Earth and Planetary Astrophysics
Revisiting the Exo-Mercury Candidate GJ 367 b with ESPRESSO and a Self-Consistent Tidal Distortion Model
Rena A. Lee, Fei Dai, Ellen M. Price et al. (+18 more)
We report revised mass and radius measurements for GJ 367 b, an ultra-short-period (7.7 hr) sub-Earth in a multi-
planet system orbiting a nearby (~9 pc) M
dwarf host. Previous mass and radius measurements have suggested GJ 367 b has an anomalously high bulk density, close to that of solid iron. The existence of such an iron-rich
planet is in tension with established
planet formation scenarios. We utilized newly available TESS short-cadence photometry to constrain the radius of GJ 367 b to 0.736 +/- 0.035 R_Earth. We consider observational and modeling effects such as photometric dilution,
stellar activity, and
tidal distortion to account for possible inaccuracies in the
star and
planet radius measurements. From our radial velocity (RV) analysis using VLT/ESPRESSO data covering nearly the full orbit in a single night, we find a mass of 0.503 +/- 0.078 M_Earth, corresponding to a bulk density of 6.9 +1.6/-1.4 g cm-1. We present a new
tidal distortion and interior composition modeling framework to assess the iron mass fraction of GJ 367 b. Considering several different interior composition assumptions and radial aspect ratios, we find an iron fraction of ~50-70%, which is broadly consistent with that of Mercury and not as iron rich as previously suggested.
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All authors Rena A. Lee, Fei Dai, Ellen M. Price, Te Han, Davide Gandolfi, Mathias Zechmeister, Gu{\dh}mundur Stefánsson, Jiayin Dong, Simon H. Albrecht, Kristine W.F. Lam, Federica Chiti, Jennifer L. van Saders, Daniel Huber, Heather A. Knutson, Karen A. Collins, Michael Zhang, Leslie A. Rogers, Eleonora Armano, Casey L. Brinkman, Nicholas Saunders, Daniel Hey
High Energy Astrophysical Phenomena
Late-time JWST/NIRCam Observations of the Extremely Long-duration GRB 250702B/EP 250702a and Its Host Galaxy
Huei Sears, Jean J. Somalwar, Ryan Chornock et al. (+22 more)
We present JWST/NIRCam observations of the extremely long-duration gamma-ray burst (GRB) 250702B taken at ~ 95 days post-GRB (observer frame). The observations of the host
galaxy reveal a single
galaxy with a prominent
dust lane observed nearly edge-on. Prospector modeling of the host
galaxy photometry finds a high
stellar mass (log(M_*/M_Sun) = 11.0 +0.2/-0.3) and large
dust column (A_V = 2.8 +/- 0.3 mag), in agreement with previous results. If GRB 250702B is a collapsar-driven GRB, the host
galaxy is the brightest (in rest-frame r and rest-frame H) and most massive compared to GRB hosts at similar
redshifts. The transient localization is near the
dust lane, and while we find no evidence for transient emission in F277W, F356W, and F444W, forced photometry in F150W and F200W reveals possible ~ 3 sigma detections of the transient at m_{F150W} ~ 27.9 AB mag and m_{F200W} ~ 27.4 AB mag. If these are secure detections, they are indicative of a late-time light curve flattening. This behavior is consistent with that of jetted
tidal disruption events (TDEs); however, it is also consistent with a
supernova plus GRB afterglow model. Alternatively, if these are upper limits, they are consistent with, but do not further constrain, the extrapolated power-law decline of the afterglow. The ambiguity of the possible detection of the transient in F150W and F200W highlights the need for late-time template observations with JWST/NIRCam.
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All authors Huei Sears, Jean J. Somalwar, Ryan Chornock, Tanmoy Laskar, Andrew Levan, Raffaella Margutti, Brendan O'Connor, Nayana A. J., Tomas Ahumada, Kate D. Alexander, Igor Andreoni, Akash Anumarlapudi, Jonathan Carney, James Freeburn, Lluís Galbany, Benjamin P. Gompertz, Or Graur, Saarah Hall, Xander J. Hall, Erica Hammerstein, Saurabh W. Jha, Mansi M. Kasliwal, Dheeraj Pasham, Itai Sfaradi, Yuhan Yao
Astrophysics of Galaxies
TNG SAM: Bridging Hydrodynamical Complexity and Semi-Analytic Efficiency to Model Galaxy Formation
Osase Omoruyi, Bryan A. Terrazas, Yossi Oren et al. (+5 more)
All cosmological models of
galaxy formation must navigate the trade-off between physical accuracy and computational efficiency. Hydrodynamical simulations provide spatially resolved predictions for the co-
evolution of dark matter, gas,
stars, and black holes, but rely on phenomenological subgrid models for small-scale processes (e.g.,
star formation). Semi-analytic models (SAMs), by contrast, gain efficiency through simplified, analytic treatments of the same processes, at the cost of reduced predictive scope. In this work, we leverage the strengths of the Santa Cruz SAM and the IllustrisTNG hydrodynamical simulation to develop the TNG SAM. Calibrated to reproduce
baryon cycling in
stellar feedback-dominated TNG
galaxies ($\sim 10^{10}M_\odot < M_{200} < 10^{12}M_\odot$), the TNG SAM introduces several key updates to the Santa Cruz framework regarding: 1)
halo gas (re-)
accretion efficiency, 2) a cooling model that moves beyond the traditional cold/hot mode dichotomy, 3) explicit treatment of both
galactic- and
halo-scale
outflows, 4)
star formation efficiency, and 5) the circulation of metals between
galaxies and their surroundings. These changes enable the TNG SAM to reproduce TNG's flow of gas and metals from the scale of the
galaxy to the
halo, as well as global
galaxy (e.g.,
stellar mass) and
halo (e.g. hot
halo gas mass) properties within $\lesssim 30\%$ accuracy out to $z=6$. This work demonstrates that, with appropriate calibration, SAMs can capture the complex physics of
galaxy formation modeled in hydrodynamical simulations while providing a flexible framework for studying
galaxy evolution across the large cosmological volumes targeted by future observational surveys.
