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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 29 July

Solar and Stellar Astrophysics

An interstellar energetic and non-aqueous pathway to peptide formation

Alfred Thomas Hopkinson, Ann Mary Wilson, Joe Pitfield et al. (+13 more)

The origin of the molecular building blocks of life is a central question in science. A few $\alpha$-amino acids such as glycine, the simplest proteinogenic amino acid, have been detected in meteorites and comets, indicating an extraterrestrial origin for some prebiotic molecules. However, the formation of peptides, short chains of $\alpha$-amino acids linked by peptide bonds, under astrophysical conditions has remained unresolved. Here we show that the building blocks of proteins can form in interstellar ice analogues exposed to ionising radiation, without the presence of liquid water. Using isotopically labelled glycine irradiated with protons at cryogenic temperatures, we detect the formation of glycylglycine, the simplest dipeptide, along with deuterated and non-deuterated water as by-products. Peptide bond formation is confirmed by infrared spectroscopy and high-resolution mass spectrometry, which also reveal the production of other complex organic species. These findings demonstrate a non-aqueous route to peptide formation under space-like conditions and suggest that such molecules could form in the cold interstellar medium and be incorporated into forming planetary systems. Our results challenge aqueous-centric models of early biochemical evolution and broaden potential settings for the origins of life.
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All authors Alfred Thomas Hopkinson, Ann Mary Wilson, Joe Pitfield, Alejandra Traspas Muiña, Richárd Rácz, Duncan V. Mifsud, Péter Herczku, Gergő Lakatos, Béla Sulik, Zoltán Juhász, Sándor Biri, Robert W. McCullough, Nigel J. Mason, Carsten Scavenius, Liv Hornekær, Sergio Ioppolo

Earth and Planetary Astrophysics

Exploring the radial velocity variations of RY Lup with VLT/ESPRESSO: Binary versus spot hypotheses

Hala Alqubelat, Claudia Di Maio, Antonio Frasca et al. (+7 more)

Stellar multiplicity is a possible cause for creating protoplanetary disc substructures, as tidal forces from a close-in spectroscopic companion can carve out gaps and shape disc architecture. However, in young, active systems, the radial velocity (RV) signatures are often complicated by stellar activity. We investigate RY Lup, a classical T Tauri star hosting a disc with a ~60 au cavity, where studies with Gaia astrometry and VLT/SPHERE imaging hinted at an unseen companion. Using high-resolution VLT/ESPRESSO spectra and the least-squares deconvolution (LSD) technique, we analyse RV variations over 327 days. We detect significant line profile variations with a periodic signal of ~3.75 days, aligning with prior photometric estimates. The variations are compatible with a close-in binary system at ~0.04 au and a mass ratio of q ~ 0.6. Combined analysis of RV data and ALMA dynamical mass estimates, using 13CO and 18CO, reveals a highly misaligned system. The nearly face-on binary i ~ 13 deg is misaligned to both the inner and outer discs i ~ 50 deg and ~70 deg, respectively. The derived orbital separation is compatible with the inner disc size, with the inner rim at a = 0.12 au, measured from VLTI/GRAVITY, which suggests a highly warped disc structure. Nonetheless, the short orbital period conflicts with the derived eccentricity (e ~ 0.23). To explore alternative explanations, we assess the impact of stellar spots on RV signals. While the LSD deformations can be modelled by different cool spot configurations, a 15% dispersion in retrieved v sin i values – coupled with the lack of a significant periodic signal – suggests that spots alone cannot explain the observed variability. As neither hypothesis is ruled out, we recommend future combined RV and interferometric monitoring to clarify the nature of the spectroscopic variability.
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All authors Hala Alqubelat, Claudia Di Maio, Antonio Frasca, Carlo F. Manara, Monika G. Petr-Gotzens, Enrico Ragusa, Evelyne Alecian, Louise D. Nielsen, Lisa Drouglazet, Justyn Campbell-White

High Energy Astrophysical Phenomena

Effect of Multi-Species Plasma on Fanaroff-Riley Radio Jets

Priyesh Kumar Tripathi, Indranil Chattopadhyay, Raj Kishor Joshi et al. (+3 more)

The Fanaroff-Riley (FR) dichotomy observed in extragalactic radio jets has been attributed to a range of possible mechanisms, including intrinsic jet properties such as the presence of different species in the plasma. Jet material may span from a pure electron-positron pair plasma to mixed plasmas containing electrons, positrons, and protons, or even to hadronic jets made up of electrons and protons only. To investigate this aspect, we present results from three-dimensional simulations of low-power, supersonic, magnetized jets at kiloparsec scales in a magnetohydrodynamic framework. By varying the plasma composition, we show its impact on jet stability and on the development of diffuse structures typical of core-brightened FR type I sources. Our results indicate that the growth of non-axisymmetric instabilities plays a key role in disrupting the jet head.
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All authors Priyesh Kumar Tripathi, Indranil Chattopadhyay, Raj Kishor Joshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan

Solar and Stellar Astrophysics

Energetic Particle Acceleration and Transport: Interplanetary Coronal Mass Ejections and Shocks

Olga E. Malandraki, Christina M. S. Cohen, Joe Giacalone et al. (+16 more)

