Earth and Planetary Astrophysics
Giant impact between high-viscosity Theia and low-viscosity proto-Earth: Origin of lunar isotopic crisis
Wenshuai Liu
According to the
giant impact theory, the Moon was formed by
accretion of the debris disk that resulted from the collision between Theia and the proto-Earth. Although this theory accounts for most characteristics of the Earth-Moon system, numerical simulations of impacts between a planetary embryo and the accreting proto-Earth indicate that more than 40 percent of the material in the circum-terrestrial disk generated by such an impact originates from the impactor. This poses a challenge for the
giant impact theory in explaining the Moon's Earth-like isotopic composition, a discrepancy known as the lunar isotopic crisis. Since terrestrial
planets were melted one or more times during accretionary processes, magma ocean on the surface of a growing
planet would appear. Small terrestrial
planets with magma ocean cool faster than large ones, resulting that the viscosity of small terrestrial
planets is larger than that of large terrestrial
planets still covered by magma ocean. Here, it shows that
giant impact between a high-viscosity Theia and a low-viscosity proto-Earth could produce a circum-terrestrial debris disk predominantly composed of material from the proto-Earth without violating the angular momentum constraint of modern Earth-Moon system. The theory proposed here may provide a natural way of explaining the lunar isotopic crisis.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
New Gauge Forces, Neutron Stars and Schwinger Neutrino Production
Yuxin Liu, Zhen Liu, Andrey Shkerin et al. (+2 more)
We investigate
neutrino effects of new long-range forces arising from gauging $B-L$, $L_e-L_{\mu/\tau}$ or $L_{\mu}-L_{\tau}$
symmetries of the Standard Model. The leptonic potential generated by astronomical bodies, such as the Earth, the Sun or a
neutron star, results in the Schwinger pair production of
neutrinos charged under the new gauge
symmetry. The oppositely charged particles accumulate in the potential well forming a degenerate
Fermi gas, while equally charged particles fly away forming a steady flux of
neutrinos. We find that, for the $B-L$ and $L_e-L_{\mu/\tau}$ forces, these effects are too weak to be observable. For the $L_{\mu}-L_{\tau}$ force these effects are significant in
neutron stars if the gauge coupling is $g\gtrsim 10^{-18}$. The muonic force changes the element abundances of a
neutron star in
equilibrium and suppresses its $L_{\mu}-L_{\tau}$ charge. This invalidates the constraint on $g$ from
neutron star mergers, at $g\gtrsim 10^{-17}$. Furthermore, for such values of $g$, the
neutrino flux produced by the Schwinger effect could potentially be detected from a single young
neutron star at a distance of $\simeq 100$ pc, with the typical
neutrino energy $E_\nu\sim 100$ MeV. A dedicated search for such a signal will reassert the bound $g\lesssim 10^{-18}$.
Read the full abstract ▾
All authors Yuxin Liu, Zhen Liu, Andrey Shkerin, Jing Shu, Yue Zhao
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Phase Transitions and Gravitational Wave Production at the End of Thermal Inflation
Hyukjung Kim, İlayda Kuzu, Kerem Özsoy et al. (+3 more)
We investigate the first-order phase transition that terminates thermal inflation and evaluate the associated
stochastic gravitational-wave signals. The transition is first characterized through semi-analytic calculations of the bounce action, which are compared with numerical results obtained using CosmoTransitions. We then study its real-time
evolution in a three-dimensional Langevin
lattice simulation that incorporates Hubble expansion and the corresponding temperature
evolution throughout the transition. The
lattice dynamics are consistent with the bounce-action estimates: the transition proceeds through localized bubble nucleation and subsequent bubble growth, rather than through a phase-mixing instability. Using the resulting transition parameters, we estimate the gravitational-wave spectra generated by bubble collisions and acoustic motions in the
plasma. The predicted
stochastic background lies within the projected sensitivity ranges of future gravitational-wave observatories, including BBO and DECIGO.
Read the full abstract ▾
All authors Hyukjung Kim, İlayda Kuzu, Kerem Özsoy, Zeynep Kahraman, Wan-Il Park, Heeseung Zoe
Instrumentation and Methods for Astrophysics
ELMA: ELlipse-based bar MAjor axis estimator
Bruna R. Bragança de Lima, Andressa Wille, Rafael S. de Souza et al. (+1 more)
Galactic bars are key non-axisymmetric structures in disk
galaxies, driving angular-momentum redistribution and contributing to secular
evolution, central mass build-up, and the formation of
nuclear structures. Robust and homogeneous measurements of bar length, however, remain challenging, particularly for large imaging surveys, where manual estimates are time-consuming and sensitive to methodological choices. We introduce elma, a standalone, pip-installable Python package for automated bar-length estimation in
galaxies already identified as candidate barred systems. The method operates directly on two-dimensional imaging data, using iterative elliptical-isophote fitting to trace the radial ellipticity profile and identify a projected bar-length estimate from the semi-major axis associated with the local maximum in ellipticity. Using the image WCS information and a user-supplied
redshift, elma converts angular measurement into a projected physical length. We demonstrate the package on JWST/NIRCam imaging of barred
galaxies in the GOODS-South field. The code is released under the MIT license at a repository in Github.
