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Physics Astrophysics

astro-ph Watch Astrophysics

Friday 28 November

Cosmology and Nongalactic Astrophysics

High-resolution cosmological simulations of primordial dark matter clustering under long-range and fractional forces

Derek Inman

Long-range attractive fifth forces can lead to exponential instabilities in the early Universe. For fermions with a Yukawa coupling to a sufficiently light scalar mediator, rapid oscillations of the scalar field can lead to a conservative force law with fractional behaviour on sufficiently large scales. We study cosmological systems evolving under both this fractional potential and the Newtonian potential using high-resolution N-body simulations. We find that, at the same mass scale, halos that form under the fractional potential are much more dense than those that from the Newtonian potential. However, we also find that the perturbed scalar field may have large fluctuations once halo sizes become comparable to an effective Compton length, which will modify subsequent clustering and collapse.
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Earth and Planetary Astrophysics

ExoJAX Retrievals of VLT/CRIRES Spectra of Luhman 16AB: C/O Ratios and Systematic Uncertainties

Hibiki Yama, Kento Masuda, Yui Kawashima et al. (+1 more)

We present atmospheric retrievals of the benchmark brown dwarf binary Luhman 16AB using high-resolution VLT/CRIRES spectra and the differentiable framework ExoJAX. We derive elemental abundances and temperature-pressure ($T$-$P$) profiles while explicitly testing the robustness of the results against major sources of systematic uncertainty. We first perform retrievals with a power-law $T$-$P$ profile and assess the sensitivity of inferred molecular abundances and C/O ratios to different CO line lists (ExoMol, HITEMP with air- and H2-broadening). We then introduce a flexible Gaussian process-based $T$-$P$ profile, allowing a non-parametric characterization of the thermal structure and a more conservative treatment of uncertainties. For both components, we infer C/O ratios of about 0.67, slightly above solar, with line list systematics at the 7 percent level emerging as the dominant source of uncertainty, whereas assumptions about $T$-$P$ parameterization or photometric variability play a lesser role. The retrieved $T$-$P$ profiles and molecular abundances are broadly consistent with atmospheric models and equilibrium chemistry. Our results establish Luhman 16AB as a key anchor for substellar C/O measurements, demonstrate the utility of flexible $T$-$P$ modeling in high-resolution retrievals, and highlight the importance of systematic tests – particularly line list uncertainties – for robust comparisons between brown dwarfs and giant exoplanets.
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All authors Hibiki Yama, Kento Masuda, Yui Kawashima, Hajime Kawahara

Solar and Stellar Astrophysics

Blending-induced beating and emission in the symbiotic star Terz V 2513

J. Merc, J. Mikołajewska, C. Gałan et al. (+4 more)

We present a detailed analysis of Terz V 2513 (=2MASS J17334728-2719266), a poorly studied symbiotic star. Our motivation was a peculiar beating pattern in its light curves from all-sky surveys and our own observations. Using Gaia DR3 and OGLE-IV photometry, we show that this variability arises from blending with a nearby, unrelated Mira variable (Gaia DR3 406134544052580377 = OGLE-BLG-LPV-241930). Analysis of VPHAS+ and Pan-STARRS imaging, combined with optical and infrared spectroscopy from the Southern African Large Telescope and ESO New Technology Telescope, further reveals that the symbiotic star has been misidentified in the literature. We identify the correct counterpart as Gaia DR3 4061345440488592896 (=OGLE-BLG-LPV-241932), a Mira with a 161-day period. Its infrared spectrum displays prominent emission lines and is remarkably similar to those of other symbiotic Miras. Based on our data and previous studies, Terz V 2513 likely experienced a symbiotic nova outburst in the past. This study highlights the importance of careful analysis of survey light curves in crowded fields and demonstrates how combining multi-wavelength photometry, spectroscopy, and high-precision Gaia data can disentangle blended sources and accurately determine their nature.
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All authors J. Merc, J. Mikołajewska, C. Gałan, K. Iłkiewicz, P. G. Beck, B. Monard, M. Gromadzki

High Energy Astrophysical Phenomena

Incorporating neutron star physics into gravitational wave inference with physics-informed priors using normalizing flows

Thibeau Wouters, Peter T. H. Pang, Tim Dietrich et al. (+1 more)

Bayesian inference, widely used in gravitational-wave parameter estimation, depends on the choice of priors, i.e., on our previously existing knowledge. However, to investigate neutron star mergers, priors are often chosen in an agnostic way, leaving valuable information from nuclear physics and independent observations of neutron stars unused. In this work, we propose to encode information on neutron star physics into physics-informed prior distributions constructed with normalizing flows. These priors take input from constraints on the nuclear equation of state and neutron star mass distributions. Applied to GW170817, GW190425, and GW230529, we highlight two contributions of the framework. First, we demonstrate its ability to provide source classification and to enable model selection of equation of state constraints for loud signals such as GW170817, directly from the gravitational-wave data. Second, we obtain narrower constraints on the source properties through these informed priors. As a result, these physics-informed priors consistently recover higher luminosity distances compared to agnostic priors. Our method provides a scalable way for classifying future ambiguous low-mass mergers observed through gravitational waves and for informing single-event gravitational-wave data analysis with neutron star physics.
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All authors Thibeau Wouters, Peter T. H. Pang, Tim Dietrich, Chris Van Den Broeck

Astrophysics of Galaxies

Connecting Star Formation in the Milky Way and Nearby Galaxies -II. An Observationally Driven Analytical Model for Predicting Cloud-Scale Star Formation Rates