Solar Energetic Particles from suprathermal (few keV) up to relativistic (few GeV) energies constitute an important contributor to the characterization of the space environment. Emitted from the Sun they are associated with solar flares and shock waves driven by Coronal Mass Ejections. This review presents important recent results of the study of Interplanetary CMEs and shocks in relation to energetic particle acceleration and transport, taking advantage of multi-point, multi-instrument observations available by a fleet of spacecraft in the heliosphere. In particular, the Solar Orbiter and Parker Solar Probe pioneering missions providing unprecedented measurements of energetic particles in the near-Sun environment offer promising insights into several unresolved questions particularly regarding the mechanisms responsible for the acceleration and transport of energetic particles in the heliosphere and their relative contributions.
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All authors Olga E. Malandraki, Christina M. S. Cohen, Joe Giacalone, Leng Ying Khoo, Domenico Trotta, Laura Rodriguez-Garcia, Athanasios Kouloumvakos, Zheyi Ding, Yuncong Li, Alexander Kollhoff, John G. Mitchell, David J. Mccomas, Nathan A. Schwadron, Javier Rodriguez-Pacheco, Robert F. Wimmer-Schweingruber, George C. Ho, Glenn Mason, Michalis Karavolos, Jingnan Guo

Cosmology and Nongalactic Astrophysics

Global 21cm Measurement Calibration Methodology

Martin Bucher, Christian J. Kirkham, Eloy de Lera Acedo et al. (+2 more)

21cm global signal observations present a unique set of calibration challenges owing to the absolute character of the required measurement. Since differential measurements on the sky cannot be used for observing the global signal, typically a number of calibration sources with differing noise temperatures and source impedances are used to determine the four noise parameters and the power gain of the amplification chain. Because of the broadband nature of the measurement, the antenna impedance varies with frequency in a manner different from the calibration sources, so that the simplest three-way Dicke switching strategy is not adequate. We present a self-contained and explicit derivation of the calibration equations and reconcile expressions from the early global 21cm observation literature with the results obtained following the amplifier noise representation formalism commonly used in the electrical engineering literature. We also present a condition in terms of Möbius geometry on the complex $\Gamma $- (or $Z$-) plane defining the choice of calibration source impedances required.
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All authors Martin Bucher, Christian J. Kirkham, Eloy de Lera Acedo, Dirk I. L. de Villiers, Saurabh Pegwal

Astrophysics of Galaxies

Effects of a disk structure on stellar motion at the Galactic Center

Arianna Foschi, Frederic H. Vincent, Thibaut Paumard et al. (+1 more)

Stellar orbits are key for probing the environment of the supermassive black hole at the Galactic Center, Sagittarius A$^*$. So far, the mass around SgrA$^*$ has been assumed to be spherically distributed. However, the extended mass may instead be flattened, creating disk-like structures. We investigate the effects that a thin disk structure would have on stars at the Galactic Center, focusing on star S2 and S301 and the clockwise stellar disk. We derive analytically the acceleration exerted by a disk with power law density $\Sigma \propto r^{-\gamma}$. We use this acceleration to compute the osculating equations and the variations of the orbital elements, showing how the latter depend on the orientation of the disk with respect to the orbital plane. We find that the disk structure induces a secular shift in the semi-latus rectum, an extra in-plane precession and an out-of-plane precession. The former is neither present at the low-order post Newtonian description that we use for the black hole, nor when a spherical mass distribution is considered. The latter can be competitive with the Lense-Thirring precession induced by the spin of SgrA$^*$ on S301 motion, depending on the mass, the radial extent and the orientation of the disk. Since the Lense-Thirring precession is negligible in S2 motion, the out-of-plane precession can be used to place upper limits on the non luminous mass of disk-like structures at the Galactic Center. The limits might significantly differ from those obtained for spherical distributions and depend on the disk parameters. These results highlight the importance of constraining disk-like structures when using stellar orbits to probe the central black hole, in particular its spin. Once mass estimates are at hand, one can quantify the disk's effect on S301 motion and the resulting degeneracy with a future measurement of SgrA$^*$ spin.
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All authors Arianna Foschi, Frederic H. Vincent, Thibaut Paumard, Guy Perrin

Solar and Stellar Astrophysics

The Internal Magnetic Field Structure of ICMEs in the Heliosphere

Ziwei Huang, Zhenjun Zhou, Yudong Ye et al. (+7 more)

Interplanetary coronal mass ejections (ICMEs) are major drivers of heliospheric disturbances and space-weather effects. Here we present a multi-spacecraft study of 96 magnetic clouds (MCs) distributed over a broad range of heliocentric distances, and reconstruct their internal magnetic structure with a uniform-twist Gold–Hoyle (GH) flux-rope model. From the fits, we derive the axial field strength $B_0$, the twist density (turn density) $\tau$, the GH parameter $\omega$, and the integrated twist number $n$. We find that $B_0$ and the turn density $\tau$ both decrease with increasing heliocentric distance, consistent with expansion and axial stretching during propagation. A key result is that the upper envelope in the $\tau$–$R$ plane corresponds to a nearly constant boundary in the dimensionless GH parameter $\omega=2\pi R\tau$, close to $\omega\sim2$. Therefore, the inferred upper value of $\tau$ is not scale-independent, but follows $\tau_{\max}\simeq \omega_{\max}/(2\pi R)$ for a given flux-rope radius. In contrast, the estimated integrated turn number $n$ shows no similarly clear radial organization in the present sample. This study investigates the ICME structure and magnetic field characteristics across heliocentric distances from 0.07 to 5.4~AU, thereby providing observational constraints on the large-scale evolution of interplanetary magnetic flux ropes.
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All authors Ziwei Huang, Zhenjun Zhou, Yudong Ye, Ming Xiong, Yuming Wang, Yutian Chi, Daniel Heyner, Hans-Ulrich Auster, Ingo Richter, Beatriz Sanchez-Cano

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Bayesian nonparametric estimation of correlated gravitational wave detector network noise using matrix-gamma process priors

Yixuan Liu, Renate Meyer, Nelson Christensen et al. (+4 more)

