High Energy Astrophysical Phenomena
Fast and Accurate Prediction of Neutron Star Structure with Deep Neural Networks
Kaushikk V N, Bhaskar Biswas and Stephan Rosswog
Solving the Tolman–Oppenheimer–Volkoff (TOV) equations, together with the
tidal perturbation equations, for large numbers of equation-of-state (EOS) samples is a major computational bottleneck in
Bayesian inference of the dense-matter EOS, and this will become increasingly limiting as next-generation observatories deliver far larger and more precise
datasets. We develop neural-network surrogates for the forward TOV mapping that predict
neutron star mass, radius, and
tidal deformability simultaneously and directly from the EOS parameters and central density. We train and compare two architectures: a conventional feedforward network and a residual network, the latter of which, to our knowledge, has not previously been explored for TOV surrogate modeling. Trained on a piecewise polytropic EOS parameter space, both networks reproduce the numerical solutions to high accuracy, with the coefficient of determination exceeding 0.999 for all three observables, while accelerating the evaluation of
stellar observables by roughly two orders of magnitude relative to direct numerical integration. We find that both architectures achieve excellent predictive accuracy at the network sizes considered here, with the residual network providing a modest improvement in accuracy over the feedforward network at the expense of slightly longer inference times. The overall performance differences remain small, indicating that a feedforward network already has sufficient capacity for this mapping while residual connections offer only incremental gains. Nevertheless, the residual architecture provides a robust baseline for future extensions to richer EOS parameterizations or higher-dimensional regression tasks. The resulting surrogates are well-suited to large-scale
Bayesian EOS inference and population studies, where repeated TOV evaluations would otherwise dominate the computational cost.
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Quantum Physics
Quantum Relaxometry Under Continuous Wave Excitation
Vladimir Verkhovlyuk, Chayma Bouchair, Oleg A. Anisimov et al. (+2 more)
Quantum relaxometry is one of the most successful applications of nitrogen-vacancy (NV) centers in diamond and, more broadly, solid-state
spin qubits, enabling ultrasensitive detection of
magnetic noise and paramagnetic species via measurements of the
spin-
lattice relaxation time $T_1$. Conventional pulsed protocols, however, probe $T_1$ efficiently only over a limited temporal range, which restricts the scope and throughput of the technique. Here we introduce a continuous-wave
quantum relaxometry protocol that operates in the frequency domain. By measuring the frequency response of the optically detected
magnetic resonance signal under low-frequency microwave amplitude modulation, we extract $T_1$ from the characteristic response time of the
spin system. The method enables efficient $T_1$ measurements spanning more than three orders of magnitude – directly demonstrated from 60 $\mu$s to 200 ms in our experiments – across a broad temperature range and under substantial ensemble inhomogeneity. We further show that this protocol enables quantitative relaxometry-based sensing in nanodiamonds, achieving a substantial speed-up over the pulsed methods and offering a practical approach to optimizing nanodiamond size for enhanced sensitivity.
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All authors Vladimir Verkhovlyuk, Chayma Bouchair, Oleg A. Anisimov, Anton Pershin, Adam Gali
Quantum Physics
Preparing approximate $N$-fold cat states with the phase space instruction set
Shuyan Zhou and Andrew Lucas
The phase space instruction set is a continuous-variable universal gate set involving single-
qubit rotations and
qubit-dependent displacements on a single
boson. Using these gates, we prove that a
circuit depth $\mathrm{\Omega}(\varphi(N))$ is necessary to approximately prepare a large $N$-fold rotationally invariant Schrödinger cat state; here $\varphi(N) \gtrsim N/\log\log N$ is the Euler totient function. A protocol saturating this asymptotic bound on
circuit depth is obtained for every
prime number $N$. This protocol has an asymptotically optimal runtime, when the gates are generated by
Hamiltonian evolution. Our results provide a sharp example where a universal gate set is surprisingly inefficient at preparing a simple family of states, and further imply that converting bosonic
circuits between different universal gate sets can be extremely inefficient.
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Quantum Physics
State Preparation Protocols for Entangled States via Open Quantum Walks
Pedro Linck and Nadja K. Bernardes
Open
quantum walks couple transitions on a graph to
quantum operations on an internal degree of freedom. We use this structure to formulate protocols for
quantum state preparation with nonunitary Kraus operators. We construct a ring-shaped OQW preparing an ensemble of Dicke states, with W states appearing as the single-excitation case, from which any individual Dicke state is recovered by postselecting the walker position; its convergence is governed by the spectral gap of the underlying Markov chain, for which we obtain a closed-form approximate expression. For GHZ states we present a two-node protocol using Kraus operators built from projective measurements that prepares them deterministically without requiring a measurement of the walker, and analyze how unsharp measurements affect the results and the convergence of the walk. We also show that the
quantum trajectories method embeds naturally in the OQW framework as a graph-structured collision model.
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High Energy Physics (Theory)
Updates on Calabi-Yau manifolds from pairs of non-compact Calabi-Yau manifolds
Nam-Hoon Lee
We discuss developments in the construction of Calabi–Yau
manifolds by smoothing normal crossing unions of quasi-Fano
manifolds, following the introduction of this method to the physics community in 2010. We describe constructions of Calabi–Yau threefolds with unbounded second Betti numbers and with very small Hodge numbers, as well as the first non-Kähler examples in dimensions greater than three. The role of Landau–Ginzburg models in mirror constructions is also explained.
