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Physics Astrophysics

astro-ph Watch Astrophysics

Friday 12 June

Solar and Stellar Astrophysics

Realtime forecasting of solar energetic particle event and proton flux using multi-source solar observations and multi-task deep learning

Yian Yu, Yang Chen, Lulu Zhao et al. (+3 more)

Solar energetic particle (SEP) events, defined by proton flux exceeding 10 pfu in the > 10 MeV channel, pose major risks to spacecraft operations, astronaut safety, and high-latitude aviation. Due to the complexity and rarity of SEP events, reliable operational SEP forecasting remains an important challenge in space weather. Here we present a novel 24-hour-ahead realtime forecasting framework, SEPNET-PRISM, based on a multi-task learning structure and a thoroughly constructed list of features from multiple sources spanning multiple solar cycles, that jointly predicts SEP event occurrence and future proton and soft X-ray fluxes. SEPNET-PRISM extends the earlier-introduced SEPNET-based models by integrating a broader range of solar observations, including active-region magnetic parameters from SHARP and SMARP, solar-flare information, coronal mass ejections, soft X-ray flux, and historical > 10 MeV proton flux. As compared with SEPNET, the inclusion of SMARP data expands the temporal coverage of magnetic-field predictors to earlier solar cycles, while flux-based inputs provide additional precursor information. Evaluation on the CLEAR SEP benchmark dataset shows improved classification performance over the earlier SEPNET-O (operational version of SEPNET) on the newly aligned dataset. The best operational model is obtained when magnetic, radiative, and proton-flux predictors are combined, highlighting the value of expanded historical coverage and complementary precursor information for improving realtime SEP forecasting.
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All authors Yian Yu, Yang Chen, Lulu Zhao, Kathryn Whitman, Ward Manchester, Tamas Gombosi

Earth and Planetary Astrophysics · Cross-listed from eess.SY

Orbital Station-Keeping in the Earth-Moon System via Nonlinear Backstepping

António Nunes, Pedro Batista and Sérgio Brás

A nonlinear orbital station-keeping solution for the circular and elliptic versions of the Earth-Moon Restricted Three-Body Problem (R3BP) is developed via a backstepping technique. Formal guarantees for global asymptotic stability (GAS) are attained, as shown through Lyapunov's stability theory. The adequacy of the proposed control law is evaluated through the means of numerical trials over closed periodic solutions of the circular and elliptic R3BPs. The ramifications of the control gain choice are carefully studied and simulated.
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Earth and Planetary Astrophysics · Cross-listed from eess.SY

A Floquet Mode LQR for Orbital Station-Keeping in Cislunar Space

António Nunes, Sérgio Brás and Pedro Batista

A linear optimal control law for orbital station-keeping in the Earth-Moon Restricted Three Body Problem (R3BP) is developed via Linear Quadratic Regulator (LQR) theory. First, the cost function is established considering a periodic state-weight matrix, leveraging stability information of the target orbits retrieved through Floquet theory. Then, the resulting periodic Riccati differential equation is solved and local asymptotic stability guarantees are shown. Finally, the performance of the proposed LQR when tracking periodic orbits in the circular and elliptic R3BPs is analyzed numerically.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Dynamical tidal response of neutron stars via scattering amplitudes

M.V.S. Saketh, Suprovo Ghosh and Nils Andersson

A key challenge of gravitational-wave physics is distinguishing the nature of compact objects in binary coalescences, in particular whether they are black holes or neutron stars. Neutron stars are set apart by a stronger tidal response, whose static and dynamical aspects are directly linked to their rich internal physics. Measurements of this response through gravitational-wave observations constrain the neutron-star equation of state and provide insight into the physics of high-density matter. However, defining the tidal response in general relativity is difficult due to coordinate ambiguities and the complexity of connecting the star's response to the binary dynamics and the associated waveforms. In this paper, we show how the dynamical tidal response of a neutron star can be systematically defined within the worldline effective field theory (EFT) framework, and relate it to the gauge-invariant amplitude for gravitational-wave scattering off an isolated star. We compute this amplitude both within the EFT, using standard quantum field-theory techniques, and within stellar perturbation theory (the corresponding ultraviolet theory), solving the coupled metric and matter perturbation equations numerically in the stellar interior and matching to the analytical Mano-Suzuki-Takasugi (MST) solutions in the vacuum exterior. Matching the amplitude between the two theories fixes the dynamical tidal response. The result is consistent with known expectations, including the static limit and the behaviour near the star's resonant modes, and it recovers the imaginary part of the dominant oscillation mode induced by gravitational-wave dissipation. We conclude with a discussion of potential improvements within both the EFT and perturbation theory.
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Solar and Stellar Astrophysics

Morphokinematic structure of the Planetary Nebula NGC 6563

Zahra Al, Federico Soto-Badilla, Yüksel Karataş et al. (+2 more)

We present a morphokinematic analysis based on high-resolution long-slit echelle spectroscopy of the \nii$\lambda6583$ line and narrowband imaging. Position-velocity diagrams reveal asymmetric expansion and localized kinematic features. We derive a systemic velocity of $V_{\rm sys}^{\rm LSR} = -25\pm1$\kms\ ($V_{\rm sys}^{\rm HEL} = -34 \pm 1$\kms) and a main shell expansion velocity of $V_{\rm exp} = 22 \pm 1$\kms. Three-dimensional modeling indicates an ellipsoidal main body surrounded by a thin shell, two ear-like protrusions, and additional small-scale structures. The corresponding kinematic ages are $3\,600 \pm 700$ yr for the ellipsoid and ring, and $7\,500 \pm 1\,000$ yr and $8\,800 \pm 1\,500$ yr for the two opposite ear-like protrusions, respectively, indicating that these outer structures predate the main nebular envelope. The kinematic asymmetry and enhanced emission regions suggest evolution within a non-uniform ambient medium. At the same time, the presence of collimated ear-like structures is consistent with shaping influenced by binary interaction, where earlier outflows preceded the ejection of the dense shell. NGC\,6563 therefore appears to be a dynamically evolved system shaped by the combined effects of episodic mass ejection and environmental interaction.
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All authors Zahra Al, Federico Soto-Badilla, Yüksel Karataş, Gerardo Ramos-Larios, Roberto Vázquez