This paper addresses the important problem of estimating the noise spectral density of next-generation gravitational-wave detectors, such as LISA and the Einstein Telescope (ET), where cross-channel correlations must be accounted for to avoid biased parameter estimation of gravitational-wave signals. Unlike approaches that estimate test-mass and optical-metrology-system noise separately at the single-link level and then map them to the Time-Delay Interferometry (TDI) channels through known transfer functions, we develop a Bayesian nonparametric method that directly estimates the spectral density matrix of the XYZ channels, thereby accommodating additional sources of uncertainty. Our approach combines a flexible matrix-gamma process prior on the matrix-valued coefficients of a Bernstein polynomial basis expansion with a blocked multivariate Whittle likelihood. The prior guarantees Hermitian positive definiteness of the spectral estimate at every frequency. To avoid reversible-jump methods, we use an adaptive Markov chain Monte Carlo (MCMC) algorithm for posterior sampling. The proposed framework can also be used to correct misspecified parametric noise models. Results from a simulation study and simulated correlated-noise data for both LISA and ET demonstrate the effectiveness of the proposed method.
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All authors Yixuan Liu, Renate Meyer, Nelson Christensen, Jeung Eun Lee, Jianan Liu, Patricio Maturana-Russel, Avi Vajpeyi

Cosmology and Nongalactic Astrophysics

Probing Primordial Chirality in the Matter Distribution

Fang-Na Shao, Hao-Ran Yu, Ming-Jie Sheng et al. (+2 more)

Whether parity symmetry was violated in the early universe remains one of the fundamental open questions in cosmology. If so, it may leave an intrinsic handedness in the large-scale matter distribution. Here we formulate a helicity-based estimator to measure this handedness. Using cosmological simulations with parity-violating initial conditions, we show that it survives nonlinear structure formation. Applying the estimator to density fields reconstructed from the SDSS DR7 galaxy catalog, we find mild deviations but statistically insignificant evidence for parity violation in the local universe. Our results establish the intrinsic handedness of the matter distribution as an observable relic of primordial parity violation, enabling a direct probe with current and future large-scale structure surveys.
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All authors Fang-Na Shao, Hao-Ran Yu, Ming-Jie Sheng, Bing-Hang Chen, Huiyuan Wang

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

Particle Production via Rippled Bubble Walls

Ryusuke Jinno, Shota Nakagawa, Yuichiro Nakai et al. (+1 more)

We investigate non-thermal particle production during first-order phase transitions in the presence of ultra-relativistic thick bubble walls with non-trivial internal structure. Extending the framework of bubble-expansion particle production, we consider bubble walls containing multiple ripples and study how such spatial modulations affect the production of heavy particles coupled to the order parameter field. By modeling an oscillatory thick-wall profile, we derive the transition probability for particle splitting processes in the wall background, and identify a new contribution associated with momentum transfer from the wall microstructure. In addition to the conventional channel, we find an enhanced production mode arising from resonant momentum exchange with the ripples. For sufficiently large numbers of ripples, the new contribution can dominate the production rate and significantly increase the abundance of particles much heavier than the phase-transition scale. Our results demonstrate that the internal structure of expanding bubble walls can play an important role in particle production and should be taken into account when assessing the cosmological implications of strongly first-order phase transitions.
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All authors Ryusuke Jinno, Shota Nakagawa, Yuichiro Nakai, Yaoduo Wang

Astrophysics of Galaxies

An Enhanced Catalog of Gaia DR3 Galaxy Candidates with Spectroscopic and Machine-Learning Photometric Redshifts

Junghyun Hwang and Ho Seong Hwang

We present an updated galaxy catalog based on the Gaia Data Release 3 (DR3) Galaxy Candidates table, augmented with both spectroscopic and machine-learning based photometric redshift estimates. While the original catalog of Gaia DR3 galaxy candidates provides an unprecedented all-sky sample of extragalactic sources, its scientific utility for extragalactic and cosmological studies has been limited by the absence of redshift information and by its relatively low source purity. To address these limitations, we cross-match the catalog of Gaia DR3 galaxy candidates with existing spectroscopic redshift catalogs including DESI, SDSS, 2MRS, and NED. For sources without spectroscopic measurements, we compute photometric redshifts using a Multiple-Bin Regression Neural Network (MBRNN) machine-learning model. The input features for this model are drawn from a newly constructed multiwavelength catalog that combines Gaia DR3 measurements with 2MASS and unWISE photometry, as well as shape parameters, QSO classification flags, and extinction values. The model is trained and validated using the spectroscopic subsample. As a result, spectroscopic redshifts are assigned to 24.5% of the catalog sources, while photometric redshifts are provided for the remaining objects. The MBRNN model achieves improved redshift accuracy and precision compared to previously published photometric redshift estimates based on Gaia data alone. In addition to redshift values, we provide a score quantifying the likelihood that a given source represents a statistical outlier. The resulting catalog significantly enhances the scientific value of the Gaia DR3 galaxy candidates sample and provides a valuable resource for large-scale extragalactic and cosmological studies.
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Instrumentation and Methods for Astrophysics

Impact of microlens shape on the performance of Laser Guide Star wavefront sensors for ELT-class telescopes

Paul Rouquette, Benoit Neichel, Cédric Taisir Heritierc et al. (+4 more)