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All authors Osase Omoruyi, Bryan A. Terrazas, Yossi Oren, Austen Gabrielpillai, Viraj Pandya, Rachel S. Somerville, Amiel Sternberg, Lars E. Hernquist
High Energy Physics (Theory)
Probing weak chaos in $\mathcal N=4$ super Yang-Mills and long-range spin chains
Pawel Caputa, Brian Creed, Rathindra Nath Das et al. (+2 more)
We study signatures of
quantum chaos in finite-loop truncations of the planar dilatation operator in the $\mathfrak{su}(2)$ sector of $\mathcal N=4$ super Yang-Mills and its $\beta$-deformation. These truncations define holographically motivated long-range deformations of the nearest-neighbour XXX
spin chain. At one-loop the model is integrable, while the all-loop planar theory is expected to again be integrable. Finite-loop truncations therefore provide a natural setting for investigating how chaotic behaviour emerges between these two integrable limits. We analyse this question using spectral statistics, eigenvector diagnostics and spread complexity. We find that the two- and four-loop truncations develop GOE-like level statistics at sufficiently large coupling but with features characteristic of weak integrability breaking. The integrability breaking at four-loops is weaker than at two-loops and the critical coupling at which chaos occurs is larger, at least for long
spin chains. The three-loop truncation does not show the same onset of chaos in the range studied. Eigenvector diagnostics show that the corresponding eigenstates remain less random than GOE vectors, indicating weak ergodicity and multifractality. Finally, we can identify signatures of the
eigenvalue and eigenvector chaos in the Krylov-space data. Namely, we demonstrate a correlation of the level spacing statistics with the peak of spread complexity and disorder on the Krylov chain. The delocalisation of the initial state in the
Hamiltonian eigenbasis is shown to strongly affect the saturation of complexity. Our results suggest that finite-loop dilatation operators are not generic long-range
spin chain
Hamiltonians, but already display patterns consistent with the restoration of integrability in the all-loop planar theory.
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All authors Pawel Caputa, Brian Creed, Rathindra Nath Das, Saskia Demulder, Tristan McLoughlin
Astrophysics of Galaxies
A Long Period Stellar-Mass Black Hole Binary in $\omega$ Centauri
Matthew Whitaker, Evan Kerr, Anil Seth et al. (+16 more)
Modern simulations of
stellar dynamics in globular clusters peg a dominant role for
stellar-mass black holes, but direct evidence for black holes in clusters remains limited. We present the discovery of an astrometric
stellar-mass black hole–main sequence
star binary in $\omega$ Centauri, the most massive
Galactic globular cluster, using Hubble Space
Telescope data from the oMEGACat project and additional JWST data that span a total of 23 years. The luminous companion to the black hole is a main-sequence turnoff
star, and has a period of $94^{+63}_{-42}$ years, a semi-major axis of $31^{+15}_{-12}$ AU, and an eccentricity of $e=0.72^{+0.08}_{-0.13}$. Since we observe the binary during periastron, the mass of the black hole is well-constrained even though we only observe a partial orbit: the inferred black hole mass is $4.46^{+1.22}_{-1.01}$ M$_\odot$. We call this black hole oMEGACat BH-2. This is the first astrometric discovery of a
stellar-mass black hole in a globular cluster, and is the longest period black hole binary system yet discovered. The low mass of this black hole is perhaps surprising given the low
metallicity of the cluster, and shows that at least some low-mass black holes form at
metallicity $Z<10^{-3}$. We find that the binary is almost certainly dynamically formed and is soft, with an expected binary disruption timescale of $\sim$800 Myr. While the total number of black hole binaries in $\omega$ Centauri is uncertain, we show that existing surveys only cover a small area of parameter space, and that the presence of additional detectable black hole binaries is likely.
