CO}_2$ in layered sandstone reservoirs is controlled by thin shale barriers whose properties are often poorly known. We develop a
Bayesian framework that uses time-lapse seismic plume observations to estimate effective parameters governing lateral and vertical $\mathrm{CO}_2$ migration. The forward model is a fast graph-based invasion-percolation model that extends conventional IP by representing both capillary-controlled filling of structural traps beneath shale barriers and finite-rate transfer through them. Parameters are inferred with approximate
Bayesian computation and sequential Monte Carlo sampling, and the posterior samples are propagated into forecasts. Applied to real data from Sleipner, posterior simulations reproduce the broad distribution of $\mathrm{CO}_2$ across nine sand units and its redistribution between 2010 and 2023. In contrast, the quasi-static model fails to reproduce this temporal
evolution. Complementary synthetic experiments assess parameter recovery,
forecasting, monitoring duration, and model misspecification. These experiments show that the information gained from monitoring depends on the migration events captured, with breakthrough and post-breach redistribution providing particularly strong constraints. This combination of fast simulation, probabilistic updating, and interpretable effective parameters makes the framework well suited to repeated forecast revision during active injection, especially when full-physics inference is too computationally demanding.
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All authors Elling Svee, Jo Eidsvik, Kasper Hunnestad, Philip Ringrose
Mathematical Physics · Cross-listed from math.DG
Weak Lie 3-groups, 2-gerbes over torus fibrations of type F1, and T-Duality
Roberto Tellez-Dominguez
We construct a weak Lie 3-group $T_2 \mathbb B^{F_1}_n$ from the 2-category of gerbes over $\mathbb R^n / \mathbb Z^n$ and the $\mathbb R^n/ \mathbb Z^n$-action on it by pullback along translations. We also construct a homotopy equivalence between $T_2 \mathbb B^{F_1}_n$ and a different Lie 3-group $T_2 \mathbb D^{F_1}_n$, which admits a dimensional reduction to the homotopy equivalence of Lie 2-groups introduced by Nikolaus and Waldorf to model half-
geometric T-duality. This is a first step towards establishing a higher form of T-duality for 2-gerbes over
torus fibrations, relevant to supergravity and M-theory.
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Earth and Planetary Astrophysics
Multi-Wavelength Post-Perihelion Polarimetry of Interstellar Comet 3I/ATLAS
Zuri Gray, Galin Borisov, Ludmilla Kolokolova et al. (+15 more)
We present new post-perihelion polarimetric observations of the third discovered interstellar object, 3I/ATLAS (C/2025 N1; hereafter 3I), obtained using FORS2 at the Very Large
Telescope, ALFOSC at the Nordic Optical
Telescope, and FoReRo2 at the 2 m Ritchey-Chrétien-Coudé
telescope. The observations span phase angles 1-30$^{\circ}$, providing the most extensive polarimetric phase angle coverage obtained for an interstellar object to date. The post-perihelion measurements reveal that the unusual polarimetric properties of 3I persist across perihelion and match recent independent post-perihelion observations, indicating no significant
evolution in the polarimetric properties. The increased phase angle coverage allowed us to further constrain the minimum polarisation to $-2.9\%$ at phase angle $5.5^{\circ}$. Multi-band BVRI observations reveal a wavelength dependence of polarisation, with the negative polarisation branch becoming deeper and shifted toward smaller phase angles at longer wavelengths. The polarimetric colour is predominantly red and increases with phase angle, consistent with behaviour observed in other comets. Imaging and polarimetric maps show a substantially more extended coma after perihelion, while the polarisation distribution itself remains smooth and spatially homogeneous. Numerical modelling suggests that the unusually deep polarisation phase curve originates from moderately porous
dust aggregates consisting of weakly absorbing sub-micron monomers, resulting in much brighter
dust than that in typical
solar system comets.