Laser Guide Star (LGS) adaptive optics systems on extremely large telescopes (ELTs) rely on Shack-Hartmann wavefront sensors (SHWFS) equipped with large-format microlens arrays. Manufacturing imperfections in the microlens surface profile degrade spot quality and reduce centroiding accuracy, yet this effect is rarely quantified in the context of full AO system performance. This paper presents a comprehensive characterization of the impact of microlens shape on LGS wavefront sensing, using the MORFEO-HARMONI LGS wavefront sensor design as the primary test case, results are directly applicable to any ELT-class or future large-telescope LGS instrument, including systems on the GMT and TMT. Starting from interferometric surface profile measurements of prototype microlenses, we derive the induced phase errors and compute the degradation of center-of-gravity (CoG) spot detection accuracy as a function of LGS elongation and flux. A real microlens degrades CoG variance by a factor of 1.8 to 2.4 compared to an ideal lens, equivalent to requiring approximately twice the photon flux to maintain the same measurement accuracy. This effect is shown to decrease with increasing LGS elongation, and to improve with higher microlens sag. The per-subaperture flux-loss model is then propagated into tomographic AO end-to-end simulations, where measurement redundancy across multiple LGS and MMSE reconstructor weighting partially mitigate the penalty, reducing the effective Strehl ratio flux loss to factors of 1.25-1.4. Experimental validation is provided with the LGS wavefront sensor optical bench prototype at LAM, which also enables full-array characterization in a single measurement. The methodology is broadly applicable to any Shack-Hartmann system operating in a low-flux regime.
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All authors Paul Rouquette, Benoit Neichel, Cédric Taisir Heritierc, Pierre Jouve, Anne Costille, Kjetil Dohlen, Thierry Fusco

Instrumentation and Methods for Astrophysics

Towards an Extended VLTI: Turbulence Characterization for Kilometer-Scale Optical Links at Paranal

B. Neichel, T. Pichon, G. Bourdarot et al. (+10 more)

Future extensions of the VLTI aim to push infrared interferometry toward kilometer scale baselines, enabling angular resolutions of a few tens of micro-arcseconds. A first step would couple a new telescope on the VISTA platform to the existing VLTI infrastructure, creating a 1.4 km baseline at Paranal. Among the possible beam-transport solutions, direct free-space transmission with adaptive-optics (AO) pre-compensation, inspired by Free-Space Optical (FSO) communications, offers an attractive combination of spectral flexibility, moderate cost, and preservation of field information. We present a preliminary AO dimensioning study, including fitting error, photon noise, anisoplanatism, and scintillation, showing that moderate-order correction (around 10x10 actuators) may be sufficient, but that performance depends critically on the poorly known turbulence distribution along the horizontal path. We therefore propose a dedicated turbulence-monitoring experiment across the VISTA-VLTI line of sight, using two 30-50 cm telescopes equipped with calibrated light sources. The experiment combines a wide-field Shack-Hartmann sensor for tomographic reconstruction of the turbulence volume with an event-based (neuromorphic) camera capable of capturing fast, anisotropic turbulence at microsecond timescales. The resulting dataset will provide the first systematic characterization of kilometer-scale horizontal turbulence at Paranal, paving the way toward an extended kilometer-baseline VLTI.
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All authors B. Neichel, T. Pichon, G. Bourdarot, D. Perez, E. Vera, V. Chambouleyron, T. Fuscod, C.-T. Heritier, F. Eisenhauer, N. Vedrenne, D. Delamoye, F. Glasser, S. Esposito

Instrumentation and Methods for Astrophysics

HARMONI@ELT: instrument design, performance, and science capabilities

B. Neichel, J. Dunlop, S. Chittick et al. (+17 more)

HARMONI is the integral field spectrograph for the Extremely Large Telescope (ELT). Designed as the primary workhorse near-infrared spectrograph of the ELT, it will deliver spatially resolved spectroscopy at diffraction-limited angular resolution over the wavelength range 0.75 - 2.4 um, addressing science questions ranging from the characterization of exoplanet atmospheres to the internal kinematics of galaxies at the epoch of reionization. This paper presents the current status of the HARMONI project following its recent rescope, describing the new instrument architecture, its key subsystems, and the three adaptive optics modes (Single Conjugate AO (SCAO), Multi-Conjugate AO (MCAO) provided by MORFEO, and High Contrast AO (HCAO)). We present the top-level technical specifications and the expected on-sky performance in terms of Strehl ratio, PSF FWHM, sky coverage, sensitivity, and astrometric accuracy. We describe the new project organization, with a new leadership and Project Management Office (PMO), and provide an update on the project schedule and the path toward instrument delivery.
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All authors B. Neichel, J. Dunlop, S. Chittick, D. Le Mignant, M. Swinbank, A. de Lorenzo-Caceres, W. Taylor, M. Tecza, B. Johnson, A. Costille, N. Bouche, A. Delsanti, T. Morris, J. Piqueras Lopez, B. Garcia, M. Mateo, A. Carlotti, Dan Dickens, Edgard Castillo Dominguez, the HARMONI Consortium

Cosmology and Nongalactic Astrophysics

Phantom-divide crossing and suppressed structure growth in kinetically braided dark energy with momentum exchange

Masroor C. Pookkillath and Shinji Tsujikawa

We construct a linearly stable scalar-field model that realizes both an upward crossing of the dark-energy equation of state, from $w_{\rm DE}<-1$ to $w_{\rm DE}>-1$, and weakened gravitational clustering in the cold dark matter (CDM) sector. An exponential potential breaks shift symmetry and drives the background from a stable phantom phase toward the nonphantom regime, while a pure momentum-transfer interaction increases the dynamical inertia of CDM without altering its background dilution law. We derive the background and linear perturbation equations and establish the no-ghost and Laplacian-stability conditions. For perturbations deep inside the Hubble radius, where the quasi-static approximation applies, the effective gravitational coupling for CDM can fall below Newton's constant, suppressing late-time growth and small-scale matter power, while the baryonic coupling remains enhanced by Galileon braiding. A modified CLASS calculation, including the scalar-field perturbation and the full Boltzmann hierarchies, reveals signatures of transient braiding around radiation–matter equality. For the representative stable solutions studied here, these signatures include an enhancement of matter power toward the lowest wavenumbers probed numerically and a reduction of CMB temperature power over the multipole range $2\leq\ell\leq30$. We also find small shifts in the acoustic scale and the position of the first temperature peak. These results motivate a full likelihood analysis of the model.
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Solar and Stellar Astrophysics

