Differential Geometry
The sharp isoperimetric inequality for varifolds in codimension two
Raphael Tsiamis
We prove a Michael-Simon inequality for a class of varifolds in Euclidean space that includes all integral varifolds with locally bounded first variation of arbitrary dimension and codimension. In codimension $2$, this inequality is sharp and implies the sharp isoperimetric inequality for varifolds, which attains equality precisely for the round disk. Our proof uses the optimal transportation approach of Brendle-Eichmair.
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General Economics
Biased Agents, Extreme Beliefs: Motivated Reasoning Under Competing Models
Zhongheng Qiao
People often face environments where multiple models compete to explain the same observations. This paper examines how people update beliefs in such settings and how preferences over payoff-relevant states shape model selection and belief updating. This paper first develops a framework where preference-driven bias distorts the perceived model, affecting
Bayesian and best-fit updating differently. In a laboratory experiment, most participants are classified as
Bayesian updaters, who average across models, while a substantial minority are classified as best-fit updaters, who select the model that best fits the observed signal. Within-participant comparisons between the symmetric payoff and asymmetric payoff conditions indicate that asymmetric payoffs shift reported beliefs toward the preferred state, particularly among participants classified as best-fit updaters. Relative to symmetric payoffs, asymmetric payoffs increase the reported belief of the preferred state by about 8 percentage points among best-fit updaters, while the estimated effect among
Bayesian updaters is close to zero. These findings help us better understand model-based learning and have implications for domains such as political polarization and financial investment, where competing narratives and strong preferences often coexist.
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Quantum Physics
A Near-Optimal Joint Lower Bound for Sparse Quantum Linear System Solvers
Dhrumil Patel
Quantum linear system solvers form one of the central algorithmic primitives in
quantum computing, with applications ranging from differential equations and optimization to machine learning. Their cost is commonly measured through query complexity, which counts the number of oracle calls needed to access the input
matrix. In the sparse-access model, this complexity is governed by three parameters: the condition number $\kappa$, the sparsity $s$ of the input
matrix, and the target precision $\varepsilon$. The dependence on $\kappa$ and $\varepsilon$ is already well understood through the lower bound $\Omega(\kappa\log(1/\varepsilon))$, which matches the best known scaling in these parameters. Once the sparsity $s$ is included, however, the expected lower bound has long been conjectured to be $\Omega(\kappa\sqrt{s}\log(1/\varepsilon))$. Recent work by Mori et al. [
Quantum Sci. Tech. 11 035063 (2026)] made an important step towards this goal by establishing the lower bound $\Omega(\kappa\sqrt{s})$ for constant error $\varepsilon$. In this work, we complete the picture and prove the full joint lower bound $\Omega(\kappa\sqrt{s}\log(1/\varepsilon))$ in the sparse-access model, thereby establishing the anticipated dependence on all three parameters simultaneously.
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Statistics Theory
Asymptotics and finite sample bounds for prediction and smoothing in Wright-Fisher hidden Markov models
Luigi M. Malgieri, Filippo Ascolani, Matteo Giordano et al. (+1 more)
We study signal prediction and smoothing in hidden Markov models whose latent signal is a multi-type Wright-Fisher
diffusion and whose discrete-time observations are categorical. We consider a repeated-sampling regime with finitely many inspection times and large within-time samples. Under neutrality and parent-independent mutation, the
Bayesian predictive and smoothing laws admit exact representations as mixtures of Dirichlet distributions. We show that the one-step predictive and local smoothing laws converge in total variation to the corresponding Wright-Fisher transition and bridge laws determined by the neighboring population frequencies, thereby justifying plug-in approximations based on empirical proportions. For prediction, we derive explicit finite-sample bounds for this approximation and for bounded predictive functionals such as diversity, together with a finite-sample concentration bound for the marginal smoother. The joint posterior at the inspection times concentrates at the target frequencies and satisfies a Bernstein-von Mises limit with distinct interior and boundary regimes, with Gaussian and Gamma limits on different scales. The results allow arbitrary dependence across inspection times. A key technical ingredient is a fixed-interval tail bound for the coalescent-based dual death process.
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All authors Luigi M. Malgieri, Filippo Ascolani, Matteo Giordano, Matteo Ruggiero
Distributed Computing
Trust-Aware Output Management for Physical Neural Network in Cloud-Continuum Systems
Maliheh Hariri and Stefan Fischer
Physical Neural Networks (PNNs) introduce new opportunities for cloud continuum computing, but their outputs may be affected by noise, drift, delay, and incomplete reliability information. Existing substrate-management approaches mainly focus on discovery, invocation, and monitoring, while the reliability of the returned output is often left unaddressed. This paper proposes a trust-aware output management framework for heterogeneous PNNs. Each output is represented with quality and context information, and a lightweight edge-level trust score decides whether it should be accepted, rejected, or forwarded to the fog. At the fog layer, compatible outputs are checked for disagreement and combined using reliability- and uncertainty-aware fusion. Historical trust is also tracked to detect sustained degradation and support recalibration requests. The framework is evaluated using controlled and randomized PNN output models. Across 20 random seeds, the proposed full-trust policy reduces unsafe acceptance from approximately 61.5% for raw output handling to about 5.0%, while accepted-output MAE decreases from 0.504 to 0.242. Risk coverage analysis shows that this improvement is not explained only by lower local acceptance. The proposed fog fusion method also achieves the lowest aggregate mean error among the evaluated methods, with a small but consistent advantage over strong uncertainty-aware baselines. The prototype adds about $2~\mu\text{s}$ of edge processing per evidence record. These results show that post-invocation reliability management can improve the safe use of PNN outputs across edge–fog–cloud systems.