Read the full abstract ▾
All authors Bruna R. Bragança de Lima, Andressa Wille, Rafael S. de Souza, Ana L. Chies-Santos
Solar and Stellar Astrophysics
DEM analysis of the 6 September 2011 large-scale coronal wave
Amaia Razquin, Astrid M. Veronig and Karin Dissauer
Large-scale coronal waves are globally propagating intensity enhancements in extreme-ultraviolet (EUV) and soft X-ray (SXR) observations, associated with
solar flares and coronal mass ejections (CMEs). They are interpreted as low-coronal signatures of a large-amplitude fast magnetosonic wave. On 6 September 2011, a fast (v = 1000 km/s) large-scale coronal wave accompanied an eruptive X2.1 class
flare. A segment of the wave front temporarily dissappeared in EUV channels sensitive to quiet-Sun
plasma, while it remained visible in higher temperature channels. We apply differential emission measure (DEM) diagnostics to SDO/AIA EUV observations to derive local density, temperature, emission measure, and DEM distributions, and examine their temporal
evolution during the wave passage. The wave passage causes increases of 6-8% in density and 10-18% in temperature. While the density increase is comparable to earlier reports, the temperature increase exceeds expectations. This indicates that the temperature enhancement cannot be explained by compressional adiabatic heating alone, and instead suggests the presence of additional heating mechanisms, such as
magnetic reconnection or wave mode conversion. During the temporary disappearance of the wave, the
plasma parameters at the wave front increase, but with a strong spatial variability, with density increases ranging from 1% to 10%. The initial temperature in the affected area is notably higher than typical quiet-Sun regions (T > 1.7 MK), which allows
plasma to be heated beyond the peak response of the AIA 193 and 211 Åchannels. We conclude that the apparent temporary disappearance of the wave front is primarily due to the combined effects in the intensity of the CME-associated coronal dimming following the wave and the wave itself, with heating further reducing its detectability in channels sensitive to quiet-Sun temperatures.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Advancing Astrophysics with the SKA II
Anna Bonaldi, Tyler L. Bourke, Philippa Hartley et al. (+45 more)
Advancing Astrophysics with the SKA II (AASKAII), written by our science community, outlines the transformative scientific advances that will be enabled by the SKA
telescopes. In the decade since the publication of the previous edition,
telescope designs have matured, construction has commenced, and the SKA Organisation has evolved into the SKA Observatory (SKAO). At the same time, observations from SKA precursor and pathfinder
telescopes have provided new insights into longstanding scientific challenges while revealing entirely new phenomena. Published in advance of the first science verification campaign for the SKA Observatory, this volume looks ahead to the coming decades of discovery and innovation in
radio astronomy. AASKAII spans the broad range of scientific research enabled by the SKA
telescopes, SKA-Mid and SKA-Low. The contributions are organised into six thematic categories according to their scientific focus. The opening section presents overview chapters from the SKA Science Working Groups, around which our community is organised. Each overview provides the broader context that connects the contributions in this volume to the key scientific questions being pursued by their respective communities.
Read the full abstract ▾
All authors Anna Bonaldi, Tyler L. Bourke, Philippa Hartley, Tao An, Marc Audard, Olga Bayandina, Nicola Bellomo, Eleonora Bianchi, Marta Burgay, Joseph Callingham, Stefano Camera, Viviana Casasola, Virginia Cuciti, Philippa Cole, Neeraj Gupta, Catherine L. Hale, Ian Harrison, Jason Hessels, Tim Huege, Bhal Chandra Joshi, Aris Karastergiou, Dharam Lal, Adrian Liu, James Miller-Jones, S. A. Mao, Javier Moldon, Leah K. Morabito, Katharine Mulrey, Shane O'Sullivan, Divya Oberoi, D.J. Pisano, Kaustubh Rajwade, Mark T. Sargent, Rohit Sharma, Marta Spinelli, Xiaohui Sun, Fatemeh S. Tabatabaei, Cathryn Trott, Jacco Th. van Loon, Tessa Vernstrom, Jeff Wagg, Jing Wang, Ke Wang, Sven Wedemeyer, Jennifer L. West, Patrick Woudt, Jun Yang, Pietro Zucca
Instrumentation and Methods for Astrophysics
Lightstack: A Python Package for Creating Photometric Data Cubes
Andressa Wille, Rafael S. de Souza, Ana L. Chies-Santos et al. (+3 more)
Multi-band photometry traces diverse physical processes across a wide range of wavelengths. In recent decades, this field has been driven by the rapid growth of multi-imaging
datasets, from high-resolution observation from Hubble Space
Telescope and James Webb Space
Telescope to the forthcoming large-scale surveys enabled by the Roman Space
Telescope and Rubin Observatory, for example. In this work, we present lightstack, a Python package for combining standalone images into photometric data cubes. The workflow consists of three main steps: cropping a region of interest from a mosaic across all available filters; stacking the images to construct the data cube; and performing PSF matching on the cube. This package is intended for preparing data for studies involving multi-band photometry. The code is released under an MIT license and is available on GitHub together with a Jupyter tutorial notebook. The version used for this publication (v0.2.1) is archived on Zenodo.
Read the full abstract ▾
All authors Andressa Wille, Rafael S. de Souza, Ana L. Chies-Santos, Thallis Pessi, Emille E. O. Ishida, Alberto Krone-Martins
Earth and Planetary Astrophysics
A long-term spectro-temporal study of Jovian X-ray and Ultraviolet response to solar activity
Megha Tomer, Mayukh Pahari, Anurag Baruah et al. (+1 more)
We present results from a multi-decade investigation of
solar activity-driven variability in Jupiter's emissions, using
solar X-ray flux and sunspot numbers as activity indicators and ultraviolet (UV) and X-ray observations from the International Ultraviolet Explorer (IUE; 1978-1996) and the Chandra X-ray Observatory (2011-2021). Analysis of 51 high-SNR UV spectra spanning two
solar cycles shows that Jupiter's Ly$\alpha$ emission contains narrow and broad components, likely associated with the disk and auroral regions, respectively. The Ly$\alpha$ line and the 1330-1400 Angstrom continuum flux closely follow variations in
solar X-ray flux and sunspot numbers throughout all phases of two consecutive
solar cycles, indicating a direct connection with
solar irradiation processes, including resonant scattering of
solar Ly$\alpha$
photons and photoelectron-driven atmospheric excitation. In contrast, ionised UV lines such as Fe II (1608 Angstrom and 1575 Angstrom) show no correlation with
solar activity over a
solar cycle, suggesting an internal or magnetospheric origin, potentially linked to Io-derived charged particles or UV/X-ray radiation. To determine whether Jupiter's X-ray response resembles its UV response to
solar activity, we analysed 29 Chandra/HRC observations obtained during 2014-2021 and two Chandra/ACIS observations from 2011. Significant X-ray
flares are detected in both ACIS and HRC lightcurves 7-15 days after major reported coronal mass ejections (CMEs). Post-CME ACIS auroral spectra reveal a significant ($\geq 3\sigma$) Ne$^{8+}$ emission feature ($\sim$0.94-0.98 keV) near 70-80$^\circ$ latitude at Jupiter's north pole. Owing to the high ionisation energy required ($\sim$1.19 keV for the Ne VIII to Ne IX bound-bound transition), this feature is unlikely to arise from local interactions, supporting CME-driven auroral excitation on Jupiter.
