Quantum Physics
Quantum deformations of $\mathcal{U}(\mathfrak{sl}(2, \mathbb{R}))$. Part I: Fidelity and experimental benchmarking
V. Mariscal, J.J. Relancio and L. Santamaría-Sanz
This work explores the effects of both the standard
quantum $q$-deformation and the non-standard $h$-deformation of the
Hopf algebra $\mathcal{U}(\mathfrak{sl}(2, \mathbb{R}))$ on multi-
qubit systems. By constructing the states of a
Hilbert space of $N$
qubits through the Clebsch-Gordan coefficients associated with the deformed
algebras, we show that these states naturally coincide with the eigenstates of the
Hamiltonian of the $q$- and $h$-deformed Kittel-Shore models. We compare the resulting deformed states with those typically targeted in
quantum information experiments, providing a bridge between algebraic constructions and experimentally relevant
quantum resources. Fidelities with respect to the undeformed states are computed to establish how the
quantum correlations are affected, both for few-
qubit systems (including Dicke and non-Dicke states), and in the macroscopic limit ($N \to \infty$) through closed-form formulas derived for arbitrary Dicke states. The results reveal different behaviors between the two deformations. The $q$-deformation smoothly modifies the states and maintains a residual overlap with the original configurations, while the $h$-deformation rapidly makes the states orthogonal to their undeformed counterparts. Both models demand a standard $N^{-1}$ rescaling to preserve fidelity stability in the macroscopic limit.
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Astrophysics of Galaxies
Characterizing the Formation and Evolution of S0-galaxies (CaFES-0): Their formation pathways around Galaxy Clusters
Diego Pallero, Yara L. Jaffé, Amelia Fraser-McKelvie et al. (+7 more)
The formation pathways of lenticular
galaxies (S0s), which lie morphologically between elliptical and spiral
galaxies, remain a topic of active research. Environmental effects, merging histories, and pre-processing mechanisms are often proposed as key factors influencing their transformation. However, the relative importance of these processes remains unclear, particularly when compared with other
galaxy types. We use the Hydrangea cosmological zoom-in simulation suite to analyse the environmental histories of S0
galaxies, defined here as central and satellite quenched disk
galaxies. We find that the vast majority (>85%) of our sample of S0s are satellites in massive
haloes (log$_{10}$M$_{200}/$M$_\odot$ > 13), while only $\sim10\%$ are centrals in low-mass
haloes. Satellite S0s exhibit a highly quiescent merging history, with $\sim60\%$ experiencing no significant mergers since $z=2$. Centrals show more varied merging histories, although our results may be affected by limited sample size. Contrary to expectations, no clear trends in merger ratios with morphology are observed. However, mergers involving lenticular and spiral
galaxies tend to occur in low-density environments and are likely gas-rich, enabling disk reformation. Pre-processing effects in groups are critical, influencing both quenching and morphological transformation.} Our results strongly suggest that S0
galaxies predominantly form from faded/stripped spirals in clusters, with a minority forming via mergers in smaller
haloes. These results are in agreement with previous observations of lenticular
galaxies around
galaxy clusters.
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All authors Diego Pallero, Yara L. Jaffé, Amelia Fraser-McKelvie, Lodovico Coccato, Facundo A. Gómez, Yannick Bahé, Evelyn J. Johnston, Ciria Lima-Dias, Arianna Cortesi, Maria Emilia De Rossi
Cosmology and Nongalactic Astrophysics
Fireworks at Cosmic Dawn: relieving BAO-CMB tensions with the Pop III.1 Flash
Yash Aggarwal, Christopher Cain, Garett Lopez et al. (+4 more)
A
Cosmic Microwave Background (CMB) optical depth of $\tau \sim 0.09$, several $\sigma$ in excess of the latest Planck low-$\ell$ EE polarization measurement, has been proposed as a way to reconcile the preference for a sub-minimal
neutrino mass sum in a combined analysis with CMB and Dark Energy Spectroscopic Instrument (DESI) three-year data. Reionization, however, is not just probed by $\tau$. It is also constrained by Ly$\alpha$ forest observations that indicate a late end of reionization, and the patchy kinetic Sunyaev-Zel'dovich (pkSZ) effect which prefers a short duration. We explore whether an early phase of reionization can achieve a high $\tau$ while remaining consistent with both Ly$\alpha$ forest and pkSZ constraints. As a concrete example, we consider supermassive Pop III.1
stars, dark-matter-powered metal-free
stars proposed as progenitors of supermassive black holes. Within this framework, self-regulating ionizing feedback imposes a minimum source separation of $\sim 1 \, \text{cMpc}$, consequently limiting large-scale ionization fluctuations and reducing the pkSZ power on observationally relevant scales. Our fiducial model realizes an optical depth of $\tau = 0.087$ with a Pop III.1-driven flash ionization phase centered at $z = 20$, while evading the most conservative $2\sigma$ upper limits on the pkSZ signal from the most recent South Pole
Telescope data release. More broadly, our findings motivate further exploration of early reionization models with weakly clustered sources as a possible resolution of tensions between BAO and CMB measurements.