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Quantum Physics
Extracting Electromagnetic Bare Mode Couplings in Large Superconducting Quantum Processors
Reza Molavi, Ebrahim Forati, Yaxing Zhang et al. (+9 more)
High-fidelity control of superconducting
quantum processors requires accurate characterization of electromagnetic coupling strengths among the device's constituent elements. Accurately extracting these couplings across large-scale architectures, presently featuring hundreds of
qubits, poses a challenging multi-scale modeling problem. This requires resolving scales from the nanometer-scale geometry of Josephson junctions and their leads to the centimeter-scale size of the enclosing metallic packages. We present four numerical coupling extraction methods based on the avoided level crossing, the energy participation ratio, the induced electromotive force, and the impedance
matrix. These methods are tailored to work with commercially available 3D electromagnetic solvers. We
benchmark these techniques on a $10\times10$ array of transmon
qubits, extracting their couplings to standing package modes. Our results show that these methods yield consistent coupling strengths with a maximum relative difference of less than 5%.
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All authors Reza Molavi, Ebrahim Forati, Yaxing Zhang, Andrey R. Klots, Juan Atalaya, Brandon W. Langley, Dogan A. Timucin, Moein Nazari, Ghazi Khan, Zlatko K. Minev, Alexander N. Korotkov, Michel H. Devoret
Machine Learning
Connected Content Retriever: Dense Graph Edge Features Powering Pre-Ranking at LinkedIn
Akhilesh Gupta, Sudarshan Srinivasa Ramanujam, Chirag Bhanuprasad Mehta et al. (+6 more)
In large-scale recommendation systems like the LinkedIn Feed, content generated by a member's network (connections and follows) makes up over 70% of impressions and engagement. It is therefore essential that the pre-ranking layer forwards the best possible few hundred candidates to the ranking layer. LinkedIn's professional knowledge graph carries engagement signals across both the first degree network (connections and follows) and the second-degree network: posts that a 1st-degree connection reacted to, commented on or reshared but did not author (a.k.a. stranger viral). Due to this fan out, the resulting candidate index exceeds one billion; selection of activities from the viewer's network narrows it down to roughly tens of thousands of activities that must be scored within a 120 ms p99 latency budget. We present Connected Content Retriever (CC Retriever), a pre-ranking system that scores these candidates with a full deep ranking model on GPUs at low latency. At its core is a sorted-search GPU primitive that joins dense graph affinity features (viewer to author) with document level features stored on the GPU at runtime in 5-10 ms. The shift to GPU served scoring enabled a 50x scale up of the ranking model's parameters and delivered a +2.5% lift in content time spent on the LinkedIn Feed in online experiments, significantly higher than the typical gains observed in LinkedIn Feed experiments. In this work, we describe the feature set we leverage from LinkedIn's economic graph and the model architecture used for scoring, with a particular emphasis on the online system that scales the stack.
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All authors Akhilesh Gupta, Sudarshan Srinivasa Ramanujam, Chirag Bhanuprasad Mehta, Reshma Asharaf Beena, Dhritiman Das, Birjodh Singh Tiwana, Bhargavkumar Kanubhai Patel, Mack Lee, Renyi Tang
Materials Science
A low-symmetry ground state of dense two-dimensional hydrogen
Cesare Cozza, Chris J. Pickard and Guglielmo Mazzola
Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic
crystals. This preference already emerges with classical
nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although
crystals with very large primitive
cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
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Information Theory
One-Shot Information Hiding and Compound Wiretap Channels
Yanxiao Liu and Cheuk Ting Li
In recent years, due to the growing reliance on large amounts of data that are communicated, analyzed, and utilized, which inherently contain sensitive and personal information, secrecy and
privacy in communication have become increasingly important. We present nonasymptotic information-theoretic analyses of two fundamental secrecy problems under channel uncertainties: the information hiding problem and the compound wiretap channel. The former admits a game-theoretic formulation, where one party (an information hider and a decoder) seeks to embed secret messages into a host signal for later reconstruction, while the opposing party (an attacker) attempts to remove or degrade the embedded information. The latter generalizes Wyner's wiretap channel by allowing multiple potential channel states. The information hiding problem concerns active attacks during data transmission, while the compound wiretap channel addresses passive eavesdropping and information leakage. The two problems, both of which consider channels with uncertainties, can be studied under a unified framework by utilizing a covering argument and the Poisson matching lemma by Li and Anantharam. We derive novel one-shot achievability results for both problems that are applicable to any source distribution and any class of channels (not necessarily memoryless or ergodic), and that apply to both discrete and continuous cases. We also show that existing asymptotic results on both problems can be recovered by applying our results to discrete memoryless channels.
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High Energy Physics (Phenomenology)
Non-Perturbative Modulus Decay and Multi-Component Dark Matter
Gordon Kane, Leia Price, Luis Rufino et al. (+2 more)
Non-thermal cosmological histories rest on the assumption that scalars displaced during inflation undergo coherent oscillations, dominate the energy density of the universe before Big Bang Nucleosynthesis, and decay perturbatively through gravitationally suppressed interactions. In addition, usually a single dark matter component is assumed. This early matter-dominated era is the basis for the usual predictions of non-thermal WIMP production,
axion dark matter,
entropy generation, and dark radiation. This paper examines whether this picture is dynamically robust against non-perturbative decay of the modulus condensate. In this work, we study non-perturbative particle production from oscillating
moduli using the effective field theory appropriate to $G_2$ compactifications. We find that non-perturbative production of Wino-like
fermions is strongly suppressed in the relevant parameter regime. In contrast, a modulus-dependent
axion kinetic term admits narrow instability bands with growth rates that can exceed the Hubble rate. A linear Floquet analysis alone, however, cannot determine whether these bands significantly deplete the modulus condensate, since
cosmic expansion, backreaction, rescattering, and higher-order operators in the effective theory can become important. As a result, the conventional modulus-dominated cosmology remains robust against Wino and gauge-field preheating, while the
axion channel provides a potentially important modification that requires nonlinear study. If sufficiently efficient,
axion production can alter the division of dark matter between Winos and
axions and enhance the dark-radiation abundance.