J. W. Zhou, Amelie Saintonge, Sami Dib et al. (+1 more)

We construct a model by integrating observational constraints from the Milky Way and nearby galaxies to predict cloud-scale star formation rates (SFRs). In the model, we first estimate the initial total mass of clumps in a cloud based on the cloud mass, and then generate the initial clump population of the cloud using the initial clump mass function. Next, we model the star formation histories (SFHs) of the cloud to assign an age to each clump. We then sort out the intermediate-age clumps and calculate the total embedded cluster mass. Finally, we predict the SFR based on the duration of the embedded phase. The model-predicted SFR is broadly consistent with the observed SFR, supporting the plausibility of the model. The model primarily provides a theoretical framework that integrates a wide range of observational results, thereby clarifying the tasks for future observations.
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All authors J. W. Zhou, Amelie Saintonge, Sami Dib, Pavel Kroupa

Cosmology and Nongalactic Astrophysics

Collapse of Axion Domain Wall Induced by Helical Primordial Magnetic Fields

Zizhuo Zhao, Yuefeng Di, Ligong Bian et al. (+1 more)

Stable domain wall (DW) must decay to avoid overclose the Universe. A commonly used solution is to slightly break the PQ symmetry by introducing a bias term in the potential. In this work, we propose an alternative, symmetry-preserving mechanism: coupling the axion field to a helical primordial magnetic field (PMF) via the Chern-Simons term. Using three-dimensional lattice simulations, we evolve the DW network and demonstrate that it can successfully drive DW decay. Our quantitative results further show that the correlation length of the PMF plays a crucial role in determining the decay rate of the DW network and the resulting axion and gravitational wave radiation.
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All authors Zizhuo Zhao, Yuefeng Di, Ligong Bian, Jing Shu

Solar and Stellar Astrophysics

SN 2021ukt: A Transitional Supernova with a Short Plateau and Persistent Interaction

Neil R. Pichay, Sergiy S. Vasylyev, Audrey M. Liddle et al. (+21 more)

We present spectroscopic and photometric observations of supernova (SN) 2021ukt, a peculiar short-plateau object that was originally identified as a Type IIn SN and later underwent an unprecedented transition to a Type Ib (possibly Type IIb) SN. The early-time light curves of SN 2021ukt exhibit a ~25 day plateau. Such a short phase of hydrogen recombination suggests a rather thin H-rich outer envelope of the progenitor star. The relatively narrow Balmer emission lines in spectra of SN 2021ukt during the first week indicate the interaction between the expanding ejecta and the immediate circumstellar material (CSM). This H{\alpha} line is observed throughout its helium-rich ejecta-dominated phase and nebular phase, suggesting persistent interaction with a radially extended CSM profile. We explore the synthetic light-curve model among grids of parameters generated by MESA+STELLA. We also compare the spectrophotometric evolution of SN 2021ukt with several well-sampled supernovae that exhibit a short plateau and persistent ejecta-CSM interaction. An estimate of the progenitor mass of SN 2021ukt is made based on the flux ratio between [Ca II] {\lambda}{\lambda} 7291, 7324 and [O I] {\lambda}{\lambda} 6300, 6364 during its nebular phase. Our analysis suggests that the progenitor star of SN 2021ukt has a zero-age main-sequence (ZAMS) mass of about 12 solar masses, a mass of radioactive nickel-56 synthesized in the SN ejecta of about 0.04 solar masses, and a mass of the H-rich envelope of about 0.5 solar masses. This study adds to the growing sample of transitional supernovae, reinforcing evidence for a continuum of underrepresented progenitors whose evolutionary pathways lie between those of standard SN models.
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All authors Neil R. Pichay, Sergiy S. Vasylyev, Audrey M. Liddle, Alexei V. Filippenko, WeiKang Zheng, Thomas G. Brink, Yi Yang, Matthew Graham, Daniel Stern, Daichi Hiramatsu, Claudia P. Gutiérrez, K. Azalee Bostroem, Estefania Padilla Gonzalez, D. Andrew Howell, Curtis McCully, Megan Newsome, Craig Pellegrino, Giacomo Terreran, Ivan Altunin, Raphael Baer-Way, Vidhi Chandler, Asia A. deGraw, Connor F. Jennings, Michael B. May

Solar and Stellar Astrophysics

BSN: The First Multiband Light Curve Analysis of the W UMa-type Contact Binary System EM Tucanae

Sepideh Houshiar, Atila Poro, Abbas Abedini et al. (+1 more)

We present a comprehensive photometric light curve and orbital period analysis of the W UMa-type contact binary EM Tuc. The O-C analysis constructed from all available eclipse timings exhibits a clear upward parabolic trend, indicating a continuous increase in the orbital period at a rate of \(dP/dt = (1.401 \pm 0.042)\times10^{-7}\,\mathrm{d\,yr^{-1}}\). This behavior is consistent with mass transfer from the less massive to the more massive star in the system, and the corresponding mass-transfer rate is estimated to be \(\dot{M} = -(4.62 \pm 1.54)\times10^{-8}\,M_\odot\,\mathrm{yr^{-1}}\). Light curve modeling with the PHysics Of Eclipsing BinariEs (PHOEBE) Python code, refined through MCMC sampling, confirms an overcontact configuration and yields a mass ratio of q=3.987. A cool photospheric starspot on the cooler component is required to reproduce the observed O'Connell asymmetry. Using Gaia DR3 parallax together with the photometric solution, the absolute masses of the components are derived as \(M_h = 0.24 \pm 0.05\,M_\odot\) and \(M_c = 0.97 \pm 0.19\,M_\odot\).
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All authors Sepideh Houshiar, Atila Poro, Abbas Abedini, Eduardo Fernández Lajús