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All authors Yash Aggarwal, Christopher Cain, Garett Lopez, Hy Trac, Anson D'Aloisio, Philip Tanedo, Jonathan C. Tan
Quantum Physics
Efficient classical representation and quantum state preparation of complete active space wavefunctions
Hamza Jnane
Quantum computers promise to solve the electronic structure problem for a large class of molecules. However, the performance of relevant
quantum algorithms hinges on preparing initial states with substantial overlap with the target eigenvector. For classically challenging molecules with strong electron correlation, starting from multi-reference states, such as complete active space (CAS) wavefunctions is necessary. Unfortunately, the most advanced state preparation protocols applied to such states result in a gate complexity that scales exponentially with the active space size $d$. In fact, even encoding a CAS state classically is traditionally believed to be intractable for chemically relevant systems. Here, we draw insights from the recently introduced
Quantum Paldus Transform (QPT) to show that there exists an efficient classical representation of CAS states and to design a new state preparation routine outperforming previous ones. The QPT represents a transformation from the Fock basis to a friendlier
symmetry-adapted basis. Our main contribution consists in showing that CAS states expanded in this basis can efficiently be represented as a
matrix product state (MPS) with a bond dimension scaling as $O(d^2)$. One can then efficiently load the MPS on a
quantum computer and use the inverse QPT to transform the state to the Fock basis. Moreover, our method can easily be extended to the efficient preparation of CAS states in first quantisation with similar complexity. Crucially, we demonstrate that the complexity of both state preparation protocols only grows polynomially as $O(d^3)$ , which constitutes to the best of our knowledge an exponential improvement over the state of the art.
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High Energy Astrophysical Phenomena
Short-Range Forces Can Catalyze Extreme Orbital Evolution in Hierarchical Triples
Ygal Y. Klein and Chris Hamilton
Hierarchical triples are promising environments for producing exotica such as black hole mergers and hot Jupiters, because of the von Zeipel-Lidov-Kozai (ZLK) effect, whereby a distant tertiary can torque an inner binary to high eccentricity over secular timescales. In the double-averaged (DA) approximation to ZLK, this eccentricity excitation is suppressed by apsidal precession due to "short-range forces" (SRFs) like relativity and
tidal/rotational bulges. Here we show that, when the DA approximation breaks down, SRFs often catalyze, rather than suppress, extreme eccentricity behavior. This occurs because SRFs can drive large, discrete jumps in the binary's effective "adiabatic invariants" during high-eccentricity episodes. These nonadiabatic jumps can dramatically alter the maximum/minimum eccentricity and secular period of astrophysically relevant triples, including some for which SRFs were previously thought irrelevant. Even the angular momentum component j_z evolves secularly – to our knowledge, this is the first time such
evolution has been demonstrated from a test-particle quadrupole-order, three-body mechanism. In short, binaries may explore much more of phase space than is implied by any (semi-)analytic ZLK theory of which we are aware. We demonstrate this at the test-particle quadrupole level; in a companion work we show how even more-extreme behavior occurs when the jumps are combined with octupolar ZLK
evolution.
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Solar and Stellar Astrophysics
X-Shooter survey of disk accretion in Upper Scorpius II. A lack of correlation between accretion rates and disk properties
A. Empey, C.F. Manara, R. Garcia Lopez et al. (+19 more)
The
evolution of protoplanetary discs is intertwined with the process of
planet formation, growth and migration. Studies of nearby
star forming regions of different ages and properties provide the necessary information needed to understand the processes dictating their
evolution. This paper presents the results of a spectroscopic study of the
stellar and
accretion properties of a large sample of 127
stars with protoplanetary discs in the Upper Scorpius region with disc
dust masses inferred from ALMA continuum measurements. The
accretion luminosity is derived from the excess UV continuum emission with respect to the photospheric and chromospheric one self-consistently with the
stellar spectral types, extinction and luminosity, using FRAPPE. We apply a new method to evaluate upper limits to the
accretion luminosity. In ~50% of cases we evaluate upper limits on the
accretion luminosity, either because the S/N of the data is insufficient or because the measured value of the
accretion luminosity is below the estimate of the emission due to chromospheric activity. The results show that the mass
accretion rate has a weak correlation with the
stellar mass, while no correlation is observed with disc properties such as
dust mass or gas disc radius. The dispersion is larger than what is found in younger
star forming regions such as Lupus and Cham. I, and suggests a fading of the correlations with age. We find no evidence that membership to Upper Scorpius sub-groups, nor the properties of known binary or transition discs can explain the origin of this dispersion. The lack of correlation and large dispersion of
accretion rates challenge the current expectations of evolutionary models. The observed properties point to a decoupling of the inner and outer disc by the age of Upper Scorpius and a fading of the relations observed in younger
star forming regions.
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All authors A. Empey, C.F. Manara, R. Garcia Lopez, A. Natta, R. Claes, F. Zagaria, J.M. Alcalá, R. Anania, G. Beccari, J. Carpenter, S. Facchini, D. Fedele, G. Lodato, K. Mauco, A. Miotello, B. Nisini, I. Pascucci, L. Piscarreta, G. Rosotti, A. Scholz, L. Testi, M. Vioque
Astrophysics of Galaxies
Baryonic mass budgets in the central regions of the Bullet Cluster and their consistency with strong lensing in MOND
Dong Zhang, Hosein Haghi, Elena Asencio et al. (+8 more)
Strong
lensing observations of the Bullet Cluster have traditionally been regarded as strong evidence for dark matter and a major challenge to Milgromian dynamics (MOND). The offset between the
lensing mass and the X-ray gas centroids implies a substantial amount of unseen mass near the brightest cluster
galaxies (BCGs). However, the high
metallicities observed in both the intracluster gas and the massive early-type member
galaxies suggest a past
stellar population dominated by massive
stars, whose evolved remnants contribute additional baryonic mass. This effect is naturally incorporated in the integrated
galaxy-wide initial mass function (IGIMF) theory, which predicts substantially larger baryonic masses than a canonical IMF. In this work, we re-estimate the baryonic masses of the three BCG-centred core regions of the Bullet Cluster using recent JWST photometry and compare them with MOND strong-
lensing masses. We derive IGIMF masses using
stellar population synthesis models with constant and (self-) enriched
metallicities, representing lower and upper mass limits, respectively. We find that the MOND strong-
lensing masses of all three cores lie within the range predicted by the IGIMF models. These results suggest that the baryonic mass budget is consistent with MOND requirements from strong-
lensing observations in the core regions of the Bullet Cluster. However, the physical viability of this scenario also depends on the spatial distribution and dynamical behavior of the remnant population, which remain to be established. More generally, regardless of the validity of MOND, the results imply that less dark matter may be required than previously inferred.