Astrophysics of Galaxies

Lensed hot stars with HST in the 2030s

J.M. Diego

In the late 20th century, the Hubble Space Telescope (HST) revolutionized astronomy, showing the Universe with a detail never seen before in the ultraviolet (UV), optical and infrared (IR) bands. In the early 2020s, the James Webb Space Telescope started a similar revolution in the IR. The launch of Roman in late 2026 challenges the reign of HST in the optical band, but even after Roman's launch, HST will remain as the only telescope capable of high-quality imaging in the UV band. In the optical bands, HST provides superior resolution than Roman for point sources. Although equipped with more sensitive MOS, Roman's sensors have a pixel size about 3 times larger than HST's CCDs, hence undersampling the point-spread-function, and resulting in a worse spatial resolution. The UV-capable and higher-resolution of HST in the UV and optical band, makes HST the best instrument for specific science cases. This paper responds to the "Building a Roadmap for Hubble science into the 2030s" call and focuses on science with lensed hot stars at $z>0.5$ in the UV and optical bands, exploiting the features that makes HST the best instrument in the UV/optical until the launch of the Habitable World Observatory in the 2040s.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

High-scale Mirror Standard Model Dark Matter, Dark Phase Transitions and Gravitational Waves Implications

V.K. Oikonomou

We consider a scenario for dark matter in the Universe, according to which the dark matter sector is comprised by a dark Standard Model sector which interacts only gravitationally with the ordinary Standard Model sector. This dark Standard Model sector is assumed to have the same symmetries as the ordinary Standard Model, with the couplings and the scale of the mirror Standard Model sector being different than the ordinary Standard Model sector. Specifically, the scale of the mirror Standard Model sector will be assumed to be quite higher compared to the ordinary Standard Model. Also the Yukawa couplings among the mirror Higgs and the mirror fermions are assumed to be different from those of the Standard Model and we examine the effects of the different scale and of the different Yukawas on the evolution of the Universe. As we show, a mirror world phase transition occurs at high temperatures of the baryonic Universe, which can be first order or second order, depending on the scale of the Universe and the Yukawa couplings. These are dark phase transitions which occur quite earlier than the real world Standard Model electroweak phase transition. The case of a second order phase transition is quite interesting phenomenologically, since it can potentially have a direct imprint on the spectrum of stochastic gravitational waves for frequencies probed by the future gravitational wave detectors. Also we examine whether this mirror dark matter world can form atoms and as we show in some scenario the high scale mirror dark matter can have both atomic and subatomic particle components. We also give an approximation of the total equation of state of high scale mirror DM and we discuss how high scale mirror DM can reconcile contradicting observations like the Bullet cluster and the Abell 520 cluster.
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Earth and Planetary Astrophysics

Dust and coma radicals in C/2024 E1 (Wierzchos): evolution of the activity

Irene Mariblanca-Escalona, Pedro J. Gutiérrez, Fernando Moreno et al. (+1 more)

We present multi-epoch R-band imaging and long-slit spectroscopy of the dynamically new comet C/2024 E1 (Wierzchos) during its pre-perihelion phase, spanning heliocentric distances from 4.5 to 2.3 au. The most prominent fluorescence emissions in the visible wavelength range are detected. We measure production rates of CN, C$_2$, and C$_3$, while no significant NH$_2$ signal is identified. In our dataset, CN became detectable at 3.48 au, and C$_3$ and C$_2$ at 2.80 au. The mean ratios $\log\mathrm{C}_2/\mathrm{CN} = 0.00 \pm 0.07$ and $\log\mathrm{C}_3/\mathrm{CN} = -1.03 \pm 0.09$ place the comet in an intermediate taxonomic regime between typical and carbon-depleted populations. Dust production rates, ejection velocities, and particle size distributions are constrained using a Monte Carlo dust tail model that reproduces the observed coma morphology. The dust population is characterized by a power-law size distribution with an exponent of $\sim -3.5$, and particle sizes ranging from 1~$\mu$m to 4~mm. The inferred initial ejection velocities span from $\sim$20$ m $s$^{-1}$ to $\sim$100$ m $s$^{-1}$. We use the empirical relation between CN and OH to estimate the water production rate and derive the dust-to-gas mass ratio for heliocentric distances $r_{\rm{h}} \lesssim 3$ au, where water sublimation is expected to dominate the activity regime. The dust-to-gas mass ratio remains consistently above unity, ranging from $\sim$1 to 3 depending on the choice of scale lengths and the CN–OH conversion factor. This result characterizes C/2024 E1 as a “dust-rich” comet, where the mass loss is dominated by the refractory component rather than volatiles.
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All authors Irene Mariblanca-Escalona, Pedro J. Gutiérrez, Fernando Moreno, Luisa M. Lara

High Energy Astrophysical Phenomena

Simulating observed point-symmetric core-collapse supernova morphologies with the jittering jets explosion mechanism

Jessica Braudo, Amir Michaelis, Muhammad Akashi et al. (+1 more)

We conduct two three-dimensional hydrodynamic simulations of the jittering-jets explosion mechanism (JJEM) of core-collapse supernova (CCSN), launching three pairs of inclined opposite jets into the core of an enveloped-stripped stellar model, and reproduce some morphological features of observed CCSN remnants (CCSNRs) that a single pair of jets or instabilities alone cannot reproduce. We launch the three pairs of jets within about a second, and follow the ejecta for more than 10 seconds until after shock breakout. Our main findings are: (1) Although the jets are choked deep inside the star, they manage to form a pronounced multipolar (point-symmetric) morphology. (2) Instabilities and vortices resulting from the jet-star interaction form small clumps and narrow filaments, some of which form point-symmetric morphology, resembling some observed CCSNRs. (3) The most energetic jet of one simulation forms a large low-density blowout ahead of the ejecta, with filaments dragging behind it, resembling the blowout of the Cygnus Loop. (4) The inner ejecta presents two symmetry axes along two of the three jet axes: one of a pair of rings and one of a pair of nozzles, resembling the structure of the point-symmetric SNR J0450.4-7050. (5) The three pairs of jets compress two dense blocks between their axes. The blocks exhibit a Doppler-shift bipolar outflow highly inclined to the morphological axes along the jet axes. The inclined Doppler-bipolar outflow and morphology axis resembles the CCSNRe W49B and SNR G292.0+1.8. Our study supports the claim that the JJEM is the primary explosion mechanism of CCSNe.
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All authors Jessica Braudo, Amir Michaelis, Muhammad Akashi, Noam Soker