High Energy Astrophysical Phenomena · Cross-listed from nucl-th

Constraining of Nuclear Matter Equations of State With Rotating Neutron Stars

Hyukjin Kwon and Kazuyuki Sekizawa

Neutron stars can be regarded as natural laboratories that enable us to investigate nuclear matter properties under extreme conditions that are otherwise impossible to access in terrestrial experiments. Astrophysical observations of neutron stars provide invaluable information on existing nuclear interaction models and equations of state (EoSs) at various densities. Most studies of neutron star structure employ the Tolman-Oppenheimer-Volkoff (TOV) equation which describes spherically symmetric, non-rotating stars in hydrostatic equilibrium. However, since neutron stars rotate fast, they could experience significant centrifugal deformation, and axially-symmetric calculations are required for accurate description of internal structure. The Komatsu-Eriguchi-Hachisu (KEH) method is well known for modeling rapidly-rotating compact objects in a fully general relativistic manner. In this contribution, we report results of KEH calculations for rapidly-rotating neutron stars using EoSs based on Gogny-type finite-range effective nucleon-nucleon interactions. Our results show that the mass-radius relation systematically changes with increasing angular velocity, highlighting the importance of including rotational effects when confronting theoretical EoSs with observational data.
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Cosmology and Nongalactic Astrophysics

The Shear-to-Cosmology Paradigm I. Hybrid Field-Level and Simulation-Based Framework for Weak Lensing Surveys

Jiacheng Ding, Chen Su, Ji Yao et al. (+2 more)

Precise cosmological inference from next-generation weak lensing surveys requires extracting non-Gaussian information beyond standard two-point statistics. We present a hybrid machine-learning (ML) framework that integrates field-level inference (FLI) with simulation-based inference (SBI) to map observed shear fields directly to cosmological parameters, eliminating the need for convergence reconstruction. The FLI network extracts rich non-Gaussian information from the shear field to produce informative features, which are then used by SBI to model the resulting complex posteriors. To mitigate noise from intrinsic galaxy shapes, we develop a blind, training-free, PCA-based shear denoising method. Tests on CSST-like mock catalogs reveal significant performance gains. The shear-based inference achieves approximately twice the cosmological constraining power in Figure of Merit (FoM) compared to the conventional convergence-based approach. Moreover, the combination of PCA denoising and ML compression can deliver a 36.4% improvement in FoM over standard shear two-point statistics. This work establishes a scalable and robust pathway for cosmological inference, unlocking the full potential of Stage-IV weak-lensing surveys.
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All authors Jiacheng Ding, Chen Su, Ji Yao, Le Zhang, Huanyuan Shan

Thursday 27 November

Instrumentation and Methods for Astrophysics

Gravity-darkening exponents for MESA stellar evolution models

A. Claret and G. Torres

In this Research Note we present new gravity-darkening exponents ($\beta$) for several stellar evolution models from the ZAMS up to the giant phase. The models were computed using the MESA code (version 7385) for the composition $X = 0.70$ and $Z = 0.02$, adopting A09 opacities and a mixing length parameter of $\alpha_{\rm MLT} = 1.84$. Results were calculated using the triangle strategy, for initial stellar masses of 1.0, 1.5, 2.0, 2.5, 3.0, 5.0, 7.0, 10.0, 15.0, and 20.0 $M_{\odot}$, and provide an update on previously available $\beta$ values that used older models.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Letelier black hole immersed in an electromagnetic universe

Ahmad Al-Badawi, Faizuddin Ahmed and İzzet Sakall{\i}

We investigate a static, spherically symmetric black hole solution surrounded by a cloud of strings and immersed in an electromagnetic universe. By deriving the event horizon from the lapse function, we demonstrate that both the string cloud parameter and the electromagnetic background parameter significantly modify the horizon radius compared to the Schwarzschild case. Consequently, thermodynamic quantities-including the Hawking temperature, Bekenstein-Hawking entropy, and heat capacity-become explicit functions of these additional parameters, with the heat capacity exhibiting divergences that signal phase transitions. We analyze the motion of massive test particles in this spacetime, deriving the effective potential and calculating the innermost stable circular orbit radius, which governs the inner edge of accretion disks and influences orbital stability. Scalar perturbations are examined through the associated effective potential, and quasinormal mode frequencies are computed using the sixth-order WKB approximation; the negative imaginary parts confirm the stability of the black hole under such perturbations. We also study the photon sphere structure, black hole shadow radius, and photon trajectories, showing how the interplay between string clouds and the electromagnetic background shapes the optical properties of this spacetime. Finally, we investigate weak gravitational lensing phenomena by deriving the deflection angle for both massive particles and photons using the Gauss-Bonnet theorem applied to the optical geometry. The results exhibit notable deviations from the Schwarzschild geometry, with the string cloud enhancing the deflection through a $(1-\alpha)^{-1}$ factor while the electromagnetic parameter introduces competing corrections at second order.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Inflation, black holes with primary hair, and regular planar black holes from an infinite tower of regularized Lovelock-Proca corrections

Pedro G. S. Fernandes, Jingqian Gou, Lavinia Heisenberg et al. (+1 more)

Infinite towers of higher-order corrections to General Relativity have been proposed as a mechanism to resolve singularities in early-universe cosmology and black holes, in a variety of settings. In this work, we consider an infinite tower of higher-order Proca corrections inspired by dimensional regularizations of Lovelock invariants. We find that the Big Bang singularity present in General Relativity is replaced by an inflationary epoch. Furthermore, the Lovelock-Proca tower allows for regular planar black hole solutions and spherically symmetric black holes with primary hair.
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All authors Pedro G. S. Fernandes, Jingqian Gou, Lavinia Heisenberg, Nadine Nussbaumer

Solar and Stellar Astrophysics

The Hubble Ultracool Multiplicity (HUM) Survey. I. Characterizing Sensitivity to Companions at Sub-Diffraction Limit Separations with HST WFC3/IR

Kunal Mehta, Matthew De Furio, Daniella Bardalez Gagliuffi et al. (+6 more)