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All authors Dong Zhang, Hosein Haghi, Elena Asencio, Indranil Banik, Akram Hasani Zonoozi, Sangjun Cha, Boseong Young Cho, Hyungjin Joo, Pavel Kroupa, Anastasia Lazutkina, Eda Gjergo
Cosmology and Nongalactic Astrophysics
Validation of the Hybrid Bias Expansion model for the galaxy bispectrum
Marcos Pellejero Ibáñez, Raul E. Angulo, Laila Linke et al. (+8 more)
The Hybrid Bias Expansion model (also known as Hybrid Effective Field Theory, HEFT) provides a promising way to extend the range of validity of perturbative large-scale structure modelling by replacing perturbative gravitational
evolution with the nonlinear displacement field measured from $N$-body simulations. While this approach has already been shown to improve the modelling of the power spectrum, its validity at the bispectrum level has not yet been established. In this work we perform a first systematic real-space validation of the Hybrid bispectrum model using DESI-like LRG and ELG mock catalogues constructed at fixed cosmology on volumes similar to those of DESI's LRG samples. We find that the model remains self-consistent up to $k_{\rm max}^B \simeq 0.25\,h\,{\rm Mpc}^{-1}$, while clear signs of breakdown appear for a similar EFT tree-level bispectrum approach at $k_{\rm max}^B \gtrsim 0.13\,h\,{\rm Mpc}^{-1}$. We also show that adding matter cross-statistics significantly improves the precision of the recovered bias parameters, while a partial third-order extension including only the $\delta^3$ operator does not extend the validity range. Finally, we find a strong hierarchy among the bispectrum basis terms when grouped by total bias-operator order, with the lowest-order sectors dominating the total amplitude, which has important implications in emulation strategies.
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All authors Marcos Pellejero Ibáñez, Raul E. Angulo, Laila Linke, Sara Ortega-Martinez, Maria Tsedrik, Sergio Contreras, John A. Peacock, Kate Storey-Fisher, Jens Stücker, Rodrigo Voivodic, Matteo Zennaro
High Energy Astrophysical Phenomena
Nonlinear Decay of Fast Magnetosonic Waves through Weak Turbulence: Force-Free Electrodynamics Simulations
Siddhant Solanki, Jens Mahlmann and Alexander Philippov
We investigate the propagation of low-frequency fast-magnetosonic (FMS) waves in highly magnetized environments. Such conditions are relevant to the escape of GHz fast
radio bursts potentially produced in the inner magnetospheres of magnetars. It remains an open question whether such waves can escape without substantial reprocessing. Using relativistic force-free electrodynamics simulations, we confirm the key theoretical predictions of Golbraikh & Lyubarsky (2023) and demonstrate that FMS waves undergo efficient nonlinear conversion into secondary FMS and Alfvén waves via the parametric decay instability. This process continues to drain energy from the primary FMS waves even after approximate energy equipartition between the FMS and Alfvén components is established. The resulting spectrum of excited waves is broad, extending across much of the inertial range in $k$-space within the simulation domain. Our results indicate that FMS waves likely do not escape magnetar magnetospheres without substantial dissipation and spectral broadening.
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Cosmology and Nongalactic Astrophysics
A self-consistent analytical model for both the photoionization rate and reionization history
Christopher Cain, Kevin S. Croker, Anson D'Aloisio et al. (+4 more)
Recent developments at the intersection of cosmology and astrophysics have highlighted the need for improved analytical models of observables that probe the Epoch of Reionization. With few exceptions, fast analytical treatments of reionization suitable for use in
Bayesian inference have been limited to modeling the reionization history, $x_i(z)$. Such models cannot take full advantage of observables that constrain $x_i$ indirectly. One such observable is the photoionization rate of neutral hydrogen, $\Gamma_{\rm HI}(z)$, which can be inferred from the mean transmission of the Lyman-$\alpha$ forest of high-
redshift quasars and
galaxies. It has been shown by several prior works that the
evolution of $\Gamma_{\rm HI}$ at $5 \lesssim z \lesssim 6$ is highly sensitive to the tail end of reionization, potentially providing a tight astrophysical constraint on the reionization timeline. We present a new analytical formalism, based on the cosmological radiative transfer equation, that self-consistently predicts $x_i$ and $\Gamma_{\rm HI}$. We test our model against detailed radiative transfer simulations and find it to be percent-level accurate in $x_i$ and $20-30\%$ accurate in $\Gamma_{\rm HI}$ at $z \lesssim 6$ - better than or comparable to existing observational uncertainties. Finally, we demonstrate that modest shifts in the ionizing
photon output of high-
redshift galaxies and/or the endpoint of reionization lead to differences in $\Gamma_{\rm HI}$ much larger that the model's intrinsic uncertainty, highlighting its utility for interpreting existing data. We explore the origin of modeling uncertainty in $\Gamma_{\rm HI}$ and comment on future pathways for improvement.