Read the full abstract ▾
All authors Megha Tomer, Mayukh Pahari, Anurag Baruah, Renu Malhotra
Solar and Stellar Astrophysics
V7995 Sgr: A New FU Orionis Accretion Outburst Near NGC 6589/6590
Lynne A. Hillenbrand, Kishalay De Adolfo S. Carvalho, Dan Stern et al. (+2 more)
We announce a new FU Orionis type outburst that reached peak brightness in late 2024, following a steep 4.6 month photometric rise of -2.85 mag in the $r$ band. This rapid brightening at all wavelengths was preceeded in the infrared by a much shallower rise over 4 years. The progenitor object was an unstudied young
stellar object having a flat-spectrum type spectral energy distribution, and extended nebulosity. We present multi-wavelength lightcurves covering the photometric low-state, the outburst, and early post-outburst epochs. Optical imaging shows a concurrent brightening of the extended nebular environment. We also present follow-up optical/near-infrared spectroscopy taken 1.5 years after the inferred photometric peak. The spectra confirm an FU Ori type outburst. The outburst source exhibits a mixed-temperature absorption spectrum, formed in an
accretion disk, and it shows several line species with blueshifted absorption profiles that are formed in a strong wind.
Read the full abstract ▾
All authors Lynne A. Hillenbrand, Kishalay De Adolfo S. Carvalho, Dan Stern, Evan Portnoi, Nicholas Earley
Instrumentation and Methods for Astrophysics
Instruments for Focal Plane X-Ray Polarimetry in the Next Decade
Fabio Muleri, Stefano Cesare, Enrico Costa et al. (+18 more)
The successful detection of X-ray polarization from many celestial sources belonging to different classes by the IXPE mission has opened a new window in X-ray astronomy. While an impressive number of scientific topics have already been addressed by IXPE, many of them would benefit from a new class of instrumentation that could be launched on a relatively short time scale. In this contribution, we present the development activities of a focal-plane polarimeter whose goal is to extend the energy range of IXPE up to tens of keV, with better sensitivity and lower background. Our design is based on the use of multilayer mirrors and stacked instrumentation, comprising either a low- or medium-energy imaging photoelectric polarimeter and an active Compton polarimeter. Such an approach relies on hardware with flight heritage and – although still under development for the specific application in X-ray polarimetry – it has the potential to answer compelling scientific questions and to soon become competitive from the point of view of feasibility for space applications.
Read the full abstract ▾
All authors Fabio Muleri, Stefano Cesare, Enrico Costa, Walter Cugno, Klaus Desch, Alessandro Di Marco, Sergio Fabiani, Riccardo Ferrazzoli, Markus Gruber, Daniel Heuchel, Saba Imtiaz, Jochen Kaminski, Dawoon Edwin Kim, Alessandro Lacerenza, Carlo Lefevre, Hemanth Manikantan, Vladislavs Plesanovs, John Rankin, Ajay Ratheesh, Alda Rubini, Paolo Soffitta
Astrophysics of Galaxies
A merger shock traced by radio arcs and ultra-long radio tails in galaxy cluster A2142
Chong Ge, Ming Sun, Chris Nolting et al. (+2 more)
Abell 2142 (A2142) is a massive, nearby
galaxy cluster undergoing a complex merger. It exhibits an elongated X-ray morphology along the northwest-southeast axis and hosts four known cold fronts. Using XMM-Newton observations, we detect a merger shock on the northwest side of the cluster with a Mach number of $M \sim 1.3$. The observed shock front and four cold fronts can be reproduced by numerical simulations of an off-axis merger with a large impact parameter, which imparts significant angular momentum to induce the sloshing of the subcluster core and large-scale ambient gas. In projection, the shock front is spatially coincident with arc-shaped
radio filaments observed behind the prominent head-tail
radio galaxies T1 and T2. We interpret these
radio arcs as partial
vortex ring structures (resembling “smoke rings”) produced by the interaction of the merger shock with the low-density cocoons of
radio galaxies. The shock strips and rolls the jet cocoon into a toroidal
vortex, as predicted by recent magnetohydrodynamic simulations. We further demonstrate that the merger shock can significantly elongate the
radio tails by re-accelerating aged relativistic electrons and stretching the tail
plasma via the post-shock wind. This process provides a natural explanation for the $>$500 kpc tail observed in this and other merging clusters. Our findings establish
radio arcs and ultra-long
radio tails as independent, complementary tracers of merger shocks in
galaxy clusters. Our results demonstrate that merger shocks can reshape both the thermal and non-thermal components of
galaxy clusters, and that tailed
radio galaxies serve as sensitive probes of intracluster medium weather.
Read the full abstract ▾
All authors Chong Ge, Ming Sun, Chris Nolting, Fabio Gastaldello, Dominique Eckert
High Energy Astrophysical Phenomena
Evidence for candidate X-ray pulsations from the ultraluminous X-ray source NGC 7456 ULX-1
Yuanle Yao, Xiang-Dong Li and Xiao-Jie Xu
We report evidence for a candidate pulsational signal at $\sim0.22$~Hz from NGC7456 ULX-1, a previously identified ultraluminous X-ray source (ULX). The signal is identified in the 2023 XMM-Newton observation using independent timing techniques including accelerated searches, $Z^2_n$ statistics, and an orbital-demodulation analysis designed to restore phase coherence in the presence of binary motion. The candidate pulsation frequency drift within the observation suggests rapid
spin evolution driven by
accretion torque. We further estimate the surface dipole
magnetic field strength to be $B\sim 10^{12}-10^{14}$ G. These results provide evidence that NGC7456 ULX-1 may host an accreting
neutron star, although confirmation with independent
datasets or additional observations is required.