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All authors Zuri Gray, Galin Borisov, Ludmilla Kolokolova, Johannes Markkanen, Yuna G. Kwon, Stefano Bagnulo, Alberto Cellino, Rosemary C. Dorsey, Grigori Fedorets, Mikael Granvik, Eric MacLennan, Antti Penttilä, Karri Muinonen, Olga Muñoz, Philippe Bendjoya, Maxime Devogèle, Simone Ieva, Francisco J. García-Izquierdo
Soft Condensed Matter
Liquid-liquid phase separation precedes crystallization in supercooled water-glycerol solutions
Iason Andronis, Sharon Berkowicz, Mariia Filianina et al. (+10 more)
Understanding the structural
evolution of supercooled water-glycerol solutions is important for cryopreservation, yet distinguishing
liquid-state transformations from ice crystallization remains challenging. Here, we investigate a deeply supercooled water-glycerol solution by X-ray
photon correlation spectroscopy (XPCS) in ultra-small-angle X-ray scattering (USAXS) geometry, combined with wide-angle X-ray scattering (WAXS). This combination simultaneously captures the structural and dynamical
evolution of the supercooled
liquid upon quenching to cryogenic temperatures (172 K). We observe discontinuous changes in the
liquid structure on molecular length scales and formation of microscale domains. The dynamics slow down during this stage and exhibit hyper-diffusive, ballistic-like relaxation. This transformation precedes ice crystallization, which we identify from the emergence of ice Bragg peaks in WAXS, allowing the two processes to be temporally separated. Phase-field (Cahn-Hilliard) simulations qualitatively reproduce the experimental observations and show that a spinodal-decomposition scenario is consistent with the measured scattering
evolution. These findings are consistent with a
liquid-
liquid phase separation scenario preceding ice crystallization and provide a route to disentangle the two processes in supercooled aqueous systems.
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All authors Iason Andronis, Sharon Berkowicz, Mariia Filianina, Maddalena Bin, Robin Tyburski, Robert Bauer, Yuriy Chushkin, Federico Zontone, Michael Sprung, Wojciech Roseker, Fabian Westermeier, Felix Lehmkühler, Fivos Perakis
Nuclear Theory
Thermal boundaries for relativistic fluids without a conserved charge
Lorenzo Gavassino, Soeren Schlichting and Gabriel S. Denicol
We study an ultrarelativistic fluid with no conserved particle number in a planar slab geometry bounded by two parallel, thermally conducting plates held at fixed (possibly different) temperatures. The fluid-wall interaction is described within kinetic theory by modeling the fluid as self-interacting radiation: a gas of
bosons emitted and absorbed by the walls according to black-body laws, while mutual collisions enforce local equilibration. From this microscopic setup we derive effective boundary conditions for the hydrodynamic fields, finding that the walls behave as modified absorbing boundaries (and not as thermostats). In particular, the fluid temperature at the boundary does not generally coincide with the wall temperature. We prove that the resulting initial-boundary-value problem is well posed. When the plates are held at different temperatures, the system develops a uniform steady flow from the hotter to the colder wall, with energy density equal to the arithmetic mean of the corresponding black-body energy densities in the limit of a small temperature difference.
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Optics
Relaxing Coherence Requirements on Laser Sources for Nanoscopy through Optical Fiber Technique
Kaifa Xin, Mengdie Hou, Ao Yang et al. (+8 more)
High numerical-aperture (NA) focusing of cylindrical vector beams (CVBs) typically requires costly, high-quality
lasers to supply a stable vector pupil field. Here, we introduce fiber-conditioned vectorial nanofocusing, in which an optical-fiber-based mode-selective coupler projects a strongly distorted beam of a diode that costs two orders of magnitude less than the reference
laser into radially or azimuthally polarized CVBs. A three-tolerance analysis clarifies its operating principle by establishing separate requirements for spatial state, temporal coherence and residual wavefront error. The resulting fields reproduce expected high-NA focal signatures and generate orientation-sensitive single-molecule excitation patterns consistent with reference-
laser measurements, lowering the barrier to structured-light experiments.