Solar and Stellar Astrophysics

Gravity-mode main-sequence pulsators in the open clusters NGC 3532 and NGC 2516: Instability strip, near-core rotation, and internal structure

Gang Li, Chenyu He, Joey S. G. Mombarg et al. (+2 more)

Context. Studying pulsating stars in clusters opens a new window onto stellar physics. Gravity-mode (g-mode) pulsators in open clusters allow us to measure their near-core rotation rates and, together with cluster age and mass constraints, test angular momentum transport in stars above about 1.5 solar masses. Aims. We aim to detect g-mode pulsations in member stars of the young open cluster NGC 3532, about 300 Myr old, and to measure their near-core rotation rates and internal properties. Methods. We used TESS photometry to extract light curves of NGC 3532 members. The observed g-mode period spacings allow us to measure near-core rotation rates and the asymptotic period spacing, Pi0. We also fitted isochrones to the colour-magnitude diagrams of NGC 3532 and NGC 2516 to refine the cluster ages and obtain stellar masses. Results. We constrain the observed instability region of young gamma Doradus members from a blue edge at about 7760 K to a red edge at about 7070 K, while some hotter g-mode pulsators are also seen. The near-core rotation rates show a rotation-mass relation similar to that in NGC 2516: below 1.6 solar masses, the rotation rate increases with mass, whereas above 1.6 solar masses the NGC 3532 stars reach a plateau at about 2.8 d^-1. This mass may mark a threshold between different rotational spin-down mechanisms. Existing evolutionary models with angular momentum transport imply that these g-mode pulsators were born rotating above 55 percent of the critical value. Our simplified models, assuming spherical symmetry, angular momentum conservation, and rigid internal rotation, suggest that either mass-dependent initial rotation rates are required, or that minor angular momentum loss still operates above 1.6 solar masses. Finally, our Pi0 measurements reveal a discrepancy with theoretical predictions for some pulsators, as also found in the younger cluster NGC 2516.
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All authors Gang Li, Chenyu He, Joey S. G. Mombarg, Dario J. Fritzewski, Conny Aerts

High Energy Astrophysical Phenomena

Multiwavelength Analysis of the Einstein Probe X-ray Transient EP240305a

Ruican Ma, Ye Li, Lian Tao et al. (+32 more)

We report multiwavelength observations of EP240305a, an uncatalogued X-ray transient detected by the Einstein Probe on March 5, 2024. The source exhibits distinct characteristics across the X-ray, optical, near-infrared, and radio bands. The soft X-ray observations show two significant flares lasting ~100-250 s, accompanied by rapid flux decay in a few days, and the optical and near-infrared data reveal a faint, candidate counterpart. In contrast, the radio observations expose a long-term spectral evolution from a self-absorbed to an optically thin state within two months, implying discrete jet ejection. We compare EP240305a with known classes of X-ray transients and find that it is unlikely to be associated with long-timescale transients such as jetted tidal disruption events or X-ray binaries. Its properties also disfavor a short-timescale stellar flare origin. Although the absence of optical spectroscopy prevents a redshift determination, the source exhibits properties similar to those of gamma-ray-dark gamma-ray burst-like transients, which may be associated with relativistic jets viewed off-axis or with choked jets. The discovery of EP240305a, along with other uncataloged transients detected by the Einstein Probe, underscores the scientific potential of highly sensitive X-ray survey telescopes and rapid-response multiwavelength follow-up observations in exploring the nature of atypical astronomical transients.
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All authors Ruican Ma, Ye Li, Lian Tao, Tao An, Ailing Wang, Arne Rau, Roberto Soria, Huaqing Cheng, Jing Wang, Hua Feng, Yuanqi Liu, Seán Brennan, Jingran Xu, Dave Buckley, Philip Charles, YuPeng Chen, Francesco Coti Zelati, Sebastien Guillot, Long Ji, Chengkui Li, Jinzhong Liu, Yuan Liu, Pierre Maggi, Itumeleng Monageng, Yanan Wang, Yanjun Xu, Guobao Zhang, Qingchang Zhao, Diego Altamirano, Peter Jonker, Nanda Rea, Xiaofeng Wang, Xuefeng Wu, Weimin Yuan, Shuangnan Zhang

Cosmology and Nongalactic Astrophysics

Optimal marked statistics from the Effective Field Theory of Large Scale Structure

Marco Marinucci, Michele Liguori, Federico Semenzato et al. (+1 more)

We present a simple and robust framework to assess the information content of the power spectrum of a marked density field within the Effective Field Theory of Large Scale Structure, providing a physically motivated regime of validity of perturbation theory for such fields. We optimize the choice of mark to maximize the constraining power on cosmological parameters, focusing on the resulting reduction of parameter uncertainties. After marginalizing over the small-scale counterterms, we find improvements in the parameter error bars by a factor of approximately $1.30$-$2.3$, $1.3$-$8.3$, and $1.2$-$2.5$ for $\Omega_m$, $\sigma_8$, and $h$, respectively, depending on redshift and smoothing scale. The optimized mark exhibits a simple functional form, for which we provide a physical interpretation in terms of its response to the underlying density field. These results demonstrate the potential of marked statistics as a tool to extract additional cosmological information beyond standard two-point analyses and open a pathway for further exploration of nonlinear transformations of the density field.
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All authors Marco Marinucci, Michele Liguori, Federico Semenzato, Benjamin D. Wandelt

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Unavoidable Loop-Induced Quintessence – Higgs Mixing and Its Phenomenological Consequences

Zurab Kepuladze

We investigate a class of quintessence models in which the dark-energy scalar field interacts with sterile neutrinos responsible for neutrino mass generation through the seesaw mechanism. Radiative corrections involving sterile neutrinos induce Higgs-quintessence mixing and provide an effective portal between quintessence and Standard Model particles. We calculate the corresponding one-loop mixing amplitude and show that its structure depends on the relation between the characteristic momentum transfer and the sterile-neutrino mass. In the low-momentum regime the mixing is effectively kinetic, while at high energies it acquires a mass-mixing form. A notable result is that the overall suppression of the induced mixing is governed by the physical neutrino mass scale, leading to a predictive relation between neutrino properties and Higgs-quintessence interactions. The resulting loop-induced effects are found to be suppressed by factors comparable to those controlling the tree-level quintessence-neutrino interaction. The induced mixing generates effective couplings of quintessence to Standard Model fermions and gauge bosons, leading to modified Higgs, W and Z boson processes and opening decay channels for the quintessence field, which may prove to be cosmologically important. While the corresponding effects remain well below current experimental sensitivities in the minimal heavy-seesaw scenario, the framework establishes a direct connection between dark-energy dynamics, neutrino mass generation and Higgs-sector phenomenology and provides a basis for studying scenarios with lighter sterile neutrino states where observable effects may be enhanced.
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Solar and Stellar Astrophysics

