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Physics Astrophysics

astro-ph Watch Astrophysics

Sunday 4 October

Astrophysics of Galaxies

ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: The N83 Star-Forming Region

Marta Sewiło, Amanda Broadmeadow, Roya Hamedani Golshan et al. (+9 more)

We report the results of the 1.2 mm continuum and molecular line $\sim$0.1 parsec-scale observations with the Atacama Large Millimeter/submillimeter Array of two fields in the star-forming region N83 in the Large Magellanic Cloud (LMC). This study is third in a series of investigations exploring molecular complexity in a low-metallicity and high UV flux environment of the LMC. We determine the physical and chemical properties of five sources detected with ALMA based on spectral modeling with XCLASS and the analysis of the continuum emission. The temperatures exceeding 100 K, small sizes, and high H$_2$ volume densities of sources N83A-mm A and B indicate that they are hot cores. N83A-mm A/B are associated with complex organic molecules: methanol (CH$_3$OH), methyl cyanide (CH$_3$CN), and dimethyl ether (CH$_3$OCH$_3$). We also found CH$_3$OH in three cold cores, and extended cold CH$_3$OH emission in both fields. We detected SO, $^{33}$SO, SO$_2$, OCS, H$_2$CS, CS, C$^{33}$S, HC$^{15}$N, H$^{13}$CN, HNCO, HDCO, H$^{13}$CO$^{+}$, SiO, and CH$_2$CO in at least one core. Molecular abundances with respect to H$_2$ fit into the trends previously reported for the Magellanic hot cores: the CH$_3$OH abundance varies significantly, while the abundances of S-bearing species show small variations. We found evidence for strong UV radiation and complex kinematics in both ALMA fields in N83. The feedback-produced shocks are important drivers of the chemistry of S-bearing species, SiO, and CH$_3$OH in and outside hot cores. Local effects have a large impact on the chemical composition and abundances of star-forming cores in the LMC.
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All authors Marta Sewiło, Amanda Broadmeadow, Roya Hamedani Golshan, Steven B. Charnley, Lee Mundy, Kazuki Tokuda, Thomas Möller, Jennifer Wiseman, C.-H. Rosie Chen, Remy Indebetouw, Joana M. Oliveira, Peter Schilke

Cosmology and Nongalactic Astrophysics

Kinetic-theory derivation and Bayesian analysis of the finite-temperature shifted CMB power spectrum

I. Y. Park

Finite-temperature quantum-gravitational corrections to the cosmological constant introduce two additional density parameters, $\Omega_{\Lambda_2}$ and $\Omega_{\Lambda_3}$, the associated terms of which scale as $a^{-4}$ and $a^{-2}$, respectively. In previous work (Papers I and II), these parameters were studied using machine-learning methods that identified a best-fit point. Here we complete the picture with two complementary analyses. First, we perform a Bayesian MCMC analysis using a modified version of class against the Planck 2018 likelihoods. This tells us what the data can constrain once all parameter uncertainties have been marginalized over. Both parameters are consistent with zero, with $\Omega_{\Lambda_3}$ constrained only from one side. Second, we build a CMB pipeline from scratch, following Weinberg's kinetic-theory formulation and validating it against class. This allows us to study the underlying physics. The response analysis carried out with it shows that $\Omega_{\Lambda_3}$ is almost entirely absorbed by a shift in $h$ over the well-measured acoustic multipoles. The part of the signal that cannot be absorbed resides at low $\ell$, where cosmic variance dominates. Meanwhile, the $\Omega_{\Lambda_2}$ signature is nearly degenerate with the overall amplitude of the spectrum. The effects of both parameters on the CMB power spectrum are small, since they represent higher-order thermal corrections to the cosmological constant. The resulting constraints are correspondingly weak: the induced shifts are largely absorbed by degeneracies with $h$ and with the overall normalization of the spectrum. This is the reason why neither parameter is detected.
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Solar and Stellar Astrophysics

AI Agents as a Research Team: A Human-Supervised Case Study in Stellar Spectroscopy

Marwan Gebran and Ian Bentley

We present a qualitative case study of a human-supervised team of specialized AI agents supporting an astronomy research project. The Bot Spectroscopist team, described in the project record as operating through Grok Bot powered by xAI Grok, divided work among orchestration, numerical implementation, data curation, spectroscopy critique, literature search, figure preparation, manuscript editing, and review. Human decisions determined scientific scope, model changes, and manuscript inclusion. The scientific application is CondGen, a deterministic label-to-spectrum network extending our previous work to five individual elemental abundances. The reported baseline assessment achieved a mean absolute error (MAE) of 0.003681 in continuum-normalized flux on 21,657 synthetic test spectra. Existing binned diagnostics show that reconstruction error varies with effective temperature and abundance. The bots also flagged a non-monotonic cool-star magnesium response for further investigation; a matched SYNSPEC abundance sweep is needed to assess its physical fidelity. Building on a pre-existing spectral database, notebooks, and research program, the authors estimate that the reported analysis, diagnostics, figure preparation, and initial manuscript drafting were assembled in less than a week through human prompting and exchanges among agents. No comparison with a human team starting from the same resources was performed, so this elapsed-time account does not establish a productivity or labor saving. The study illustrates task delegation, artifact exchange, critique, and correction under human supervision.
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High Energy Astrophysical Phenomena

Radiation Reaction in Relativistic Magnetized Shocks of Neutron Star Magnetospheres