Probing the Physics of the Solar Corona with High-Resolution Observations using SKA-Mid

Mark C. M. Cheung, John S. Morgan, Rohit Sharma et al. (+3 more)

We examine the capability of the SKA-Mid telescope for probing solar coronal structure and evolution. Using radiative magnetohydrodynamics simulations of a solar flare, we synthesise radio emission in bands available to SKA-Mid. SKA-Mid observations would provide important constraints on plasma processes that are important to diverse astrophysical environments, including flares/eruptions, magnetic reconnection, particle acceleration, and gyro-emission processes. Observations with the AA4 configuration would reveal fine-scale structures in the solar atmosphere, making SKA-Mid a complementary telescope to other high resolution solar observatories operating at optical, infrared, and XUV wavelengths. Estimates of coronal scattering suggest that angular broadening rather than instrumental resolution (0.1” at 10 GHz) will limit the detection of the finest structure under typical conditions. The extent of angular broadening depends on the nature of turbulence in the corona, and the longer baselines of SKA-Mid will serve to provide new observational constraints on coronal structure.
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All authors Mark C. M. Cheung, John S. Morgan, Rohit Sharma, Sven Wedemeyer, Gregory Fleishman, Matthias Rempel

Instrumentation and Methods for Astrophysics · Cross-listed from physics.optics

Addressing rotational motion on gravitational waves detectors

Chiara Di Fronzo and Jian Liu

The rotational components of Earth's seismic motion are one of the major contributions to limit the sensitivity of terrestrial gravitational-wave detectors at frequencies below 10 Hz. The fundamental challenges lie in understanding the angular degrees of freedom of seismic motion and how they can be accurately measured. These are both crucial steps for developing an adequate control system to suppress seismic motion and maintaining resonance in the detector cavities. This review shows why the rotational ground motion limits the detector's sensitivity and gives an overview of the technological achievements of the last decade on both the sensing and control systems sides. Perspectives on future developments in the field are also briefly illustrated.
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Solar and Stellar Astrophysics

Observations of a Solar Jet Triggered by Reconnection between Super-penumbral Fibrils and a Mini-filament

Liheng Yang, Xiaoli Yan, Qingmin Zhang et al. (+10 more)

Coronal jets are highly dynamic phenomena in the solar atmosphere, yet their driving mechanisms remain an active topic of investigation. In this paper, we report a coronal jet triggered by the interaction between super-penumbral fibrils and a mini-filament, based on coordinated observations from the New Vacuum Solar Telescope (NVST), the Chinese H$\alpha$ Solar Explorer (CHASE), and the Solar Dynamics Observatory (SDO). The fibrils were anchored between the negative-polarity region of a sunspot and an emerging positive-polarity region associated with a moving magnetic feature (MMF). As the positive polarity migrated outward, the fibrils elongated and interacted with the mini-filament, one of whose footpoints was rooted in pre-existing negative-polarity fields. Intense brightenings at the interaction site, together with changes in the connectivity of the mini-filament footpoint from the pre-existing negative polarity to the sunspot, indicate the occurrence of magnetic reconnection. The event produced a narrow hot jet accompanied by a broader cool component. The cool plasma exhibited a clockwise rotation, providing evidence for the transfer of magnetic twist during reconnection. Persistent magnetic flux cancellation was observed before and during the jet eruption. These observations demonstrate that small-scale magnetic structures, such as MMFs, can significantly influence mini-filament eruptions and highlight the important role of flux cancellation in triggering coronal jet activity.
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All authors Liheng Yang, Xiaoli Yan, Qingmin Zhang, Zhike Xue, Zhe Xu, Jincheng Wang, Fangyu Xu, Yian Zhou, Defang Kong, Weijie Meng, Xinsheng Zhang, Qiaoling Li, Liping Yang

Cosmology and Nongalactic Astrophysics

No way ou$\tau$: Epoch of Reionization Observations Do not Support Large Values of the Optical Depth to Reionization

Paulo Montero-Camacho and Yi Mao

Recent cosmological analyses combining high-redshift cosmic microwave background (CMB) measurements with low-redshift baryon acoustic oscillation (BAO) data have reported a preference for dynamical dark energy, with the cosmological constant scenario ($\Lambda$CDM) disfavored at the $\sim 3\sigma$ level. These analyses, however, typically rely on large-scale CMB polarization measurements to constrain the optical depth to reionization $\tau_{\rm reio}\sim 0.06$, raising the question of whether potential systematics in this dataset could influence the inferred cosmological preference. Excluding large-scale polarization data substantially weakens the tension with $\Lambda$CDM to the $\lesssim 2\sigma$ level, nevertheless at a price of increasing $\tau_{\rm reio}$ significantly to $\sim 0.09$. Here, we use a physically motivated Gompertzian reionization framework to perform a self-consistent Bayesian analysis combining CMB (excluding large-scale polarization data), BAO, and independent measurements of the neutral hydrogen fraction evolution from quasar damping wing observations and dark pixel constraints. We derive $\tau_{\rm reio} = 0.067 \pm 0.011$ (dynamical dark energy scenario) in good agreement with cosmological analyses that would include large-scale CMB polarization data, while the inferred reionization history is consistent with multiple observational constraints. Our analysis recovers a preference for dynamical dark energy at the $\gtrapprox2\sigma$ level. These results demonstrate that astrophysical probes of reionization independently recover the optical depth required by CMB polarization measurements, suggesting that potential systematics in large-scale polarization alone are unlikely to fully explain the emerging preference for dynamical dark energy.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Dendro-GR at high mass ratios with high spins

William K. Black, David W. Neilsen, Eric W. Hirschmann et al. (+1 more)