Characterization of white-light enhancements under umbral conditions in one-dimensional simulations of solar flares

Sascha Ornig and Mats Carlsson

Solar flares with signatures in the optical continuum (white light, WL) pose a challenge to the standard flare model and to solar flare simulations. In particular, simulations are so far not able to convincingly reproduce observed WL enhancements. We investigate the effect of different electron beams on an umbral atmosphere and what the differences and similarities to the quiet-Sun response are. We characterized WL emission in one-dimensional simulations of solar flares using the radiation hydrodynamics code RADYN. We used a similar setup as the F-CHROMA grid, but with a starting atmosphere describing umbral conditions. We investigated the influence of different temporal profiles of an electron beam on this umbral atmosphere. Our simulations show maximum WL increases between 40 and 335%, which is comparable to observed values. The reduced umbral background is the main reason for these large increases. We identify hydrogen recombination in an optically thin chromosphere as the dominant process responsible for the increases, with the radiation from the heated photosphere becoming substantial in the later stages due to the longer timescale of the cooling of the photosphere compared to hydrogen recombination in the chromosphere. Shorter, more intense beams (i.e., beams with a higher maximum energy flux) lead to a faster and more dramatic atmospheric evolution. Such beams also cause larger WL enhancements due to a higher electron density in the relevant layers. Both the Balmer ratio and the Paschen ratio are substantially higher in our simulations compared to simulations with a quiet-Sun atmosphere. The detectability and amplitude of WL enhancements depends on the spectral and temporal structure of the electron beam as well as the underlying background radiation. The combination of a short, intense beam and an umbral atmosphere provides an excellent seed for substantial WL enhancements.
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Astrophysics of Galaxies

Uncovering the dark matter distribution by combining stellar kinematics and integrated HI spectra: Method validation

Yu Lei, Meng Yang and Ling Zhu

We determined the dark matter (DM) distribution in galaxies by jointly modelling stellar kinematics from integral field unit (IFU) observations and the gaseous kinematics encoded in a single integrated HI spectrum. The stellar kinematics are described by a triaxial orbit-superposition Schwarzschild model, while the HI gas is described by an idealised disc model; both are governed by the same gravitational potential. The potential comprises the stellar mass, a generalised Navarro-Frenk-White (gNFW) DM halo, and a central black hole. We validated the method on 58 simulated galaxies generated from the TNG50 cosmological simulation. For each galaxy, we created two versions of mock data with azimuthal angles viewed side-on and end-on, thus yielding 116 mock observations in total. Our model recovers the total mass, stellar mass, and DM mass profiles within the data range; the median DM mass of the 58 simulated galaxies is recovered with a relative systematic bias smaller than 20% across all radii from 2–20 kpc. The statistical uncertainties on the DM masses within 5 kpc remain similar to those found with the model constrained by IFU data only. In contrast, the relative uncertainty on the DM mass in the outer regions decreases when the HI spectrum is included; at 20 kpc, it drops markedly, from about 85% to roughly 30%. The DM density slope defined explicitly in the gNFW model is systematically underestimated and thus does not yield a reliable quantity from observations using our approach. Instead, we introduce density slopes evaluated between 2 and 20 kpc, which are statistically well recovered for both the total mass and the DM mass. We demonstrate the reliability of this method in uncovering the DM distribution and emphasise its promise for application to large samples of observed galaxies.
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High Energy Astrophysical Phenomena

Exploring the nature of Galactic unassociated sources detected by the Fermi-LAT

F. Acero, A. Acharyya, A. Adelfio et al. (+120 more)

We investigate the nature of the unassociated sources detected by the Fermi-LAT close (|b|<10{\deg}) to the Galactic plane, representing 16% of all sources in the 4FGL-DR4 catalog. The bulk of these sources (referred to as soft Galactic unassociated sources, SGUs) exhibit properties not found in known classes of gamma-ray emitters, as confirmed by a machine-learning classification approach. In particular, these properties include a steep, curved spectrum peaking below 1 GeV and a specific Galactic-latitude distribution with both a narrow and a broad component (dubbed the spike and the shoulder, respectively). Some source clusters are highlighted. New plausible source classes are explored, but only star-forming regions are found to account for a significant fraction (at most 10%) of the unassociated population. A thorough search for counterparts to the 175 brightest sources brings out a number of plausible counterparts but does not reveal clues about the nature of the whole population. We investigate the possibility that SGUs originate from mismodeled clumps of diffuse emission. Using Monte Carlo simulations, the SGU spectra can be reproduced in this scenario under an ad hoc condition concerning the clump spatial extension. The possible connection between the SGUs and gas not accounted for by the 12CO tracer is explored using the 13CO MOPRA data but leads to inconclusive results. The origin of SGUs being related to diffuse emission remains plausible. However, a scenario whereby SGUs represent a new class of gamma-ray emitters cannot be fully excluded.
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All authors F. Acero, A. Acharyya, A. Adelfio, M. Ajello, E. Aviano, L. Baldini, J. Ballet, C. Bartolini, D. Bastieri, J. Becerra Gonzalez, R. Bellazzini, A. Bhat, E. Bissaldi, R. Bonino, P. Bruel, R. A. Cameron, P. A. Caraveo, F. Casaburo, F. Casini, E. Cavazzuti, N. Cibrario, S. Ciprini, G. Cozzolongo, P. Cristarella Orestano, F. Cuna, S. Cutini, F. D'Ammando, P. de la Torre Luque, D. Depalo, N. Di Lalla, A. Dinesh, L. Di Venere, A. Dominguez, J. Eagle, C. Fernandez-Suarez, A. Fiori, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, C. Gasbarra, D. Gasparrini, S. Germani, F. Giacchino, N. Giglietto, M. Giliberti, F. Giordano, M. Giroletti, I. A. Grenier, M.-H. Grondin, S. Guiriec, R. Gupta, M. Hashizume, E. Hays, J.W. Hewitt, A. Holzmann Airasca, D. Horan, X. Hou, T. Kayanoki, M. Kerr, M. Kuss, D.A. Langis, A. Laviron, M. Lemoine-Goumard, A. Liguori, J. Li, I. Liodakis, P. Loizzo, F. Longo, F. Loparco, S. Lopez Pérez, L. Lorusso, B. Lott, M. N. Lovellette, P. Lubrano, S. Maldera, D. Malyshev, G. Marti-Devesa, R. Martinelli, M. N. Mazziotta, I.Mereu, M. Michailidis, P. F. Michelson, T. Mizuno, P. Monti-Guarnieri, M. E. Monzani, A. Morselli, M. Negro, N. Omodei, M. Orienti, E. Orlando, D. Paneque, G. Panzarini, M. Persic, M. Pesce-Rollins, R. Pillera, T. A. Porter, G. Principe, S. Raino, R. Rando, A. Reimer, O. Reimer, M. Sanchez-Conde, P. M. Saz Parkinson, D. Serini, C. Sgro, E. J. Siskind, D. A. Smith, G. Spandre, P. Spinelli, A. W. Strong, D. J. Suson, H. Tajima, J. B. Thayer, D. J. Thompson, L. Tibaldo, D. F. Torres, J. Valverde, K. Wood, Q. Yu, G. Zaharijas, W. Zhang, the Fermi-Collaboration