Arno Vanthieghem and Amir Levinson

The steepening of fast magnetosonic waves in the inner magnetospheres of magnetars can produce monster shocks, whose precursor emission may account for fast radio bursts (FRBs). For sufficiently bright bursts, particles crossing the shock radiate their energy within a single gyration period, raising the question of how radiation reaction affects the shock structure and its coherent emission. We investigate strongly cooled, relativistically magnetized shocks using a stationary multifluid model generalized to include the Landau-Lifshitz radiation-reaction force, together with particle-in-cell simulations of monster-shock dynamics. We show that the kinetic-scale shock transition is governed by only two dimensionless parameters: the Alfvénic Mach number and a cooling parameter $\tau$ that measures radiative losses over a gyration period. Coherent precursor emission is triggered above a critical Mach number that increases with $\tau$, at which the beam dynamics becomes chaotic. Above this threshold, radiative cooling shifts the peak frequency of the precursor to higher values, scaling as $\tau^{2/7}$. Remarkably, monster shocks remain far above the emission threshold even under strong radiative cooling. Radiation reaction therefore does not quench the precursor emission; instead, it primarily shifts the spectral peak into the kinetic regime. The luminosity of the precursor wave is determined solely by the luminosity of the driving kHz wave and the conversion efficiency, $\epsilon_X\sim 10^{-3} - 10^{-2}$.
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Earth and Planetary Astrophysics · Cross-listed from physics.space-ph

What Caused the Orbital Decay of the Twin Van Allen Probes to Diverge?

Ayisha M Ashruf, Ankush Bhaskar, C Vineeth et al. (+1 more)

The Van Allen Probes were launched into nearly identical orbits and experienced the same solar and geomagnetic environment, yet their post-mission lifetimes diverged dramatically. Probe A underwent rapidly accelerating orbital decay and reentered the atmosphere in March 2026, while Probe B remains in orbit. We investigate the cause of this divergence using reconstructed orbital trajectories, modeled thermospheric densities, and measures of low-altitude residence and atmospheric drag. We find that small differences in orbital evolution progressively increased Probe A residence time in the lower thermosphere, where the steep density gradient made additional low-altitude exposure increasingly important. Enhanced thermospheric density during periods of geomagnetic activity further amplified this difference, leading to greater drag and accelerating orbital decay of Probe A. Our results show how small differences in orbital evolution can be amplified through the coupled effects of thermospheric drag and space weather, producing substantially different orbital lifetimes even for twin spacecraft sharing nearly identical initial orbits.
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All authors Ayisha M Ashruf, Ankush Bhaskar, C Vineeth, Tarun Kumar Pant

Earth and Planetary Astrophysics · Cross-listed from physics.hist-ph

Astronomia Ova: Kepler's Laws, Ptolemy's Equant, and Legendre's Polynomials

Cristopher Moore, Malcolm Smith and Stephan Mertens

Motivated by Kepler's long battle with the orbit of Mars, we present a family of orbits that satisfy his second law, conserving angular momentum around a central mass, and also fulfill Ptolemy's belief in an equant — a point around which the angular speed is constant. For specific values of the angular momentum, these orbits can be written in terms of Legendre polynomials and functions of the second kind. They are analytic except at perihelion where they are twice differentiable. They resemble the "ovoid" (egg-shaped) or "metopoid" (face-shaped) orbits that Kepler considered on his way to the ellipse.
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High Energy Astrophysical Phenomena

A Brush with Turbulence: Probing the ICM Dynamics in the Merging Toothbrush Cluster using XRISM

Anjali Madangarli, Aurora Simionescu, Huub Röttgering et al. (+11 more)

The Toothbrush Cluster (1RXS J0603.3+4214) is known for its northern radio relic, radio halo, and highly disturbed X-ray morphology. It shows features of both shock-driven and turbulent reacceleration, the latter of which is invoked to explain its radio halo. However, how kinetic energy from the merger is distributed into gas motions across spatial scales remains unclear. We probe the intracluster medium (ICM) dynamics in the southern, X-ray-brightest region of the cluster using a 167 ks XRISM/Resolve observation. We conduct both full-array and quadrant sub-array analyses by fitting the spectra with single and multi-component thermal models in the 3-8 keV band. The full-array spectrum favours two ICM components with a transonic line-of-sight (LOS) velocity difference of $\Delta v_{\mathrm{bulk}}=1635^{+165}_{-110}$ km s$^{-1}$, while the velocity dispersions are much lower, at $\sigma_{v,1\mathrm{D}}\sim$245-310 km s$^{-1}$. The sub-array analysis likewise reveals multiple components in at least three quadrants, with LOS bulk velocities ranging from $-2520^{+295}_{-230}$ to $+930^{+70}_{-110}$ km s$^{-1}$. The velocity dispersions remain modest at $\sim$215 km s$^{-1}$, corresponding to a turbulent pressure support of about 3-6% on scales dominating the observed line broadening. Cooler gas is detected in the NE and SW, with $kT_{\mathrm{NE}}=3.13^{+0.33}_{-0.30}$ keV and $kT_{\mathrm{SW}}=2.32^{+0.43}_{-0.37}$ keV, likely associated with a third, northern subcluster identified in weak-lensing and optical studies. Our results indicate a complex ICM kinematic structure, with evidence for at least three subclusters exhibiting supersonic bulk velocity offsets and much smaller velocity dispersions. This shows that the merger geometry has a significant line-of-sight component and may indicate that the cluster collision is relatively young, with the turbulent cascade not yet fully established.
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All authors Anjali Madangarli, Aurora Simionescu, Huub Röttgering, Anwesh Majumder, Soeda Haruse, Kazuhiro Nakazawa, Yuusuke Uchida, Daisuke Ito, Gianfranco Brunetti, Reinout van Weeren, Congyao Zhang, Kamlesh Rajpurohit, Priyanka Chakraborty, Hiroki Akamatsu

Instrumentation and Methods for Astrophysics · Cross-listed from hep-ex

Precision measurement of ocean tides using cosmic-ray muons

Jiwon Seo, Jongseok Chung, Chang Hyon Ha et al. (+8 more)