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All authors Gordon Kane, Leia Price, Luis Rufino, Scott Watson, Fred Adams
Solar and Stellar Astrophysics
Super-Chandrasekhar white dwarfs by the evolution of magnetized main-sequence stars: New mass-limits from STARS simulation
Zenia Zuraiq, Banibrata Mukhopadhyay, Achal Kumar et al. (+4 more)
We explore the time
evolution of the magnetized main-sequence
stars (MSs) to magnetized non-rotating white
dwarfs (WDs) with a series of models, capturing modified Hertzsprung-Russell diagram. We use the Cambridge
Stellar evolution code,
STARS, with modifications by introducing
magnetic effects and cooling. We investigate the possible existence of stable, magnetized, massive, super-Chandrasekhar, approximately spherical WDs, away from Chandrasekhar's mass-radius curve. These we refer to as B-WDs. They are inferred from the observations of peculiar over-luminous type Ia
supernovae, e.g. SN2003fg. We show that the classical effects of
magnetic fields significantly impact MSs and their time
evolution to WDs. Moreover, the
magnetic field could be decisive in explaining the unusually large radius observed in some sub-Chandrasekhar WDs, e.g. SDSS J123204.19+522548.2, along with the finite temperature effect. We further investigate the stability of magnetized WDs, both below and above the Chandrasekhar limit and confirm the possibility of super-Chandrasekhar B-WDs with new mass limits that depend on the
magnetic field geometry, mass
accretion from a companion and cooling rates. Therefore, while the "Chandrasekhar limit" may be sacrosanct, its value severely depends on the underlying physics, here the
magnetic field.
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All authors Zenia Zuraiq, Banibrata Mukhopadhyay, Achal Kumar, Arnab Sarkar, Alexander J. Hackett, Projjwal Banerjee, Christopher A. Tout
Astrophysics of Galaxies
Low-power jet-ISM coupling and disk-plane perturbations in the edge-on Seyfert galaxy NGC 4388
M. Ceci, G. Venturi, C. Marconcini et al. (+26 more)
Active
galactic nuclei (AGN) may regulate
galaxy evolution through radiatively driven winds and collimated jets, but their relative impact and coupling to the interstellar medium (ISM) remain uncertain. We investigate the ionized gas in the nearby ($D\sim$ 17 Mpc) Seyfert 2
galaxy NGC 4388, hosting a
galaxy-scale ($\sim$1.6 kpc), low-power ($\sim1.4~\times~10^{42}~erg~s^{-1}$) bipolar
radio jet projected roughly perpendicular to its edge-on disk. We analyze optical integral-field spectroscopic observations from the Wide Field Mode with adaptive optics of VLT/MUSE, complemented by VLA
radio data tracing the jet. We map ionized-gas emission, kinematics, excitation, and
dust attenuation. We reconstruct the de-projected 3D
outflow geometry and velocity field using the MOKA3D kinematic model, and estimate its mass and energetics. The ionized gas shows a rotating disk and a kpc-scale biconical
outflow. We measure a total ionized
outflow mass of $\sim10^6~M_\odot$, a mass
outflow rate of $\sim0.2~M_\odot$~yr$^{-1}$, and a kinetic power of $\sim3\times10^{40}~erg~s^{-1}$, which gives a coupling efficiency of $\sim1\%$ relative to both the jet kinetic and the radiation-driven
nuclear wind power, indicating that either mechanism could drive the
outflow. We detect an extended ($\sim$2 kpc) enhancement of the gas velocity dispersion along the
galaxy disk plane, oriented perpendicular to the
outflow and jet axes. These regions show optical line ratios consistent with shock excitation. The spatial correspondence with ALMA CO(2-1) emission is marginal, while enhanced
stellar velocity dispersion prevents an exclusive jet interpretation. We report the first observational evidence that even a low-power
radio jet oriented nearly perpendicular to the
galaxy disk can efficiently couple with the ISM, suggesting that jet-induced perturbations are an important AGN feedback channel regardless of jet orientation.
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All authors M. Ceci, G. Venturi, C. Marconcini, M. V. Zanchettin, G. Cresci, M. Tartėnas, K. Zubovas, E. Treister, E. Amenta, E. Bertola, F. Belfiore, C. Bracci, E. Cataldi, Q. D'Amato, A. Feltre, M. Ginolfi, I. Lamperti, F. Mannucci, A. Marconi, A. Marasco, M. Meenakshi, M. Mingozzi, B. Moreschini, D. Mukherjee, E. Nardini, M. Perna, F. Ricci, M. Scialpi, L. Ulivi
Nuclear Theory
Probing the nucleon axial form factor via the $\vec{e}^{\,+} + {}^2\text{H} \rightarrow \bar{\nu}_e + p + p$ reaction below the pion-production threshold
A. M. Ankowski, J. Golak, E. Pérez del Rio et al. (+7 more)
The nucleon axial form factor $F_A(Q^2)$ is a primary source of systematic uncertainty in charged-current quasielastic interactions, of critical importance for long-baseline
neutrino-oscillation studies. Its low-$Q^2$ behavior is particularly problematic to pin down in
neutrino measurements. To address this limitation, we investigate the weak process of polarized positron capture on the deuteron, $\vec{e}^{\,+} + {}^2\text{H} \rightarrow \bar{\nu}_e + p + p$. Employing a relativistic momentum-space formalism, we present predictions for the total cross section. Focusing on the kinematic regime free from pion-production backgrounds, we analyze various differential cross sections and their sensitivity to the $F_A(Q^2)$ variation. Our results demonstrate that thanks to the positron upgrade, Jefferson Lab will gain a unique position to make inroads into determining the low-$Q^2$ behavior of the axial form factor.