Solar and Stellar Astrophysics

Magnetically Structured Oscillatory Power Along an Active-Region Transect in Near-UV Sunrise-III/SUSI Spectroscopy

Shahin Jafarzadeh, David B. Jess, Marco Stangalini et al. (+33 more)

We present a multi-line characterisation of how oscillatory power is organised across distinct magnetic environments in an active region using seeing-free, stratospheric near-ultraviolet spectroscopy from the Sunrise-III UV Spectropolarimeter and Imager (SUSI). A two-hour time series of short raster scans in the line-rich 327-329 nm window samples along a single transect that contains the following regions: weak magnetic-field surroundings, a plage, a sunspot, and a pore. From a set of 30 selected, relatively unblended absorption lines, we extract line-core Doppler-velocity time series and compute Morlet-wavelet refined global spectra from which we form band-integrated power maps for three frequency bands (2-4, 4-6, and 6-12 mHz). The stacked, line-resolved maps reveal a clear environment-dependent redistribution of power: 2-4 mHz power is strongest in the weak-field/plage segments but is commonly suppressed in the umbra and pore cores, while 4-6 mHz and 6-12 mHz power becomes relatively enhanced in the strongest-field regions, with line-dependent behaviour in the penumbra and plage. Across the line ensemble, this broad frequency structuring is coherent, but the detailed spatial distribution and relative band ranking are not identical from line to line - even among spectral lines with comparable effective formation depths - demonstrating clear line dependence. This novel result implies that single-line measurements may miss secondary components of the local wave spectrum because different lines weight co-existing perturbations and modes differently; therefore, the SUSI near-UV window provides a uniquely diagnostic-rich mapping of oscillations, offering leverage that is difficult to obtain with traditional one- or two-line approaches.
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All authors Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Peter H. Keys, Samuel D. T. Grant, Timothy J. Duckenfield, Glen Chambers, Sami K. Solanki, H. N. Smitha, Andreas Lagg, Achim Gandorfer, Alex Feller, Francisco A. Iglesias, Tino L. Riethmüller, Bianca Grauf, Johannes Hoelken, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alberto Álvarez-Herrero, Masahito Kubo, David Orozco Suárez, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović

High Energy Astrophysical Phenomena

Fortifying gravitational-wave population inference with normalizing flows

Christian Adamcewicz, Hugh McDougall, Paul D. Lasky et al. (+1 more)

As the LIGO-Virgo-KAGRA collaboration's (LVK's) gravitational-wave transient catalog grows, we are learning a wealth of information from the population properties of binary black hole mergers. Events in the catalog are represented with posterior samples describing the astrophysical parameters for each event. Population studies combine these samples to measure the distribution of astrophysical parameters such as black hole masses and spins. However, the posterior-sample representation of each event is only approximate. We construct a mock population with masses drawn from an astrophysically-motivated distribution with sharp features. Using this, we demonstrate that when $\gtrsim 300$ events are combined, even with each event's posterior represented by $1 \times 10^4 {-} 2 \times 10^4$ samples, the numerical error can become large enough that the resulting population inference is unreliable. We consider two solutions. In the short term, we show that nested samples (already produced by LVK analyses) can be used to more accurately describe each event in population studies. But this will only grant a temporary reprieve until the nested-sample representation becomes inadequate. In the longer term, we propose to represent each event with a normalizing flow. In order to represent each event with sufficient accuracy, each normalizing flow can be used to generate an arbitrarily large number of new posterior samples with a significantly reduced computational cost relative to traditional sampling methods. When compared to nested sampling, our normalizing flows produce posterior draws with a median of $\approx 80\%$ fewer likelihood evaluations per sample, while also providing greater opportunity for parallelization. We believe refinement of normalizing flow architectures and training techniques in future works could further reduce this per-sample cost significantly.
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All authors Christian Adamcewicz, Hugh McDougall, Paul D. Lasky, Eric Thrane

High Energy Astrophysical Phenomena

Licence to Bin: Accurate and Scalable Inference for Binary Neutron Stars in Next-Generation Gravitational-Wave Detectors

Nir Guttman, A. Makai Baker, Paul D. Lasky et al. (+1 more)

Next-generation gravitational-wave observatories will observe binary neutron-star mergers with much higher signal-to-noise ratios, over much longer durations and across broader frequency bands than current detectors. These long-duration signals present a major computational challenge for Bayesian parameter estimation. Reduced-order quadrature is a promising approach for accelerating inference, but in this regime its standard construction encounters severe memory and accuracy limitations. We present a practical reduced-order quadrature construction for long binary neutron-star signals with time-dependent detector response and full effects of the observatories' free-spectral range. Our approach combines improved adaptive frequency sampling, disk-backed streaming, and subbanded reduced-order quadrature construction, enabling efficient and accurate reduced-order models for signals that were previously intractable. We demonstrate for the first time reduced-order Bayesian inference on an approximately 2 h binary neutron-star signal extending down to 5 Hz and with signal-to-noise ratio 2090. We show the resulting reduced-order quadrature remains sufficiently accurate for practical inference. The full analysis is carried out in about 48 h using 128 CPU cores. We also find that, when time-dependent detector-response effects are included, a single Cosmic Explorer detector can localize such a signal to a 90% credible sky area of approximately $41~\mathrm{deg}^2$, with important implications for multimessenger astronomy and cosmology. These results demonstrate that reduced-order methods can make next-generation binary neutron-star inference computationally feasible.
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All authors Nir Guttman, A. Makai Baker, Paul D. Lasky, Eric Thrane