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All authors Matthew Whitaker, Evan Kerr, Anil Seth, Maximilian Häberle, Jay Strader, Jay Anderson, Andrea Bellini, Callie Clontz, Zack Freeman, Massimo Griggio, Sebastian Kamann, Mattia Libralato, Nadine Neumayer, Elena González Prieto, Carl L. Rodriguez, Sara Saracino, Peter Smith, Glenn van de Ven, Zixian Wang
High Energy Physics (Theory)
Ghosts versus Unstable Particles in Quantum Field Theory
Luca Buoninfante
We elucidate the physical nature of ghosts above the multi-particle threshold by contrasting them with unstable particles in
quantum field theory. We first consider the asymptotic formulation, where ordinary positive-norm one-particle states can be unstable and decay, whereas ghosts survive asymptotically without decaying, yet admit no particle interpretation due to interference with the multi-particle component which masks the negative-norm one-particle state. This distinction originates from two different analytic structures of the dressed propagator, whose complex conjugate poles lie on the first or second Riemann sheet in the ghost or ordinary case, respectively. Ghost resonances are, in principle, phenomenologically distinguishable from ordinary ones, being narrower and exhibiting weaker interference between positive- and negative-energy peaks. We then formulate the
quantum field theory in a finite interval of time and, working within a suitable approximation for the dressed propagator, find that finite-time effects amplify differences in the resonant behavior and give rise to new features, such as higher peaks in ghost resonances. Distinct temporal regimes are also identified: for times shorter than the inverse width, an approximate free-particle description is valid; at later times interactions and interference dominate, leading to decay or multi-particle masking. This study supports the absence of freely propagating ghost particles in the asymptotic limit.
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Quantum Physics
Steady-state spectral kissing and dissipative phase transitions
Devesh Karthik, Jorge Chávez-Carlos, Edson M. Signor et al. (+3 more)
Spectral kissing, recently realized in a Kerr parametric oscillator (KPO), refers to the merging of pairs of energy levels and arises as a manifestation of an excited-state
quantum phase transition (ESQPT). Here, we show that this phenomenon has a dissipative counterpart encoded in the spectrum of the steady-state density
matrix. Using a dissipative KPO as a representative example, we demonstrate that, in the weak-dissipation regime, the
eigenvalues of the steady-state density
matrix organize into quasi-degenerate pairs that mirror the spectral kissing of the corresponding closed system. As the dissipation strength increases, this pairing gradually disappears. By analyzing the classical limit of the system, we derive analytical expressions for the critical lines governing both the onset of steady-state spectral kissing and its disappearance at a dissipative phase transition.
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All authors Devesh Karthik, Jorge Chávez-Carlos, Edson M. Signor, Victor S. Batista, Francisco Pérez-Bernal, Lea F. Santos
High Energy Physics (Phenomenology)
Self-Calibration of the Neutrino-Argon Cross Section with Solar Neutrinos
Rasmi Hajjar, Obada Nairat and John F. Beacom
The success of DUNE's MeV physics program depends upon high-precision knowledge of the charged-current (CC) $\nu_e+\mathrm{^{40}Ar}$ cross section. While there are indirect constraints at the 10% level for the
nuclear transitions that constitute this cross section, the only direct measurement in the MeV range has an uncertainty of $\sim$50%. We show, surprisingly, that the cross section can be precisely measured using the
solar-
neutrino data themselves. This is possible because of independent knowledge of the $^8$B flux and survival probability, plus the distinctive angular distributions of the
Fermi and Gamow-Teller transitions that comprise the cross section. We propose new methods to extract the transition strengths, considering both intuitive groupings and a Principal Component Analysis. Under pessimistic assumptions about detection, but taking detector uncertainties to be controlled, we demonstrate that a precision of $\lesssim$2% on the cross section can be achieved in the 9-15 MeV energy range. These results will be an important foundation for studying the cross section up to several tens of MeV, where the complexity increases significantly due to
nuclear breakup channels but where reducing uncertainties is critical for
supernova and atmospheric
neutrino studies.
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Mesoscale and Nanoscale Physics
Quantum Geometry and Topology of Bulk Plasmons in Weyl Metals
Hong-Yi Xie, Peter Abbamonte and Bruno Uchoa
We address the
quantum geometric structure of plasmons in
Fermi surfaces enclosing a topological charge. We demonstrate that Weyl
fermion plasmons have monopole structure, are topological and have a finite vorticity $\zeta=2\mathsf{C}_{\text{w}}$, where $\mathsf{C}_{\text{w}}$ is the Chern number of the
Fermi surface enclosing the Weyl point. We show that these plasmons selectively couple to light linearly polarized along the plasmon effective dipole moment $\mathbf{d}$, which has
quantum geometric origin and points along the direction of the plasmon center of mass momentum $\hat{\mathbf{Q}}$. We suggest that Weyl metal topological plasmons have distinctive optical properties compared to conventional plasmons.
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High Energy Physics (Theory)
Exponentiation of higher-point and higher-genus Virasoro conformal blocks in the semiclassical limit
Marius Gerbershagen and Jakob Hollweck
A long-standing
conjecture claims that Virasoro conformal blocks exponentiate in the semiclassical limit $c \to \infty$ with $h/c$ finite. However, this has been proven only for four-point blocks on the sphere and one-point blocks on the
torus. Here we extend the proof to general conformal blocks for higher-point functions and higher-genus backgrounds in arbitrary channels. The statement is to be understood at the level of a formal power series. Our proof builds upon a novel extension of the oscillator method for the computation of conformal blocks to cases where three internal lines meet at a vertex. This extension also gives a new constructive method to compute global conformal blocks in 2d CFTs at general genus.
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High Energy Physics (Theory)
Black p-brane Thermodynamics without Constructing Solutions
Bing-Yang Han and H. Lu
This paper generalizes the method used in the previous article 2512.09930 to black $p$-brane thermodynamics in arbitrary dimensions containing black holes and strings as special cases: thermodynamic quantities can be derived without constructing the corresponding black $p$-brane solutions. We further extend the discussion to black holes or $p$-branes involving a general scalar coset.