Cosmic-ray muons provide a natural probe of the integrated mass along their trajectories. Here we show that cosmic-ray muons can monitor ocean-tide-induced variations in seawater overburden within an underwater tunnel. The observed modulation closely tracks independent tide-gauge measurements, yielding an attenuation response coefficient of $k=43.2\pm1.0$~counts$\rm /h/m$ and resolving meter-scale variations in seawater overburden. A spatial muography scan validates the overburden model, confirming that the seawater contribution is essential to reproduce the observed attenuation. Unlike conventional tide gauges that measure sea level locally, muography measures the integrated overburden above the detector. These results demonstrate that muography can quantitatively resolve small, time-dependent variations in environmental overburden, providing a new approach to monitoring dynamic natural systems.
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All authors Jiwon Seo, Jongseok Chung, Chang Hyon Ha, TongZhou Huang, Jinyoung Kim, Sooa Kim, Hani Kimku, Byoung-cheol Koh, Minsu Kwak, Sihyun Lee, Yujin Lee

Earth and Planetary Astrophysics

Irradiated Atmospheres VII. Effect of Mixing Energy Flux on Atmosphere-Interior Coupling

Wei Zhong, Zhen-Tai Zhang, Mei Ting Mak et al. (+5 more)

Highly irradiated, underdense rocky planets such as puffy Venuses may host strong coupling between their atmospheres and magma-ocean interiors. Previous studies have mainly treated this coupling through radiative transfer and chemical equilibrium, leaving the role of vertical mixing unclear. Here we quantify how energy transport associated with vertical mixing modifies the thermal structure, volatile chemistry, and emission spectra of puffy Venuses. Atmospheric circulation and gravity-wave breaking are possible dynamical sources of such transport. We show that this energy transport provides an additional greenhouse-like heating pathway by warming the deep atmosphere, thereby increasing the pressure and temperature at the magma-ocean surface. The resulting thermal changes also reshape the atmospheric composition, especially the abundances of \ce{CO} and \ce{H2O}, and change the partitioning of C-, H-, and O-bearing volatiles between the atmosphere and the magma ocean. Moreover, these changes reshape the mid-infrared planet–star flux ratio, especially at low equilibrium temperatures and in higher-mass planets. Under high C/O, it slightly increases the flux near $3.5$–$4.0\,\mu$m, but more broadly reduces atmospheric transparency and suppresses the flux. This may affect radius estimates for puffy Venuses over a limited temperature range.
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All authors Wei Zhong, Zhen-Tai Zhang, Mei Ting Mak, Xiang-Xing Chen, Bo Ma, Xian-Yu Tan, Cong Yu, Dong-dong Ni

High Energy Astrophysical Phenomena

Pulsations and constraints on time lags in two distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1

Rajath Sathyaprakash, Matthew J. Middleton and Chris Done

The nature of ultra-luminous X-ray sources (ULXs) is shrouded in mystery as they're believed to be point sources with luminosities above the classical Eddington limit for a 10$M_{\odot}$ black hole (BH), but generally fit into the classification tree of super-Eddington X-ray binaries. Studies of reverberation lags and lag-energy spectra provide some insight into the nature of viscous turbulence in optically thick, super-Eddington discs, and are useful in conjunction with modelling multi-wavelength spectra and covariance spectra. In this study, we focus on the timing properties of two classically distinct ULXs: NGC 5204 X-1 and NGC 55 ULX-1, both of which are known to emit relativistic winds, as observed by modelling emission line spectra with photo-ionisation models such as SPEX, but are thought to be viewed at slightly different inclinations due to differences in the hardness-ratio of their X-ray continuum. Here, we perform an extensive timing study of the two ULXs to reveal new constraints on the accretion disc size scale and structure. We also perform an accelerated search for pulsations (including the correction for an orbital modulation of the signal) to discover significant spin-periodicities in both NGC 5204 X-1 and NGC 55 ULX-1 (at $> 3\sigma$ significance).
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High Energy Astrophysical Phenomena

Large offsets of double-neutron-star mergers: degeneracies and implications for host associations

Xiao-Tian Xu, Bin-Bin Zhang, Wenjie Wu et al. (+1 more)

The projected offset of a Gamma-Ray Burst (GRB) from its host galaxy is an important diagnostic of its physical origin, where the host associations are usually evaluated through chance-coincidence probabilities. However, as shown by observations, the host associations given by this approach may be ambiguous in some cases. In this work, we revisit the modelling of the offsets of double-neutron-star (DNS) mergers with controlled numerical experiments using Monte Carlo simulations. To isolate the dynamical effects of the second supernova (SN) from uncertainties in the upstream binary evolution, we parametrise the direct progenitor of DNSs and integrate the post-SN trajectories in galactic potentials using galpy. Complementary to previous population synthesis calculations, our Monte-Carlo tool, GRB-offset, provides a lightweight framework to identify sensitivities and expose degeneracies in offset modelling. With GRB-offset, we have investigated the following physical ingredients, supernova physics (ejected mass and kick velocity), galactic potential (potential shape, galaxy virial mass), DNS birth location, star formation history, and redshift. The offset distributions given by our reference Monte-Carlo simulation peak at around 30 kpc and 1000 kpc for the DNSs bound to and unbound from the host galaxy, which sensitively depends on the considered physical ingredients. A given offset can arise from various combinations of these ingredients, introducing substantial degeneracies when interpreting observed offsets. Therefore, an observed offset alone can hardly constrain the properties of the DNS progenitor and of the host galaxies.
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All authors Xiao-Tian Xu, Bin-Bin Zhang, Wenjie Wu, Suoning Wang

Astrophysics of Galaxies

Spatio-temporal progression of star formation in the Carina OB1 association

C. Göppl and T. Preibisch

The Carina OB1 association, harboring the famous Carina Nebula near its center, is the most massive, well-studied OB association in our Galaxy. Containing several massive star clusters with different ages, it shows a complex spatio-temporal structure. We explore the formation history and kinematic evolution of the eight most massive clusters in Car OB1. We determine the cluster ages, stellar populations, the initial massive star content, and the number of supernova explosions since the time of each cluster's formation. Using Gaia DR3 astrometry, we determine the 3D configuration of the association and perform a traceback analysis of the cluster positions over the last 13 Myr. The traceback analysis places the birth location of the oldest (13 Myr) cluster, NGC 3293, in the Carina spiral arm. Approximately four Myr later, a series of 11 supernova explosions started in NGC 3293. We construct a possible scenario in which the expanding bubble driven by these supernova explosions interacted with the southern part of the original cloud complex and led to the sequential formation of the younger clusters in the central Carina Nebula. Our scenario suggests that the sequence of 16+/-4 supernova explosions in the association during the last 10 Myr played an important role in creating the massive clusters in Car OB1. However, the supernova feedback does not dominate the large-scale expansion of the association; the general expansion rather seems to reflect the initial kinematics of the original unbound cloud complex.
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Cosmology and Nongalactic Astrophysics