Read the full abstract ▾
Solar and Stellar Astrophysics
Intermittent turbulent fluctuations in solar coronal mass ejections
Apurva Bhagat, Sumit Tambe, Debesh Bhattacharjee et al. (+1 more)
Localised regions of high intensity fluctuations are known to be signatures of intermittency in fluid and
plasma turbulence. We investigate such turbulent spots using near-Earth in-situ spacecraft observations of a sample of 125
solar coronal mass ejections (CMEs). We present statistical results which suggest that the intensity of the strongest turbulent spot and the turbulent spot occurrence rate are reliable indicators of the onset of the leading part of the CME event. Our findings also suggest that turbulent spots can be sites of enhanced
proton heating. The findings of this study can enhance our understanding of intermittence in collisionless
plasma turbulence and can improve CME/sheath-driven space weather impact prediction models.
Read the full abstract ▾
All authors Apurva Bhagat, Sumit Tambe, Debesh Bhattacharjee, Prasad Subramanian
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Constitutive birefringence and critical curves in the rotating García–Díaz black hole
Ariel Guzmán, Mohsen Fathi and J.R. Villanueva
We study high-frequency electromagnetic propagation in the rotating García–Díaz solution of Einstein
gravity coupled to NLED. In this system, light is not governed only by the null cone of the spacetime metric, because the NLED field also behaves as an optical medium whose constitutive response determines the physical optical cones. Starting from the mixed electromagnetic potentials, we project the field $F$ and the excitation $P$ on a principal tetrad and obtain the aligned scalars $E$, $B$, $D$ and $H$. These scalars allow us to reconstruct the regular local constitutive branch connected with Maxwell theory through the map $(D,B)\mapsto(E,H)$. We then insert the resulting response
matrix into the Fresnel characteristic problem. At the perturbative order considered here, the Fresnel quartic factorizes into two quadratic branches, each defining an effective optical metric. Both optical metrics admit Carter-type separation of the Hamilton–Jacobi equation and possess their own radial and angular potentials, critical constants and unstable critical families. By projecting these families onto the celestial sphere of a finite-distance observer, we obtain two critical contours, $\Gamma_+$ and $\Gamma_-$, which coincide in the Maxwell limit and split when the nonlinear constitutive response is active. We quantify this birefringent splitting through the maximum angular separation, the relative diameter shift and the normalized birefringent width. Numerical scans over the nonlinear coupling,
spin and observer inclination show that the splitting is generated by the constitutive response, redistributed by rotation and stable under local projection changes within the perturbative domain. This provides a direct geometrical link between the local NLED response and a polarization-dependent critical structure on the observer screen.
Read the full abstract ▾
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
An explicit and differentiable Wilson-Daubechies-Meyer transform for gravitational-wave data analysis
Avi Vajpeyi, Giorgio Mentasti, Quentin Baghi et al. (+2 more)
The Wilson-Daubechies-Meyer (WDM) time-frequency transform has been widely used in gravitational-wave astronomy, yet a self-contained, mathematically explicit reference for practitioners remains lacking. This is especially true for those wishing to adopt the transform in modern Python and JAX inference workflows. We present wdm_transform, an open-source Python package implementing the WDM wavelet-packet time-frequency transform, and document its mathematical foundations, statistical properties, and practical implementation for gravitational-wave data analysis. The package supplies NumPy and JAX backends, both transforms (forward and inverse) validated to floating-point precision, with the JAX backend enabling GPU-accelerated transforms of million-point data streams in tens of milliseconds. As a worked example, we verify that the WDM-domain likelihood reproduces frequency-domain posteriors for a resolved LISA
galactic binary under a shared stationary noise model, confirming numerical equivalence of the two representations in that controlled setting. This work paves the way for systematic optimisation of WDM tilings, a particularly promising direction for the non-stationary noise,
stochastic backgrounds, and data gaps anticipated in future detectors, and for direct comparisons with alternative time-frequency representations needed to meet the challenges of future gravitational-wave data analysis.
Read the full abstract ▾
All authors Avi Vajpeyi, Giorgio Mentasti, Quentin Baghi, Ollie Burke, Lorenzo Speri
Astrophysics of Galaxies
UCLCHEM 4.0: An open source gas-grain astrochemistry simulation framework
Gijs Vermariën, Serena Viti, Tobias M. Dijkhuis et al. (+4 more)
Astrochemical modelling is a key tool for interpreting the formation and destruction of molecules in the interstellar medium, complementing the increasingly detailed observations enabled by modern day observational facilities. UCLCHEM is a comprehensive gas-grain astrochemical modelling framework that can compute the chemical
evolution inside a parcel of gas and
dust under a specified, time-dependent physical description. This allows both the post-processing of hydrodynamical simulations and the usage of physical parametrizations, ranging in context from extra-
galactic to protoplanetary disk scales. The framework consists of a core routine that solves gas-grain chemical reaction networks as a function of time, self-consistently coupled to either a user-defined or parametrized physical
evolution of density, temperature and other physical input parameters. The chemistry is solved with a rate-equation formalism, and includes a three phase description, namely gas phase, ice surface and bulk ice. This includes transport between the gas and ice phases via freeze-out, thermal and non-thermal desorption mechanisms, as well as a geometrical treatment of the growth and shrinkage of the surface and bulk chemistry. The framework includes parametrizations for astrochemical modelling of cloud collapses, protostellar cores and shocks as well as the ability to provide user-defined inputs. This release of the framework focuses on many quality-of-life-improvements, including an object-oriented Python interface, an upgrade from two phase to three phases and expanded support for post-processing of hydrodynamical simulations and user-defined parametrizations. This manuscript provides an overview of the physics and chemistry included in UCLCHEM, as well as the inner workings of the solver routine and the programming interface.