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High Energy Physics (Theory)
The pole truth: an analytical graviton propagator from Asymptotic Safety
Benjamin Knorr
We derive an analytical approximation for the graviton propagator from Asymptotic Safety. We find neither extra poles nor indications of unitarity or causality violations in the
spin-two sector. Our results strengthen the case that Asymptotic Safety does not introduce new degrees of freedom, and thus propagates the same field content as General Relativity. We also identify the underlying mechanism: the residues of spurious poles in finite-order derivative expansions approach zero as the order is increased.
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Astrophysics of Galaxies
Compact Core, Extended Reach: A Bipolar kpc-Scale Elongation in a Little Red Dot at $z \approx 5.5$
Zhiyuan Ji, Yang Sun, Mauro Giavalisco et al. (+7 more)
Little Red Dots (LRDs) appear extremely compact at rest-frame optical wavelengths, yet many show extended rest-frame UV morphology revealing more complex internal structure. We present a combined analysis of VLT/MUSE rest-frame UV integral-field spectroscopy and continuum-subtracted [O III], H$\beta$, and H$\alpha$+[N II] emission-line maps from JWST/NIRCam imaging at sub-kpc resolution for LRD-204851 at $z=5.482$ in GOODS-S. We find that LRD-204851 hosts a remarkably thin, bipolar, elongated structure passing through the optical continuum centroid and extending several kpc on either side, traced by both the UV continuum and the rest-frame optical emission lines, with a bright [O III] clump-like structure $\sim$2 kpc to the south-east of the centroid. The MUSE observations reveal a double-peaked Ly$\alpha$ profile, with a broad and bright near-systemic red peak and a relatively faint peak blueshifted by $\sim$430 km s$^{-1}$, accompanied by a tentative N V $\lambda 1238$ detection at similar velocity. In narrow-band imaging extracted from the MUSE IFU cube, both the blue Ly$\alpha$ peak and the tentative N V emission lean toward this same south-eastern direction. Independently, radiative-transfer modeling of the integrated Ly$\alpha$ profile favors a biconical low-column-density cavity in a dense, slowly expanding neutral envelope, in support of the bipolar geometry traced by the line maps. Together, these results suggest that the elongated emission of LRD-204851 is connected to radiation and/or gas flow from its central engine through a low-column-density channel with a small opening angle that may trace either a slow
outflow or a quasi-static ionization cone. LRD-204851 is one of the first LRDs where the central engine's impact on its host
galaxy is potentially directly observable on kpc scales.
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All authors Zhiyuan Ji, Yang Sun, Mauro Giavalisco, Yongda Zhu, George H. Rieke, Christina C. Williams, Michael V. Maseda, Jianwei Lyu, Marcia Rieke, Sandro Tacchella
General Relativity and Quantum Cosmology
Orbital evolution of asymmetric binaries within accreting environments
Albert Radulea, Marcelo E. Rubio, Konstantinos Kritos et al. (+1 more)
Extreme mass-ratio inspirals embedded in
accretion disks provide a natural arena for studying the interplay between relativistic orbital dynamics and environmental effects. In this work, we develop a framework to investigate the secular
evolution of compact objects repeatedly crossing an
accretion disk around a supermassive black hole. The orbital motion is modeled through Kerr geodesics, while disk interactions are encoded through effective prescriptions for mass
accretion and dynamical friction. We find that disk-induced dissipation generically drives a two-stage
evolution characterized by rapid
alignment of the orbital plane with the disk, followed by slower eccentricity damping. By systematically comparing the dynamics with a purely Keplerian treatment, we show that cumulative relativistic effects produce deviations even at large orbital separations, where the Keplerian approximation would naively be expected to remain accurate. These discrepancies grow through repeated disk crossings and become increasingly pronounced in more relativistic orbital configurations. We further investigate the impact of the
accretion-disk model by comparing the Sirko-Goodman and Novikov-Thorne prescriptions. Relativistic disk structures predict systematically lower densities and larger scale heights, leading to weaker orbital dissipation and slower secular
evolution. By contrast, the
spin of the central black hole has only a minor effect on the overall circularization efficiency. Our results demonstrate the importance of consistently modeling both relativistic orbital dynamics and disk structure when studying compact objects embedded in AGN disks, and provide a framework for exploring their long-term
evolution, as well as a possible connection to quasi-periodic eruptions.
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All authors Albert Radulea, Marcelo E. Rubio, Konstantinos Kritos, Andrea Maselli
Quantum Physics
Chaos from quantum bath fluctuations
Ilan Baud, Tamoghna Ray, Mahaveer Prasad et al. (+2 more)
The effect of a large environment on a finite-size
quantum mechanical system is two-fold: It brings dissipation, but also fluctuations of thermal and
quantum origin. While dissipation tends to stabilize the dynamics, we question if and how environmental
quantum fluctuations can generate chaos in an otherwise classically non-chaotic system. We work out a paradigmatic model of
quantum optics: the dissipative Dicke model, where a large
spin interacts with a dissipative harmonic mode. We dial in the classical/
quantum correspondence by working in the semiclassical regime at large but finite
spin. We demonstrate that, starting from a classically regular phase space in the superradiant regime,
quantum noise can generate a strange attractor with fractal dimension and a positive Lyapunov exponent. We unveil the deep connection with shear-induced chaos that was recently developed in the mathematical community.