We characterize the sensitivity of a double point-spread function (PSF) fitting algorithm – employing empirical, position-dependent PSF models – for detecting companions using the infrared channel of the Wide Field Camera 3 (WFC3/IR) on the Hubble Space Telescope (HST). The observed separation distribution of known brown dwarf (BD) binaries is potentially biased towards separations larger than the angular resolution limits of current techniques. Previous imaging analyses suffer from incompleteness at separations $<2\lambda/D$; our aim is to probe within this limit to identify previously missed companions. We evaluate the performance of our technique on artificial data across 8 WFC3/IR filters and a broad range of signal-to-noise ratios (S/N), determining our ability to accurately recover injected companions and identifying the region of parameter space where false positive fits are likely. Here, we demonstrate the capability of this technique to recover companions at sub-pixel separations on the WFC3/IR detector – below the diffraction limit in multiple filters. For F160W at a typical S/N of 75, we resolve companions separated by 0.8 pixels (104 mas, $0.759\lambda/D$) at 1.5 magnitudes contrast with $>90\%$ confidence. We achieve the closest angular resolution for any detection method with WFC3/IR imaging to date. Compared to previous BD multiplicity surveys with WFC3/IR, we achieve a 2.5$\times$ improvement in separation sensitivity at contrasts of 0-3 magnitudes in F127M. We have demonstrated that applying our improved technique to archival HST images of field BDs will thus probe down to separations of 1 au, in one of the largest high angular resolution surveys of such objects to date.
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All authors Kunal Mehta, Matthew De Furio, Daniella Bardalez Gagliuffi, Trent J. Dupuy, Clémence Fontanive, Adam L. Kraus, Michael R. Meyer, Matthew Cole, Fernanda Sophia Morais Laroca

Astrophysics of Galaxies

Closing the gap: Follow-up observations of peculiar dusty objects close to Sgr A* using ERIS

F. Peißker, M. Zajacek, V. Karas et al. (+8 more)

Context. In addition to the supermassive black hole Sgr A*, the inner parsec of our Galactic center is home to numerous fruitful scientific habitats. One of these environments is the S cluster, which consists of two distinct populations: the main-sequence S stars and the dusty G objects. While the majority of the brightest S stars can be classified as young B stars, the G sources can be described as dusty objects whose nature is still under debate. Aims. In this work, we focus on the most prominent G objects in the S cluster and follow their Keplerian trajectory around Sgr A*. With this, we test the predictions based on almost two decades of monitoring of the direct vicinity of our central supermassive black hole using NACO and SINFONI, formerly mounted at the Very Large Telescope (VLT). The goal is to increase the existing data baseline for G2/DSO, D9, and X7 to get insights into their evolution on their Keplerian trajectories. In addition, we revisit the massive Young Stellar Object (YSO) X3 and scrutinize the potential impact of its environment on this highly dynamic source. Methods. The successor to the two instruments is called ERIS and offers upgraded optics and improved properties, including an enhanced spectral resolution. We utilize the IFU mode of ERIS, called SPIFFIER. We search for the Doppler-shifted Br{\gamma} emission line to rediscover peculiar objects in the S cluster using SPIFFIER with the highest available spatial plate scale of 12.5 mas. Furthermore, we will derive the Br{\gamma} luminosity of G2/DSO to inspect the degree of its change more than ten years after the pericenter passage. If present, a decrease in the Br{\gamma} luminosity of G2/DSO on its descending part of the orbit would directly impact the direction of the debate about its nature.
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All authors F. Peißker, M. Zajacek, V. Karas, V. Pavlík, E. Bordier, L. Šubr, J. Haas, M. Melamed, L. Großekathöfer, N. Schmökel, M. Singhal

Cosmology and Nongalactic Astrophysics

EMU and Euclid: Detection of a radio-optical galaxy clustering cross-correlation signal between the Evolutionary Map of the Universe and Euclid

G. Piccirilli, B. Bahr-Kalus, S. Camera et al. (+173 more)

Synergies between large-scale radio-continuum and optical/near-infrared galaxy surveys are a powerful tool for cosmology. Cross-correlating these surveys can constrain the redshift distribution of radio sources, mitigate systematic effects, and place constraints on cosmological models. We perform the first measurement of the clustering cross-spectrum between radio-continuum sources in the Evolutionary Map of the Universe (EMU) survey and galaxies from the ESA Euclid satellite mission's Q1 release. Our goal is to detect and characterise the cross-correlation signal, test its robustness against systematic effects, and compare our measurements with theoretical predictions. We use data from the Australian SKA Pathfinder's EMU Main Survey, which overlaps with the Euclid Deep Field South. We generate two radio-source catalogues using different source finders to create galaxy maps. We measure the harmonic-space cross-correlation signal using a pseudo-spectrum estimator. The measured signal is compared to theoretical predictions based on a {\Lambda}CDM cosmology, using several models for the EMU source redshift distribution and bias. We report detection above 8{\sigma} of the cross-correlation signal consistent across all tested models and data sets. The measured cross-spectra from the two radio catalogues are in excellent agreement, demonstrating that the cross-correlation is robust against the choice of source-finding algorithm. The measured signal also agrees with theoretical models developed from previous cross-correlation studies and simulations. This pathfinder study establishes a statistically significant cross-correlation between EMU and Euclid. The robustness of the signal is a crucial validation of the methodology, paving the way for future large-scale analyses leveraging the full power of this synergy to constrain cosmological parameters and our understanding of galaxy evolution.
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All authors G. Piccirilli, B. Bahr-Kalus, S. Camera, J. Asorey, C. L. Hale, G. Fabbian, A. D. Asher, M. Vai, C. S. Saraf, D. Parkinson, N. Tessore, K. Tanidis, M. Kunz, A. M. Hopkins, T. Vernstrom, M. Regis, M. J. I. Brown, D. Carollo, T. Zafar, R. P. Norris, F. Pace, J. M. Diego, H. Tang, F. Rahman, D. Farrah, J. Th. van Loon, C. M. Pennock, J. Willingham, S. Andreon, C. Baccigalupi, M. Baldi, S. Bardelli, A. Biviano, E. Branchini, M. Brescia, G. Cañas-Herrera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, H. Dole, M. Douspis, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, L. Guzzo, S. V. H. Haugan, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, M. Kilbinger, B. Kubik, M. Kümmel, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, S. Mei, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, R. C. Nichol, S.-M. Niemi, C. Padilla, K. Paech, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, D. Sapone, B. Sartoris, J. A. Schewtschenko, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, A. Spurio Mancini, L. Stanco, J.-L. Starck, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, E. Zucca, J. García-Bellido, J. Martín-Fleitas, A. Pezzotta, V. Scottez, M. Viel