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All authors Christopher Cain, Kevin S. Croker, Anson D'Aloisio, Ivelin Georgiev, Hurum Maksora Tohfa, Yongda Zhu, Rogier Windhorst
High Energy Astrophysical Phenomena
Damping of Fast Radio Bursts in the Inner Magnetospheres of Magnetars
Siddhant Solanki, Jens Mahlmann, Alexander Philippov et al. (+1 more)
We investigate the propagation of fast
radio bursts (FRBs) through magnetar magnetospheres. Previous work showed that, in the inner magnetosphere, GHz
radio waves propagate as fast magnetosonic waves and undergo resonant three-wave interactions that transfer their energy into trapped Alfvén waves. Using three-dimensional force-free electrodynamics simulations, we demonstrate that FRBs would excite Alfvénic fluctuations, leading to strong nonlinear attenuation of the
radio signal. In quiescent dipolar magnetospheres, the nonlinear decay stays efficient within $\sim10$–$100$ magnetar radii; charge starvation of the excited Alfvén waves stops the decay at larger radii. For FRBs propagating within relativistic
magnetic outflows launched during magnetospheric eruptions, three-wave interactions remain efficient and constrain the escape radius to $\gtrsim10^2$–$10^3$ magnetar radii for luminous bursts. Our results confirm that nonlinear
plasma processes strongly limit the escape of FRBs from the inner magnetospheres of magnetars.
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All authors Siddhant Solanki, Jens Mahlmann, Alexander Philippov, Andrei Beloborodov
Astrophysics of Galaxies
Reimagining SED Fitting with Cosmological Galaxy Simulations and Machine Learning
Dhruv T. Zimmerman and Desika Narayanan
SED fitting is the most common technique to recover
galaxy physical properties from observed photometry. However, SED fitting requires many assumptions that essentially collapse a
galaxy from a three-dimensional spatially varying object with complex structure into a scalar point. Moreover, modern inference techniques are computationally intensive, which presents a unique challenge in the era of extremely large
datasets. We present Phot-Gal, a new
galaxy SED modeling tool that solves the inverse problem of SED fitting by training a machine learning model on photometry generated from 3D radiative transfer of simulated
galaxies with a wide range of implemented physics. Phot-Gal is designed to accept an arbitrary amount of input photometry by utilizing a $K$-nearest neighbors imputation strategy. Our fiducial model predicts
redshift,
stellar mass,
dust mass, and
star formation rate with uncertainties based on the provided input photometry. We evaluate the performance of Phot-Gal relative to the commonly-used SED fitting tool prospector in successfully recovering each of these properties with several metrics for the inferred values and uncertainties and find that it outperforms the accuracy of standard SED fitting software on the testing set. However, with fewer photometric constraints, Phot-Gal is more likely to have output uncertainties that do not reflect the offset from the ground truth. We dissect the components of Phot-Gal to find reasonable physical justifications for the photometry it relies on most, understand how each step in its workflow contributes to the eventual output posterior, and evaluate its ability to generalize to novel data.
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General Relativity and Quantum Cosmology
Dynamical tidal response of neutron stars: From effective field theory to gravitational waveforms
Thomas Apostolidis, Valerio De Luca, Leonardo Gualtieri et al. (+3 more)
We investigate the fully relativistic dynamical
tidal response of
neutron stars up to second order in the frequency. Combining the worldline effective field theory for extended gravitating bodies with perturbation theory of relativistic
stellar models, we derive the
tidal deformation induced by an external time-dependent field, including a universal logarithmic running term. In the effective theory, we work in dimensional regularization and, through a consistent matching procedure, obtain for the first time the complete leading-order dynamical
tidal corrections to both the conservative dynamics and the gravitational-wave signal of compact binaries, including the scheme-dependent finite terms in addition to the running. We show that, in the relativistic regime, dynamical effects cannot be fully captured by mode excitations alone. The magnitude of the additional contribution depends on the
stellar compactness, the equation of state, and the running term. Dynamical Love numbers are significantly enhanced with respect to their static counterparts for relatively small compactness. As a result, although they formally enter the gravitational-wave phase at eighth post-Newtonian order, dynamical
tidal effects yield a nonnegligible contribution during the late inspiral. Using a Fisher-
matrix analysis, we show that third-generation detectors such as the Einstein
Telescope could measure dynamical Love numbers for a range of
neutron-
star masses and equations of state. Conversely, neglecting these effects can lead to significant biases in the inference of static Love numbers, and hence on the
nuclear equation of state. Our results highlight the importance of dynamical
tidal effects for high-precision gravitational-wave modeling with future detectors.