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All authors Ilan Baud, Tamoghna Ray, Mahaveer Prasad, Manas Kulkarni, Camille Aron
Quantum Physics
Ground state preparation of random all-to-all Hamiltonians using ADAPT-VQE
Sabhyata Gupta, Bharath Sambasivam, Sophia E. Economou et al. (+3 more)
The ground state of random
Hamiltonians with all-to-all interactions such as the
quantum Sherrington-Kirkpatrick (SK) model and the Sachdev-Ye-Kitaev (SYK) model follow volume-law
entanglement and are expected to be hard to model using tensor networks. In recent years, some progress has been made to push the limit of classical methods using neural
quantum states. However, it remains an open question whether there exist
quantum algorithms that could offer a
quantum advantage over the state-of-the-art classical methods in simulating random
Hamiltonians. In this work, we show that one such
algorithm, TETRIS-ADAPT-VQE, can construct accurate ground states for dense and sparse SYK models containing up to $N=20$ Majorana
fermions achieving fidelities $\geq 99.3\%$ and for the
quantum SK model with up to $L=18$ sites achieving fidelities $\geq 99.9998\%$. We find that while the preparation of ground states is efficient (in terms of operator pool size and
circuit depth) for the SK model, it is not efficient for either dense or moderately sparse SYK models.
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All authors Sabhyata Gupta, Bharath Sambasivam, Sophia E. Economou, Edwin Barnes, Alexander F. Kemper, Raghav G. Jha
Earth and Planetary Astrophysics · Cross-listed from cs.LG
ThousandWorlds: A benchmark for climate emulation of potentially habitable exoplanets
Edward T. Stevenson, Mei Ting Mak, Eric Wolf et al. (+4 more)
The search for life beyond Earth will depend on detecting faint signatures in the atmospheres of potentially habitable
exoplanets. Interpreting those signatures requires understanding the host
planet's
climate: the same molecule may signal life on one
planet and abiotic chemistry on another. Global
climate models (GCMs) provide this understanding, but individual runs can require up to millions of core-hours and substantial domain expert time. Machine-learning emulators could remove this bottleneck, but progress has been limited by the absence of a curated, multi-model exoclimate
dataset. We introduce ThousandWorlds, an ML-ready
benchmark for exoclimate emulation and for the broader regime of low-data, multi-simulator, parameter-to-field regression. The
dataset contains approximately 1,700 simulations from five GCMs, mapping eight
planet parameters to 3D atmospheric fields including temperature, humidity, winds, clouds, and radiation. Three nested subsets define progressively harder challenges: single-simulator regression, multi-simulator regression with complete observations, and multi-simulator regression with structured missingness. We propose two evaluation protocols: one for ranking methods, and one that measures performance relative to the disagreement between GCMs themselves. We evaluate ten baselines spanning simple methods, trees, deep learning, and Gaussian processes. GP-based methods perform best, suggesting that ThousandWorlds exposes a regime where off-the-shelf deep learning does not yet succeed. Data: https://doi.org/10.57967/hf/8695. Code: https://github.com/edstevenson/ThousandWorlds.
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All authors Edward T. Stevenson, Mei Ting Mak, Eric Wolf, Denis E. Sergeev, Tobi Hammond, N. J. Mayne, Miles Cranmer
High Energy Physics (Phenomenology)
Standard Candles for Supernova Neutrino Detection at DUNE
Ting Cheng, Matheus Hostert, Pedro A. N. Machado et al. (+2 more)
The Deep Underground
Neutrino Experiment (DUNE) far detector is sensitive to $\mathcal{O}(10)$ MeV electron
neutrinos through $\nu_e$ charged-current reaction with argon. This capability is a unique window into the $\nu_e$ component of a
Galactic core-collapse
supernova flux. Extracting the properties of the
supernova spectrum is, however, limited by the poorly-known $\nu_e$-Ar cross section. We propose a data-driven strategy that leverages $^8$B
solar neutrinos and
muon-decay-at-rest
neutrinos as standard candles for this process. These calibration samples constrain both the low-energy and high-energy components of the cross section relevant for
supernova detection. Our method reduces the reliance on
nuclear models, which can bias the extraction of the spectral parameters by as much as 300$\%$.
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All authors Ting Cheng, Matheus Hostert, Pedro A. N. Machado, Nityasa Mishra, Adrian Thompson
Earth and Planetary Astrophysics
The Maximum Density of a Collisionally-Produced Planet is A Function of its Mass and Orbital Period
Madison Brady and Darryl Seligman
There are many different theoretical explanations for the formation of high-density Mercury-like
planets, but concrete evidence for any of these formation mechanisms remains elusive. A popular explanation for dense
planets is the collisional hypothesis, which states that iron-rich
planets can be formed as the products of high-energy, mantle-stripping impacts. Planetesimal collision simulations predict that higher-velocity collisions can form higher-density
planets. Motivated by the characteristics of the high-density, short-period (P=0.3d) GJ 367b, we study the results of previously-published smoothed-particle hydrodynamics (SPH) simulations on
exoplanet collisions, combining these with models describing the likely collision velocities of these objects, to investigate the relationship between the core mass fractions (CMFs) of
exoplanets, their masses, and their orbital periods. We predict that collisionally-produced super-Mercuries should be more common (and more dense) at low masses and short orbital periods. This correlation may enable us to pinpoint the formation mechanism of super-Mercuries as the population of observed targets grows. Afterwards, we connect our hypothesis to the observed Mercury-like population of high-density
exoplanets, and find that GJ\,367\,b is the best exoplanetary candidate for collisional formation.