Solar and Stellar Astrophysics

Evading the dust fragmentation barrier with the streaming instability in protoplanetary disks

V. Vallucci-Goy, U. Lebreuilly, M.-M. Mac Low et al. (+1 more)

Context: The streaming instability (SI) is a leading candidate for reaching solid densities sufficient to trigger the gravitational collapse needed for the formation of planetesimals. However, dust growth barriers appear to impede the ability to assemble sufficiently large dust particles to trigger strong clumping, providing a serious impediment to planetesimal formation. Aims: We aim to address the possibility to enhance dust clumping with dust growth in SI-produced structures, and to estimate the impact of the shift of the dust fragmentation threshold in regions where the SI has enhanced the dust density. Methods: We perform two-dimensional numerical simulations of the SI with a monodisperse description of dust growth, accounting for the impact of mass loading of the dust on the sound speed of the gas and dust mixture when computing dust collisional velocities. Results: Dust mass loading reduces collision velocities in high density regions, allowing dust particles to survive to larger sizes before shattering. In turn, dust clumping is boosted as particles grow in size, as long as they remain sufficiently coupled to the gas. Conclusions: This two-way synergy between dust growth and clumping, which depends on the initial dust-to-gas ratio and dust elastic properties, allows denser dust clumps to form and thus facilitates the onset of planetesimal formation.
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All authors V. Vallucci-Goy, U. Lebreuilly, M.-M. Mac Low, P. Hennebelle

Instrumentation and Methods for Astrophysics

The Parkes Observatory Pulsar Data Archive

Lawrence Toomey, George Hobbs, James Dempsey et al. (+3 more)

Data from observations of pulsars made by Murriyang, the CSIRO Parkes 64-metre radio-telescope over the last three decades are more accessible than ever before, largely due to their storage in expansive long-term archives. Containing nearly 2 million files from more than 400 Parkes pulsar projects, CSIRO's Data Access Portal is leading the global effort in making pulsar data accessible. In this article, we present the current status of the archive, and provide information about the acquisition, analysis, reduction, visualisation, preservation and dissemination of these data sets. We highlight the importance of such an archive, and present a selection of new results emanating from archival data.
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All authors Lawrence Toomey, George Hobbs, James Dempsey, Shane Majewski, Shi Dai, John Reynolds

High Energy Astrophysical Phenomena

Vortex Dynamics in the Neutron Star Inner Crust

Xin Sheng, Bennett Link, Matthew E. Caplan et al. (+1 more)

We study the superfluid vortex motion in the neutron star inner crust through direct three-dimensional simulations of the coupled dynamics of the vortex and the nuclear lattice. We demonstrate the pinning of an initially moving vortex to the lattice through excitation of lattice vibrations, and show that the efficiency of this process is higher for attractive than for repulsive nucleus-vortex interactions. We explore the unpinning of a vortex under the action of the applied Magnus force, and find that it is influenced by multiple parameters, including the sign of the pinning force, the lattice orientation, composition, temperature, and the energy of pinning to individual nucleus. In lattices with multiple grains, the unpinning transition is triggered inside the grains with weaker pinning, propagates along the vortex (mediated by the excited Kelvin waves) and crosses into grains with stronger pinning. This is likely to effectively decrease the critical force at which vortices unpin and to produce extended regions of unpinned vorticity. Shearing of the crust lattice (e.g., by a starquake) initiates the unpinning of the vortices that are crossing the slip plane. A close encounter of an unpinned vortex with a pinned vortex would cause the latter to unpin, perhaps initiating an unpinning avalanche of many vortices.
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All authors Xin Sheng, Bennett Link, Matthew E. Caplan, Yuri Levin

Instrumentation and Methods for Astrophysics

Structure-Preserving Unpaired Image Translation to Photometrically Calibrate JunoCam with Hubble Data

Aditya Pratap Singh, Shrey Shah, Ramanakumar Sankar et al. (+4 more)

Insights into Jupiter's atmospheric dynamics are vital for understanding planetary meteorology and exoplanetary gas giant atmospheres. To study these dynamics, we require high-resolution, photometrically calibrated observations. Over the last 9 years, the Juno spacecraft's optical camera, JunoCam, has generated a unique dataset with high spatial resolution, wide coverage during perijove passes, and a long baseline. However, JunoCam lacks absolute photometric calibration, hindering quantitative analysis of the Jovian atmosphere. Using observations from the Hubble Space Telescope (HST) as a proxy for a calibrated sensor, we present a novel method for performing unpaired image-to-image translation (I2I) between JunoCam and HST, focusing on addressing the resolution discrepancy between the two sensors. Our structure-preserving I2I method, SP-I2I, incorporates explicit frequency-space constraints designed to preserve high-frequency features ensuring the retention of fine, small-scale spatial structures - essential for studying Jupiter's atmosphere. We demonstrate that state-of-the-art unpaired image-to-image translation methods are inadequate to address this problem, and, importantly, we show the broader impact of our proposed solution on relevant remote sensing data for the pansharpening task.
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All authors Aditya Pratap Singh, Shrey Shah, Ramanakumar Sankar, Emma Dahl, Gerald Eichstädt, Georgios Georgakis, Bernadette Bucher