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All authors A. M. Ankowski, J. Golak, E. Pérez del Rio, S. Sharma, R. Skibiński, K. Topolnicki, H. Witała, W. N. Polyzou, H. Kamada, D. Dutta
Astrophysics of Galaxies
Galaxy-SMBH co-evolution in 2,435 DESI disk galaxies and merger-free BH growth in bulgeless disks
Sophie M. Jewell, Rebecca J. Smethurst, Chris J. Lintott et al. (+8 more)
We analyse black hole scaling relations for disk-dominated
galaxies, and present evidence for secularly driven
galaxy-black hole co-
evolution. We do this observationally by looking at “bulgeless”
galaxies, where the lack of a
stellar bulge suggests a quiet merger history. We first compose a sample of 2,435 disk-dominated
galaxies hosting optical broad line active
galactic nuclei (AGN) from DESI data, and find a $M_{\mathrm{BH}}$–$M_{*}$ scaling relation of $\log(M_{\mathrm{BH}})= - 3.7^{+0.3}_{-0.3} + 1.00^{+0.03}_{-0.03} \log(M_*)$. From these, we identify 546 bulgeless
galaxies hosting AGN, a factor of $\gtrsim 5$ larger than pre-existing samples, and find they follow the same $M_{\mathrm{BH}}$–$M_{*}$ relation as the general disk
galaxy sample. Comparing the bulgeless
galaxies to those with some bulge component, we find good agreement in the $M_{\mathrm{BH}}$–$M_{*}$ relation (within $3 \sigma$), but disagreement in the $M_{\mathrm{BH}}$–$M_{*, \mathrm{bulge}}$ relation (at $>7 \sigma$). This is the opposite of what is expected from merger-driven co-
evolution, suggesting secular growth is significant in establishing observed $M_{\mathrm{BH}}$–$M_{*}$ scaling relations. Furthermore, in a control sample of early-type
galaxies we find tentative evidence of increased AGN luminosity compared to the bulgeless sample, but no statistical difference in black hole mass. This suggests the assumed merger-dominated evolutionary history of early-type
galaxies does not lead to significantly increased long-term BH growth. These results support numerous recent observational and theoretical studies which suggest secular processes fuel significant supermassive black hole growth and
galaxy-black hole co-
evolution.
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All authors Sophie M. Jewell, Rebecca J. Smethurst, Chris J. Lintott, Brooke D. Simmons, Ricarda S. Beckmann, Izzy L. Garland, Tobias Géron, Benne W. Holwerda, Karen L. Masters, Ragadeepika Pucha, Ashley Spindler
Astrophysics of Galaxies
Direct imaging of sub-parsec binary SMBHs in the central galaxy of the NGC 5044 group
Francesco Ubertosi, Gerrit Schellenberger, Ewan O'Sullivan et al. (+7 more)
Binary active
galactic nuclei (AGN) consist of two supermassive black holes (SMBHs) hosted in a single
galaxy that are simultaneously accreting gas. These systems are key to understanding hierarchical
galaxy evolution and represent
prime targets for low-frequency gravitational wave (GW) experiments. However, binary AGN remain extremely rare: only a handful are confirmed at separations of a few hundred parsecs, and just one pc-scale binary - in an elliptical
galaxy at the center of a
galaxy cluster - has been securely and visually identified. Direct imaging of sub-parsec binary AGN, the final stage before the GW regime, has so far been missing. Here we report on Very Long Baseline Array (VLBA) observations of NGC 5044, the central
galaxy of the X-ray brightest
galaxy group. This
galaxy is known to exhibit pc-scale
radio jets nearly orthogonal to two older AGN outbursts. The 4.9, 8.4, 15.2, and 23.6 GHz VLBA images reveal two compact, flat-spectrum, and variable
radio cores separated by just 0.38 parsec at the heart of the
galaxy, forming the tightest directly imaged binary AGN known by an order of magnitude. This discovery suggests that the older outbursts may have been powered by jets from the secondary core, without invoking any reorientation of the primary jet axis. More broadly, comparison with other systems points to massive, cluster-central elliptical
galaxies being promising targets to search for binary SMBHs.
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All authors Francesco Ubertosi, Gerrit Schellenberger, Ewan O'Sullivan, Laurence P. David, William Forman, Simona Giacintucci, Christine Jones, Kamlesh Rajpurohit, Tiziana Venturi, Jan Vrtilek
Solar and Stellar Astrophysics
A Quantitative Method to Investigate the Spectral Class Time Evolution of Novae
Maria Kopsacheili, Martin Guerrero and Diego Alejandro Vasquez Torres
Novae are spectroscopically classified as Fe II or He/N according to the dominance of Fe II, or He and N emission lines in their pre-nebular spectra, while spectra exhibiting both are classified as hybrid. Whereas the spectral class of a nova is known to correlate with its progenitor properties, a recent detailed spectroscopic follow-up of ten novae suggests instead a time
evolution from "early He/N" to "Fe II" and to "late He/N". We investigate here this apparent contradiction using a spectroscopic
dataset of 26 novae from the Astronomical Ring for Amateur Spectroscopy (ARAS) Database. For this purpose we introduce a quantitative coefficient, $\kappa$, defined as the ratio of the flux of the Fe II $\lambda$5169 line to the mean flux of five He and N emission lines, with $\kappa > 1$ indicating Fe II-dominated spectra and $\kappa < 1$ indicating He/N-dominated spectra. This coefficient is shown to provide a reliable quantitative tool for tracing nova spectral
evolution while reducing biases from incomplete coverage. A significant fraction of the novae in our sample exhibit at least one transition between Fe II- and He/N-dominated phases. The time
evolution of $\kappa$ closely follows their optical light-curves, repeatedly crossing unity in novae exhibiting jitters, which reveal non-monotonic spectral
evolution. Since the light-curve shapes and their time-scales depend on intrinsic progenitor properties, particularly white
dwarf mass, they also determine the duration of Fe II- and He/N-dominated phases, introducing a bias in spectral classification when it relies on early, sparse spectra.