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High Energy Physics (Phenomenology)
Weak corrections to Minimal Dark Matter annihilations
Dario Buttazzo, Mateusz Duch, Pier Paolo Giardino et al. (+1 more)
We compute the one-loop weak corrections to the annihilation cross sections of fermionic Minimal Dark Matter multiplets. Infrared divergences cancel in the dominant $s$-wave combination relevant for the thermal relic abundance. Instead, infrared-enhanced corrections affect velocity-suppressed rates, through a Sudakov/Sommerfeld interplay. The corrections grow with the multiplet size and are at the $5\%$ level in the most motivated cases: the Higgsino-like doublet, the wino-like triplet, the stable quintuplet.
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All authors Dario Buttazzo, Mateusz Duch, Pier Paolo Giardino, Alessandro Strumia
Astrophysics of Galaxies
Diverse Histories and Common Origins of Nitrogen-enhanced JWST Galaxies
Vadim Rusakov, Christopher J. Conselice, Thomas Harvey et al. (+2 more)
Early JWST spectra revealed
galaxies with a strong nitrogen excess challenging
galactic chemical
evolution models. Using public JWST surveys, we construct a sample of 76 N/O-enhanced
galaxies (NOEGs) at 4 $<z<$ 8.5, the largest at high
redshift to date. The NOEG fraction rises from $\sim$3% to $\sim$18% between $z\sim$ 4 and 7 - well above the $\sim$2% measured locally - potentially driven by burstier, cluster-dominated
star formation. Stacked spectra of the most nitrogen-rich
galaxies show signatures of low-
metallicity Wolf-Rayet (WR)
stars, a likely source of primary nitrogen within the first few Myr of a starburst, with UV and optical continua dominated by young
stellar emission and Balmer jumps evident in some cases. Many NOEGs also exhibit ionised
outflows: 40% show secondary [O III] and H$\alpha$ components, while stacked spectra of the remainder reveal a broadened, offset H$\alpha$ without forbidden-line counterparts, suggesting
dust-attenuated or faded
outflows. The continuum in the latter shows a weak Balmer break, indicating these
galaxies are past their most recent burst. This suggests that
outflows dilute gas
metallicity after the first few Myr of the initial enrichment and enable renewed N/O enhancement driven by low-
metallicity Asymptotic
Giant Branch (AGB)
stars. We conclude that NOEGs are caught briefly after a recent starburst: either within $\sim$10 Myr, when WR winds drive nitrogen enrichment, or after 30-40 Myr, when AGB winds take over - following an
outflow driven by radiative or
supernova feedback, consistent with recent chemical
evolution models.
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All authors Vadim Rusakov, Christopher J. Conselice, Thomas Harvey, Jordan C. J. D'Silva, Duncan Austin
Instrumentation and Methods for Astrophysics
Polarisation and Faraday rotation measure imaging at metre wavelengths with sub-arcsecond resolution: a foundational calibration strategy
R. J. van Weeren, J. M. G. H. J. de Jong, X. K Le Saux et al. (+12 more)
Low-frequency
radio polarimetric observations provide a powerful probe of
magnetic fields in astrophysical sources and the intervening medium, as well as magnetospheric emission from compact objects such as
pulsars, magnetically active
stars, brown
dwarfs, and planetary aurorae. With baselines of up to 2000 km, LOFAR offers a unique opportunity to study the low-frequency polarised Universe at sub-arcsecond resolution. However, polarimetric studies with LOFAR have so far been limited to angular resolutions of about 6 arcsec, resulting in stronger beam depolarisation. Here we present a calibration strategy that enables full-resolution polarimetric imaging with the LOFAR pan-European array. Our method applies full-Jones corrections to the international stations using an in-field unpolarised calibrator. In addition, when a sufficiently bright polarised source is present in the field, multi-epoch observations can be aligned in Faraday depth using a visibility-based correction that accounts for polarisation angle and rotation measure offsets. This approach enables deeper combined imaging and deconvolution. We apply this strategy to the LOFAR ELAIS-N1 field, combining four 8 h observations for a total integration time of 32 h. At 0.3 arcsec resolution, we detect two previously known polarised sources identified in lower-resolution studies, resolve additional polarised components, and localise emission regions with sub-arcsecond precision. We also identify a new polarised source and detect circularly polarised emission from the binary M-
dwarf system CR Draconis, measuring its proper motion across epochs. These results demonstrate that sub-arcsecond polarimetry at metre wavelengths is now feasible with LOFAR, opening new science opportunities in the LOFAR2.0 era.