Cosmology and Nongalactic Astrophysics

Tracing Structure: Shape and Centroid Deviations in 39 Strong Lensing Clusters as a Test of Cluster Formation Predictions

Raven Gassis, Matthew B. Bayliss, Keren Sharon et al. (+10 more)

Strong lensing galaxy clusters provide a unique and powerful way to test simulation-derived structure predictions that follow from $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. Specifically, the relative alignments of the dark matter (DM) halo, stars, and hot intracluster gas in these clusters offer insights into how well theoretical structure predictions hold. We measure the position angles, ellipticities, and locations/centroids of the brightest cluster galaxy (BCG), the Intracluster Light (ICL), the hot Intracluster Medium (ICM), and the Core Lensing Mass (CLM) for a sample of strong lensing galaxy clusters from the Sloan Giant Arcs Survey (SGAS). We measure the shapes (position angles and ellipticities) and centroids of these distributions using ellipse-fitting methods applied to different datasets: HST WFC3 imaging for the BCG and ICL, Chandra X-ray observations for the ICM, and strong-lensing mass reconstructions for the CLM. Additionally, we incorporate ICM morphological measures to classify the dynamical state of the cluster sample. Using this multi-component approach, we constrain the shape and centroids of these distributions in this sample and evaluate the different observable components in terms of their ability to trace the gravitational potential of their respective clusters. We find that misalignments between cluster components can be explained by astrophysical processes related to cluster assembly, relaxation, and merger histories. We find that the ICL is most closely aligned with its host DM halo, as traced by the CLM distribution, in both position angle and centroid. Additionally, we find that on average the ICL and CLM are more elliptical than the ICM and BCG.
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All authors Raven Gassis, Matthew B. Bayliss, Keren Sharon, Guillaume Mahler, Michael D. Gladders, Michael McDonald, Hakon Dahle, Michael K. Florian, Jane R. Rigby, Lauren A. Elicker, M. Riley Owens, Prasanna Adhikari, Gourav Khullar

Cosmology and Nongalactic Astrophysics

Non-Gaussianity in SMICA

M. Citran, H.V. Tran, G. Patanchon et al. (+1 more)

We develop a new formalism for the component separation method Spectral Matching Independent Component Analysis (SMICA) in order to include the information contained in the foregrounds beyond second-order statistics. We also develop a binned bispectrum estimator that works directly using maps of different frequency channels, capable of determining the bispectrum of multiple components at the same time, shifting the traditional approach to non-Gaussianity estimation from a cleaned map to the component separation step, for a better handling of foreground uncertainty. We test our method on 400 E and B polarization simulations based on the LiteBIRD experiment, containing the two main sources of contamination for CMB polarization experiments: polarized dust and synchrotron emission. We show that the bispectrum does not improve the precision of the power spectrum estimation or of the spectral parameters. However, we are capable of recovering the correct 3-point correlator of the foregrounds and standard constraints on primordial non-Gaussianity in a coherent multi-frequency and multi-component framework. The advantage of our approach is that it combines data in an optimal way accounting for the power spectrum and the bispectrum of the various components, which is not true for the standard approach.
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All authors M. Citran, H.V. Tran, G. Patanchon, B. van Tent

Instrumentation and Methods for Astrophysics

Identifying Transient Hosts in LSST's Deep Drilling Fields with Galaxy Catalogues

Josh G. Weston, David R. Young, Stephen J. Smartt et al. (+3 more)

The upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will enable astronomers to discover rare and distant astrophysical transients. Host-galaxy association is crucial for selecting the most scientifically interesting transients for follow-up. LSST Deep Drilling Field observations will detect distant transients occurring in galaxies below the detection limits of most all-sky catalogues. Here we investigate the use of pre-existing smaller-scale, field-specific catalogues for host identification in the Deep Drilling Fields (DDFs) and a ranking of their usefulness. We have compiled a database of 70 deep catalogues that overlap with the Rubin DDFs and constructed thin catalogues to be homogenised and combined for transient-host matching. A systematic ranking of their utility is discussed and applied based on the inclusion of information such as spectroscopic redshifts and morphological information. Utilising this data against a Dark Energy Survey (DES) sample of supernovae with pre-identified hosts in the XMM-LSS and ECDFS fields, we evaluate different methods for transient-host association in terms of both accuracy and processing speed. We also apply light data-cleaning techniques to identify and remove contaminants within our associations, such as diffraction spikes and blended galaxies where the correct host cannot be determined with confidence. We use a lightweight machine learning approach in the form of extreme gradient boosting to generate confidence scores in our contaminant selections and associated metrics. Finally, we discuss the computational expense of implementation within the LSST transient alert brokers, which will require efficient, fast-paced processing to handle the large stream of survey data.
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All authors Josh G. Weston, David R. Young, Stephen J. Smartt, Matt Nicholl, Matt J. Jarvis, I.H. Whittam

Instrumentation and Methods for Astrophysics

The NANOGrav 12.5-year Data Set: Chromatic Noise Characterization & Mitigation with Time-Domain Kernels

Jeffrey S. Hazboun, Joseph Simon, Jeremy Baier et al. (+64 more)