Solar and Stellar Astrophysics

Multi-line Wave Signatures in a Sunspot from Near-UV Sunrise III/SUSI Observations

Shahin Jafarzadeh, David B. Jess, Marco Stangalini et al. (+32 more)

Magnetohydrodynamic waves redistribute energy in magnetic structures of the lower solar atmosphere, yet constraints on how wave power and dominant frequencies are organised above sunspots remain limited because most studies use only a few well-separated diagnostics. Here we present multiline wave signatures in a sunspot from near-UV spectroscopy with the Sunrise-III UV Spectropolarimeter and Imager (SUSI). We analyse a two-hour time series of repeated raster scans of a sunspot near disc centre in the 327-329 nm spectral window (> 100 lines). From these, we select 44 lines that radiative-transfer calculations suggest sample effective formation heights within the umbral core from deep photosphere toward the low chromosphere. For each line, we extract line-core intensity and line-of-sight velocity time series using a dedicated multi-line fitting routine and compute Morlet-wavelet power spectra. The refined global wavelet spectra show that most lines (in both intensity and velocity) are genuinely multi-frequency, with a dominant peak and substantial statistically significant power up to 12 mHz. Unsupervised clustering of the normalised spectra groups lines into families with similar spectral shapes and reveals a progression of dominant frequencies from ~2 to ~10 mHz across the ensemble, for both intensity and velocity (not necessarily in the same lines). This behaviour is not reproduced by a simple formation-height ranking, suggesting that uncertainties in the formation-height estimates and line-dependent diagnostic response together shape the ordering. These Sunrise-III/SUSI observations open a new regime for near-UV multi-line wave studies and provide the first systematic characterisation of frequency-structured sunspot wave behaviour in this spectral region.
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All authors Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Richard J. Morton, Tobias Felipe, Michele Berretti, Sami K. Solanki, H. N. Smitha, Andreas Lagg, Achim Gandorfer, Alex Feller, Francisco A. Iglesias, Tino L. Riethmüller, Bianca Grauf, Johannes Hoelken, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alberto Álvarez-Herrero, Masahito Kubo, David Orozco Suárez, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dusan Vukadinović

Astrophysics of Galaxies

Identifying Warped Galaxies in Pan-STARRS and Euclid using Deep Convolutional Neural Network

Saranya Suguna and Arunima Banerjee

Warped galactic discs are common, yet their detection remains challenging, as the outskirts of galaxies are typically faint. Advances in deep imaging surveys improve the detectability of such features, while machine learning enables efficient analysis of large datasets. Using the Pan-STARRS EGIPS catalogue, we develop a deep learning framework by fine-tuning the Zoobot convNext-nano model on 1000 edge-on galaxy FITS images to distinguish warped and non-warped edge-on galaxies with 83% accuracy. The trained model is then applied to a larger sample, identifying 2088 warped and 1398 non-warped galaxies with a high prediction probability threshold ($\geq 0.85$). Additionally, we use the model to predict on 3226 edge-on galaxies from the Euclid Q1 survey, demonstrating the model's ability to generalise across datasets with differing resolutions. To analyse the model predictions, we employ LayerCAM to identify the regions of galaxy images that contribute to the classification. We find that warped galaxies differ primarily in their structural properties, exhibiting lower axis ratios and higher asymmetry. Warped galaxies were found to be bluer, with younger stellar populations and enhanced star formation. These results highlight the effectiveness of deep learning methods in identifying subtle morphological features, such as warps, and demonstrate their potential for studying structural properties of galaxies in current and upcoming large imaging surveys.
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Solar and Stellar Astrophysics

Source Surface Height Optimisation for Improved Solar Wind Velocity Forecasting Across Solar Cycles 23, 24 and 25

Sandeep Kumar, Nandita Srivastava and Dana-Camelia Talpeanu

The potential field source surface (PFSS) model is a cornerstone of many state-of-the-art space weather forecasting frameworks. It includes a single physical free parameter, the source surface (SS) height. Traditionally, a fixed SS height of 2.5 solar radii has been adopted in most studies. However, several studies have investigated the SS height in the PFSS model using various datasets and temporal intervals. Earlier efforts primarily aimed to improve estimates of the heliospheric open magnetic flux. Our recent study Kumar et al. (2025), showed that optimising the SS height substantially improves the performance of the Wang Sheeley Arge (WSA) solar wind speed prediction model at L1. That analysis employed two types of GONG synoptic magnetic field maps, namely standard (STD) and zero-point-corrected (ZPC) maps, over selected periods of solar cycles (SCs) 24 and 25. In this study, we perform a comprehensive investigation of SCs 23 to 25 using synoptic magnetic field maps derived from ground-based (GONG) and space-based (SDO/HMI) observatories. Our results demonstrate that optimising the SS height in the PFSS model significantly improves the WSA model performance compared to the commonly adopted fixed SS height. We find that during solar minimum, higher SS heights (less than or equal to 2.5 solar radii) yield better solar wind speed predictions at L1, whereas during active phases the opposite trend is observed. Although the absolute optimised SS height varies across SCs, the overall distribution pattern remains similar. These finding suggests a relationship between SS height and SC phase over long time scales. Overall, the SS height optimisation enhances the background solar wind speed prediction models in the heliosphere.
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Instrumentation and Methods for Astrophysics

Demonstration of a Single-chip Dual-polarization Sideband-separation SIS mixer at 2 mm Band