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All authors R. J. van Weeren, J. M. G. H. J. de Jong, X. K Le Saux, V. A. Chakawri, Q. W. E. van Zegveld, D. de Jong, S. P. O'Sullivan, F. Sweijen, V. H. Mahatma, E. De Rubeis, L. K. Morabito, D. Alonso-López, A. Bonafede, C. Horellou, M. van der Wild
Instrumentation and Methods for Astrophysics
The Via Project: Overview of the Science, Instrument, and Survey
The Via Collaboration
Via is a forthcoming all-sky spectroscopic survey that will achieve 100 m s$^{-1}$ radial velocity stability for millions of faint ($G \lesssim 21$)
stars while reaching LSST's single-visit depth ($r \approx 24$) for transient spectroscopy, opening new regimes in near-field cosmology and time-domain astrophysics. Via will deploy identical fiber-fed, multi-object spectrographs on the 6.5m MMT and Magellan/Clay
telescopes for a five-year, dual-hemisphere survey of $>2{,}000{,}000$
stars beginning in 2027 - timed to complement LSST. Each instrument has 576 robotically positioned fibers over a $1^\circ$ field of view, feeding two spectrographs: Viaspec ($R \approx 15{,}000$; 505-595 nm; 540 fibers) and Boombox ($R \approx 1{,}000$; 360-1010 nm; 36 fibers). Four key goals drive the survey: (1) a comprehensive survey of velocity perturbations in cold
stellar streams, sensitive to $M \lesssim 10^7$ subhalos below the threshold of
galaxy formation, a stringent test of the particle nature of dark matter; (2) a chemodynamical census of Milky Way satellite
galaxies to understand the formation of the faintest
galaxies; (3) the first 3D tomographic maps of cold gas in the circumgalactic medium via NaI absorption; and (4) the rapid characterization of thousands of transients to the single-epoch survey depth of LSST. Ancillary science - including the Ly$\alpha$ forest at $z \approx 3$-$4$, polluted white
dwarfs,
exoplanet host characterization, fast
radio burst host
galaxies, and extragalactic
dwarf galaxies - will leverage spare fibers in every pointing. The Via Project is a collaboration between the Center for Astrophysics $|$ Harvard & Smithsonian, Carnegie Observatories, Stanford University, and Yale University.
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High Energy Physics (Theory)
Meromorphic amplitudes from 3-dimensional supersymmetry
Federico Ambrosino and Nathan Haouzi
We establish a new connection between supersymmetric theories and scattering amplitudes. We show that the Coon amplitude coincides with the 3d $\mathcal{N}=2$ half-index of the XYZ model with nontrivial boundary conditions. Our 3d theory, intrinsically defined in the UV, flows to a sigma model in the IR whose partition function is the Veneziano amplitude. Crossing
symmetry is realized as a consequence of 3d $\mathcal{N}=2$ mirror
symmetry between XYZ and SQED. We use this correspondence to construct a meromorphic modification of the Coon amplitude by promoting the long-standing dressing factor $\mathfrak{q}^{ST}$ responsible for a branch cut to an
elliptic completion thereof. This illustrates that one does not have to give up single-valuedness to achieve positivity at the physical poles.
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Instrumentation and Methods for Astrophysics
THOR and HAMRR
Sean K. Terry and Jay Anderson
We present the Terry Hubble Observations of Roman (THOR) data reduction pipeline and Hubble Advanced Mining Routine for Roman (HAMRR). THOR is designed to reduce HST Wide-field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) imaging data taken as part of program GO-17776: A Precursor Survey of the Roman
Galactic Bulge Time Domain Fields (Terry et al, 2024). The primary function of HAMRR is to query the THOR-derived catalog via a typical cone search
algorithm. Output products from HAMRR include calibrated photometry and astrometry for detected point sources in the HST catalog. The package supports additional output products such as cutout images, auto-generated color-magnitude diagrams, luminosity functions, and more. The HAMRR tool can be used in coordination with analyses of Roman, Rubin/LSST, and Euclid
Galactic Bulge targets in the near future.
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Cosmology and Nongalactic Astrophysics
Projecting the ultimate pulsar timing sensitivity to dark matter substructure in a stochastic gravitational wave background
Joshua W. Foster, Tanner Trickle and Fabrizio Vassallo
Pulsar timing arrays (PTAs) are sensitive to the gravitational influence of passing compact substructures, which can produce Doppler timing delays by accelerating
pulsars or the
Solar System barycenter, and Shapiro timing delays when passing near Earth–
pulsar lines of sight. Projections for the complete PTA sensitivity to compact dark matter (DM) substructures, such as
primordial black holes and
axion miniclusters, are challenging due to the variety of signal types ranging from rare, nearly static encounters, to dynamic flybys, to the
stochastic limit of many substructures. We address this challenge with a framework that combines Monte Carlo signal modeling and machine-learned surrogate likelihoods, enabling a unified likelihood-level analysis of signals previously treated only in simplified limiting regimes. We then use this framework to precisely assess the impact of a
stochastic gravitational wave background (SGWB), for which evidence was recently found, on the PTA sensitivity to compact DM substructures. The SGWB substantially weakens the sensitivity, and we find that in even the most optimistic observing scenario only a Shapiro search retains sensitivity to subdominant DM components when assuming SGWB parameters inferred from current measurements.
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Instrumentation and Detectors
Diffuse scattering of neutrons in a wave resonator
E.D. Kolupaev, V.D. Zhaketov and Yu.V. Nikitenko
In fundamental experiments with
neutrons, the
neutron flux and the
neutron storage time in the measuring setup are of primary importance. These quantities can be increased by using a storage device for
neutrons generated by a pulsed source. In a storage device with material walls, both parameters are determined by the probabilities of
neutron absorption and diffuse scattering upon reflection from the storage walls, as well as by the
neutron decay probability. This work considers a
neutron measurement method and presents the results of an experimental determination of the probability of diffuse
neutron scattering in a wave resonator.