Pulsar timing arrays (PTAs) have recently entered the detection era, quickly moving beyond the goal of simply improving sensitivity at the lowest frequencies for the sake of observing the stochastic gravitational wave background (GWB), and focusing on its accurate spectral characterization. While all PTA collaborations around the world use Fourier-domain Gaussian processes to model the GWB and intrinsic long time-correlated (red) noise, techniques to model the time-correlated radio frequency-dependent (chromatic) processes have varied from collaboration to collaboration. Here we test a new class of models for PTA data, Gaussian processes based on time-domain kernels that model the statistics of the chromatic processes starting from the covariance matrix. As we will show, these models can be effectively equivalent to Fourier-domain models in mitigating chromatic noise. This work presents a method for Bayesian model selection across the various choices of kernel as well as deterministic chromatic models for non-stationary chromatic events and the solar wind. As PTAs turn towards high frequency (>1/yr) sensitivity, the size of the basis used to model these processes will need to increase, and these time-domain models present some computational efficiencies compared to Fourier-domain models.
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All authors Jeffrey S. Hazboun, Joseph Simon, Jeremy Baier, Bjorn Larsen, Daniel J. Oliver, Paul T. Baker, Bence Bécsy, Siyuan Chen, Alberto Diaz Hernandez, Justin A. Ellis, A. Miguel Holgado, Kristina Islo, Aaron Johnson, Andrew R. Kaiser, Nima Laal, Alexander McEwen, Nihan S. Pol, Joey Shapiro Key, Min Young Kim, Matthew Samson, Brent J. Shapiro-Albert, Jerry P. Sun, Stephen R. Taylor, Caitlin A. Witt, Jeremy Volpe, Christine Ye, Harsha Blumer, Paul R. Brook, Shami Chatterjee, James M. Cordes, Fronefield Crawford, H. Thankful Cromartie, Megan E. DeCesar, Paul B. Demorest, Timothy Dolch, Robert D. Ferdman, Elizabeth C. Ferrara, William Fiore, Emmanuel Fonseca, Nathan Garver-Daniels, Peter A. Gentile, Deborah C. Good, Ross J. Jennings, Megan L. Jones, David L. Kaplan, Michael T. Lam, T. Joseph W. Lazio, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Dustin R. Madison, Maura A. McLaughlin, Chiara M. F. Mingarelli, Cherry Ng, David J. Nice, Timothy T. Pennucci, Scott M. Ransom, Paul S. Ray, Xavier Siemens, Renée Spiewak, Ingrid H. Stairs, Daniel R. Stinebring, Kevin Stovall, Joseph K. Swiggum, Jacob E. Turner, Michele Vallisneri, Sarah J. Vigeland

Cosmology and Nongalactic Astrophysics

Skew-spectra: a generalization to spin-$s$

Alexander Roskill, Sara Maleubre, David Alonso et al. (+1 more)

Skew-spectra allow us to extract non-Gaussian information by taking the square of a map and finding the power spectrum of this new map with the original map. This allows us to use much of the infrastructure of power spectra and avoid the intricacies of estimating three point statistics. In this paper we present the first extension of skew-spectra to arbitrary spin-$s$ fields, as a means to extract non-Gaussian information efficiently from cosmological data sets like cosmic shear or CMB polarization. We apply the formalism to weak lensing in the context of large scale structure, and discuss different ways of combining fields to build skew-spectra, all while avoiding the problems associated with mass-mapping. We provide plots of these new statistics for $\Lambda$CDM and vary cosmological parameters.
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All authors Alexander Roskill, Sara Maleubre, David Alonso, Pedro G. Ferreira

Cosmology and Nongalactic Astrophysics

Forecasting Constraint on Primordial Black Hole Properties with the CSST $3\times2$pt Analysis

Dingao Hu, Yan Gong, Pengfei Su et al. (+4 more)

This study forecasts the constraints on the properties of primordial black holes (PBHs) as a cold dark matter component using the galaxy clustering, weak lensing, and galaxy-galaxy lensing (i.e. $3\times2$pt) measurements from the upcoming Chinese Space Station Survey Telescope (CSST) photometric survey. Since PBHs formed via gravitational collapse in the early Universe, they can additionally affect the formation and evolution of the cosmic large-scale structure (LSS) through “Poisson" effect. We compute the angular power spectra for PBH-$\Lambda$CDM cosmology, and generate mock data based on the CSST instrumental and survey design. The Markov Chain Monte Carlo (MCMC) method is employed to constrain the free parameters, such as the product of the PBH fraction and mass $f_{\rm PBH}m_{\rm PBH}$ and other cosmological parameters. The systematic parameters are also included in the fitting process, such as the parameters of the baryonic effect, intrinsic alignment, galaxy bias, photometric redshift (photo-$z$) calibration, shear calibration, and noise terms. We find that the CSST 3$\times$2pt analysis can achieve tight constraints on $f_{\rm PBH}m_{\rm PBH}$, with 68% and 95% confidence levels (CLs) reaching $<10^{3.9} M_{\odot}$ and $<10^{4.7} M_{\odot}$, respectively. Additionally, the cosmological parameters, e.g. $\Omega_m$, $\sigma_8$ and $w$, can be constrained with the precisions of 3.3%, 1.7%, 13%, respectively. This indicates that the CSST 3$\times$2pt analysis is a powerful tool to advance the PBH dark matter studies in the near future.
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All authors Dingao Hu, Yan Gong, Pengfei Su, Hengjie Lin, Haitao Miao, Qi Xiong, Xuelei Chen

Astrophysics of Galaxies

ALMACAL. XV. Band 3 ALMA Survey and Number Counts

Matteo Bonato, Ivano Baronchelli, Gianfranco De Zotti et al. (+10 more)