Read the full abstract ▾
All authors Gijs Vermariën, Serena Viti, Tobias M. Dijkhuis, Le Ngoc Tram, Marcus Keil, Katarzyna M. Dutkowska, Felix D. Priestley
Earth and Planetary Astrophysics
Geophysical and atmospheric implications of $f$O$_{2}$-dependent melting on rocky exoplanets
Mariana Sastre, Tim Lichtenberg, Laurent Soucasse et al. (+3 more)
The geochemical
evolution of long-lived magma oceans is strongly regulated by volatile exchange between the molten mantle and the atmosphere. For
planets inside the runaway-greenhouse limit, this coupled
evolution can persist for billions of years. However, most existing studies assume Earth-like (oxidized) conditions and neglect the influence of redox state on melt thermodynamics and volatile release. We quantified how experimentally derived, oxygen-fugacity-dependent melting curves implemented within the coupled interior-atmosphere framework PROTEUS propagate into the thermal structure, melt fraction, and rheological
evolution of rocky
exoplanet interiors, applying this to the short-period super-Earth GJ 1132 b. We found strongly non-linear thermal responses to variations in melting curves. In volatile-poor systems, reduced melting curves promote earlier deep-mantle crystallisation relative to oxidised and Earth-like cases, favouring late-stage surface magma oceans sustained by greenhouse warming, while oxidized melting curves maintain higher melt fractions and a vertically extended magma ocean. Reduced mantles produce massive H$_2$-CO-rich atmospheres; oxidized mantles favour thinner H$_2$O-CO$_2$ envelopes. In volatile-rich systems, the interior reaches radiative
equilibrium at high melt fractions, sustaining a steady-state global magma ocean in which melting curve variations do not significantly influence solidification timing. This indicates a hierarchical control: volatile inventory and surface oxygen fugacity act as the primary regulators of thermal state, while oxygen-fugacity-dependent melting relations provide a secondary modulation. These contrasting regimes produce distinct atmospheric compositions and formation timescales, offering testable spectral predictions for close-in rocky
exoplanets evaluable with forthcoming JWST observations.
Read the full abstract ▾
All authors Mariana Sastre, Tim Lichtenberg, Laurent Soucasse, Dan J. Bower, Harrison Nicholls, Inga Kamp
Earth and Planetary Astrophysics
TOI-2147 b and TOI-6019 b: Two eccentric warm Jupiters detected and characterized with TESS and MaHPS
Luis Thomas, Louise D. Nielsen, Hanna Kellermann et al. (+36 more)
The population of Jupiter-sized
exoplanets with orbital periods between 10 and 200 days (WJs) exhibits a broad range of orbital eccentricities and system architectures, suggesting a diversity of formation and migration pathways. In this work, we report the detection and characterization of two new eccentric WJs, TOI-2147 b and TOI-6019 b, initially identified as
planet candidates by the Transiting
Exoplanet Survey Satellite (TESS). We combined TESS photometry with ground-based follow-up observations, including multiband photometry from LCOGT and MuSCAT2, high-angular-resolution speckle imaging, and high-precision radial velocity measurements from the high-resolution Manfred Hirt
Planet Finder Spectrograph (MaHPS). Using these data, we were able to confirm the planetary nature of both candidates. TOI-2147 b has a radius of $10.5 \pm 0.3\,\mathrm{R}_\oplus$ and a mass of $116 \pm 22\,\mathrm{M}_\oplus$. It orbits its slightly metal-poor ($\mathrm{[Fe/H]} = -0.29^{+0.07}_{-0.08}$) G-type host
star on an eccentric orbit ($e = 0.29 \pm 0.07$) with a period of 26.2 days. TOI-6019 b has a radius of $12.3 \pm 0.3\,\mathrm{R}_\oplus$ and a mass of $149 \pm 15\,\mathrm{M}_\oplus$. It orbits a slightly evolved,
solar-
metallicity G-type sub-
giant with a period of 14.5 days on a significantly eccentric orbit ($e = 0.48^{+0.05}_{-0.04}$). Both
planets have bulk densities below that of Jupiter, indicating mildly inflated radii, with interior structure modeling using GASTLI. This suggests that
tidal heating from the nonzero eccentricities likely contributes to this inflation and disfavors large atmospheric metal enrichment. No significant signals from additional companions were detected in the radial velocity time series or transit timing variations. Together with the elevated eccentricities, this is consistent with a high-eccentricity migration origin for both systems.
Read the full abstract ▾
All authors Luis Thomas, Louise D. Nielsen, Hanna Kellermann, Bibiana Prinoth, Yutong Liu, Elif Zeynep Özden, Arno Riffeser, Claus Gössl, Frank Grupp, Jerome de Leon, Karen A. Collins, Allyson Bieryla, Lorena Acuña-Aguirre, Keith Baka, Malte Busmann, David R. Ciardi, Catherine A. Clark, Juliana Ehrhardt, Mark E. Everett, Akihiko Fukui, Jan-Vincent Harre, Keisuke Isogai, Yanxi Li, Felipe Murgas, Norio Narita, Enric Palle, Hannu Parviainen, Jan-Niklas Pippert, Christoph Ries, Boris S. Safonov, Thomas Schäfer, Michael Schmidt, Richard P. Schwarz, Laura Schöller, Gregorg Srdoc, Ivan A. Strakhov, Suzanne Taylor, Wenjie Zhou, Raphael Zöller
Solar and Stellar Astrophysics
Solar Wind Dependence on Source Distance from the Open-Closed Boundary
Chloe P. Wilkins, David I. Pontin, Anthony R. Yeates et al. (+2 more)
The origin and variability of the slow
solar wind remains an open question in
solar physics, but is thought to be closely linked to dynamics at the Sun's open-closed
magnetic flux boundary (OCB). Interchange
magnetic reconnection at the OCB has been proposed as a mechanism for releasing closed-field
plasma into the heliosphere, but observational evidence linking
solar wind composition to OCB
topology remains limited. We relate in situ
solar wind measurements by Ulysses over a 10-year period to the
magnetic topology of their source regions using two coronal
magnetic field models: a potential field source surface model and a magnetofrictional model. We find a strong dependence of
solar wind composition on the distance of the source
magnetic flux from the OCB. Enhanced ion charge-state ratios, elemental abundances, and compositional variability are found to be concentrated within a supergranular-scale region (around 25 Mm) surrounding the OCB, consistent with the spatial scales of interchange
magnetic reconnection. This variability decreases systematically with increasing distance from the boundary, with coronal hole wind exhibiting more uniform fast-wind signatures. We also find that the composition of
solar wind emerging from regions close to the OCB is influenced by the strength of neighbouring closed
magnetic fields, with stronger fields preferentially associated with slow-wind properties. These results indicate that the composition of the slow wind is strongly governed by the
magnetic topology of the OCB, providing compelling evidence that interchange reconnection plays a crucial role in slow
solar wind release and structure.