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High Energy Astrophysical Phenomena
X-Ray Observation of Type II Supernova 2024ggi
Elisa J. Gao and Vikram V. Dwarkadas
We investigate the Chandra and XMM-Newton X-ray emission from the core-collapse SN 2024ggi. Spectral fitting is carried out using the vapec model. We find X-ray temperatures between 5-7 keV, lower than the value assumed by previous authors by about a factor of 4-6. However the unabsorbed flux is consistent with published values within the error bars. The X-ray luminosity
evolution is somewhat steeper than expected for a steady wind, although it could be consistent with a steady wind within the error bars.
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Medical Physics
Vendor-Agnostic Joint Relaxometry and Myelin Water Fraction Mapping with B1 and Motion Correction
Unay Dorken Gallastegi, Shohei Fujita, Yohan Jun et al. (+19 more)
Obtaining consistent quantitative maps of myelin content and relaxation times across different sites and vendors is essential for advancing our understanding of
brain development. Herein, we present a harmonized, vendor-agnostic
magnetic resonance acquisition method designed for joint T1, T2, and myelin water fraction mapping, along with a method for rapid B1+ and B1- field estimation. We used our dictionary-based fitting and multi-compartment modeling for joint mapping of T1, T2 and myelin water fraction. Self-
navigation-based retrospective motion correction was integrated with subspace reconstruction to track and correct rigid head motion during scanning, operating without the need for external hardware. Simulations, phantom and in vivo experiments confirmed the sensitivity and accuracy of the method, particularly for short T2 values corresponding to myelin, and demonstrated consistent performance across multiple scanner types. Coupled with the harmonized calibration scan, the proposed package offers a practical tool for multi-site, multi-vendor neuroimaging studies in both adult and pediatric populations.
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All authors Unay Dorken Gallastegi, Shohei Fujita, Yohan Jun, Antoine Delattre-Klauser, Gian Franco Piredda, Tom Hilbert, Cemre Ariyurek, Eugene Milshteyn, Shizhuo Li, Yuting Chen, Xingwang Yong, Kwok-Shing Chan, Qiang Liu, Seonghwan Yee, Yogesh Rathi, Maxim Zaitsev, Jon-Fredrik Nielsen, Onur Afacan, Camilo Jaimes, Patricia Ellen Grant, Borjan Gagoski, Berkin Bilgic
Quantum Physics
Tobias Rohe, Federico Harjes Ruiloba, Markus Baumann et al. (+4 more)
In the
Quantum Approximate Optimization
Algorithm (QAOA), the
entanglement topology, where
qubit pairs are connected by two-
qubit gates, is conventionally set equal to the edge set of the problem graph. This coupling ties
circuit design to explicit problem knowledge and may not yield the most trainable
circuit under limited optimization budgets. We investigate whether a reinforcement learning (RL)
agent can discover more effective
entanglement topologies for QAOA-based MaxCut optimization without direct access to the problem graph. A Masked Proximal Policy Optimization
agent sequentially places IsingZZ gates to construct a
circuit topology, while a variational inner loop optimizes the resulting QAOA parameters and returns the approximation ratio as a sparse terminal reward. The
agent's observation contains only the edges placed so far and the current approximation ratio; graph structure can only be inferred indirectly through the optimization reward. On Erdős–Rényi instances with up to $10$~
qubits, the
agent consistently converges to
topologies that are strict subsets of the problem graph, achieving overlap ratios approaching $1.0$, despite receiving no explicit information about the graph structure in its observations. These sparse, problem-aligned
topologies outperform the full graph
topology and several structural baselines when the optimization budget is limited ($50$~gradient steps), but are overtaken by denser
topologies given sufficient optimization budget. Our results reveal a trainability–expressibility trade-off governed by
topology density and suggest that the variational optimization landscape implicitly encodes structural information about the problem
Hamiltonian.
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All authors Tobias Rohe, Federico Harjes Ruiloba, Markus Baumann, Gerhard Stenzel, Leo Sünkel, Thomas Gabor, Claudia Linnhoff-Popien
Applied Physics
Determination of acoustic nonlinearity parameters using thermal modulation of ultrasonic waves
Hongbin Sun and Jinying Zhu
This study presents a test method and its theoretical framework to determine the acoustic nonlinearity parameters ($\alpha,\beta,\delta$) of material using thermal modulation of ultrasonic waves. Temperature change induced thermal strain excites the nonlinear response of the material and modulates the ultrasonic wave propagating in it. Experimental results showed a strong correlation between the relative wave velocity change and the temperature change. With a quadratic
polynomial model, the acoustic nonlinearity parameters were obtained from the
polynomial coefficients by curve fitting the experimental curves. Their effects on thermal-induced velocity change were discussed. The parameters $\alpha,\beta,\delta$ govern the hysteretic gap, average slope, and
curvature of the correlation curve, respectively. The proposed theory was validated on aluminum, steel, intact and damaged concrete samples. The obtained nonlinear parameters show reasonable agreements with values reported in the literature. Compared to other nonlinear acoustic methods using vibration or acoustic excitation, the thermal modulation method generates more uniform, slow changing, and larger strain field in the test sample. Employing thermal effect as the driving force for nonlinearity instead of an undesired influencing factor, this method can measure the absolute values of $\alpha,\beta,\delta$ with good accuracy using a simple ultrasonic test setup.