Limits on the size of electron density fluctuations in the early universe and implications for the Hubble tension

Gabriel P. Lynch, Jens Chluba, Richard Battye et al. (+1 more)

Little is known about the early universe on scales smaller than those resolved by the cosmic microwave background (CMB), where electron density fluctuations on kiloparsec to megaparsec scales are expected in many extensions of LCDM. These fluctuations nonetheless leave two imprints on the CMB. They accelerate recombination, the effect behind previous constraints and proposals to raise the inferred Hubble constant, $H_0$. Through correlations along the line of sight, they also reduce the effective Thomson scattering rate, enhancing diffusion damping by an amount that grows with their coherence length. We implement both effects in a modified Boltzmann code, classito, and use CMB data from Planck, ACT DR6, and SPT-3G D1 to place the first limits on such fluctuations that include this modified photon transport. We find no evidence for them: the variance of the electron density contrast is below $0.21$ ($95\%$ CL), falling to $0.033$ for a coherence length of $2\,{\rm Mpc}$, and we present these limits in terms of the electron power spectrum at $1\,{\rm Mpc}^{-1}\lesssim k\lesssim10^2\,{\rm Mpc}^{-1}$. We also reassess small-scale electron density fluctuations as a resolution of the Hubble tension. In Planck data the transport effect is partially degenerate with accelerated recombination, widening the range of $H_0$ allowed: combined with a distance-ladder prior, Planck gives $H_0 = 71.1\pm0.7\,{\rm km\,s^{-1}\,Mpc^{-1}}$ and an improved fit relative to LCDM. ACT and SPT-3G break this degeneracy, chiefly through the temperature–$E$-mode correlation in the damping tail, and with the same prior they give only $H_0 = 69.3\pm0.5\,{\rm km\,s^{-1}\,Mpc^{-1}}$ and no preference over LCDM. With our treatment and publicly available code, models that generate small-scale electron density fluctuations can be directly confronted with CMB data through the variance and coherence length that they predict.
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All authors Gabriel P. Lynch, Jens Chluba, Richard Battye, Geoffrey Vasil

High Energy Astrophysical Phenomena

Fast Bayesian Updating of the Neutron-Star Equation of State with Neural Posterior and Evidence Estimation

Prashant Thakur

We present two complementary neural routes for microscopic neutron-star EOS inference: truncated sequential neural posterior estimation with mixture importance sampling (TSNPE+MIS), which targets one observation, and amortized neural posterior estimation with importance sampling (A-NET+IS), which is reused across nuclear inputs and NICER sources. Both are corrected against the original prior and full likelihood, with the effective sample size as a diagnostic. We test nucleonic and hyperonic relativistic mean-field models with nuclear data, NICER, GW170817, and pQCD. For the fiducial analyses, both agree with UltraNest in the parameter posteriors and 90% mass-radius and tidal-deformability bands. TSNPE+MIS band-edge differences are only 0.024-0.033 km and 1.02-1.03%, while A-NET+IS differences are 0.019-0.050 km and 0.86-1.13%. TSNPE+MIS reduces the computing time by factors of 1.6-2.3; after training, A-NET+IS is 15-240 times faster per configuration. The frozen A-NET also analyzes three NICER sources absent from training, including the newly reported high-mass, compact PSR J1614-2230 posterior. For this source, the inferred $R_{1.4}$ agrees with UltraNest within 0.010 km for nucleonic matter and 0.009 km for hyperonic matter. We also introduce a Green-function Evidence Network (EN), a regression-based variant of Evidence Networks and, to our knowledge, the first Evidence Network applied to neutron-star EOS inference. After a one-time cost, its network queries return absolute evidences in about 0.03 s for new nuclear data and 3.5 s for a new NICER source; all 16 differences from UltraNest are below $1\sigma$, and independent importance-sampling evidences agree within the quoted EN uncertainties. Under the adopted likelihood, both evidence calculations favor nucleonic matter by Bayes factors of about 22:1-27:1.
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Solar and Stellar Astrophysics

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii. II. Dynamics of the dust in the Mira wind and the Halpha gas in the jet

H.M. Schmid, E. Lagadec, J. Milli et al. (+17 more)

R Aqr is a resolved symbiotic Mira binary and a prototype target for the study of complex hydrodynamic processes including dust-driven mass loss, mass transfer, accretion, and jet outflows and the formation of strongly asymmetric structures. We investigate for R Aqr the central Halpha emission from the ionized gas and the polarization from scattering dust based on SPHERE/ZIMPOL maps with a resolution of about 25 mas (5 AU). Data for four epochs were taken, including the dust eclipse around 2021, to follow structural changes. The central Halpha gas traces the orbital motion of the hot component. The polarization from scattering dust shows interaction effects near the binary (<60 AU), including a flattened distribution in the orbital plane, corotating dust, and a reduction of the scattering signal during the dust eclipse. The polarization shows at >60 AU a steady outflow with about a dozen dust clouds, a few of which have a comet-like core and tail features. The dust velocity is about 20 km/s, and this is faster than for the CO gas measured with ALMA. Several prominent Halpha clouds also show scattering polarization because they are just partly ionized dust clouds from the Mira wind. We also found small faster-moving transient Halpha clouds, pointing to outflow instabilities and shocks. The observed angular shift of Halpha during the dust eclipse, can be explained by strong illumination changes from the hot component. At larger separation, the H$\alpha$ clouds move faster (>100 km/s), in agreement with previous studies. This acceleration is probably a result of gas heating by photoionization and shocks, and the produced overpressure gives rise to the two well-known jet-like features expanding in polar directions. The presented R Aqr data are very useful to clarify the complex hydrodynamics taking place in AGB binaries.
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All authors H.M. Schmid, E. Lagadec, J. Milli, C. Tschudi, J. Ma, N. Engler, J.L. Beuzit, A. Boccaletti, G. Chauvin, R. Claudi, S. Desidera, K. Dohlen, M. Feldt, R. Gratton, Th. Henning, M. Kasper, M. Langlois, F. Ménard, D. Mouillet, A. Vigan