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Astrophysics of Galaxies
Dual Signatures of Bursty Star Formation in High-Redshift UV Luminosity Functions
Guochao Sun, Claude-André Faucher-Giguère, Steven R. Furlanetto et al. (+1 more)
The UV luminosity function (UVLF) encodes key information about
galaxy formation. The slowly evolving bright-end UVLFs at $z\gtrsim10$ have made UV variability from bursty
star formation a promising explanation, but the impact of such variability need not be restricted to the bright end. Motivated by ultra-deep measurements of the $z\simeq7$ UVLF, we investigate whether UV variability can provide a unified interpretation of the low-mass
star formation efficiency (SFE) at $z\simeq7$ and the abundance of UV-bright
galaxies at $z\gtrsim12$. Using abundance matching, we show that a steep faint-end UVLF at $z\simeq7$ admits a range of interpretations. For modest, mass-independent UV variability, the inferred median SFE starts flattening below $M_{\rm h} \sim10^{10.5} M_{\odot}$. If UV variability instead grows with decreasing
halo mass—a possibility motivated by simulations and observations—the inferred median SFE is steeper and lower by a factor of about three at $\sim10^9 M_{\odot}$, consistent with stronger feedback suppression in low-mass
halos. Calibrated to the common target $z\simeq7$ UVLF, these two scenarios diverge strongly when extrapolated to $12\lesssim z\lesssim17$ under
redshift-independent UV variability and SFE prescriptions. Strongly mass-dependent $M_\mathrm{UV}$ scatter links the steep $z\simeq7$ faint-end slope and high $z\gtrsim12$ bright-end abundance as dual signatures of burstiness in similarly low-mass
halos. Stronger variability makes bright
galaxies contribute a larger fraction of the UV luminosity density, whereas weaker variability favors faint sources, despite their similar predicted reionization histories. At fixed $M_\mathrm{UV}$, UV variability broadens the
halo mass distribution and lowers the clustering bias, which provides a useful diagnostic of burstiness for JWST and Roman.
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All authors Guochao Sun, Claude-André Faucher-Giguère, Steven R. Furlanetto, Adam Lidz
High Energy Physics (Phenomenology)
Gravitational Waves from Long Strings and Loops
Christos Litos, Sarunas Verner, Wei Xue et al. (+1 more)
We compute the gravitational wave spectrum produced by a global
cosmic string network in the scaling regime. The spectrum naturally divides at the string correlation length into infrared and ultraviolet parts. In the infrared, we derive the spectrum analytically from the unequal-time correlator of the string stress-energy tensor within the unconnected segment model, which we generalize for the first time to string loops. The loop contribution can be comparable to that of long strings, depending on the loop
evolution parameters. In the ultraviolet, where structure below the correlation length dominates the source, we develop a data-driven method that connects this correlator formalism to the instantaneous radiation power spectrum measured in existing
lattice simulations. The predicted spectrum rises with frequency as $\Omega_{\rm GW}\propto k$ and $k^{3}$ in the infrared, and flattens into a plateau with a mild logarithmic tilt in the ultraviolet. The turnover frequency between the two is set by the mass of the Goldstone
boson, the
axion. Confronting the predicted spectrum with current data and projected sensitivities, we map out current constraints and future probes in the plane of the
symmetry-breaking scale~$f_a$ and the
axion mass~$m_a$.
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All authors Christos Litos, Sarunas Verner, Wei Xue, Fengwei Yang
Instrumentation and Methods for Astrophysics
Probing Millisecond Optical Timescales with Continuous-Readout Mode Observations from ZTF
Shar Daniels, Federica Bianco, Igor Andreoni et al. (+6 more)
The subminute-timescale phase space is an underexplored regime of the optical sky. Sub-second optical observations are difficult to accomplish with traditional CCD exposure-readout cycles, and alternative technologies like EMCCDs and CMOS have historically limited surveys to targeted observation. Continuous-readout mode enables millisecond-timescale observations on traditional cameras by leaving the shutter open during readout, enabling high-cadence observations on all-sky surveys. We present the first results from continuous-readout mode data from the Zwicky Transient Facility. We developed a deep-learning-based data analysis pipeline and report results on 141 square degrees, or 1128
star-hours, of data, sampled at 300x/second. Our Convolutional Neural Network can retrieve optical transients of duration 9.7-29.2 milliseconds with a precision of 66% and recall of 78% for brightness changes of 10% and greater, and our subsequent light curve-based analysis has an efficiency of >94.6%. We retrieve a total of ~300,000 candidates on sources of magnitude G_{RP} < 12, of which 100 are above SNR=1.55 and were visually inspected. After accounting for noise and filtering contaminants both known and unique to this mode of observation, these 100 candidates were eliminated as being astrophysical in nature, leading to upper limits on the observed rate of ~10-ms transient events associated with point sources as well as specifically with white
dwarfs and
quasars. This first survey-scale characterization of the bright millisecond optical transient and variable sky establishes the rarity of short-timescale variability in the optical regime.