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All authors Thomas Apostolidis, Valerio De Luca, Leonardo Gualtieri, Takuya Katagiri, Paolo Pani, Luca Santoni
High Energy Astrophysical Phenomena
Evidence for protostellar jets as a population of hadronic gamma-ray sources
Javier Méndez-Gallego, Rubén López-Coto, Emma de Oña Wilhelmi et al. (+3 more)
Stars are born in darkness, deep within cold, dense molecular clouds where
gravity drives the collapse of gas and
dust, giving rise to protostars, the earliest stages of
stellar evolution. Once considered purely thermal sources, these young systems are now emerging as sites of energetic non-thermal activity. While
radio synchrotron jets hinted at the presence of relativistic electrons, direct confirmation of
proton acceleration remained elusive. Here we report a statistically significant detection of gamma rays from a population of young
stellar objects, revealing a
Galactic class of Gamma-Loud Protostars. Observations point towards particle acceleration within protostellar jets, where gamma-ray emission arises from
protons interacting with surrounding molecular clouds via pion decay. We find a correlation between
cosmic-ray output and bolometric luminosity, suggesting that particle acceleration scales with the system's mechanical power. These findings open a new observational window into the role of non-thermal processes in protostellar
evolution and suggest that gamma-ray studies of protostars can provide critical insights into
accretion, ejection, and feedback in
star formation. This previously overlooked emission traces the energetic feedback that young
stars inject into their surroundings, shaping the conditions for subsequent
star and
planet formation.
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All authors Javier Méndez-Gallego, Rubén López-Coto, Emma de Oña Wilhelmi, Stefano Menchiari, Iván Agudo, Rubén Fedriani
Quantum Gases
Unleashing Emergent Fermions with Rydberg Atom Simulators
Hanteng Wang, Xingyu Li, Shang Liu et al. (+2 more)
Rydberg atom simulators, in both analog and digital modes, have attracted significant recent interest due to their versatile
geometric reconfigurability. In this work, leveraging this feature, we propose two complementary approaches, one for each mode, to characterize emergent
fermions in critical
quantum many-body systems. In the analog mode, we assemble the Rydberg atoms in a "developable" (namely, preserving local couplings) Möbius band geometry to realize antiperiodic boundary conditions, where fermionic states reside. Spectroscopic measurement in this sector then reveals universal energy ratios of the bosonic and fermionic states. In the digital mode, we carry out a fermionic version of Kibble-Zurek ramping with a
quantum circuit, directly addressing the fermionic scaling form. Reconfigurability allows an exponential speed-up of this task, with an $O(\log L\log\log L)$
circuit-depth overhead. Our work establishes the Rydberg atom simulator as a uniquely powerful platform to attack the notoriously difficult issue of experimentally probing emergent
fermions that are nonlocally defined in a bosonic system.
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All authors Hanteng Wang, Xingyu Li, Shang Liu, Yingfei Gu, Chengshu Li
Cosmology and Nongalactic Astrophysics
The impact of evolving cosmic filaments on mass and spin evolution of dark matter halos
Hannah Jhee, Hyunmi Song, Clotilde Laigle et al. (+3 more)
The
evolution of
galaxies is closely tied to that of their host dark matter
halos, which is in turn strongly modulated by the surrounding large-scale environment.
Cosmic filaments are expected to influence the peculiar motions, mass assembly and angular momentum of nearby
halos through highly anisotropic matter flows. In order to fully capture the dynamic interplay between the filaments and
halos, we develop an
algorithm to trace the progenitors of individual filaments identified at z=0 with DisPerSE in a cosmological N-body simulation, by quantifying the spatial similarity between a descendant filament and progenitor candidates. This enables us to reconstruct filament-by-filament evolutionary histories, including their bulk drift and the
evolution of density profiles, from which splashback radii and core overdensities are derived. Using these time-dependent properties, we re-examine
halo phase-space trajectories in a filament-centric frame that evolves with time. This eliminates biases inherent to static models by separating
halo motions from the motion of the filaments, allowing trajectories to be identified more reliably. We find that as
halos approach high-density filaments, their mass
accretion rates are systematically suppressed beginning at the filament outskirts, suggestive of
tidal stripping or suppressed net
accretion. Furthermore, the
evolution of
halo spin alignments exhibits a clear departure from
stochastic random-walk expectations. This suggests that distinct mass flow regimes in and around filaments exert different torques on infalling
halos, thereby changing their angular momentum. Our findings, derived from a sample screened for major mergers, highlight the pure dynamical impact of the filamentary environment. Ultimately, we demonstrate that tracking the simultaneous co-
evolution of filaments and
halos is essential for accurately characterizing environmental effects.
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All authors Hannah Jhee, Hyunmi Song, Clotilde Laigle, Christophe Pichon, Corentin Cadiou, Ena Choi
Astrophysics of Galaxies
Eppur non si trovano Vol. 3: Phoebe – a Mirage of a Primordial Black Hole
Andrzej Udalski and Przemek Mróz
Recent preprints by Key et al. reported the discovery of a short-lived brightening of a
star (nicknamed "Phoebe") located in the Large Magellanic Cloud that was interpreted as a short-timescale gravitational microlensing event produced by a lunar-mass
primordial black hole (PBH) in the Milky Way dark matter
halo. Here, we present an independent re-analysis of the publicly available DECam observations of this object, incorporating additional data from 2020 and 2021. The object underwent at least three distinct, low-amplitude brightenings (one of which was misinterpreted as a short-timescale microlensing event) in addition to long-term variations of its mean magnitude. These characteristics indicate that Phoebe is an ordinary variable
star rather than a microlensing event. This finding resolves the apparent tension with the results from earlier microlensing experiments that rule out the hypothesis that a substantial fraction of dark matter is composed of lunar- and planetary-mass PBHs.