Astrophysics of Galaxies

Large-Scale Stellar Bars and Nuclear Activity in Narrow-Line Seyfert 1 Galaxies

Po-Chieh Yu

We present a statistical comparison between barred and unbarred narrow-line Seyfert 1 galaxies (NLS1s) to investigate the role of large-scale stellar bars in fueling AGN with low-mass black holes. From a parent sample of 492 NLS1s selected from SDSS and Pan-STARRS1 (PS1), we construct a PS1-resolved matched sample of 101 barred and 101 unbarred NLS1s, matched in redshift, inclination, and image quality. Unbarred NLS1s are modestly but consistently brighter than barred NLS1s in several optical AGN luminosity indicators, including $\lambda L_{\lambda}(5100~A)$, broad H$\alpha$, broad H$\beta$, narrow H$\alpha$, narrow H$\beta$, and [O III]~$\lambda 5007$, with typical offsets of $\sim 0.1$–$0.25$ dex; the broad H$\alpha$ and narrow-line offsets are statistically significant, while the continuum and broad H$\beta$ offsets are marginal. Monte Carlo resampling and a Bayesian model support the same direction of offset. In contrast, the main narrow-line diagnostics, including [O III]/H$\beta$, O3N2, and the [S II]-based electron density, are statistically consistent between the subsamples, although barred NLS1s show a higher N2 ratio. Within the barred subsample, the bar strength parameter $e_{\max}$ shows a mild anti-correlation with the optical continuum and broad Balmer-line luminosities. These results indicate that large-scale stellar bars are not associated with enhanced instantaneous optical AGN luminosity. Instead, barred systems may experience more regulated or time-variable inner gas delivery, building circumnuclear gas reservoirs without necessarily increasing accretion power observed at the epoch traced by optical AGN emission.
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Instrumentation and Methods for Astrophysics

Opportunity Lost in Searching for Technosignatures

Steve Prabu, David DeBoer, Andrew Siemion et al. (+6 more)

The sensitivity of radio technosignature searches has improved dramatically over the last five decades; however, as the RFI environment from which these searches are conducted has become increasingly polluted, our advancements in telescope sensitivity have not necessarily been complemented by less ambiguous technosignature searches. In this work, we investigate the resulting loss of opportunity to conduct unambiguous technosignature searches from Earth. We introduce three new concepts, opportunity lost, volume lost, and self-censorship, to quantify the impact of orbiting RFI sources on Earth-based technosignature searches. Using publicly available orbital data between 2008 and 2025, we find an approximately two-fold increase in the spatial occupancy of satellites within representative telescope beams, with the exact magnitude of the loss strongly dependent on telescope pointing. We further demonstrate that the cumulative effect of faint emission from multiple satellites increase the effective system temperature and consequently reduce the volume over which a technosignature of a given intrinsic power can be detected. Using approximately 10,000 archival observations from the Murchison Widefield Array spanning 2014–2024, we find suggestive evidence for increasing RFI occupancy across most of the frequencies observed by the MWA. While other opportunities for terrestrial technosignature searches exist, we argue for the protection and utilisation of uniquely radio-quiet environments such as the lunar farside, which offers an opportunity to regain the ability to perform unambiguous technosignature searches that is being progressively lost on Earth.
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All authors Steve Prabu, David DeBoer, Andrew Siemion, Andre R. Offringa, Natasha Hurley-Walker, Charlie K. Ashe, Sofia. Z. Sheikh, Steve Croft, Greg Sleap

Earth and Planetary Astrophysics

Candidate O I 7774 Å\ Absorption from an Escaping Rock-Vapor Outflow of BD+05 4868 Ab

Kody M. Walker and James C. Wallace II

Disintegrating rocky planets provide a rare opportunity to probe material escaping directly from intensely irradiated planetary surfaces. We present time-resolved, low-resolution ($R\simeq600$) optical spectroscopy and complementary ground-based photometry of BD+05 4868 Ab. The in-transit spectra exhibit an additional unresolved absorption feature near the O I triplet at 7771.94, 7774.17, and 7775.39 Angstroms relative to the out-of-transit baseline. The feature has an equivalent width of $W_\lambda\simeq1.4\pm0.2$ Angstroms, a maximum differential depth of approximately 9%, and an apparent width of 13-16 Angstroms, comparable to the instrumental resolution. We interpret the feature as candidate O I absorption from an oxygen-bearing mineral-vapor outflow. The $3s\,{}^5S^\circ_2$ lower level of the triplet lies 9.146 eV above the ground state and cannot be appreciably populated in LTE at the reported planetary temperature, requiring non-LTE excitation. A one-zone forward model in which photoionization, O$^+$ recombination, radiative cascade, and radiative trapping populate the excited state reproduces the measured equivalent width and instrumentally broadened line profile. The model favors an atomic component with a projected extent larger than the narrow condensed-dust layer and permits gas-to-dust mass-loss ratios of order a few for representative ionizing irradiation. Stellar O I line-profile variations remain the principal alternative at the present spectral resolution. We therefore identify escaping O I as the preferred physical interpretation while retaining the designation candidate O I. High-resolution, phase-resolved spectroscopy can directly test this interpretation by resolving the individual triplet components.
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Earth and Planetary Astrophysics

Spectral Energy Distribution and Polarimetric Properties of Dust in the Interstellar Comet 3I/ATLAS