The Laser Interferometer Space Antenna (LISA) launches in less than a decade; it will detect spinning high-mass-ratio binary black hole inspirals annually, alongside other third-generation gravitational wave detectors. High-mass-ratio systems occupy a regime where numerical-relativity simulations remain computationally expensive and technically demanding, especially with high spins at precessing orientations. This portion of parameter space thus remains undersampled, leading to significant bias in parameter estimation. We must close these gaps. Here we report key progress in Dendro-GR toward reducing the computational cost of high-mass-ratio binaries with spin. We evolve the first Dendro-GR binaries at mass ratio $q=24$ (nonspinning) and at $q=12$ with spins up to $\chi=0.8$ on both black holes, spanning various configurations. These proof-of-concept runs show strong evidence that Dendro-GR can simulate in this regime and beyond. The simulations generate accurate gravitational waveforms through multipole modes up to $\ell=8$, remain stable, keep constraint violations low and largely constant, conserve horizon mass, and have high computational efficiency with relatively low wall-hour cost. These results establish our starting line for systematic exploration of the high-mass-ratio, high-spin binary black hole systems that are needed for gravitational wave analysis.
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All authors William K. Black, David W. Neilsen, Eric W. Hirschmann, David F. Van Komen

Tuesday 28 July

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

Multiparameter sensing of axion dark matter with superconducting-qubit networks

Le Bin Ho

We propose a quantum sensor network for direct detection of quantum chromodynamics (QCD) axion dark matter using entangled superconducting qubits. In the presence of a static magnetic field, the oscillating axion field induces a coherent qubit rotation described by an encoding angle proportional to the axion-photon coupling and an unknown dark-matter phase. Treating the phase as an additional unknown parameter turns axion detection into a two-parameter quantum estimation problem. We formulate these signals in Cartesian coordinates, thereby avoiding the singularity that arises in the weak-signal regime and establishing a regular framework for multiparameter quantum estimation. Using this framework, we optimize the quantum sensor network and combine it with Bayesian inference to reconstruct the axion-photon coupling. The optimized protocol accurately recovers the KSVZ and DFSZ benchmark couplings over the mass range $m_a\in[0.1,10]~\mu{\rm eV}$, generalizes to previously unseen masses, and remains robust against realistic superconducting-qubit decoherence and gate errors.
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Solar and Stellar Astrophysics

A quadratic balance relation for radial nonadiabatic pulsations

Jan Zalewski

Using a sesquilinear pressure - rate of volume change kernel and linear pulsation equations, we formulate a balance relation combining work integral, surface terms, norm integral and the real part of pulsation frequency (for $\exp({\omega t})$ time dependence) in terms of linear radial pulsation variables. The resulting relation is exact within the adopted radial nonadiabatic formulation. We apply the quadratic balance relation to radial pulsations in AGB envelopes and use it to check the accuracy of computation and to obtain information about mode excitation and damping. We also compare the balance relation with the classical formulation based on dissipation and kinetic energy integrals and discuss the meaning of the components made explicit by the present decomposition that appear in our balance equation and their relevance for ordinary and strange modes in AGB envelopes.
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High Energy Astrophysical Phenomena

Synchrotron and Inverse-Compton Signatures of Black to White Hole Explosions: Weibel-Mediated External Shocks in the Interstellar Medium

Hoang Van Quyet

We study the non-thermal electromagnetic counterpart expected when the relativistic, near-isotropic ejecta of a black-to-white hole transition sweep up the interstellar medium (ISM). Building on a photospheric model for the prompt $\gamma$-ray emission~\cite{Villani2026}, we parametrize the kinetic energy available for an external shock, $\eiso=R_k\egprompt$, and model the resulting collisionless forward shock with a Weibel-mediated field~\cite{Weibel1959,MedvedevLoeb1999,SironiSpitkovsky2011}. We estimate the synchrotron and synchrotron self-Compton (SSC) emission from shock-accelerated electrons in a one-zone, Thomson-regime approximation, including inverse-Compton cooling, Klein-Nishina suppression, self-absorption, and $\gamma$-$\gamma$ opacity, all at order-of-magnitude or first-order accuracy. For illustrative parameters ($\egprompt\sim10^{44}$ erg, $R_k=0.1$, $\Gamma_0=100$), the electrons are slow-cooling, so for $p=2.5<3$ the synchrotron spectrum peaks at the cooling frequency $\nu_c$, in the MeV-to-GeV range and softening with time; the afterglow evolves in a fraction of a second to tens of seconds – orders of magnitude faster than a classical long-duration GRB afterglow at comparable energy, density, and Lorentz factor – with duration, peak energy, and flux depending sensitively on $R_k$, $\nism$, and $\epse,\epsB,\xie$. We identify parameter regions where a 1 keV photon-count estimate, below the intrinsic peak, exceeds a nominal detection threshold, and discuss features – a fast, faint, roughly isotropic transient after a hard-spectrum prompt flash, without an achromatic jet break – that may distinguish this scenario from short GRBs, magnetar giant flares, and other fast transients, while flagging the assumptions (forward-shock-only dynamics, one-zone Thomson-regime radiation, an illustrative detectability criterion) limiting its quantitative reach.
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Instrumentation and Methods for Astrophysics

Co-design of ground-based gravitational wave detector networks

Daniel Lanchares, Lysiane Mornas, Luigi Toffolatti et al. (+1 more)