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Mesoscale and Nanoscale Physics
Optimally embedded tight binding for reproducing geometry dependent observables
Jonas J Telle and Gunnar F Lange
In tight-binding models, the position operator is reduced to intra-
cell orbital positions (
embeddings). While accurately reproducing band structures, such models often fail for geometry dependent responses depending on the position operator. To address this, we investigate the role of these
embeddings and introduce the general framework of optimally embedded tight binding. Treating the
embeddings as
geometric tuning parameters to be fixed against a reference response (obtained from ab-initio computation or experiment), we obtain tight-binding models of GaAs and CdS which quantitatively reproduce non-linear optical responses at no cost to band structure accuracy. The optimal
embeddings are determined efficiently using position derivatives obtained from decomposing tight-binding observables into a geometry independent and dependent part, and explicit derivatives are provided for key quantities such as the
quantum geometric tensor. The decomposition reveals where
geometric effects dominate, and we show in both toy models and in the Chern
insulator V2O3 how geometry can dramatically alter the local metric trace. Our results highlight that orbital
embeddings should be treated as a genuine model parameter which should be explicitly fixed against physical data to get accurate minimal models.
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Data Analysis and Statistics · Cross-listed from cs.LG
PhysAttNet: Enhancing Predictive Performance in Industrial and Astrophysical Time Series via Physics-Informed Attention
Amal Saadallah, Julia Tjus, Petra Wiederkeher et al. (+1 more)
Accurate and robust time series
forecasting is essential in many applications involving physical processes, such as manufacturing monitoring and astrophysical event detection. In these settings, predictive models must remain reliable under noise, variability, and measurement uncertainty while capturing temporally localized structures corresponding to physically meaningful events. Convolutional neural networks (CNNs) are widely used for such tasks due to their computational efficiency and strong representational capacity. However, their learned temporal representations often exhibit unstable or physically inconsistent
attention patterns, reducing robustness, generalization, and interpretability. This paper introduces PhysAttNet, a physics-informed
attention framework for time series
forecasting. PhysAttNet augments a lightweight CNN forecaster with an
attention head guided by domain-informed regularization reflecting the structural properties of physical signals. Specifically, three complementary constraints are imposed during training: an
alignment regularization that encourages
attention to follow smooth, peak-centered temporal structures derived from the input signal, a smoothness regularization that enforces continuous temporal
evolution, and a sparsity regularization that promotes selective focus on informative intervals. These differentiable regularization terms introduce physics-guided inductive bias without requiring annotated explanations or manual supervision. Experiments on two distinct applications, namely predicting cutting forces during milling and
forecasting flares in blazar time series, demonstrate that PhysAttNet improves
forecasting accuracy, generalization, and prediction performance on structurally important events.
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All authors Amal Saadallah, Julia Tjus, Petra Wiederkeher, Wolfgang Rhode
Astrophysics of Galaxies
The large-scale ordered magnetic field in the Galactic halo and the Local Bubble
Elena Orlando
All-sky synchrotron polarization observations are the primary probe of the
Galactic large-scale ordered
magnetic field, which includes both coherent and ordered random components. However,
magnetic-field strength estimates from synchrotron observations depend on the assumed
cosmic-ray electron model, which itself depends on the
magnetic-field configuration and strength throughout the
Galaxy. We aim to constrain the strength of the large-scale ordered
magnetic field in the
Galactic halo through a self-consistent treatment of
cosmic-ray electrons with the latest coherent
magnetic-field configuration inferred by Xu & Han from rotation measures corrected for local contamination. We compare the Planck 30 GHz synchrotron polarization maps with our large-scale synchrotron models that jointly treat
cosmic rays and
magnetic fields and are constrained by direct
cosmic-ray measurements and multifrequency data. Since the inferred field strength depends on the
halo size, we explore different
cosmic-ray propagation
halo sizes. We observe a significant large-scale synchrotron excess relative to model predictions, which requires an ordered toroidal
magnetic-field component in the
halo with a peak strength of 3.2-4.3 microG, depending on the assumed
halo size. We also find that the
cosmic-ray propagation model with a 4 kpc
halo size is preferred by the Planck synchrotron polarization maps. This result shows that the ordered
magnetic field is 4-6 times stronger than the coherent field inferred from rotation measures by Xu & Han, establishing the presence of an ordered random field in the
Galactic halo that is not traced by rotation measures. Attributing the synchrotron excess entirely to the Local Bubble would require non-standard Local Bubble properties, disfavoring this interpretation.
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General Relativity and Quantum Cosmology
The Ringdown and the Tide: Fingerprints of Dark Matter Halo Profiles
Arkadip Bhowmik, Avijit Chowdhury and Sayan Chakrabarti
Astrophysical black holes (BH) are not isolated, but embedded in matter supplied by their host
galaxies. We study how the shape of a surrounding dark matter (DM)
halo modifies the ringdown and
tidal response of an asymptotically flat, static, spherically symmetric BH. The
halo is modelled as an anisotropic Einstein cluster with vanishing radial pressure and a generalized $(\alpha,\beta,\gamma)$ density profile, supplemented by an inner cut-off near the BH and, where required, an outer
tidal truncation. We derive the axial gravitational perturbation equation and compute the quasinormal mode (QNM) spectrum using sixth-order Wentzel-Kramers-Brillouin (WKB) methods and time-domain evolutions. The
halo redshifts both the oscillation frequency and the damping rate, by an amount set not only by the
halo compactness but also by the profile parameters: the inner slope $\gamma$ dominates for centrally concentrated
halos, while $\alpha$ and $\beta$ give subleading but profile-dependent corrections. In the eikonal limit, the shift is governed by a single
redshift integral encoding the
halo mass distribution outside the light ring, explaining the close correspondence between the QNM frequencies, the light ring frequency, and the Lyapunov exponent. We also show that different combinations of compactness and profile shape can yield nearly degenerate ringdown spectra. Time-domain evolutions confirm the WKB frequencies and display the expected late-time Price law decay, with an intermediate tail controlled by the outer density falloff for slowly decaying profiles. Finally, we compute the static axial
tidal Love number and show that it probes the
halo with a radial weighting different from the ringdown sector. The combined ringdown and
tidal response therefore provides a possible way to distinguish environmental effects from genuine deviations of the
vacuum BH geometry.