Read the full abstract ▾
All authors Chloe P. Wilkins, David I. Pontin, Anthony R. Yeates, Nicholeen M. Viall, Spiro K. Antiochos
High Energy Astrophysical Phenomena
Dependences of radio pulsar parameters on the kick velocity
Anton D. Lazarev and Sergei B. Popov
According to several studies, analysis of observational data and theoretical modeling favor a bimodal distribution of the natal velocity kick of
neutron stars. We analyze this proposal by using available data on
radio pulsars. For $\sim200$ normal isolated
radio pulsars with well-measured
spin and kinematic parameters, we determine if they belong to the low- or high-velocity mode of such a distribution by applying the parametrization proposed by Igoshev (2020). Our results demonstrate that about $23\%$ belong to the low-velocity mode. We then analyze the differences in the properties of the two sets of
pulsars belonging to the two modes. For some parameters (characteristic ages and distances), we see a clear difference between the two modes. However, for these quantities, it can be attributed to selection bias. For those parameters that are not subject to strong selection, such as pulse width, we do not observe any difference. Interestingly, we detect a notable difference in the
magnetic field distribution between the two modes. Lower-field
pulsars ($B\lesssim 10^{12}$~G) are overabundant among objects from the low-velocity mode. Among
pulsars with low fields ($\lesssim 10^{11}$~G), we do not identify any objects from the high-velocity mode of the kick distribution. The origin of this discrepancy is not clear, and we discuss several possibilities. Our analysis demonstrates that, most probably, this feature can be explained by selection effects. Thus, we conclude that there is no robust bimodality in physical parameters of
radio pulsars that can be related to the proposed bimodality of the kick velocity. This can be considered as an indirect argument against the hypothetical bimodality in the NS kick distribution. (abridged)
Read the full abstract ▾
Astrophysics of Galaxies
Abundances of CNO in candidate young metal-poor stars
Piercarlo Bonifacio, Elisabetta Caffau, Luca Sbordone et al. (+6 more)
In this contribution we investigate the CNO abundances in five apparently young evolved
stars, with the aim of discriminating between truly young
stars and
stars that were rejuvenated by accreting mass from another
star.
Stars that have accreted mass are expected to show low C and O and a very low [C/O] ratio, as displayed by some
stars in the Globular Cluster 47 Tuc, that are believed to have undergone mass-transfer. In our sample the low [C/O] ratios observed appear to be compatible with their evolutionary status. There is thus no indication for these
stars having accreted mass.__
Read the full abstract ▾
All authors Piercarlo Bonifacio, Elisabetta Caffau, Luca Sbordone, Lorenzo Monaco, Linda Lombardo, Rosine Lallement, Monique Spite, Patrick Francois, Alessio Mucciarelli
Instrumentation and Methods for Astrophysics
MOSAIC at ELT: Design and First Prototyping of Novel Robotic Optical-Relay Positioners
Maxime Rombach, Markus Thurneysen, Lucas Ortolani et al. (+27 more)
The Extremely Large
Telescope (ELT) is, to date, the most ambitious ground-based
telescope under construction. MOSAIC is a multi-objects spectrograph (MOS) that aims to make full use of the largest
telescope in the world. At its heart, about 300 robotic positioners will pick-off skylight from the focal surface of the ELT to feed it to its Near Infrared (NIR) and visible (VIS) spectrographs. The gigantic scale of the ELT presents three main challenges for MOSAIC positioners: (1) the light beams on the focal surface cannot be focused in a single fiber, similarly to other MOS instruments, involving a design with relay mirrors patrolling the field of view, and reimaging the sub-field on 2 fixed fiber bundles located 600 mm behind the ELT focal plane (2) The positioner needs to adapt to the local telecentricity, which means it has to point at the ELT pupil center located 37.868 m away from the focal plane (3) The Atmospheric Dispersion Corrector (ADC) needed to cover the whole focal surface of the ELT is impossible to build to this scale; hence each positioner needs its own ADC. EPFL is responsible for designing and supervising the mass manufacturing of the positioners. This paper aims to present its initial design and prototypes.
Read the full abstract ▾
All authors Maxime Rombach, Markus Thurneysen, Lucas Ortolani, Jurgen Schmoll, Diane Chapuis, Malak Galal, Sebastien Pernecker, Alec York, Ellen Schallig, Ian Lewis, Louis Gabarra, Cassio Berni, Ojonugwa Adukwu, Gavin Dalton, Fabio Fialho, Michaela Hirschmann, Thomas Augustejin, Kacem El Hadi, Marisa Garcia-Vargas, Marie Larrieu, Alessandro Meoli, Tim Morris, Roser Pello, Mathieu Puech, Myriam Rodrigues, Ruben Sanchez-Janssen, Alondra Sola, Jay Stephan, Christian Surace, Jean-Paul Kneib
Astrophysics of Galaxies
A Consistent Comparison of Intracluster Light Assembly in Simulations I. Redshift Evolution and Progenitor Galaxies
Harley J. Brown, Garreth Martin, Frazer R. Pearce et al. (+5 more)
The
tidal stripping of satellite
galaxies and the
stellar detritus ejected during
galaxy mergers builds up a diffuse
stellar component in
galaxy clusters known as the intracluster light (ICL). We investigate ICL assembly in cluster-mass
haloes ($M_{178c}\sim10^{14}-10^{15}$ M$_\odot$) using four different hydrodynamical simulations (Horizon-AGN, TNG100, The Three Hundred Gizmo-Simba 7K, and Hydrangea) under a homogenized ICL identification framework. For our fiducial ICL definition we obtain broadly consistent $z\approx0$ ICL
stellar mass fractions ($\sim0.1-0.2$) and, by tracking the progenitors of $z\approx0$ clusters back to $z\gtrsim2$, find no significant
evolution in average ICL mass fractions. Alternative approaches for distinguishing the ICL from the central
galaxy show the absolute ICL fraction to be highly sensitive to adopted definition, but we never find any significant inter-simulation discrepancies when implementing a consistent methodology to identify the ICL. Whether the average ICL mass fraction falls with increasing
redshift or does not evolve is determined by the ICL definition adopted. By tracing $z\approx0$ ICL
stars back to their progenitor
galaxies, we find that lower-mass satellites typically make slightly larger ICL contributions relative to their mass in every considered simulation, but which
galaxies make the dominant contribution to the ICL is primarily controlled by the infalling satellite mass function. Most ICL
stars sourced from satellite
galaxies are therefore expected to originate from
galaxies with infall
stellar masses above $\sim10^{10}$ M$_\odot$ and largely within $10^{10.5}-10^{11.5}$ M$_\odot$.