Discussions around the design philosophy and location of the next generation of ground-based gravitational wave detectors are still underway. In this context, we propose IfoScout, an innovative methodology for detector co-design based on state-of-the-art machine-learning (ML) techniques. As a simple demonstration, we present a two-stage simulation of a network of fictional L-shaped interferometers whose sensitivity is optimized within physical and geographical constraints, indirectly resulting in reducing the costs. To achieve this, we gather publicly available data for two token locations and establish the length and orientation with reinforcement learning (RL). Next, we optimize the internal detector parameters related to cavity stability to achieve the best possible sensitivity by means of differential programming (DP). We make the case that pipelines such as IfoScout could have a positive impact on the final design of new generation detectors (e.g. the Einstein Telescope, the Cosmic Explorer, etc.), given precise data and detailed, realistic simulations of the interferometers.
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All authors Daniel Lanchares, Lysiane Mornas, Luigi Toffolatti, Pietro Vischia

Solar and Stellar Astrophysics

Three-dimensional Magnetic Field Structure of a Quiet-Sun Region Revealed by Sunrise III/SCIP

Masahito Kubo, Yukio Katsukawa, Yusuke Kawabata et al. (+38 more)

The balloon-borne stratospheric solar observatory Sunrise III successfully completed 6.5 days of observations in July 2024. One of its focal-plane instruments, the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP), is a slit-scanning spectropolarimeter that simultaneously measures full Stokes profiles of multiple spectral lines in the 850 nm and 770 nm bands. SCIP obtained an unprecedented data set of a quiet-sun region near disk center, covering a $58'' \times 58''$ field of view. With an integration time of 10 s per slit position, the scan was completed in 107 minutes without interruption, achieving remarkably stable polarimetric precision of 0.03-0.04% (1$\sigma$) of the continuum level. The multi-wavelength SCIP observations reveal that the chromospheric line-of-sight (LOS) magnetic field exhibits thread-like, elongated structures over the internetwork regions, with no obvious photospheric counterpart directly below. These threads are typically narrower than $1''$ and are embedded within the canopy fields extending from the network regions. Their LOS field strengths derived from the weak-field approximation are typically 10-20 G weaker than the surrounding canopy. In particularly clear cases, the magnetic polarity of the threads is opposite to that of the adjacent canopy. These findings suggest that the canopy field is not simply an expanding structure originating from network regions, but instead has a complex three-dimensional configuration containing numerous localized substructures. These observations provide new constraints on the quiet-sun magnetic topology from the photosphere to the chromosphere.
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All authors Masahito Kubo, Yukio Katsukawa, Yusuke Kawabata, Takayoshi Oba, Hirohisa Hara, Toshifumi Shimizu, Ryohtaroh T. Ishikawa, Takuma Matsumoto, Yoshihiro Naito, Fumihiro Uraguchi, Toshihiro Tsuzuki, Kazuya Shinoda, Tomonori Tamura, Yoshinori Suematsu, Jose Carlos del Toro Iniesta, David Orozco Suárez, Maria Balaguer Jiménez, Carlos Quintero Noda, Sami K. Solanki, Andreas Lagg, Achim Gandorfer, Pietro Bernasconi, Thomas Berkefeld, Alex Feller, Tino L. Riethmüller, Alberto Álvarez-Herrero, H. N. Smitha, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Johannes Hölken, Francisco A. Iglesias, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović, Patrick A. Ondratschek

Astrophysics of Galaxies

Stellar Population Astrophysics (SPA) with the TNG. Beyond the iron peak: Galactic evolution of molybdenum, ruthenium and zirconium through open clusters

Natalia Alvarez-Baena, Valentina D'Orazi, Christopher Sneden et al. (+11 more)

Context: Open clusters serve as key laboratories for studying the chemical evolution of the Milky Way. In particular, leveraging these coeval groups of stars to study elements beyond the iron peak provides insights into heavy-element nucleosynthesis, whose origins remain uncertain. Aims: This work aims to determine the Mo, Ru, and Zr abundances for 81 stars across 30 open clusters. We compare these new chemical patterns with those of key reference elements (Y, Sr, Eu), which were previously derived by our group. This comparison seeks to disentangle the distinct contributions from various nucleosynthetic processes. Methods: Using the high-resolution spectra acquired within the Stellar Population Astrophysics programme using the HARPS-N echelle spectrograph at the Telescopio Nazionale Galileo, we estimate chemical abundances through spectral synthesis with TSFitPy under local thermodynamic equilibrium (LTE) conditions. Results: This study provides the first Ru abundances for a large open cluster sample, alongside new measurements for Mo and Zr. We observe tight correlations between Mo, Ru, and other s-process elements (Sr, Y, Zr), with slopes near unity, suggesting common enrichment timescales. Conversely, relations with the r-process element Eu show significant deviations, implying additional nucleosynthetic contributions. Crucially, chemical planes involving [Mo/Ru] and [s/Mo] ratios suggest systematic offsets when compared to theoretical s-process predictions.
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All authors Natalia Alvarez-Baena, Valentina D'Orazi, Christopher Sneden, Athanasios Psaltis, Frédéric Thévenin, Angela Bragaglia, Tamara Mishenina, Shilpa Bijavara Seshashayana, Ricardo Carrera, Laia Casamiquela, Marina Dal Ponte, Henrik Jönsson, Antonino Nunnari, Marco Pignatari

Earth and Planetary Astrophysics

Dynamical evolution and surface accretion of DART impact ejecta in the (65803) Didymos system

Xiaoyu Fu, Nicolo Stronati, Stefania Soldini et al. (+6 more)