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Solar and Stellar Astrophysics
An Ultramassive White Dwarf with a Likely Oxygen-Neon Core
Stefan M. Arseneau, J.J. Hermes, Vedant Chandra et al. (+4 more)
The core composition of ultramassive white
dwarfs remains an open question in
stellar evolution. The carbon content of white
dwarf cores is critical to their role as progenitors of Type Ia
supernovae. However, because the
stellar photosphere only extends to the outermost layer of the
star, observational probes of core compositions are limited. Here we present gravitational
redshift measurements of an ultramassive white
dwarf, SDSS J060851.44-005950.3, which indicate the likely presence of an oxygen-neon core. We measure the mass ($1.226_{-0.025}^{+0.024} M_\odot$) and radius ($0.491_{-0.009}^{+0.009}~R_\oplus$) of the white
dwarf using gravitational
redshifts from high-resolution UVES and MagE spectra paired with independent constraints from photometry. By comparing to state-of-the-art mass-radius relations for ultramassive white
dwarfs, we find preference for a oxygen-neon core over a carbon-oxygen core, with a Bayes factor of $2.7$. This is a white
dwarf which is likely structurally incapable of producing a Type Ia
supernova, according to current understanding of
supernova physics. This object provides evidence that white
dwarfs which pass through the Q-branch without experiencing a delay in cooling compared to the normal white
dwarf cooling sequence likely have oxygen-neon cores.
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All authors Stefan M. Arseneau, J.J. Hermes, Vedant Chandra, Roberto Raddi, Maria E. Camisassa, Alberto Rebassa-Mansergas, Santiago Torres
High Energy Physics (Theory)
Moduli Stabilisation for ADD and the Dark Dimension Scenario
Andreas P. Braun, Michele Cicoli, Riccardo Milioli et al. (+1 more)
We provide a
moduli stabilisation mechanism for realising anisotropic string compactifications with one or two large extra dimensions, corresponding to the ADD and Dark Dimension scenarios. This is achieved within the type IIB Large Volume Scenario, where an exponentially large Calabi-Yau volume in string units can naturally generate a parametrically low Kaluza-Klein scale. Anisotropy is realised by considering a Calabi-Yau threefold which is a K3 fibration over a $\mathbb{P}^1$ base. The volume of the 4D K3 fibre is stabilised at relatively small values by perturbative corrections to the effective action, in particular string loops and higher-derivative effects, leaving an exponentially large volume of the 2D $\mathbb{P}^1$ base. We argue that complex structure
moduli stabilisation can dynamically deform the $\mathbb{P}^1$ base, corresponding to a Tyurin degeneration limit where the internal geometry effectively develops a single large 1D cycle. Within a unified description, the ADD case is instead recovered as a symmetric alternative limit. The potential can feature either a dS
vacuum or a quintessence runaway, although in both cases some degree of tuning is required to match the observed cosmological constant scale. We also present an explicit Calabi-Yau orientifold example with consistent brane setup, tadpole cancellation and
moduli stabilisation. We analyse the resulting
moduli spectrum and associated phenomenological constraints, including supersymmetry breaking, cosmological
moduli overproduction and fifth force bounds.
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All authors Andreas P. Braun, Michele Cicoli, Riccardo Milioli, Roberto Valandro
High Energy Physics (Phenomenology)
From Rags to Jeans: Axion Miniclusters from Early matter domination
Ariel Angulo, Paola Arias, Nicolás Bernal et al. (+1 more)
In an early matter-dominated era, density and temperature inhomogeneities of the radiation bath grow more efficiently than in the standard radiation-dominated history. If the
axion mass depends on temperature, these inhomogeneities induce spatial fluctuations of the
axion mass, providing a new source term for
axion density perturbations. We show that this mechanism is most efficient when the reheating temperature lies just below the mass-saturation scale $T_\Lambda$, and can drive
axion overdensities to order unity by matter–radiation equality. For the QCD
axion saturating the observed dark matter abundance, the nonlinear spectrum at equality exhibits two characteristic regions: one associated with the gravitational enhancement already present in
moduli-driven cosmologies, and another produced by the temperature dependence of the
axion mass. We estimate the resulting minicluster masses and discuss the possible formation of
axion miniclusters and
axion-
star substructure.
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All authors Ariel Angulo, Paola Arias, Nicolás Bernal, Javier Redondo
Quantum Physics
Indefinite Quantum Causality
Fabio Costa, Giulia Rubino, Cyril Branciard et al. (+2 more)
In recent years, operational approaches to
quantum foundations have been developed as a means of understanding the core principles and distinctive features of
quantum theory. Such approaches typically view physical processes as sequences of operations, with earlier operations serving as causes of later effects. However, a growing literature is emerging on the possibility of relaxing this assumption and allowing for
quantum indefiniteness in the causal order. This development stems from a variety of motivations, both fundamental and applied, including exploring the role of causality in
quantum theory, the interplay between
quantum theory and general relativity, and higher-order
quantum computing. A prominent offshoot of this development is the emergence of indefinite causal order as a feasible resource for
quantum information processing. This review provides an overview of the current state of the art in the field, covering the methodology underlying indefinite
quantum causality within the so-called "process
matrix formalism", outlining key results and experimental implementations, and discussing recent advances.