Seungwon Choi, Masateru Ishiguro, Hiroyuki Naito et al. (+13 more)

The interstellar comet 3I/ATLAS exhibits unusual polarimetric properties compared with Solar System comets, while constraints on its fundamental physical properties, such as dust albedo and grain-size distribution, remain limited. We obtained new optical polarimetry near opposition with the Pirka Telescope, combined it with previously reported polarimetric measurements, and constructed a visible-to-mid-infrared spectral energy distribution (SED) from HST, VLT, SPHEREx, and JWST observations. The SED indicates that the coma is dominated by dark, absorbing dust, with an effective V-band albedo of $p_{\rm eff}\sim0.04$. Modeling the SED with a power-law grain-size distribution yields a size index of $q=3.0$–$3.3$. The mid-infrared spectral structure is better reproduced by adding a minor amorphous-silicate component. The combined polarimetric data further favor a highly porous scattering structure. Despite its unusual polarimetric behavior, the dust of 3I/ATLAS has an albedo and grain-size distribution within the range found for Solar System comets.
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All authors Seungwon Choi, Masateru Ishiguro, Hiroyuki Naito, Yoonsoo P. Bach, Jooyeon Geem, Bumhoo Lim, Moonkuk Hur, Sihu Ahn, Sunho Jin, Hisayuki Kubota, Seiko Takagi, Tatsuharu Ono, Max Mahlke, Carey Lisse, Tomohiko Sekiguchi, Makoto Watanabe

Solar and Stellar Astrophysics · Cross-listed from nucl-th

Nuclear mass table in deformed relativistic Hartree-Bogoliubov theory in continuum, III: nuclei with $8 \leq Z \leq 120$

DRHBc Mass Table Collaboration: Peng Guo, Xiaojie Cao, Kangmin Chen et al. (+89 more)

The mass table in the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the PC-PK1 density functional has been established for nuclei with $8 \leq Z \leq 120$, extended from the previous works for even-even nuclei [Zhang et al. (DRHBc mass table collaboration), At. Data Nucl. Data Tables 144, 101488 (2022)] and for even-$Z$ nuclei [Guo et al. (DRHBc mass table collaboration), At. Data Nucl. Data Tables 158, 101661 (2024)]. The calculated binding energies, two- and one-nucleon separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, neutron and proton Fermi surfaces, and the blocked neutron (proton) orbitals of odd-$N$ ($Z$) nuclei are tabulated and compared with the available experimental data. A total of 9495 nuclei are predicted to be bound, with an rms deviation of 1.444 MeV from the 2380 mass data. Good agreement with the available experimental pairing gaps, $\alpha$ decay energies, and charge radii is also achieved. The accuracies of the calculated nuclear masses and nucleon separation energies as well as the prediction for drip lines are compared with those obtained by other relativistic and nonrelativistic density functional calculations. It turns out that the DRHBc theory with PC-PK1 provides one of the best microscopic descriptions for nuclear masses. The systematics of nucleon separation energies, pairing gaps, pairing energies, two-nucleon gaps, $\alpha$ decay energies, rms radii, quadrupole deformations, potential energy curves, neutron density distributions, and neutron mean-field potentials are discussed.
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All authors DRHBc Mass Table Collaboration: Peng Guo, Xiaojie Cao, Kangmin Chen, Qibo Chen, Myung-Ki Cheoun, Yongbeom Choi, Wenmin Deng, Jianmin Dong, Pengxiang Du, Xiaokai Du, Kangda Duan, Xiaohua Fan, Wei Gao, Lisheng Geng, Xi Guo, Yixin Guo, Eunja Ha, Xiao-Tao He, Jinniu Hu, Rongyan Hu, Jingke Huang, Kun Huang, Yanan Huang, Zidan Huang, Xiaofei Jiang, Seonghyun Kim, Youngman Kim, Chang-Hwan Lee, Jenny Lee, Jian Li, Minglong Li, Zhipan Li, Zhengzheng Li, Zhanjiang Lian, Haozhao Liang, Boran Liu, Lang Liu, Xiao Lu, Chenjun Lv, Jie Meng, Myeong-Hwan Mun, Yifei Niu, Zhongming Niu, Cong Pan, Panagiota Papakonstantinou, Jing Peng, Xiaoying Qu, Tianshuai Shang, Xinle Shang, Caiwan Shen, Guofang Shen, Ting Sun, Tingting Sun, Wei Sun, Xiang-Xiang Sun, Chen Wang, Peng Wang, Sibo Wang, Yiran Wang, Yuanyuan Wang, Yumeng Wang, Jiawei Wu, Liang Wu, Xinhui Wu, Xuewei Xia, Yingfeng Xu, Yonghe Xue, Jiangming Yao, Yaochen Yang, Guixiang Ye, Lian Ye, To Chung Yiu, Jianghan Yu, Yangyang Yu, Wentao Zeng, Kaiyuan Zhang, Jinzhe, Zhang, Ning Zhang, Shijie Zhang, Shuangquan Zhang, Wei Zhang, Xiaoyan Zhang, Yanxin Zhang, Ying Zhang, Yingxun Zhang, Zhenhua Zhang, Qiang Zhao, Ruyou Zheng, Chang Zhou, Shan-Gui Zhou, Lianjian Zou