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All authors Shar Daniels, Federica Bianco, Igor Andreoni, Ashish Mahabal, Rich Dekany, Gregory Dobler, Matthew Graham, Roger Smith, Rujula Yete
Astrophysics of Galaxies
Star Formation and Nebular Attenuation from Pa$\alpha$, Br$\alpha$, and Br$\beta$ in Massive Dust-obscured Galaxies at Cosmic Noon using JWST
Virginia Vanicek, Jed McKinney, Alexandra Pope et al. (+14 more)
Near-infrared hydrogen recombination lines can provide robust
star-formation rates if the effects of
dust attenuation continue to diminish towards longer wavelengths. To quantify near-infrared attenuation and ultimately measure accurate
star-formation rates (SFRs) at the height of
cosmic star-formation, we present Pa$\alpha$, Br$\alpha$, and Br$\beta$ detections in $27$ luminous infrared
galaxies at $z\sim 1-2$, including pure
star-forming
galaxies as well as
dust-obscure Active
Galactic Nuclei (AGN). Using combined spectra from the JWST MIRI (Mid-Infrared Instrument) LRS (Low Resolution Spectrometer) and the Spitzer Space
Telescope IRS we quantify the
star formation rates of our sample using a sub-sample of 13
galaxies detected in Pa$\alpha$ emission ($1.87\, \mu$m), 14
galaxies detected in Br$\alpha$ ($4.05\, \mu$m), and 12
galaxies detected in Br$\beta$ ($2.63\, \mu$m). By combining multiple near-infrared recombination lines in individual
galaxies we calculate nebular attenuation, finding $A_\lambda\sim3$ mag at $\sim2\,\mu$m and $A_\lambda\sim1$ mag at $\sim4\,\mu$m. Nebular lines trace the SFR on $\sim 10$ Myr timescales, which we compare to the total infrared luminosity ($L_{\rm IR}$) which probes the
star formation over the last $\sim 100$ Myr. SFRs measured from $L_{\rm IR}$ using common conversions are systematically higher than the SFRs derived from attenuation-corrected nebular line measurements by a factor of $\sim2.5$. This could be indicative of a declining or static
star formation history with a past burst or systematic effects on $\rm SFR_{{\rm IR}}$ such as
dust heating from evolved
stellar populations, and/or an active
galactic nucleus.
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All authors Virginia Vanicek, Jed McKinney, Alexandra Pope, Anna Sajina, Stacey Alberts, Meredith Stone, Lee Armus, Sinclaire M. Manning, Olivia Cooper, Tanio DÍaz-Santos, Miriam Eleazer, Caitlin Casey, Thomas S.-Y. Lai, Steven Finkelstein, Leonid Sajkov, Allison Kirkpatrick, Anthony Taylor
Astrophysics of Galaxies
Linking X-ray emission to galaxy populations in GAMA groups
Selene Levis, Hernán Muriel, Valeria Coenda et al. (+3 more)
We study how the presence of a detectable hot intragroup medium affects
galaxy colour and
star-formation properties, and how these trends depend on dynamical stage within the group. We analysed
galaxies in GAMA groups with and without X-ray detection (XG and NXG) at 0.1 <= z <= 0.2, using samples with similar
halo-mass distributions, compared with a field control sample.
Galaxies were classified as red, green, or blue by UV-optical colour, and group
galaxies further classified into dynamical classes based on projected phase-space position and host
halo mass. We examined
galaxy populations as a function of orbital class,
star-formation activity,
nuclear activity, and cluster-centric distance. The
galaxy population is systematically more evolved in XG than NXG, with lower blue and
star-forming fractions and higher red and passive fractions. The green fraction is stable across environments and orbital classes, though high-mass recent arrivals show a mild excess of green systems while retaining relatively high
star-forming and low passive fractions, suggesting an intermediate quenching stage. The active
galactic nucleus fraction shows no environmental dependence, while the post-starburst fraction increases strongly in XG, reaching nearly 20 percent, consistent with enhanced rapid quenching.
Galaxy properties show stronger radial segregation in XG than NXG, with colour fractions differing from field values even at R/R200 ~ 3, consistent with preprocessing. Despite similar
halo-mass distributions, the systematic differences between XG and NXG show that
halo mass alone does not determine
galaxy properties. A detectable hot intragroup medium is associated with enhanced environmental processing, stronger quenching, and more frequent rapid transitions, highlighting the role of the intragroup medium's thermodynamical state, beyond
halo mass, in shaping
galaxy evolution at group scales.
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All authors Selene Levis, Hernán Muriel, Valeria Coenda, Andrea Biviano, Héctor J. Martínez, Martín de los Rios
High Energy Astrophysical Phenomena
GRB 220706A: a gamma-ray burst with a month-long engine and a luminous supernova
Benjamin P. Gompertz, Nusrin Habeeb, Dheeraj R. Pasham et al. (+30 more)
While the progenitors of many long gamma-ray bursts (GRBs) are well established as the core collapse of very massive, envelope-stripped, rapidly-rotating
stars, it has been suggested that bursts at the extremely long end of the duration distribution may be a separate population of `ultra-long' GRBs. With durations of thousands of seconds or more, these bursts are difficult to reconcile with the engine timescales expected from the compact Wolf-Rayet
stars that are typically assumed to produce more `standard' long GRBs. Here, we present observations of GRB~220706A, where X-ray follow-up reveals flaring episodes that last until $\approx 51$ days after trigger. At the measured
redshift of $z = 0.8577$, this corresponds to 27 days in the GRB rest frame, and represents the latest central engine activity ever observed in a GRB by a margin of $\approx 21$ rest-frame days. We also identify a likely
supernova (SN) which, when accounting for the inferred optical extinction of $0.9 \leq A_V \leq 3.6$ mag (constrained by indirect arguments), has a peak absolute magnitude of $M_r \leq -20.25$, resembling the energetic SN\,2011kl found accompanying ultra-long GRB\,111209A, and consistent with super-luminous SNe. We discuss the implications GRB~220706A has for ultra-long GRB progenitor models and possible powering mechanisms for the extremely late central engine activity.