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All authors Fabio Costa, Giulia Rubino, Cyril Branciard, Časlav Brukner, Marco Túlio Quintino
Strongly Correlated Electrons
Many-Body Protection of Topological Edge Memory in Strong Interacting Quenches
Yuxiao Hang, Stephan Haas and Rishabh Jha
Quantum quenches drive edge states far from
equilibrium, yet whether the
memory of a topological initial state survives in a non-integrable, interacting system has remained largely unexplored. We study this question in the bond-alternating XXZ chain—an interacting Su–Schrieffer–Heeger model hosting
symmetry-protected topological edge modes with markedly enhanced boundary magnetization—and analyze quenches across all combinations of single-particle and many-body initial and final
Hamiltonians. The results organize by a single distinction as we rigorously establish in this work: whether the post-quench
Hamiltonian is free or genuinely interacting. For a free post-quench
Hamiltonian, the dynamics is solved exactly by a correlation-
matrix approach; the boundary-mode return amplitude decays as $t^{-3/2}$, and initial interactions enter only through a dressed one-body density
matrix. For a genuinely interacting post-quench
Hamiltonian, finite-time stability bounds prove that away from local resonances the first-dimer magnetization remains stable on time windows growing as arbitrarily large powers of the inverse inter-dimer coupling.
Matrix product state simulations across all four protocols show that interactions in the final
Hamiltonian markedly extend finite-time boundary
memory—with local suppression near the isotropic $SU(2)$ point—revealing a many-body protection mechanism in a non-integrable system where scrambling would otherwise wash out initial-state
memory fast.
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Disordered Systems and Neural Networks
Observation of complete delocalization in disordered photonic lattices
Biplab Pal and Rodrigo A. Vicencio
We present the exceptional phenomenon of complete absence of Anderson localization, and perfect transmission of particles, in a completely disordered diamond-dot chain. We analytically show a proof for the condition to observe this exceptional phenomenon, based on a transparent window emerging from a geometrical condition. We support our theoretical prediction by numerical simulations and direct experimental observation of the transmission probabilities of the light in a femtosecond
laser-written diamond-dot photonic
lattices. We additionally show that for a $\pi$ effective
magnetic flux, extreme localization of the light in the same system may occur, independently on the specific geometry. Our results open up an excellent platform for controlling the transmission of energy from ballistic to zero transmission, in a completely disordered
lattice system..
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General Relativity and Quantum Cosmology
Deriving effective descriptions and signal predictions for dynamical gravitational systems
Steven B. Giddings and Madhur Mehta
We investigate top-down derivations of effective descriptions of radiation from gravitational systems such as binaries. With a specified cutoff prescription, one can derive worldline effective field theories, although the associated cutoff dependence can complicate their formulation. We investigate a related effective approach in which the dynamics are parameterized by an action on the boundaries of cavities enclosing the individual bodies. We present examples of such cavity descriptions for black holes and for simple models of modified black hole behavior. We also show how cavity effective descriptions connect to observable quantities including Love numbers and aspects of wave profiles, such as the accumulated phase shifts of emitted signals. A primary motivation is to develop a systematic framework for inferring how modifications of classical black hole behavior affect gravitational wave signals. Such modifications may be motivated by the requirement that black hole
evolution be consistent with
quantum mechanics, or by other models of new black hole behavior. Accumulated phase shifts during the inspiral have, in particular, been argued to provide sensitivity to small new effects. To illustrate the basic principles clearly, we develop the formalism primarily for scalar radiation, and then outline its extension to gravitational perturbations.
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Cosmology and Nongalactic Astrophysics
Testing X-ray selection effects with four rich, yet X–ray–faint, galaxy clusters
S. Andreon and A. Moretti
A robust understanding of selection effects in
galaxy cluster studies is crucial for both astrophysical and cosmological applications. Examining clusters identified through different observational strategies, even in small numbers, helps to illuminate potential biases inherent to each method. We selected four rich
galaxy clusters in the Northern Hemisphere whose early Swift X-ray
Telescope (XRT) observations indicated unusually low central X-ray emission, making them unlikely to be detected in X-ray surveys. Spectroscopic follow-up confirms that all four systems are genuine
galaxy clusters, rather than projections of multiple clusters or groups along the line of sight. Their optical richness, estimated using one of the baseline Euclid cluster richness
estimators, implies masses of $\log M_{200}/M_\odot \sim 14.6$ and independently confirms the absence of additional massive structures along the line of sight. Deep XRT follow-up reveals highly disturbed X-ray morphologies: three clusters exhibit at least two distinct X-ray peaks, while the remaining cluster has an axis ratio exceeding 1.5. Spectroscopy shows that
galaxies associated with different parts share the same
redshift, demonstrating that these substructures are physically connected rather than chance projections. These clusters display low central X-ray surface brightness and total X-ray luminosities suppressed by roughly one dex for their richness, making them undetectable in X-ray surveys as eROSITA. We estimate $\sim$20% as a lower limit for the poorly sampled population, albeit based on a small sample. Our results demonstrate that even rich clusters in the northern $z<0.3$ Universe can be missed by X-ray selection and that the X-ray variety captured by X-ray surveys underestimates the true cluster diversity.
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General Relativity and Quantum Cosmology
Exact Solution of the Non-minimally Coupled Klein-Gordon Equation in the Schwarzschild Star
Reynan A. Dulinayan and Kevin T. Grosvenor
We present for the first time the exact solution of the massive Klein-Gordon equation in the Schwarzschild
star (perfect-fluid, uniform-density, spherically-symmetric
star), including the non-minimal
curvature-scalar coupling. The solution is expressed in terms of the general Heun function. A geometry-induced algebraic coordinate transformation reveals a hidden Fuchsian structure that underlies the exact solvability. Known leading- and next-to-leading-order results are recovered in the low-compactness limit. In the Buchdahl limit, we derive a regularity condition for static modes and describe analytically the divergence in amplitude and oscillation wave vector of dynamic modes as they approach the pressure singularity at the center of the
star.