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Quantum Physics
Storage, Scrambling, and Loss of Information in Quantum Reservoir Computing
Nathan Keenan and Roberta Zambrini
The performance of a
quantum reservoir computer in temporal processing tasks depends on how its driven
quantum substrate retains information about past inputs, distributes it across physical degrees of freedom, and loses it through environmental dissipation and measurement feedback. We formulate these processes using a classical-
quantum state obtained by restricting a reservoir process tensor to classical input encoding and single-time readout. Conditional subsystem Holevo quantities describe information about selected input histories and bound its accessibility to measurements on subsystems of the reservoir. In a six-
qubit all-to-all transverse-field Ising reservoir, we find that the total stored information changes relatively little across
Hamiltonian parameters, while its spatial distribution and temporal decay vary strongly. Effective diagnostics of these two behaviours identify different regions of high information-processing capacity for linear and higher-degree temporal tasks. Measurement-induced dephasing can improve noiseless task performance when it increases forgetting rates without strongly reducing information delocalisation. The framework separates storage from subsystem accessibility and provides a common description of information flow in driven
quantum learning systems.
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Instrumentation and Detectors
CMOS Image Sensors for CEvNS Detection at Nuclear Reactors
Santiago Ezequiel Perez, Dario Rodrigues and Miguel Sofo-Haro
In this work we present Complementary Metal-
Oxide-
Semiconductor (CMOS) Image Sensors (CIS) for reactor
neutrino experiments targeting coherent elastic
neutrino-
nucleus scattering (CEvNS). We have developed an active-shielding strategy for physical background reduction along with an analytical model describing the impact of intrinsic detector backgrounds from dark current and readout noise at a given frame rate (fps). Assuming a conservative background of 100 DRU, and a feasible CIS-based detector with $\sim$100g of sensitive silicon mass, 1$e^-$ of readout noise, and 200fps, it can detect CEvNS in less than 50 days at 16 meters from a 3.6 GW thermal reactor core. Improving the detector performance to 0.2$e^-$ readout noise and 1000fps substantially reduces the detection time to about 7 days. These results establish CIS technology as a promising platform for reactor monitoring and precision
neutrino measurements, with thick CMOS sensors featuring parallel and non-destructive readout emerging as particularly attractive candidates for next-generation CEvNS experiments.
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Statistical Mechanics
Classical fractons with cosmological fixed points
Akash Singh, Dileep P. Jatkar, S. L. Sondhi et al. (+1 more)
Classical fractons are
Hamiltonian systems that can develop attractors after projection onto configuration or shape variables, although the full phase space admits none. We study a scale-invariant, dipole-conserving two-parameter family of fracton
Hamiltonians $H_{\alpha,\beta}$. By separating coordinates into scale and shape, we obtain autonomous shape dynamics that admit fixed points which leave a purely scale
evolution of the form $R(t)\propto |t|^{\alpha/(\alpha-\beta)}$. The shape fixed points, which determine the distribution of the expanding particles, are central configurations of power-law Riesz potentials. The distinguished model $(\alpha,\beta)=(-2,1)$ is unique: its scale
evolution takes the Einstein-de Sitter form $R(t)\propto |t|^{2/3}$, its fixed-point equation is the equal-mass Newtonian central-configuration, its large-$N$ distribution is a homogeneous ball, and its homothetic trajectories admit a zero-energy Newtonian gravitational dual. The fixed points are locally stable, and simulations at moderate $N$ approach them from random initial data. Large $N$ simulations reveal a richer class of fixed-points: bound clusters of approximately fixed physical size retain internal motion, while their centers approach unequal-mass Newtonian central configurations and preserve large-scale homogeneity. A scale-separation
conjecture yields an effective unequal-mass fracton dynamics for the centers and a corresponding zero-energy Newtonian gravitational dual. Trajectories generically exhibit a bidirectional arrow of time: scale and shape complexity grow away from a Janus point, while Boltzmann
entropy grows logarithmically. Together, these features reproduce the salient structure of a flat matter-dominated cosmology. In the distinguished fracton model, all these cosmological analogues emerge as attractor properties, making it a toy model for cosmological dynamics without fine-tuning.