Wenlei Shan, Shohei Ezaki and Yoshinori Uzawa

Large-format heterodyne focal plane arrays require highly integrated receiver architectures while maintaining low noise and sufficient sideband rejection, which remains challenging for superconducting SIS mixers at millimeter wavelengths. In this work, we demonstrate, for the first time, a monolithic dual-polarization sideband-separating superconductor-insulator-superconductor (SIS) mixer operating at 2 mm wavelengths (125-163 GHz) on a silicon-on-insulator substrate. The integrated SIS mixer achieves a sideband rejection ratio exceeding 10 dB over the 4-8 GHz intermediate-frequency (IF) band across most of the radio-frequency (RF) range, with a minimum single-sideband (SSB) receiver noise temperature as low as approximately 60 K. As a key building block of the hybrid planar integration (HPI) architecture, this result verifies the feasibility of highly integrated large-format heterodyne focal plane arrays, providing a practical path toward substantially expanding the field of view of millimeter and submillimeter-wave radio telescopes.
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Astrophysics of Galaxies

The S-PLUS Fornax Project (S+FP): Fornax-like clusters in cosmological hydrodynamical simulations

L.J. Zenocratti, A.V. Smith Castelli, M.E. De Rossi et al. (+12 more)

The Fornax galaxy cluster constitutes a suitable laboratory to explore the evolution of galaxies in a dense environment. Recently, the Southern Photometric Local Universe Survey (S-PLUS) has obtained unprecedented photometric information of Fornax, revealing new features regarding its galaxy populations and surrounding regions. In this context, simulations are invaluable tools to interpret the past, present and fate of such observational findings. We aim to deliver a robust photometric catalog of simulated Fornax-like systems in cosmological context, to consistently contrast them with S-PLUS data. We analyze Fornax analogs from the EAGLE and IllustrisTNG simulations, selected using observed properties of the Fornax cluster and its central galaxy NGC 1399. For each system, we generated synthetic photometry in the 12 S-PLUS bands using the SKIRT radiative transfer code, reproducing the instrumental configuration of the S-PLUS survey. Simulated data cubes, mock images, spectral energy distributions, magnitudes and colors were obtained for each galaxy in our selected simulated Fornax analogs. The synthetic photometry and spectra derived from simulations show a good agreement with the S-PLUS observations. We identify particular systems which show some similarity with the spatial distribution of galaxies in Fornax. Such simulated candidates reproduce the observed color-magnitude relation and the spatial substructure between the cluster core and the Fornax A region. Also, simulated galaxies are bluer at higher cluster-centric distances, in agreement with observations. Although modest discrepancies were obtained between the observed and simulated color-magnitude diagrams in some cases, our results support the suitability of our selection criteria and synthetic photometry, and the reliability of current cosmological simulations to reproduce key general features of the Fornax cluster.
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All authors L.J. Zenocratti, A.V. Smith Castelli, M.E. De Rossi, D. Pallero, M.C. Artale, R.F. Haack, A.R. Lopes, F.R. Faifer, D. Palma, P.K. Humire, J. Thainá-Batista, W. Schoenell, T. Ribeiro, A. Kanaan, C. Mendes de Oliveira

Instrumentation and Methods for Astrophysics

Semianalytic Sensitivity Estimates for Out-of-Bank Gravitational-Wave Signals

Aditya Vijaykumar and Reed Essick

Estimating the sensitivity of gravitational-wave searches is important for a wide variety of scientific applications spanning astrophysics and fundamental physics. In this work, we develop a fast semianalytic approximation for estimating matched-filter search sensitivity to physical effects not explicitly modeled in the template bank. This approximation utilizes fitting factors, i.e., the maximum overlap of a candidate signal over the search bank. As illustrations, we compare our estimates to the actual performance of searches against spinning binary neutron stars, and evaluate search sensitivity to compact binaries possessing orbital eccentricity or deviations from general relativity. Our work thus paves the way for fast sensitivity estimates for a variety of applications, including unmodeled effects in template banks such as deviations from general relativity, environmental effects, gravitational lensing, and waveform/calibration systematics.
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High Energy Astrophysical Phenomena

Electron-capture Supernova Candidates from Light Curves: Implications for Their Progenitors and Explosion Properties

Masato Sato, Nozomu Tominaga, Sergei I. Blinnikov et al. (+5 more)

Core-collapse supernovae are explosions of massive stars. While most massive stars end as iron-core-collapse supernovae, less massive stars are expected to explode as electron-capture supernovae (ECSNe), defining the low-mass boundary of core-collapse supernovae. ECSNe were proposed $\sim 40$ years ago, and first-principles simulations predict their successful explosions with low energies of $\sim 10^{50}$~erg. Nevertheless, only one convincing candidate, SN~2018zd, has been proposed other than SN~1054, the progenitor of the Crab Nebula. We search for ECSN candidates among Type~II SNe from the literature and a public Zwicky Transient Facility sample, using a color-based diagnostic, selecting ten candidates with blue colors at the middle of the plateau. We classify three as gold, for which a spectrum around the middle of the plateau disfavors strong circumstellar-medium interaction that would make the SN bluer, and seven as silver without such spectra. Comparing the observed multicolor light curves with radiation-hydrodynamical models, we infer the explosion energies, $(0.4-1.7)\times10^{50}$~erg for the gold candidates and $(0.4-2.7)\times10^{50}$~erg including the silver candidates, consistent with first-principles predictions and the mass-loss rates, $3\times10^{-3} - 3 \times 10^{-2}~M_{\odot}~{\rm yr}^{-1}$ for the gold candidates, which remain similar when the silver candidates are included, higher than those expected for the early super-asymptotic-giant-branch phase. The ECSN occurrence ratios among SNe~II are inferred as $3.0^{+10.6}_{-2.9}$ and $15.7^{+17.3}_{-12.7}~\%$ from the gold and silver candidates, respectively, which we interpret as lower and upper limits. To robustly identify ECSNe and refine this ratio, spectroscopic follow-ups of ECSN candidates around the middle of the plateau are essential.
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All authors Masato Sato, Nozomu Tominaga, Sergei I. Blinnikov, Marat Sh. Potashov, Takashi J. Moriya, Daichi Hiramatsu, Francisco Förster, Joseph P. Anderson

Earth and Planetary Astrophysics

Next-Generation Atmosphere Models for Giant Planets with Application to Coupled Interior Composition and Spectral Evolution I: Cloudless Models with Equilibrium Chemistry

Yi-Xian Chen, Roberto Tejada Arevalo, Adam Burrows et al. (+1 more)