Cosmology and Nongalactic Astrophysics

Measuring the Moving Lens Effect with Wide-Separation Lensed Quasars

Yupeng Zhang, Shuxun Tian and Zhengxiang Li

The transverse motion of a gravitational potential induces frequency shifts in photons propagating through it, giving rise to the moving-lens effect and providing a probe of transverse peculiar velocities. Statistical evidence for this effect has recently been reported using cross-correlations between cosmic microwave background temperature maps and large-scale-structure tracers. Here, we investigate a complementary spectroscopic approach based on wide-separation lensed quasars, for which different lensed images probe distinct deflection geometries through a moving foreground lens. We focus on SDSS J1004+4112 and assess the differential redshift that could be measured from its broad emission-line spectra. Using an estimator that combines information across the line profiles, we perform Monte Carlo forecasts for C IV and C III] under an ELT-like configuration, considering photon noise only. For an assumed lens transverse velocity of $500\,{\rm km\,s^{-1}}$ and the orientation maximizing the signal, the expected differential redshift reaches $|\Delta z_{\rm ML}|\simeq6.7\times10^{-7}$. At an integration time of 40 hr, the joint photon-noise-limited precision is $\sigma_z\simeq2.5\times10^{-7}$. C IV dominates the constraint, while C III] provides only a modest additional improvement, and integrations of tens of hours reach the $10^{-7}$ precision regime. These results show that photon statistics alone can reach the characteristic moving-lens signal scale, although practical detectability will depend on controlling astrophysical and instrumental systematics.
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Saturday 3 October

Solar and Stellar Astrophysics

The variable mass-loss in low-mass red giant stars: Chromospheric motion across stellar evolution in 47 Tuc

Ian Baeza, L. Monaco, H. Frelijj et al. (+8 more)

Mass-Loss (ML) is a critical process that remains poorly understood despite its broad implications across astrophysics. Our current knowledge is insufficient to reproduce ML consistently across stars, particularly in cool, low-mass giants, where the time-variable nature of chromospheres (CHR) —the region where most physical phenomena powering ML in this regime are expected to occur— is poorly constrained. We characterize the relevant timescales of CHR variability in red giants and explore correlations with intrinsic stellar properties. We analyze the first large temporal spectroscopic monitoring of CHR variability using the H$\alpha$ line in red giants belonging to the globular cluster NGC 104 (47 Tuc) using FLAMES/GIRAFFE data. We find that H$\alpha$ variations increase on average and span a wider range of values with luminosity, together with a systematic blueshift of the line core indicative of outflows for $\log(L/L_\odot) \gtrsim 2.4$, alongside deeper cores consistent with increased CHR optical depth. The characteristic timescale required to observe variations in the H$\alpha$ profile is approximately one day, showing a flat trend with luminosity. While shorter-timescale variations remain consistent with statistical uncertainties, a possible increase toward dimmer stars is found. These trends appear similarly correlated with luminosity and effective temperature. No further correlation is found with different cluster populations, nor are significant differences observed between AGB and RGB stars. The outflow trends closely match previous observations across a wide metallicity range. We discuss whether these observations reflect changes in H$\alpha$ sensitivity to the winds, a genuine atmospheric transition driven by changes in heating efficiency, or continued CHR expansion with geometrically dominated H$\alpha$ formation.
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All authors Ian Baeza, L. Monaco, H. Frelijj, Y. Momany, L. Sbordone, S. Zaggia, I. Yegorova, I. Saviane, A. Mucciarelli, K. Ohnaka, M. Gómez

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

The pseudospectrum for gravitational perturbations in Kerr spacetimes

Hongsheng Zhang, Zong-Kuan Guo and Rong-Gen Cai

We study the pseudospectrum of the Kerr black hole for gravitational perturbations with spin weight $s=2$, the case of greatest interest in gravitational-wave astronomy. In the hyperboloidal framework with two-dimensional Chebyshev collocation, we formulate the quasinormal mode problem as a non-self-adjoint eigenvalue problem. For $s\neq0$ the fields $\Psi^{(s)}$ and $\Psi^{(-s)}$ are independent, so the conserved current method yields no single-field energy norm. We overcome this with the Teukolsky–Starobinsky identities, which relate $\Psi^{(-2)}$ to a fourth-order operator on $\Psi^{(2)}$ and yield an $H^2$ energy norm after symmetrization. With the $H^1$ norm known for $s=0$, this suggests the pattern $H^{|s|}$, verified for $s=0$ and $s=2$. All results use an $\omega$-independent two-field hierarchy. We find that the pseudospectrum tightens by $1.1$ to $3.5$ decades at each step of $L^2\to H^1\to H^2$, yet stays large in every norm. The $s=+2$ and $s=-2$ operators are isospectral but not isopseudospectral: at twelve of fourteen probes the $\psi_0$ resolvent exceeds the $\psi_4$ one by $0.19$ to $0.82$ decades in the $H^2$ norm, while at the two probes furthest along the QNM line the ordering reverses by $0.18$ to $0.19$ decades. The gravitational pseudospectrum exceeds the scalar one by $0.5$ to $5.2$ decades in the window minimum and by $5.9$ decades in $L^2$ at $\omega M=0.47-0.17\,i$, while along the damping direction the $s=2$ resolvent is non-monotonic and the $s=0$ resolvent smooth. QNM spectral instability is therefore a universal feature of Kerr, and is stronger for gravitational perturbations.
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Solar and Stellar Astrophysics

Deriving the Continuous $\beta$-FPUT Model for Decayless Solar Coronal Oscillations Directly from Resistive MHD

D. Tsiklauri

We present an analytical framework deriving the fluid-continuum $\beta$-Fermi-Pasta-Ulam-Tsingou ($\beta$-FPUT) system directly from a third-order resistive magnetohydrodynamics (MHD) expansion to explain persistent, decayless transverse oscillations observed in solar coronal loops. For a continuous wave field propagating along a longitudinal magnetic field with cross-field density variations, a multi-scale expansion demonstrates that quadratic $\mathcal{O}(2)$ advective and Maxwell tension terms vanish identically due to out-of-plane polarization symmetry. Instead, the quadratic longitudinal ponderomotive force drives field-aligned density modulations that back-react on the primary transverse wave, yielding a cubic $\mathcal{O}(3)$ restoring force. In the long-wavelength limit, the governing equations reduce to a fluid-continuum Modified Korteweg-de Vries (mKdV) system where cross-field profile variation provides the non-linear dispersive mechanism. We prove that this internal fluid mechanism establishes stable, amplitude-dependent frequency self-focusing, which phase-locks adjacent elements and prevents phase-mixing wave attenuation without requiring external steady driving parameterizations. This framework enables macro-scale coronal seismology, providing closed-form expressions to invert observed decayless wave-packet durations to compute the unresolved cross-field density gradient scale length ($L_x$) and the internal volumetric filling factor ($f_V$) without relying on traditional emission measure or spectroscopic line-ratio diagnostics. Much like famous Enrico Fermi's historic use of macro-scale displacements to estimate complex atomic explosion yields, this framework establishes a paradigm where monitoring macroscopic oscillation durations empowers observers to extract fine-scale, otherwise unresolvable waveguide properties.
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Astrophysics of Galaxies