Read the full abstract ▾
All authors Harley J. Brown, Garreth Martin, Frazer R. Pearce, Yannick M. Bahé, Joseph Butler, Weiguang Cui, Nina A. Hatch, Alexander Knebe
Cosmology and Nongalactic Astrophysics
High-accuracy polarimetry for CMB: new frontiers with the POLOCALC project
A. Novelli, F. Astori, L. Bizzarri et al. (+8 more)
Modern
telescopes observing the
Cosmic Microwave Background (CMB) polarization require an exquisite control of systematics to target Inflationary Gravitational Waves (IGW),
Cosmic Birefringence (CB), and
Primordial Magnetic Fields (PMF). The absolute polarization angle of the detectors is a critical parameter to disentangle the $E$-modes and $B$-modes of the CMB, allowing a correct detection of
primordial $B$-modes as well as testing
Cosmic Birefringence theories. To this end, we discuss the current status of the POLOCALC project, an ERC Advanced Grant that aims to develop air-borne calibration sources for CMB small-aperture
telescopes. The main scientific objective of POLOCALC is to enable a direct calibration of the absolute polarization angle of CMB polarimeters with an accuracy of $0.01 \degree $. We present the latest developments regarding the calibration source, the calibration strategies designed to use drone-based calibrators, and the application to modern ground-based experiments.
Read the full abstract ▾
All authors A. Novelli, F. Astori, L. Bizzarri, F. Cacciotti, G. Cattaneo, G. Coppi, N. Dachlythra, I. Karaaslan, N. Mezzanzanica, F. Nati, M. Zannoni
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Hybrid stars with hyperons: structure based on QCD sum rule coupling constants
F. Moradi Jangal, H. R. Moshfegh and K. Azizi
We present a comprehensive study of hybrid
stars composed of
hadrons,
leptons, and
quarks within a relativistic mean-field framework. Using coupling constants derived from QCD sum rules (QCDSR), we first determine the bulk properties of
nuclear matter and evaluate the single-particle potentials of nucleons and hyperons to constrain the hadronic sector. The equation of state (EOS) under beta
equilibrium is then constructed employing the $\sigma-\omega-\rho$ model for the hadronic phase, while the
quark phase is described using both the MIT bag model and the Nambu-Jona-Lasinio (NJL) model. The
hadron-
quark phase transition is analyzed through both Gibbs and Maxwell constructions. Based on resulting EOSs, we obtain the mass-radius relations of hybrid
stars, investigate particle fractions and their radial distributions, and calculate the
tidal Love number ($\mathcal{K}_{2}$) and the dimensionless
tidal deformability ($\varLambda$). Our results provide quantitative predictions relevant for comparison with current multimessenger astrophysical observations.
Read the full abstract ▾
High Energy Astrophysical Phenomena
On the impact of the carbon fusion rate over the properties of superbursts – Numerical simulations of superbursts with MESA
Martin Nava-Callejas, Stéphane Goriely and Nicolas Chamel
Context: Superbursts are very energetic explosions in the crust of
neutron stars in Low-Mass X-ray Binaries (LMXBs). These are triggered by unstable carbon burning at $T\leq 10^{9}$ K. In recent years, there has been a re-examination of the carbon fusion rate, finding that at these temperatures it might be either smaller or higher with respect to the standard rate from Caughlan & Fowler (1988). Aims: We explore the consequences changing the carbon fusion rate has over the physics of superbursts. Methods: For simulating superbursts, we employ the public code \mesa\ v.24.08.1, as well as four versions of the carbon fusion reaction rate. Results: A significant enhancement of the reaction rate at $T\leq 10^9$~K would reduce the recurrence and decay times of the superburst, as well as the column depth at ignition. The opposite behavior is observed when the carbon fusion rate is reduced. The maximum temperature reached during the explosion is also sensitive to a change in the carbon fusion rate, leading to either an enhancement or a reduction in the synthesis of $\alpha$-nuclides. These changes are comparable to the effect of reducing the amount of base heating at the bottom of the envelope. Conclusions: The modelling of X-ray superburst is sensitive to the adopted carbon fusion rate at $T\leq 10^{9}$ K. Given its role for determining the ignition conditions, this rate needs to be better experimentally constrained to reduce the uncertainty in
nuclear physics when modeling the superburst light curve and the nucleosynthesis of the explosion. At the same time, multizone simulations of superburst also requires improvement in the description of the initially accreted material and
stellar conditions prior to the explosion.
Read the full abstract ▾
High Energy Astrophysical Phenomena
A FAST search for radio pulsations during the dormant state of the AMSPs IGR J00291+5934 and MAXI J1957+032
A. Marino, E. Parent, F. Coti Zelati et al. (+15 more)
Accreting millisecond
pulsars (AMSPs) and transitional millisecond
pulsars (tMSPs) are
neutron star low-mass X-ray binaries which can evolve into "recycled"
radio millisecond
pulsars. In both types of systems, X-ray pulsations have been detected during phases of X-ray activity when matter
accretion through a disc is turned on. On the other hand, when
accretion stops, and these systems enter the quiescent, low-luminosity X-ray state, only tMSPs become visible as
radio pulsars. Despite several attempts,
radio pulsations have never been detected in quiescent AMSPs, except for IGR J18245$-$2452. In this manuscript, we present the results of two observational campaigns performed on the AMSPs IGR J00291+5934 and MAXI J1957+032 with the Five-hundred-meter Aperture Spherical
Telescope ($\it{FAST}$) in L-band (1-1.5 GHz). Both sources have most likely been observed in quiescence, as suggested by the upper limits on their X-ray and optical flux obtained with Swift and the Las Cumbres Observatory, respectively. We have performed a deep search for coherent periodicities in
radio but found no significant candidate signal, either at the known
spin frequency of those sources or at other frequencies. Assuming a pulse duty cycle of 10%, we derive upper limits on the pulsed
radio flux density of 3.3 $\mu$Jy and 5.6 $\mu$Jy for IGR J00291+5934 and MAXI J1957+032, respectively, which are the most stringent limits so far for any known persistent AMSP.