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All authors Benjamin P. Gompertz, Nusrin Habeeb, Dheeraj R. Pasham, Antonio de Ugarte Postigo, Daniele B. Malesani, Phil A. Evans, Kim L. Page, Ben Rayson, J. Feliciano Agui Fernandez, Michael Bremer, Andrew J. Levan, Genevieve Schroeder, Nial R. Tanvir, Christina C. Thone, Eric Burns, Valerio D'Elia, Massimiliano De Pasquale, Dimple, Dieter Hartmann, Pall Jakobsson, Sylvio Klose, Antonio Martin-Carrillo, Matt Nicholl, Ana M. Nicuesa Guelbenzu, David O'Neill, Giovanna Pugliese, Arne Rau, Andrea Rossi, Jesper Sollerman, Rhaana Starling, Darach Watson, Isabelle Worssam, Makenzie E. Wortley
Quantum Physics
Gibbs resampling transitions and structured fast-measurement protocols
Daan Timmers, Benedikt Placke and Siddharth A. Parameswaran
Quantum Gibbs sampling
algorithms generalize classical Markov chain Monte Carlo (cMCMC) methods, and prepare thermal states on
quantum computers by implementing local dissipative
evolution for a mixing time $t_{\rm mix}$. Since
quantum measurements disrupt the prepared state, the rate of extracting unbiased information from the system depends on the recovery of the underlying thermal correlations. The corresponding ”Gibbs resampling” time $t_{\rm res}$ is distinct both from $t_{\rm mix}$ and from the autocorrelation time relevant to cMCMC sampling. We study this problem in effective classical models that emulate disruptive
quantum measurements of local observables on extensive subsystems. When such subsystems are chosen randomly, in models with non-local order parameters we uncover a ”resampling transition” as a function of the fraction of sites $p$ that are measured, from $t_{\rm res}\propto \log L$ for small $p$ to $t_{\rm res}\propto {\rm poly} L$ for large $p$, in systems of linear size $L$. We argue that this transition is generically absent in systems with local order parameters, and relate this dichotomy to one between the coarsening of initial states that break 1- and 0-form
symmetries under Glauber dynamics. Finally, we devise a structured fast-measurement protocol that evades slow resampling even with non-local order parameters, while leaving only a vanishing fraction of all sites unmeasured.
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Astrophysics of Galaxies
Multi-tracer constraints on quasar outflows. Acceleration from BLR to galactic scales
M. Brazzini, M. Bischetti, S. Hagen et al. (+14 more)
Black hole-driven
outflows are a fundamental component of the Active
Galactic Nuclei (AGN) paradigm, and may play a major role in regulating the
evolution of both supermassive black holes and their host
galaxies. Yet, their physical properties remain challenging to constrain, due to their multi-phase and multi-scale nature which demands a combined approach of different complementary observational tracers. In this work, we investigate AGN-driven ionized
outflows from
nuclear to
galaxy scale within individual
quasars, with the aim of establishing whether and how these phenomena are physically connected. We assemble a luminosity-matched sample of 148
quasars with bolometric luminosities higher than 10^47 erg/s, spanning the
redshift range z~2-6.5. We perform a homogeneous analysis of CIV emission and broad absorption line (BAL) profiles to derive
outflow properties on different spatial scales. We find statistically significant correlations between emission- and absorption-based
outflow diagnostics, including the minimum and maximum BAL velocities, vmin,BAL and vmax,BAL, and the v98 of CIV emission lines. These correlations are tighter in high
redshift quasars. We also find evidence for an
evolution of
outflow properties across
cosmic time, with high-
redshift quasars exhibiting systematically larger CIV line shifts and broader profiles, and faster BAL
outflows. According to our
outflow toy model, these correlations suggest a scenario in which a clumpy BAL wind is composed of expelled and accelerated broad-line region gas clouds.
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All authors M. Brazzini, M. Bischetti, S. Hagen, V. D'Odorico, N. Arav, G. Becker, G. Cupani, F. Fiore, M. Ghosh, E. Piconcelli, F. Salvestrini, M. Sharma, A. Travascio, A. Tortosa, G. Vietri, L. Zappacosta, C. Feruglio
High Energy Physics (Phenomenology)
Resonant Gravitational Production of Chiral Dark Photons
Leah Jenks, Marc Kamionkowski and Edward W. Kolb
Vector fields with a
chiral, parity-odd coupling to a pseudoscalar field are known to undergo resonant amplification. In this work, we study this phenomenon in the context of cosmological gravitational particle production during early-universe inflation. We consider a massive vector (dark
photon) field with a parity-odd coupling to the inflaton. There are two regimes of production, delineated by the relative size of the coupling and the dark
photon mass, arising from a tachyonic instability, and a parametric resonance, respectively. As a result of the coupling, the transverse modes, subdominant in both the minimally and nonminimally coupled theories, can dominate the total late-time abundance. The viable parameter space for dark-
photon dark matter is thus widened. Furthermore, in the tachyonic case, the production is dominated by a single helicity mode, leading to a population of
chiral dark
photons that can lead to potential parity-violating observational signatures. We further explore the dependence of the production on the reheating history, and find that information about reheating is encoded in the number density spectrum.
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High Energy Physics (Theory)
Microcanonical Operator Spectrum, BPS Chaos and Free Probability Theory
Alexandre Belin, Yichao Fu and Federico La Rocca
Matrix elements of simple operators are central to thermalization in chaotic
quantum many-body systems. Their moments are often described statistically through the Eigenstate Thermalization Hypothesis. In this paper, we study a more refined characterization of these
matrix elements: the eigenspectrum of simple operators once projected to microcanonical energy windows. The spectrum encodes all moments of the
matrix elements at once, and is particularly relevant when the spectrum of the
Hamiltonian is degenerate. Assuming that the eigenbasis of the simple operator is Haar-randomly oriented with respect to that of the
Hamiltonian, we prove that the spectrum of an operator projected to a small microcanonical window obeys Gaussian random
matrix statistics. We do this directly by studying the probability distribution inherited from the random orientation, as well as using tools from Free Probability Theory. We discuss the implications for BPS chaos and more generally for eigenstate thermalization.