The ALMACAL project leverages ALMA maps of calibrator-centered fields to conduct deep mm/sub-mm surveys, enabling the detection of extragalactic sources with flux densities orders of magnitude fainter than achievable with other instruments. These faint sources are critical for refining evolutionary models, as their number counts provide key constraints. In this study, we analyzed band-3 ALMACAL maps from 606 calibrator fields, employing a novel machine learning approach to mitigate the often-overlooked bias introduced by the calibrator itself. Supported by extensive simulations, we extended 100 GHz radio AGN counts by approximately 1.5 orders of magnitude in flux density and refined constraints on dusty star-forming galaxies, reaching sensitivities as low as $\sim$180 $\mu$Jy. We have improved the sampling, compared to previous results, in the region of the dominant population transition (between dusty star-forming galaxies and radio AGN). Our results are in good agreement with model predictions.
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All authors Matteo Bonato, Ivano Baronchelli, Gianfranco De Zotti, Leonardo Trobbiani, Michele Delli Veneri, Fabrizia Guglielmetti, Rosita Paladino, Viviana Casasola, Martin Zwann, Marcella Massardi, Elisabetta Liuzzo, Vincenzo Galluzzi, Erlis Ruli

Cosmology and Nongalactic Astrophysics

The network analysis of the cosmic web as a tool to constrain cosmology and cosmic magnetism

Anton Rudakovskyi, Franco Vazza and Maksym Tsizh

Context. The spatial distribution of haloes in the Cosmic Web encodes a wealth of information about the underlying cosmological model. These haloes can be represented as nodes of a graph, whose structural properties reflect cosmological parameters. Aims. Using our new MAKITRA suite of cosmological magneto-hydrodynamical simulations covering a total volume of $(300\,\text{Mpc})^3$ and with 21 physical model variations (including variations of $\sigma_8$ and of different models of primordial magnetic fields, PMFs), we investigate the sensitivity of network-based statistics describing the Cosmic Web to variations in cosmological and PMF scenarios. Methods. We focus on several complementary metrics that characterise the spatial distribution of dark and baryonic matter haloes: two-point correlation functions, network-centrality statistics, and counts-in-cell measurements. We first compare the halo-halo correlation functions across different cosmological models. For the network analysis, we represent haloes as vertices of the Cosmic Web and compute multiple centrality measures, whose cumulative distributions we evaluate for universes with varying PMF strengths. Finally, we quantify halo abundances within randomly placed spheres of fixed radius to assess differences between scenarios. Results. First, we find that the statistics of the centralities of the network can serve as a novel sensitive probe of the cosmological parameter $\sigma_8$. Moreover, we find that this network analysis approach can allow us to distinguish the presence of PMFs with initial strength $\approx\,4 \text{nG}$ from the scenarios with much weaker PMFs.
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Cosmology and Nongalactic Astrophysics

Cosmology of axion dark energy in supersymmetric models and constraints on high scale parameters

Amin Aboubrahim, Andrew H. Giman and Pran Nath

An analysis is given of interacting dark energy and dark matter where the dark energy is assumed to be an ultralight axionic field with a pseudo-Nambu-Goldstone Boson potential which is in general a superposition of $N$ number of cosine terms motivated by supergravity and string models with a $U(1)$ global symmetry, where the symmetry is broken by instanton effects. The case $N=2$ is investigated in detail and a fit to cosmological data is performed where it is found that a better fit is obtained in comparison with the $N=1$ case. The fits also constrain high scale parameters, i.e., the axion decay constant which is determined to be sub-Planckian, a result consistent with string theory that disfavors trans-Planckian axion decay constant. Furthermore, the dark energy-dark matter interaction strength is constrained to be feeble, i.e., $\lambda\lesssim 4\times 10^{-6}$ m$_{\rm Pl}^{-2}$ Mpc$^{-2}$. We study possible implications of this type of potential on the Hubble tension and on the dynamics of the dark energy equation of state using the DESI-DR2 data. For the cases $N=3,4$, the analysis exhibits the phenomenon of transmutation even in the absence of coupling to dark matter, where thawing quintessence transmutes to freezing quintessence. The analysis is internally consistent in its treatment of the dark energy-dark matter interaction as it is based on an underlying Lagrangian, in contrast with several previous works where the sources are chosen in an ad hoc manner to satisfy energy conservation.
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Astrophysics of Galaxies

Laboratory Detection and Rotational Spectroscopy of $trans$-HNSO: Implications for Astronomical Observations

Valerio Lattanzi, Miguel Sanz-Novo, Víctor M. Rivilla et al. (+2 more)

Sulfur-bearing molecules are central to interstellar chemistry, yet their observed abundances in the gas phase remain far below cosmic expectations in dense interstellar regions. Mixed N-S-O species such as thionylimide (HNSO) are particularly relevant, as they incorporate three key biogenic elements. The $cis$ conformer of HNSO has recently been detected in the Galactic Center cloud G+0.693-0.027, but no high-resolution data for the higher energy conformer ($trans$-HNSO) had been available until now. We report the first laboratory detection and rotational spectroscopic characterization of $trans$-HNSO. Spectra were recorded with the Center for Astrochemical Studies Absorption Cell (CASAC) free-space spectrometer employing a hollow-cathode discharge source, yielding 104 assigned transitions between 200 and 530 GHz. A Watson S-reduced Hamiltonian fit reproduced the data with an rms of 40 kHz, providing accurate rotational and centrifugal distortion constants in excellent agreement with CCSD(T) predictions. Although $trans$-HNSO lies only a few kcal/mol above the $cis$ form, it has larger dipole components, making its lines particularly intense (more than 5 times brighter, assuming equal abundances) and a very promising candidate for future astronomical detection. The new measurements enable reliable frequency predictions for astronomical searches and will be added to public databases. Combined with recent evidence for tunneling-driven $trans$-to-$cis$ isomerization at cryogenic temperatures, these results open the way to test directly whether quantum tunneling governs the interstellar distribution of HNSO isomers.
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All authors Valerio Lattanzi, Miguel Sanz-Novo, Víctor M. Rivilla, Izaskun Jiménez-Serra, Paola Caselli