Read the full abstract ▾
All authors A. Marino, E. Parent, F. Coti Zelati, M. C. Baglio, A. Papitto, A. Sanna, A. Anitra, C. Kazantsev, N. Rea, A. Borghese, L. Burderi, T. Di Salvo, C. Espinoza, X. Hou, R. Iaria, G. Illiano, D. M. Russell, R. Sathyaprakash
Instrumentation and Methods for Astrophysics
VASTER: The ASKAP real-time fast-imaging pipeline – overview and discovery of two long period transients
Yuanming Wang, Dougal Dobie, Tara Murphy et al. (+22 more)
Recent developments in widefield
radio telescopes have enabled searches of a new region of parameter space in the time domain: timescales of seconds to minutes, that have been overlooked in traditional surveys. These searches have revealed a new population of sources: long period transients, which typically show periodic behaviour of minutes to hours. In addition they have detected phenomena ranging from extreme scintillation to
stellar radio bursts. However, almost all searches to date have involved archival data that has been processed in offline, batch mode. In this context, we present VASTER, the first short-timescale imaging and transient detection pipeline running in real time on a widefield
radio telescope. VASTER has been running on the Australian SKA Pathfinder (ASKAP) since July 2025, and images most of the ASKAP survey project data on timescales of 15 minutes. In this paper we describe the VASTER system, and present the results from the first two weeks of operation, including the discovery of two long period transients: ASKAP~J165130.3$-$450520 with a period of 6.48 hours and ASKAP~J170036.6$-$445758 with a period of 4.69 hours. The detection of these two sources adds to the small, but growing, population of long period transients, as well as demonstrating the potential of VASTER to explore this region of transient parameter space.
Read the full abstract ▾
All authors Yuanming Wang, Dougal Dobie, Tara Murphy, Emil Lenc, David L. Kaplan, Joshua Pritchard, Daniel Mitchell, Wasim Raja, Matthew Whiting, Owen Cole, Paul J. Hancock, Jiting Hu, Yu Wing Joshua Lee, Alex Massen-Hane, Shibli Saleheen, Raymond Shao, Lei Zhang, Adarsh Bathula, Manisha Caleb, Raghav Girgaonkar, Ashna Gulati, Natasha Hurley-Walker, Iris de Ruiter, Ryan M. Shannon, Gregory R. Sivakoff
Cosmology and Nongalactic Astrophysics
Evolving Dark Energy Is Vacuum Energy After All
Dong Ha Lee, Carsten van de Bruck, Eleonora Di Valentino et al. (+2 more)
We investigate a physically motivated model of dynamical dark energy arising from the non-perturbative topological structure of the
Quantum Chromodynamics (QCD)
vacuum. The model introduces no new fundamental field or propagating degree of freedom: the dark energy (DE) density emerges as a global
vacuum response to an expanding spacetime. We develop the first comprehensive cosmological implementation of this QCD-DE scenario and confront it with current observations, including Planck, ACT and SPT-3G
cosmic microwave background data, DESI DR2
baryon acoustic oscillation measurements, and Type Ia
supernova samples from Pantheon+ and DES-Dovekie. We compare the model with $\Lambda\mathrm{CDM}$ and $w_0w_a\mathrm{CDM}$ cosmologies. The model provides an excellent fit to the data and reproduces the late-time DE
evolution preferred by DESI. The model naturally predicts effective phantom crossing behaviour at intermediate
redshifts ($z\sim0.67$) while avoiding the instabilities associated with phantom scalar fields. Using goodness-of-fit statistics and
Bayesian model-selection tools, including Akaike and Deviance Information Criteria and
Bayesian evidence estimated from Markov-Chain Monte Carlo chains, we find that the QCD-induced model is consistently favoured over $\Lambda\mathrm{CDM}$ for the full combination of early and late-time
datasets. Unlike the conventional descriptions of dynamical DE, support for QCD-DE in
Bayesian evidence remains more consistent across
datasets, suggesting that a physically motivated departure from a cosmological constant may provide a more economical description of the expansion history preferred by current observations.
Read the full abstract ▾
All authors Dong Ha Lee, Carsten van de Bruck, Eleonora Di Valentino, Ludovic Van Waerbeke, Ariel Zhitnitsky
High Energy Astrophysical Phenomena
A Whisper from Within: Response of a Pulsar Timing Array to an Internal Gravitational-wave Source
Houyuan Qi, Xian Chen, Lin Wang et al. (+1 more)
Millisecond
pulsars (MSPs) are abundant in globular clusters (GCs) and probably also in
galactic nuclei. They offer the potential to form a miniature
pulsar timing array (mini-PTA) to detect nanohertz gravitational-wave (GW) sources located inside the array. Since the size of such an array is comparable to the wavelength of GW, the conventional plane-wave approximation becomes invalid, and near-field effects, including wavefront
curvature, non-radiative self-field of the GW source, and direct perturbation of
pulsar by GW, become significant. In this work, we incorporate these effects in a comprehensive model to calculate the timing residual induced by a GW source inside a mini-PTA. We also consider realistic GW source configurations in GCs (M15 and $\omega$ Centauri) and in
galactic nuclei (Sgr A* and M31), and find that for MSPs located sufficiently close to the GW source (within a few wavelengths), the residual can reach $1~\mu\mathrm{s}$ in GCs and up to milliseconds in
galactic centers, within the potential detection reach of current
radio telescopes. Crucially, when the
pulsar lies within a few GW wavelengths of the source, the non-radiative field dominates and causes the residual to rise much more steeply (between $1/r_e^2$ and $1/r_e^4$, where $r_e$ is the distance to the source) than the conventional far-field scaling ($1/r_e$). These results demonstrate that mini-PTAs in GCs or
galactic nuclei can serve as powerful probes of otherwise invisible GW sources, including intermediate-mass and supermassive black hole binaries.
Read the full abstract ▾
All authors Houyuan Qi, Xian Chen, Lin Wang, Kuo Liu