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All authors Akash Singh, Dileep P. Jatkar, S. L. Sondhi, Abhishodh Prakash
Astrophysics of Galaxies
Radial Stellar Age Gradients in 42 Local Volume Dwarf Galaxies
Roger E. Cohen, Kristen B. W. McQuinn, O. Grace Telford et al. (+4 more)
We present radial
stellar age gradients measured from
star formation histories (SFHs) fit to resolved color-magnitude diagrams (CMDs) of 42 Local Volume
dwarfs (6$\lesssim$Log M$_{\star}$/M$_{\odot}$$\lesssim$9), spatially divided into elliptical annuli. Ages in each annulus are quantified using $\tau_{90}$ and $\tau_{50}$, the lookback times to form 90% and 50% of the cumulative
stellar mass. We find that radial age gradients are uncorrelated with environment, but gradients in $\tau_{90}$ are significantly correlated ($p$-values$\lesssim$0.001) with lifetime
galaxy-wide "global" SFHs, in agreement with two independent cosmological zoom-in simulations. For radial gradients of $\tau_{50}$, simulation predictions differ. We demonstrate that given our large (N=42) and diverse observational sample, the strength of an observed correlation with global SFH is an actionable parameter to discriminate between different simulations with differing
stellar feedback prescriptions. Overall, our results support predictions that
dwarfs form inside-out like their more massive counterparts, with a combination of feedback-driven outward radial
stellar migration and increasing birth radii for young
stellar populations yielding present-day
stellar age gradients ranging from outside-in to flat. In addition, the lack of a correlation between $\tau_{50}$ gradients and global SFH argues against recent
star formation in radially outflowing gas. We also discuss the impact of differences between our observational sample and samples available in the latest simulations, highlighting areas for future investigation.
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All authors Roger E. Cohen, Kristen B. W. McQuinn, O. Grace Telford, Liese Van Zee, Laura Congreve Hunter, Andrew E. Dolphin, Suchindram Dasgupta
High Energy Physics (Phenomenology)
Quest for an Understanding of Pion and Kaon Structure
Zhen-Ni Xu, Daniele Binosi, Craig D. Roberts et al. (+1 more)
The emergence of massless (Nambu-Goldstone)
bosons in association with a dynamically global broken
symmetry is a long known and widespread phenomenon in physics. However, practically nothing is known about the expressions of Nambu–Goldstone
boson character on the internal structure of these bound states. Indeed, their structure is often ignored. In strong interactions, pions and kaons are the (would-be) Nambu-Goldstone
bosons and experiments underway or planned at existing or anticipated high-energy, high-luminosity facilities will gather data that it is hoped will enable maps to be drawn of their internal structure. Meanwhile, theory and phenomenology find themselves in something of a quagmire. Herein, we provide a snapshot of the current status, highlighting issues under debate and identifying areas that deserve greater
attention so that best use can be made of what is likely to be a huge volume of data delivered in the next decade or so.
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All authors Zhen-Ni Xu, Daniele Binosi, Craig D. Roberts, José Rodríguez-Quintero
Astrophysics of Galaxies
Scattering from Dusty Outflows in Hot Dust-Obscured Galaxies with Blue Excess Emission
R.J. Assef, M. Stalevski, F.E. Bauer et al. (+15 more)
(Context) Hot
Dust-Obscured
Galaxies (Hot DOGs) are a population of hyper-luminous
quasars heavily obscured by
dust and gas. While most have rest UV/optical SEDs dominated by their host
galaxy emission, a small fraction shows blue emission in excess of what is expected for
star-formation. Detailed multi-wavelength studies from X-rays to the far-IR of these Blue Excess Hot DOGs (BHDs) have concluded the most likely origin of this blue excess is scattered light from the central engine. This scenario was confirmed by previous studies for the BHDs W0116-0505 and W0204-0506 which found highly polarized UV emission, a key signature of scattered light. (Aims) In this article we investigate this scattered light scenario in three other BHDs and further constrain the properties of the scattering material in W0116-0505. (Methods) We analyze new VLT/FORS2 imaging polarimetry observations in the $R_{\rm Special}$-band of three BHDs and additional observations of W0116-0505 in the $v_{\rm High}$- and $I_{Bessel}$-bands. (Results) We find spatially integrated polarization fractions in all three BHDs observed in the $R_{\rm Special}$-band ranging from about 6% to 15%. This confirms that their blue excess emission is due to AGN scattered light. We also find that the polarization fraction has a significant dependence with rest-frame wavelength in W0116-0505 and that it cannot be explained by Thomson scattering or by an AGN shining onto a smooth ISM. We find that a dusty bi-conical
outflow acting as the scatterer can successfully explain the observations as long as the
dust is dominated by graphites. This may be due to the high temperatures of the outflowing gas and the higher sublimation temperature of graphites compared to silicates.
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All authors R.J. Assef, M. Stalevski, F.E. Bauer, A. Blain, T. Diaz-Santos, P.R.M. Eisenhardt, R. Fernandez-Aranda, H.D. Jun, M. Liao, E. Shablovinskaia, A. Sarath, M. Stepney, D. Stern, C.-W. Tsai, A. Vayner, D.J. Walton, D. Wylezalek, D. Zewdie
Astrophysics of Galaxies
First Light and Assembly of GalaxieS (FLAGS) I: The JWST/NIRCam Number Counts and IGL as Constraints on Galaxy Formation Models
Jack C. Turner, Stephen M. Wilkins and Aswin P. Vijayan
JWST observations have been used in conjunction with SED fitting to infer the physical properties of
galaxies throughout
cosmic time, revealing tensions with the predictions of theoretical models. However, the biases associated with this process are poorly understood, which limits its true constraining power. We introduce the First Light and Assembly of
GalaxieS (FLAGS) series, which will leverage forward modelling to confront models with more reliable direct observables. We describe the consistent processing of NIRCam imaging spanning $>1 \ \mathrm{deg}^{\, 2}$ across 30 independent fields, which can be used to measure the
galaxy number counts from $0.9-4.4 \ \mu\mathrm{m}$. The integrated
galaxy light (IGL) is constrained with a certainty of $\sim2.5\%$ at the longest wavelengths, producing novel constraints of $6.92^{\, +0.17}_{\, -0.17}$ and $3.46^{\, +0.09}_{\, -0.08} \ \mathrm{nW\,m^{-2}\,sr^{-1}}$ at $2.77$ and $4.10 \ \mathrm{\mu m}$ respectively. We compare these measurements with predictions from
galaxy evolution models and find that the IGL is an unreliable measure of model performance. Comparing against the number counts directly reveals SC-SAM as the best-performing model ($\chi^{2}_{\nu}=18.6$), with its superior performance relative to SAGE attributed to efficient SNe feedback in low-mass
halos. We investigate the impact of systematic photometry and forward modelling uncertainties, confirming that the number counts can be a reliable means of evaluating model predictions and performing simulation-based astrophysical parameter inference in the future.