The DART spacecraft impacted Dimorphos, the small moonlet of Didymos binary system, on 26 September 2022. The impact ejected dust, fragments, and boulders into the near-binary environment. In November 2026, ESA's Hera mission is expected to arrive at the binary system to characterise both asteroids and investigate the post-impact consequences in detail. In this research, we aim to investigate the dynamical evolution of DART-generated impact ejecta and to quantify their surface accretion patterns within the Didymos binary system. High-fidelity ejecta dynamics, including polyhedron asteroid gravity and solar radiation pressure with combined occultations, are constructed. The ejecta initial conditions are generated from the observation-constrained velocity-size distribution and ejecta-cone geometry. In total, 20 million trajectories are integrated to characterise the ejecta evolution and surface accretion. More than 93.5% of DART-generated ejecta particles escape from the system within two years, while only approximately 0.002% remain in the near-binary environment. The deposited layer on Dimorphos reaches the order of 1.5 mm at mid-to-low latitudes. On Didymos, the accreted layer is mostly thinner than 0.3 mm, but may reach 3-11.5 mm in a localised high-density region. The results indicate that, most DART-generated ejecta are removed from the binary system, while a small but dynamically meaningful subset remains near the system or accretes onto the asteroid surfaces. The surface accretion distribution is strongly controlled by the initial ejecta-cone geometry, especially the cone-axis direction.
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All authors Xiaoyu Fu, Nicolo Stronati, Stefania Soldini, Fabio Ferrari, Carmine Giordano, Paolo Panicucci, Alessandro Rossi, Adriano Campo Bagatin, Michael Kueppers

Solar and Stellar Astrophysics

Ultracool and Brown Dwarf Candidates Identified via CatWISE-2MASS-Gaia DR3

Daniel Majaess, Dante Minniti, Matias Gomez et al. (+2 more)

Ultracool and brown dwarf candidates ($d_{\odot}\lesssim 125$ pc, $|b|>8^{\circ}$) were identified via multiband and astrometric data from CatWISE ($W_1W_2$), 2MASS ($JHK_s$), and Gaia DR3 ($G$, $G_{RP}$, $\pi$, $\mu_{\alpha}$, $\mu_{\delta}$). $N\approx 11.8 \times 10^3$ candidates emerged once simultaneously constrained by color and absolute magnitude criteria (e.g., $G-W_2 \ge 1.75(G-J)-2.25$), whereby $\simeq 350$ sources are absent from the Gaia Ultracool Dwarf (UCD) catalog. Spectral types were approximated using a hybrid $M_G-M_{W_1}$ sigmoid that offers additional temperature coverage in certain cases. Subsequent efforts may focus on extending sampling to the deeper NIR VVVX footprint that partly encompasses the Galactic plane, and over the long-term spectroscopically (in)validating candidates missing from the Gaia UCD database.
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All authors Daniel Majaess, Dante Minniti, Matias Gomez, Roberto K. Saito, Maria G. Navarro

Astrophysics of Galaxies

Automated Computer Vision Cluster Identification in the Fireworks Galaxy

Debby Tran, Benjamin F. Williams, Emily M. Levesque et al. (+5 more)

We present the integrated photometry, radii, and spatial distribution of young ($\leq$ 25 Myr) star cluster candidates in NGC 6946. NGC 6946, also known as the Fireworks Galaxy, is a highly star-forming galaxy with numerous young massive clusters. We have developed a modified computer vision algorithm using photometry from images taken with Hubble Space Telescope (HST) Wide Field Camera 3 Ultraviolet channel (WFC3/UVIS) F275W and F336W filters to identify and outline candidate clusters. We describe our technique in detail, including extensive testing with artificial clusters, where the algorithm recovers 60.7% of synthetic clusters and has a conservative false positive rate of 27.3% down to luminosities of M$_{F336W} \sim -6$. We identify 6410 cluster candidates down to much fainter magnitudes (M$_{F336W} \sim -4$) via the aforementioned algorithm which are more difficult to verify, but are still of interest as the luminosity function of these candidates is consistent with a standard power law with a slope of $\sim$2.
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All authors Debby Tran, Benjamin F. Williams, Emily M. Levesque, Tobin M. Wainer, Emerson Bowles, Bo-Eun Choi, L. Clifton Johnson, Anil C. Seth

Earth and Planetary Astrophysics

Nanoscale Storage of Incompatible Elements at Olivine Grain Boundaries in Natural Basalts

Wenhao Zhao, Reid Cooper, Stephen Parman et al. (+2 more)

Grain boundaries are pervasive in polycrystalline olivine, yet their structure and trace-element chemistry remain poorly constrained. We characterize boundaries in undeformed olivine aggregates from Piton de la Fournaise (La Reunion) and Mauna Loa (Hawaii) by correlating electron backscatter diffraction, transmission electron microscopy, and atom probe tomography. The boundaries are crystalline, with a structural width of about 1 nm and no continuous glassy film resolved. Ca, Al, P, Na, and Ti are selectively enriched, whereas Mg, Fe, Ni, and Mn remain homogeneous. Several enriched mass windows coincide with nominal rare-earth-element ion positions, but unresolved isobars and the lack of a diagnostic isotope envelope preclude secure assignments. Divalent-cation segregation follows an ionic-size-misfit trend, while aliovalent departures require unconstrained contributions. The Ca interfacial excess is 2.94-2.97 atoms per square nanometer, equivalent to 0.327-0.330 monolayers, and lies near the upper published 1523 K equilibrium segregation isotherm of Hiraga et al. (2004), within the range of basaltic olivine crystallization temperatures. This supports boundary formation during crystal growth, although synneusis followed by high-temperature residence could produce a similar signature. Ca chemical widths are about 6-9 nm, and those of the most strongly enriched elements reach about 10-15 nm, demonstrating decoupling between the narrow structural core and broader chemical segregation. Compared with published atom-probe data on deformed olivine, these boundaries preserve broader halos, although analytical differences make the contrast tentative. Olivine grain boundaries therefore constitute a distinct nanoscale reservoir that should be included alongside crystal interiors and residual melt in trace-element mass balances of olivine-rich aggregates.
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All authors Wenhao Zhao, Reid Cooper, Stephen Parman, Austin Akey, Greg Hirth