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High Energy Physics (Phenomenology)
Partial-wave unitarity and long-range interactions
Ryan Plestid and Pablo Quílez Lasanta
Theories with massless particles contain $t$-channel (forward scattering) singularities that cause standard fixed order expressions for partial-wave amplitudes to be ill-defined. This presents an obstruction to systematically improvable partial-wave unitarity bounds. In this work, we study the construction of partial-wave amplitudes in a modified perturbation theory that incorporates long-range interactions focusing on the role of off-shell Coulomb modes. We find that there exists a universal description of the forward scattering region that renders the amplitudes renormalization scale independent. The resulting partial-wave amplitudes become well defined single-scale objects without spurious dependence on the infrared regulator, and we present a practical method for their computation order-by-order in perturbation theory.
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Statistical Mechanics
Odd fluids from chiral cellular automata
Andrew A. Allocca, Shiva Heidari, Thomas Iadecola et al. (+3 more)
Cellular automata are discrete dynamical systems defined on a
lattice, in which each site carries a finite set of states that evolve in time according to local deterministic rules. An important application of cellular automata is in
lattice gas models of fluids, where the cellular automaton framework provides a particle-based microscopic description of hydrodynamic behavior. The macroscopic fluid equations emerge after coarse-graining over many
lattice sites and time steps, offering a bottom-up route to hydrodynamics. A celebrated example is the Frisch-Hasslacher-Pomeau (FHP) model, an automaton defined on a two-dimensional triangular
lattice that yields the two-dimensional Navier-Stokes equations upon coarse-graining. In this work, we construct a parity-breaking generalization of the FHP model through two modifications: introducing
chiral two-body collision rules and systematically rotating particle velocities to mimic the effect of a background
magnetic field. We show that this automaton yields a hydrodynamic model with odd viscosity, a transverse transport coefficient that is a hallmark of odd fluids. We verify the analytical transport coefficients using Poiseuille-flow simulations of the
chiral FHP automaton. Our results demonstrate that the
chiral automaton introduced here provides a bridge between microscopic parity-breaking scattering processes and macroscopic odd-fluid hydrodynamics.
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All authors Andrew A. Allocca, Shiva Heidari, Thomas Iadecola, Armin Rahmani, Pouyan Ghaemi, Sriram Ganeshan
Quantum Physics
Solving Nonequilibrium Dynamics via Influence Matrix Bootstrap: Floquet-PXP Model
Xiao-Yang Yang, He-Ran Wang and Zhong Wang
Studies of integrable systems have profoundly deepened the fundamental understanding of
quantum many-body physics. While
equilibrium properties such as ground states and thermodynamics can often be characterized efficiently, accurately characterizing nonequilibrium integrable dynamics remains a significant challenge. Here, we develop an influence
matrix bootstrap approach for exactly solving nonequilibrium dynamics. This approach begins with an ansatz consisting of a set of local tensor relations, termed generalized zipper conditions, and uses finite-time data to construct exact solutions of local dynamics that extend to arbitrarily long times. We demonstrate this approach in the "Rule 201"
quantum cellular automaton, an integrable Trotterization of the PXP
Hamiltonian. This uncovers a rich landscape of nonequilibrium behavior exhibiting initial-state dependence. As an example, we investigate the fate of persistent oscillating dynamics under local non-integrable perturbations, and present analytical results for non-thermal relaxation constrained by conservation laws. We also obtain numerically exact results for
entanglement growth across a broad class of initial states. Furthermore, from an information-theoretic perspective, we identify a refined structure of multitime correlations termed the hidden Markov orde}: the
memory encoded in the dynamics separates into finite-length and long-range distributed components, which becomes transparent in an exact split-index
matrix-product-state representation of the influence
matrix. Our approach enables unified investigations of nonthermalizing and thermalizing regimes of nonequilibrium dynamics within a single analytically tractable model, and can be tested experimentally in state-of-the-art
quantum simulators such as Rydberg atom arrays.
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Cosmology and Nongalactic Astrophysics
BayeSN $\times$ Dovekie: Joint Photometric Cross-calibration and SED Modelling of Type Ia Supernovae
M. Grayling, B. Popovic, M. Ginolin et al. (+2 more)
We present a new framework for BayeSN, the hierarchical
Bayesian SED model for type Ia
supernovae (SNe Ia), incorporating cross-calibration of samples observed across heterogeneous
telescopes. This framework is the first to parametrise the filter wavelength and zero-point offsets commonly used in SN~Ia cosmology within SN SED model training, enabling additional constraint on cross-calibration from SNe beyond the standard
stellar-based cross-calibration pipeline. We apply this framework to train a new G26 BayeSN model on the same SED model training sample used in recent cosmological analyses, an order-of-magnitude increase over previous BayeSN training samples, and include a novel training methodology to leverage high-
redshift SNe Ia in BayeSN training. We present the G26 model and apply it to the DES-SN5YR sample to assess performance, finding a 12 per cent reduction in $\sigma_{\rm NMAD}$ scatter when compared with SALT3$.$Dovekie; 0.164 mag compared with 0.185 mag for a sample of likely SNe Ia at $z < 0.7$, without bias corrections. We additionally present constraints on cross-calibration wavelength and zero-point shifts from our framework when using the latest `Dovekie' calibration constraints as a prior. This work is a key step towards a full end-to-end cosmological analysis with BayeSN; the new G26 model is incorporated within the public BayeSN code.
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All authors M. Grayling, B. Popovic, M. Ginolin, A. Do, K. S. Mandel