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Instrumentation and Methods for Astrophysics
Ultra-High-Resolution Astronomy with the Solar Gravitational Lens
Slava G. Turyshev
The
solar gravitational lens (SGL) is a target-specific observatory: the Sun supplies the wave-optical element, while spacecraft provide occultation, annular photometry, sampling, metrology, and inverse reconstruction. We develop an observability framework for non-
exoplanet SGL astronomy. Viability is set by image-plane scale, raster pitch, finite-source gain, source-to-background ratio, temporal coherence, PSF knowledge, calibration, metrology, and focal-line access. We separate the vector Poisson measurement operator from the scalar convolution used for
benchmarks. Four analytic scenes are propagated and reconstructed: a
solar analog and
magnetic white
dwarf at 10 pc, an M87*-scale millimeter ring/jet source, and a bright 0.1 AU protoplanetary subfield at 140 pc. Under stated kernel-mismatch, background, calibration-floor, support-mask, sampling, regularization, and imposed information-floor assumptions, the scalar reconstructions give SSIM values of 0.993, 0.918, 0.973, and 0.923. These metrics quantify scalar inverse conditioning, not delivered flight performance; FRC50, support-leakage, and information-floor sensitivity diagnostics expose the dependence on assumptions. Many self-luminous compact targets are not
photon-starved relative to a reflected-light exo-Earth reference, shifting the dominant requirements to ring extraction, coronal subtraction, detector dynamic range, PSF knowledge, cadence, spectroscopy, metrology, scan overhead, and access. The strongest bounded cases are white-
dwarf surface and
magnetic mapping, nearby
stellar surfaces, compact AGN/black-hole structure with long-wavelength instrumentation, velocity-resolved broad-line-region mapping, and
planet-forming subfields. The priority enabling program is SGL transfer-function characterization: measuring
solar-multipole,
plasma, extended-Sun, and instrumental response needed for scientifically interpretable imaging.
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Instrumentation and Methods for Astrophysics
Building a Roadmap for Hubble Science into the 2030s: Revealing Atmospheric Structure and Evolution in Substellar Worlds Using HST
Allison M. McCarthy, Merle A. Schrader, Johanna M. Vos et al. (+15 more)
Substellar objects occupy a unique place in our universe, bridging the gap between the smallest
stars and the largest
planets, and serving as powerful laboratories for understanding extrasolar atmospheric physics without the contaminating glare of a host
star. Previous studies into the atmospheric structure of these objects have revealed clouds, disequilibrium chemistry, thermal inversions, and auroral processes which each contribute to wavelength-dependent brightness variations. HST remains uniquely positioned to address key open questions in the field, such as resolving the vertical atmospheric structure, long term
evolution of the atmosphere, and detection of UV aurora in the upper atmosphere, primarily in conjunction with other facilities that probe wavelength regimes that cannot be reached with instruments on HST. We advocate for three large scale initiatives and argue that the study of the atmospheres of substellar worlds directly prepares the community for atmospheric characterization with the Habitable Worlds Observatory.
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All authors Allison M. McCarthy, Merle A. Schrader, Johanna M. Vos, Sven Kiefer, Cian O'Toole, Michael K. Plummer, Michael Poon, Daniella Bardalez Gagliuffi, Samuel Beiler, John E. Gizis, Melodie M. Kao, Gabriel-Dominique Marleau, Elisabeth C. Matthews, Philip S. Muirhead, Evert Nasedkin, Natalia Oliveros-Gomez, J. Sebastian Pineda, Kimberly Ward-Duong
Superconductivity
Superconductivity from interband coupling to ferroelectric quantum critical fluctuations in two dimensions
Sudip Kumar Saha, Jonathan Ruhman and Avraham Klein
Soft critical fluctuations associated with ferroelectric
quantum phase transitions are typically transverse owing to their polar nature. This implies that the conventional density–density electron–
phonon coupling to these modes is strongly suppressed, which is puzzling as a variety of materials exhibit enhanced superconductivity in the vicinity of ferroelectricity. An alternative coupling mechanism is an interband “Stark”-like coupling that connects bands of opposite parity. In the limit where one of the bands is far in energy, these processes generate an effective quadratic (two-
phonon) coupling. In contrast, when both bands lie close to the
Fermi energy, the resulting interaction develops singular behavior due to the additional gapless electronic states, motivating a detailed study into the dynamics of this effective two-
phonon coupling. To this end, we construct the
quantum critical Eliashberg theory for a two-dimensional system across a wide range of interband gap magnitudes, near the
quantum critical point. We find that the critical temperature $T_c$ is strongly enhanced relative to conventional BCS expectations. In the large-gap limit, the pairing kernel acquires higher-order logarithmic contributions, leading to a parametrically enhanced $T_c$ governed by cubic and quadratic logarithmic terms. In the small-gap regime, the pairing scale exhibits a modified BCS-like form with an enhanced dependence on the inverse square root of the dimensionless coupling constant. The enhancement is due to the dynamics of the two-
phonon pairing whose infrared cutoff is set by $T_c$, resulting in a significant enhancement of superconductivity compared to three-dimensional systems, where it is set by the
Fermi energy. Our results elucidate the unique dynamical properties of effective two-
phonon interactions, and may be relevant to layered compounds like Td-MoTe$_2$ and doped SrTiO$_3$ membranes.
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