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All authors Kaifa Xin, Mengdie Hou, Ao Yang, Márton Gelléri, Hyun-Keun Lee, Antonio Virgilio Failla, Jiafeng Lu, Xianglong Zeng, Mischa Bonn, Jesper Lægsgaard, Xiaomin Liu
Chemical Physics
Derivation of the Sample-Size Scaling of TWO-NN Intrinsic-Dimension Estimates from Molecular Dynamics Trajectories
Riccardo Capelli
The intrinsic dimension of a
dataset is the number of independent directions needed to describe the space occupied by its data. Nearest-neighbor
estimators infer it from how the probability of finding a neighbor grows around each sampled point. Because the neighbor distances $r$ decrease as the sample grows, the estimated dimension can depend strongly on the number $N$ of available points, which in molecular dynamics is set by trajectory length and saving frequency. We derive the large-sample behavior of the TWO-NN
estimator for data drawn from a smooth $d$-dimensional space. The typical nearest-neighbor distance scales as $N^{-1/d}$, and smooth deviations from local uniformity produce corrections in powers of $N^{-2/d}$. Isotropic noise adds a correction proportional to $N^{+2/d}$; for a five-dimensional hyperplane in 100 noisy features, the extended expansion recovers the dimension within a few percent when noise is moderate. We test the scaling on ten independent 100 $\mu$s simulations of alanine dipeptide, represented by the pairwise distances among its ten heavy atoms, whose
geometric dimension is $3n_{\mathrm{at}}-6=24$. Over the investigated range, the estimate does not depend systematically on the temporal spacing between configurations, but increases from $7.6$ to $15.6$ as $N$ grows from $10^2$ to $2\times10^5$. Extrapolations that retain corrections through $r^2$, $r^4$, and $r^6$ give limiting dimensions of $24.81$, $23.47$, and $25.30$, respectively. All three estimates lie within 6% of the known dimension and bracket it, and their spread measures the uncertainty due to truncation. The derived scaling provides a practical route from finite-sample estimates to the
geometric dimension.
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Quantum Physics
Microkelvin resolution thermometry at the nanometre scale
Jack W. Hart, Soham Pal, Julien R. E. Roth et al. (+8 more)
Accurate temperature readings of transient events at the nanometer scale are challenging due to the low sensitivity of available sensors. Nanodiamonds containing nitrogen-vacancy (NV) centers have been used for nanoscale thermometry in complex environments, including inside living
cells. However, their performance has been limited by short coherence times and low
photon counts. In this work, we use isotopically-purified dual-NV nanodiamonds and a bespoke
quantum sensing chip to showcase an order of magnitude improvement in temperature measurement sensitivity compared with previous reports. We demonstrate robust temperature measurements with an error of 682 $\mu$K, experimental sensitivities below 50 mK/$\surd \text{Hz}$ and a shot-noise limited sensitivity of 9.6 mK/$\surd \text{Hz}$. To confirm the utility of these high-performance nanothermometers, we quantify the temperature change induced by the thermometry measurement itself, specifically the optical excitation
laser used to probe the NV
spin state. In addition, we observe directly at the nanometre scale the transient heating caused by the exothermic mixing of dimethyl sulfoxide in water. Sub-millikelvin resolution and millikelvin sensitivity thermometry unlock the possibility of monitoring minute thermal fluctuations in living systems and assessing catalyst performance at the nanometre scale.
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All authors Jack W. Hart, Soham Pal, Julien R. E. Roth, Katie Ninham, Abbie H. Aleksandrova, Xander Peetroons, Soumen Mandal, Oliver A. Williams, Gavin W. Morley, Mete Atature, Helena S. Knowles
Quantum Physics
Ancilla mediated steady-state engineering in open quantum systems
Soham Pal, Karen Hovhannisyan, Omri Porat et al. (+3 more)
Engineering the properties of a reservoir and its coupling to a
quantum system is a powerful tool for simulating
quantum thermodynamic processes and for generating otherwise inaccessible steady states. Yet tailoring both the reservoir and its coupling within a single platform remains challenging. Here we introduce a platform, in which an ancilla
qubit mediates the coupling of a target system to a reservoir, providing independent control over the interaction form, coupling strength, and effective reservoir temperature. Our implementation uses the electron
spin of a single nitrogen-vacancy center in diamond as the ancilla and a proximal $^{13}$C
nuclear spin as the target. By alternating engineered
unitary interactions with dissipative ancilla resets, we realize dynamics naturally described by a collision model, enabling straight-forward tracking of the work, heat, coherence, and
entropy generated at every collision. We experimentally demonstrate conventional thermalization and also realize anti-thermalization: the stabilization of the target system in a temperature opposite to that of its reservoir. Finally, harnessing this steady-state engineering, we utilize the
nuclear spin as a
quantum battery, achieving a steady-state ergotropy exceeding $70\%$ of the theoretical maximum.
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All authors Soham Pal, Karen Hovhannisyan, Omri Porat, Shovan Dutta, Janet Anders, Helena Knowles