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Cosmology and Nongalactic Astrophysics
Probability of gravitational-wave lensing by intermediate-mass black holes and globular clusters
Luka Vujeva, Jose María Ezquiaga, Rico K. L. Lo et al. (+1 more)
Strongly lensed gravitational waves (GWs) are powerful probes of substructure in the lens. Intermediate-mass black holes (IMBHs) are postulated to be efficient lenses that may distort the lensed waveforms of currently detectable
stellar-mass compact binaries, as hinted by GW231123. Assuming that IMBHs are located in globular clusters (GCs), we compute the rate at which they would affect strongly lensed repeated chirps produced by
galaxy-scale lenses, considering a compound lens system. Exploring different astrophysical model assumptions and
lensing criteria, we find that the relative rate is at most 1/1000 and decays to 1/10,000 for our fiducial optimistic scenario. At high magnifications, $\mu$ > 100, the relative rate approaches 1%, but these cases are intrinsically rare in absolute value. Our results imply that GW
lensing by IMBHs and GCs is unlikely, disfavoring such an interpretation for GW231123. In turn, they point towards lensed GWs being a clean probe of dark matter substructures and
primordial black holes.
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All authors Luka Vujeva, Jose María Ezquiaga, Rico K. L. Lo, Lorenz Zwick
Materials Science
Defect-Controlled Multiferroicity via Stacking Control in Nonmagnetic van der Waals Bilayers
Bumseop Kim, Sayed Ali Akbar Ghorashi and Andrew M. Rappe
We present a general paradigm that directly couples vacancy-localized magnetism to interfacial sliding ferroelectricity in nonmagnetic van der Waals (vdWs)
bilayers. Utilizing
bilayer hexagonal boron nitride (hBN) as a prototypical vdWs host system, we use first-principles calculations to show that a single vacancy acts as a local registry sensor, lifting the degeneracy between polar sliding partners via a defect-centered polarization offset. For interlayer vacancy pairs, we discover a defect selectivity where the hosting sublattice fully dictates the interlayer exchange, stabilizing either ferrimagnetic or
antiferromagnetic configurations. Applying an out-of-plane electric field selects the polar registry and drives an amplitude modulation of the compensated Néel order parameter. These findings establish a robust, sublattice-dependent engineering of multiferroic functionality via stacking control across a wide class of nonmagnetic 2D
heterostructures.
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Astrophysics of Galaxies
GLOW II: A Census of Oxygen in Low-Mass Galaxies
Kristen B. W. McQuinn, O. Grace Telford, Andrey V. Kravtsov et al. (+12 more)
Oxygen is forged by
stars and redistributed through
galaxies by feedback-driven
outflows, leaving a record of
star formation and the
baryon cycle imprinted on its present-day abundance and distribution. The
Galaxies Losing Oxygen via Winds (GLOW) project quantifies the production, distribution, and retention of oxygen in 37 low-mass, low-
metallicity, gas-rich
galaxies in the nearby universe (D<6 Mpc) spanning a critical
stellar mass range (10^6.5<Mstar<10^9.5) where feedback is expected to strongly shape
galaxy evolution. We incorporate literature results to extend the analysis over 10^5<Mstar<10^11.5. We couple
star formation histories derived from resolved
stars with measurements of ISM
metallicity and gas mass, and compares the oxygen budgets with empirical constraints in the circumgalactic medium (CGM). We find low-mass
galaxies retain between 4-25% (mean 11%) of their oxygen produced by
stellar nucleosynthesis, and nearly all retained oxygen residing in the gas.
Galaxies exhibit increased scatter to higher oxygen retention fractions when residing in denser environments (Theta_5>0.5) and within 1 Mpc of a massive
galaxy (Mstar>10^9 Msun), indicating environment likely affects the amount of oxygen retained, recycled, or accreted to
galaxies. Contrary to expectations, oxygen retention does not correlate with position on the mass-
metallicity relation. Although ionized oxygen is detected in the CGM, it remains unclear whether most missing oxygen resides there or has been expelled entirely. Hydrodynamical simulations, despite successfully reproducing the mass-
metallicity relation, predict much higher retention fractions than measured in low-mass
galaxies. Simple modeling indicates that wind mass-loading and
outflow metallicity govern oxygen retention, and that low-mass
galaxies accrete less baryonic material relative to the
cosmic baryon fraction.