We present updated atmosphere models designed for calculating the post-formation evolution and cooling of giant planets with masses between $0.3$ and $10$ $M_J$. Our tables provide the entropy in the convective region at the base of the atmosphere, temperature ($T$)pressure ($P$) profiles, and emergent spectra for atmospheres calculated using the radiative transfer code CoolTLusty for $T_{\mathrm{eff}}$s over the range 100 to 1400 Kelvin and log$_{10}$($g$) from 2.8 to 4.4 ($cgs$) with the latest opacities and equations of state. Each spectrum and thermal profile is calculated using line-by-line opacity sampling. We construct tables at 3 different metallicities ($Z = 1, 3.16, 10 Z_\odot$) and 2 different helium fractions ($Y=0.15, 0.275$), with the improvement that we adopt a metal-inclusive EOS that treats heavy elements consistently with the opacity metallicity (rather than folding it into an effective $Y$). The result is tables that accommodate both changes in $Y$ due to helium rain and potential variations in $Z$ during envelope evolution. We present a comparison between TP profiles, modeled spectra, and evolutionary tracks, and find that on-the-fly interpolation of boundary conditions in atmospheric composition has a notable impact on the late stages of giant planet evolution, altering the timing of helium rain and therefore the subsequent cooling history and atmospheric helium depletion. We also provide an available toolkit that generates spectra and boundary conditions via efficient interpolation across the 4D parameter space $(T_{\rm eff}, \log_{10} g, Y, Z)$, which is useful for post processing evolutionary tracks to produce fully time-resolved spectral evolutions.
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All authors Yi-Xian Chen, Roberto Tejada Arevalo, Adam Burrows, Ankan Sur

Cosmology and Nongalactic Astrophysics

Constraints on Stable Scalar-Tensor Dark Energy from DESI Data and Solar System Tests

Husam Adam, Mark P. Hertzberg and Daniel Jiménez-Aguilar

We investigate the viability of scalar-tensor (quintessence) models of dark energy with a quartic polynomial nonminimal coupling to gravity and a linear scalar potential. The polynomial nonminimal coupling is used to ensure that the field is well stabilized in the early universe. We perform a systematic exploration of the parameter space spanned by the quadratic and quartic nonminimal couplings, as well as the slope of the potential. We confront the predictions of the model with the latest Dark Energy Spectroscopic Instrument (DESI) constraints on the dark energy equation of state and also with complementary bounds from local tests of gravity, including solar system constraints and limits on the time variation of the effective Newton's constant. We identify bands in parameter space where all these constraints are satisfied, finding such bands to be very narrow.
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Instrumentation and Methods for Astrophysics

Prime Focus Spectrograph on the Subaru Telescope: Overview of Science Operations

Masayuki Tanaka, Akira Arai, Wanqiu He et al. (+30 more)

The paper presents the science operation framework for Prime Focus Spectrograph (PFS or 'Onohi'ula in its Hawaiian name) installed at the 8.2m Subaru Telescope on the summit of Maunakea. PFS is a massively multiplexed, wide-field, fiber-fed spectrograph covering 1.25 square degrees with 2386 science fibers. The instrument has been offered to the Subaru scientific community since March 2025. In order to fully exploit the unique capabilities of PFS, the Subaru Telescope has introduced a new, dedicated science operation framework for PFS. The default observing mode is queue observing, and multiple observing programs (in the same field) can be executed in the same exposure to achieve high observing efficiency. The quality of an exposure is based on the delivered signal-to-noise ratio and is quantified in terms of 'effective exposure time', and exposures are taken until the allocated 'fiber hours' for each program or target are achieved. The fiber hour is a new unit for observing time at Subaru; if we expose a fiber for 1 hour under the fiducial conditions, it is 1 fiber hour. Each observing program is granted the total fiber hours by the Time Allocation Committee. In addition to normal observing programs, which are selected through the standard peer-review process, there are two filler categories; community filler and observatory filler. As the names imply, the former is proposed by the community and the latter is prepared by the observatory. These filler targets are used whenever unassigned fibers are available. After an observing run, the data are fully reduced by the observatory and delivered to the users through the PFS Science Platform, a cloud-based data analysis environment. The paper gives a summary of all of this new framework and the actual implementation of it.
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All authors Masayuki Tanaka, Akira Arai, Wanqiu He, Miho N. Ishigaki, Eric Jeschke, Russell Kackley, Shintaro Koshida, Yuki Moritani, Masato Onodera, Vera Maria Passegger, Tae-Soo Pyo, Yuhei Takagi, Naoyuki Tamura, Ichi Tanaka, Kiyoto Yabe, Sadman S. Ali, Javier Gracia Caprio, Maximillian Fabricius, Wilfred Gee, James E. Gunn, Michitaro Koike, Arnaud Le Fur, Zhuoming Li, Yongming Liang, Craig Loomis, Robert Lupton, Sogo Mineo, Takahiro Morishima, Sakurako Okamoto, Yuki Okura, Paul Price, Martin Reinecke, Michael A. Strauss

Instrumentation and Methods for Astrophysics

Efficient Evaluation of Gravitational Lensing Amplification Factors: A Deep Learning Framework

Fan Zhang, Qikai Zhang, Qiyuan Yang et al. (+2 more)

Wave optics is essential for analyzing lensed gravitational waves (GWs), yet evaluating the diffraction integral $F(\omega, y)$ is computationally expensive. We present a Sinusoidal Representation Networks (SIRENs) framework for the dimensionless amplification factor, demonstrating its efficacy and generalization through Point Mass Lens (PML) and Singular Isothermal Sphere (SIS) test cases. Unlike standard architectures that suffer from spectral bias, the network's periodic activation functions structurally align with the integral's oscillatory kernel, effectively resolving high-frequency spectral features. The resulting estimator achieves $\mathcal{O}(10^{-3})$ relative accuracy and a $\sim 100\times$ speedup compared to direct numerical integration. By shifting the computational burden to offline training, our framework yields a stable $\mathcal{O}(1)$ inference complexity. This guarantees constant, sub-millisecond evaluation times even in the weak-lensing diffraction tail where traditional methods stagnate. Additionally, the dimensionless formulation ensures intrinsic scale invariance, enabling direct application across astrophysical regimes from stellar-mass lenses in the ground-based LVK band to supermassive black holes in the space-based LISA band.
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All authors Fan Zhang, Qikai Zhang, Qiyuan Yang, Yong Yuan, Xilong Fan