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High Energy Astrophysical Phenomena
Geometrically Thin Sub-Eddington AGN Accretion Disks show a suppressed Lyman Edge
Ish Kaul, Yan-Fei Jiang, Omer Blaes et al. (+1 more)
The observed ultraviolet continua of active
galactic nuclei (AGN) generally lack a strong intrinsic HI Lyman edge predicted by classical optically thick
accretion disk atmosphere models. We revisit this long-standing problem using our previous sub-Eddington ($L/L_{\rm Edd}\sim 0.03$) geometrically thin 3D
accretion disk simulation evolved with gray angle-dependent radiation magnetohydrodynamics (MHD) around a $10^8M_{\odot}$ black hole. This disk is
magnetic pressure dominated, and has surface densities more than two orders of magnitude below the corresponding radiation-pressure-supported $\alpha$-disk prediction. By restarting the simulation with multiple frequency groups, we compute the emergent continuum directly from the frequency-dependent radiation fluxes and find no sharp HI Lyman edge at 13.6 eV. This suppressed Lyman edge is mainly caused by the low densities in a
magnetic pressure supported disk where the Lyman opacity jump is far weaker than in standard disk models. These results indicate that
magnetic pressure support may provide a possible solution to reconciling optically thick AGN disks with the smooth observed continuum emission around the Lyman edge. However, in this simulation, a substantial fraction of the emission near 13.6 eV is expected to originate at smaller radii closer to the central black hole, which is outside our simulation domain. More detailed predictions of the spectrum will require an extension to the inner disk, non-LTE radiation transfer, higher frequency resolution and a survey across a broader range of
accretion rates.
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All authors Ish Kaul, Yan-Fei Jiang, Omer Blaes, Lizhong Zhang
Strongly Correlated Electrons
Bootstrap certification of string order in quantum spin chains
Sagnik Banerjee, Haoyu Guo and Debanjan Chowdhury
The many-body bootstrap certifies ground-state properties by minimizing energy over correlators constrained only by positivity, without any variational wavefunction. Its cost, however, grows exponentially with the size of the operators involved, placing the long-range string correlators that diagnose topological phases out of reach. We overcome this by treating string operators as primary objects: bare and endpoint-dressed strings satisfy a closed operator
algebra with one another and with local words, yielding a semidefinite program whose cost grows only polynomially with string length. A single computation then yields estimates of string correlators of all lengths. Rigorous two-sided bounds are obtained for each target string once the ground-state energy is pinned within a window. When benchmarked against density-
matrix renormalization group computations on the cluster Ising and
spin$-1$ Heisenberg chains, the method certifies the nonlocal string order of the cluster and Haldane phases directly from the
Hamiltonian. Our rigorous certification of string order parameters reveal that the sharpness of the bounds is set by which operators enter the calculation, not by their length alone. By exploiting algebraic closure of strings and local words, our framework lifts spatially extended observables into polynomially tractable bootstrap variables, opening up a route to wavefunction-free certification of nonlocal order in
quantum many-body systems.
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Statistics Applications
Projected Effects of Naloxone and Buprenorphine Scale-Up on Opioid Overdose Mortality in Six Pennsylvania Counties
Abdulrahman A. Ahmed, M. Amin Rahimian, Qiushi Chen et al. (+1 more)
Opioid overdose deaths remain a severe public health crisis in the US, with heterogeneous burden across counties that differ in epidemic trajectory, baseline resources, and local context. While harm reduction through naloxone distribution and buprenorphine treatment are both evidence-based strategies, limited information on county-level effects hinders the ability of policymakers to prioritize resources across counties. We developed a simulation model of opioid use disorder (OUD), calibrated separately to six Pennsylvania counties spanning large urban (Allegheny, Philadelphia), intermediate-sized (Erie, Dauphin), and rural (Clearfield, Columbia) settings. We projected county-specific overdose mortality trajectories under three levels of increase in buprenorphine dispensing and naloxone distribution (10%, 20%, and 30% above each county's baseline), over a five-year horizon from 2025 to 2029. A 30% increase in naloxone distribution above projected county baseline levels was projected to reduce 2029 overdose deaths by approximately 70% (95% uncertainty interval, UI: 55-81%) in Allegheny County, 11% (95% UI: 4-17%) in Erie County, and 28% (95% UI: 2-64%) in Clearfield County. The relative projected benefits of naloxone and buprenorphine varied by county; buprenorphine produced larger reductions in Erie and Dauphin. The same proportional increase in naloxone distribution produced substantially different projected mortality reductions across the six Pennsylvania counties. County-level context is important for informing harm reduction and treatment prioritization at the county level.
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All authors Abdulrahman A. Ahmed, M. Amin Rahimian, Qiushi Chen, Praveen Kumar
Differential Geometry
The suboptimal Penrose inequality for charged initial data sets
Eunice Ng
Given a complete, 3-dimensional, asymptotically flat initial data set for the Einstein-Maxwell equations with vanishing
magnetic field, we show that there exists a small universal constant $\mathcal{C}$ such that $m\geq\mathcal{C}(\sqrt{\mathcal{A}/(16\pi)}+\mathcal{Q}^2\sqrt{\pi/\mathcal{A}}\,)$. An analogous statement holds for asymptotically hyperboloidal initial data sets with the ADM mass replaced by
hyperbolic energy. Under the additional assumption of axisymmetry, the inequality may be further strengthened to include angular momentum. These results extend the Penrose-type inequalities recently obtained by Allen-Bryden-Kazaras-Khuri to the charged setting.
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