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All authors Kristen B. W. McQuinn, O. Grace Telford, Andrey V. Kravtsov, Joseph Burchett, Roger Cohen, Laura Hunter, Evan D. Skillman, Julia Roman-Duval, Danielle A. Berg, John M. Cannon, John Chisholm, Julianne J. Dalcanton, Andrew E. Dolphin, Liese van Zee, Benjamin Williams
High Energy Physics (Theory)
R7-branes and AdS$_{\text{9}}$ solutions in type IIB
Giuseppe Dibitetto, Cameron Gibson, Nicolò Petri et al. (+1 more)
We consider the recently found $\mathrm{AdS}_9$ backgrounds in type IIB supergravity. We start by reviewing the solutions in a more convenient set of coordinates, which allows us to explicitly compute a few relevant observables, including the
holographic central charge. Subsequently, we study non-supersymmetric 7-brane configurations sourced by the IIB axio-dilaton. We find explicit analytic 7-brane solutions that possess the above $\mathrm{AdS}_9$ backgrounds as their near-horizon geometry. Finally, we discuss the relation of these 7-brane solutions to the R7 branes by imposing the reflection monodromy $\tau \rightarrow -\bar \tau$ in the transverse plane.
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All authors Giuseppe Dibitetto, Cameron Gibson, Nicolò Petri, Colin Sterckx
General Relativity and Quantum Cosmology
The G347.3-0.5 outlier from O3: a follow-up case study for continuous gravitational-wave candidates
L. Mirasola, F. Amicucci, M. Carrio et al. (+31 more)
We report a multi-pipeline follow-up study of the continuous gravitational-wave (CW) outlier identified by the Ming et al. Einstein@Home directed search for the young
supernova remnant G347.3-0.5 (containing the central compact object RXJ1713.7-3946). The outlier was initially identified in LIGO data from the O3a observing run and followed up with the addition of O3b and O4a data by the Einstein@Home pipeline, with O4a producing weaker evidence. Here, we show extended data quality checks and results from three pipelines that have independently investigated this outlier, including the newly released O4b data set. We can robustly recover the outlier in O3, while we find no evidence for a related standard CW signal in O4a (consistent with Ming et al.) and O4b data. This work serves as a useful test case for future multi-pipeline follow-ups of CW candidates that aim to investigate their astrophysical or noise nature, and it is therefore an important step in preparation for the first CW detection.
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All authors L. Mirasola, F. Amicucci, M. Carrio, D. H. T. Cheung, M. A. Ferrer-Martinez, E. Goetz, D. Keitel, A. M. Knee, P. Leaci, C. Palomba, K. Pham, O. J. Piccinni, M. Pitkin, I. Prohens, K. Riles, S. Safi-Harb, G. Woan, Z. Zhang, M. Bejger, A. Calafat, R. Jaume, D. I. Jones, A. Krolak, I. La Rosa, A. Melatos, J. R. Mérou, A. Nemmani, B. Rajbhandari, C. Salvadore, A. M. Sintes, R. Tenorio, K. Wette, J. T. Whelan, T. S. Yamamoto
High Energy Astrophysical Phenomena
Wild behaviour near the finish line: the Type Ibn SN 2020able and its stratified environment
L. Tartaglia, E. Cappellaro, G. Valerin et al. (+29 more)
We present spectrophotometric observations of the Type Ibn
supernova SN~2020able, along with a comprehensive analysis and modelling of its
evolution. The transient occurred in SDSS J092602.93+243115.1, a faint host
galaxy characterised by significantly sub-
solar metallicity ($12+\log(\rm{O/H})\simeq8.28\,\rm{dex}$). The early photometric
evolution and high peak luminosity ($L_{peak}\simeq4.4\times10^{43}\,\rm{erg}\,\rm{s^{-1}}$) indicate an efficient conversion of ejecta kinetic energy into radiation via interaction with the circumstellar medium. Light-curve modelling suggests that this interaction involves ejecta with a mass of $M_{\rm{ej}}\simeq1.3\,M_{\odot}$ impacting a shell of $M_{\rm{CSM}}\simeq0.6\,M_{\odot}$. However, interaction is found to be geometrically and temporally confined within a few days after explosion, with the later
evolution of the transient being dominated by the free expansion of the ejecta. Spectroscopic analysis reveals a complex, stratified circumstellar environment. In addition to the innermost shocked region, we identify two additional He-rich shells: a dense inner one ($n_{\rm{e}}\simeq1.4\times10^{9}\,\rm{cm^{-3}}$) located at $R\gtrsim9.3\times10^{14}\,\rm{cm}$, and a more extended outer component reaching $R_{out}\simeq3.3\times10^{15}\,\rm{cm}$ and expanding at approximately $1.2\times10^3\,\rm{km}\,\rm{s^{-1}}$. The physical parameters of the former suggest it was produced by a discrete pre-
supernova eruptive event similar to that of SN~2006jc, which expelled approximately $1.8\times10^{-2}\,M_{\odot}$ of material. Conversely, the expansion velocity of the outermost shell is consistent with the escape velocity of WR
stars, pointing towards a late WN to WC-type progenitor as the most viable candidate for SN~2020able.
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All authors L. Tartaglia, E. Cappellaro, G. Valerin, A. Pastorello, S. Benetti, A. Reguitti, L. Tomasella, P. Lundqvist, K. Misra, A. Gangopadhyay, R. Dastidar, B. Ailawadhi, Dimple, B. Kumar, V. K. Jha, M. Singh, N. Elias-Rosa, C. P. Gutiérrez, D. A. Howell, D. Hiramatsu, C. Pellegrino, J. Andrews, D. J. Sand, N. Smith, J. Pearson, S. Wyatt, P. Ochner, Y.-Z. Cai, J. Burke, C. McCully, M. Newsome, E. Padilla Gonzalez
High Energy Physics (Theory)
Superconformal indices and black hole saddles
Maciej Kolanowski, Donald Marolf, Zi-Yue Wang et al. (+1 more)
The AdS/CFT correspondence implies that the superconformal index ${\mathcal I}$ in ${\mathcal N=4}$ SU(N) supersymmetric Yang-Mills theory can be computed using the dual bulk theory. In particular, in the limit of large $N$, the index should be given by a sum over appropriate saddles. However, ${\mathcal I}$ depends on potentials $\sigma, \tau, \vec \Delta$ and, at large ${\rm Im}\, \tau = {\rm Im}\, \sigma$, the CFT index ${\mathcal I}$ rapidly approaches $1$ at all values of $N$. As a result, black hole saddles associated with exponentially large contributions in $N$ cannot contribute in this limit. This in particular excludes saddles that were previously suggested to be relevant in such regimes. We thus consider an approach to the bulk path integral motivated by taking it to be defined as an integral over real Lorentz-signature spacetimes with codimension-2 singularities. This approach leads only to saddles that satisfy the above bound, and to the enforcement of this bound via Stokes phenomena. We also find similar results for bulk AdS$_4$ calculations of the ABJM superconformal index.
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All authors Maciej Kolanowski, Donald Marolf, Zi-Yue Wang, Wenwen Zheng
Astrophysics of Galaxies
GLOW I: Comprehensive Measurements of Gas-Rich, Star-Forming, Low-Mass Galaxies in the Nearby Universe
Kristen B. W. McQuinn, O. Grace Telford, Roger Cohen et al. (+12 more)
Gas-rich,
star-forming, low-mass
galaxies in the nearby universe are powerful laboratories for studying baryonic physics in detail including:
stellar mass assembly,
stellar feedback, chemical enrichment, and the interplay of the interstellar medium with
star formation. Investigating these disparate yet interconnected processes requires data obtained by myriad observatories. Here, we present a comprehensive atlas of uniformly processed data on 37 low-mass
galaxies within 6 Mpc. The atlas includes archival data on (i) the HI from the Very Large Array observatory; (ii) resolved
stars from Hubble Space
Telescope optical imaging; (iii) Spitzer Space
Telescope 3.6 micron imaging; and (iv) optical imaging from ground-based
telescopes. We also compile measurements of (i) tip-of-the-red-
giant-branch (TRGB) distances to the
galaxies; (ii) direct method gas-phase oxygen abundances and nitrogen to oxygen abundance ratios; (iii) constraints on the local environment around each
galaxy; and (iv) other measurements from the literature. We supplement the data with new observations where needed to complete the measurements for all
galaxies in the sample. From these data, we find good agreement between
stellar masses measured from color-magnitude diagrams and those estimated from 3.6 micron imaging by assuming a mass-to-light ratio. We also provide the first mapping of the HI profiles as a function of structural parameters. These data sets and measurements are the foundation for the
Galaxies Losing Oxygen via Winds (GLOW) project whose main aim is to characterize the
star formation - chemical enrichment cycle of low-mass
galaxies by measuring the production, distribution, and retention of oxygen on a
galaxy-by-
galaxy basis.
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All authors Kristen B. W. McQuinn, O. Grace Telford, Roger Cohen, Liese van Zee, Laura C. Hunter, Madison Smith, Evan D. Skillman, Benjamin Williams, John M. Cannon, Joseph Burchett, Danielle A. Berg, Julianne J. Dalcanton, Andrew E. Dolphin, Suchindram Dasgupta, Avery Kiihne
High Energy Physics (Theory)
Towards a Holographic dual of Carrollian BCFT
Pronoy Chakraborty, Ritankar Chatterjee and Priyadarshini Pandit
In this work we aim to lay the foundation of flat version of AdS$_3$/BCFT$_2$ correspondence through Carrollian framework. We begin with discussing the recently discovered Boundary Carrollian Conformal
Algebra (BCCA), the
symmetry algebra of Carrollian BCFT. We identify this
algebra at the null infinity of flat spacetime with appropriate choice of the end-of-the-world (EOW) brane. The properties of this EOW brane have been analysed both intrinsically and by taking flat limit from its AdS counterpart. We also find that the global as well as asymptotic
symmetries of flat spacetime restricted by this EOW brane coincide exactly with the
symmetries of BCCA.
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High Energy Physics (Phenomenology)
Neutrinoless Double-Beta Decays from Operator Mixing
J. de Vries, S. Fajfer, L. P. S. Leal et al. (+2 more)
We perform a complete one-loop Renormalization Group (RG) analysis of neutrinoless double-beta decays within the Standard Model Effective Field Theory (SMEFT). Although several effective operators do not contribute to these processes at tree level, we show that they can generate sizable contributions through operator mixing. By accounting for the full one-loop RG
evolution within the SMEFT, we find that the resulting constraints provide the most stringent bounds on numerous dimension-seven operators, improving upon limits derived from
meson decays. We also highlight the importance of contributions beyond the first leading logarithm, which can provide the leading effects for specific operators and
flavor combinations.
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All authors J. de Vries, S. Fajfer, L. P. S. Leal, O. Sumensari, R. Zukanovich Funchal