Power-law Coupling and Mock Validation of a Surface-density Anisotropy Diagnostic for 85 Rich Galaxy Clusters

Sardor Sharipbayevich Kutlimuratov and Ikram Uralbayevich Tadjibayev

We assess a surface-density anisotropy diagnostic, $A_{\rm ani}$, and its association with the slope $\alpha$ of a power-law galaxy profile. We reprocess 20-annulus profiles of 85 optically rich clusters on a canonical grid, $0 \leq A_{\rm ani} \leq 1.92$, and an extended grid reaching 1.99. Twenty-four canonical fits and 12 extended fits reach their respective upper boundaries; 69 of 85 upper $\Delta\chi^2=1$ bounds remain open, and only four clusters have two-sided intervals. Among 40 preselected power-law fits, the observed $\alpha$-$A_{\rm ani}$ Spearman coefficient is 0.616. In a model-native forward-recovery experiment with 11 injected values, all 935 noiseless profiles recover the input within 0.02. Across 46,750 Poisson catalogs matched to observed count and background conditions, recovery instead has root-mean-square error (RMSE) 0.992 and Spearman $\rho=0.093$; 40.0% of fits reach the canonical upper boundary and 81.4% have an open upper interval. Fixing both background and radial scale improves RMSE to 0.564 in a 9,350-catalog sensitivity test. As a separate structural control, 4,250 Poisson catalogs generated from fitted power laws reproduce the observed slope association: the median mock coefficient for the 40-cluster subset is 0.608 (95% range 0.453-0.731). Thus the diagnostic is numerically recoverable under its defining model without noise, but the available photometry does not reliably identify it for individual clusters. The power-law correlation can arise from shared projected profile shape and is not independent evidence for orbital anisotropy.
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Solar and Stellar Astrophysics · Cross-listed from nucl-th

Radii and Scaling Relations of Dark-Matter-Admixed Neutron Stars

Zhi-yao Li, Wei-zhou Jiang and Dian Sun

The radius of a neutron star is closely related to the equation of state (EOS) of asymmetric nuclear matter, particularly to the nuclear symmetry energy. At fixed stellar mass, the neutron-star radius and the nuclear-matter pressure near saturation density approximately satisfy a pressure–radius (R-P) scaling relation, linking stellar geometry to strong-interaction matter. In the presence of dark matter (DM), changes in the stellar geometry can modify this relation. We investigate how GeV- and sub-GeV-scale DM affects the R-P relation in DM-admixed neutron stars (DANSs) within a gravity-only two-fluid framework. We extend the Buchdahl analytic solution to a two-fluid configuration to demonstrate this scaling and then use 21 nuclear EOSs to fit the relation $R_{\rm NM}=\bar C P_{\rm NM}^{\eta}$ for $1M_\odot$ and $1.4M_\odot$ DANSs. The exponent $\eta$ and coefficient $\bar C$ jointly quantify the DM-induced modification and depend on the DM particle mass, stellar DM content, and self-interaction strength. For bosonic DM, changes in $\eta$ and $\bar C$ occur mainly in the sub-GeV range, whereas significant fermionic-DM effects persist up to about 1.5 GeV. Increasing the DM content or strengthening a repulsive self-interaction generally increases $\eta$ and decreases $\bar C$. The modified R-P relation therefore encodes information about the DM particle mass, abundance, and self-interaction, and affect the extraction of the nuclear EOS from celestial observations. At DM masses of several hundred MeV, both fermionic and bosonic DM can also produce DM-dominated low-mass ($1M_\odot$) DANSs with large radial extensions, for which the conventional scaling relation ceases to apply.
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High Energy Astrophysical Phenomena

Jets with Streaks: the Global Dynamics and Structure of Striped Poynting flux dominated Jets

Ho-Sang Chan, Anna Chashkina, Omer Bromberg et al. (+2 more)

Striped jets, characterized by magnetically dominated regions with alternating polarity, can enable fast magnetic energy dissipation in global current sheets formed in between the stripes, and are thus considered as a viable source for the high-energy emission observed in blazars and gamma-ray burst prompt emission. We perform the first global axisymmetric GRMHD simulations that follow the evolution of striped jets from their launching, by accretion of poloidal magnetic loops with alternating polarity onto a spinning black-hole, to their energy dissipation at large distances. The accretion of each loop launches a Poynting-flux-dominated mini-jet carrying a helical magnetic field whose polarity is inherited from the loop, and the collection of which forms the jet core. The relativistic core is surrounded by a non-relativistic sheath composed of returning fieldlines from previously launched mini-jets in a nested configuration. Efficient mini-jet launching requires poloidal loops in the accretion disk to form close to the black hole ($r \lesssim 50\,r_g$); otherwise, they lose coherency due to turbulence. Once launched, the mini-jets accelerate electromagnetically, similar to steady-state jets, with the Lorentz factor increasing linearly with the jet cross-sectional radius as long as lateral causal contact with the jet axis is maintained. Current sheets form when two trailing mini-jets carrying oppositely directed magnetic fields come into contact. Early sheet formation is facilitated by the longitudinal expansion of the mini-jets, driven by internal pressure before the flow becomes super-fast-magnetosonic. We measure an energy dissipation rate of a few tens of percent of the jet Poynting power in the observer frame, within our simulation box of $10^4\,r_g$. Our results can account for the bright superluminal features observed in BL Lac type blazars.
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All authors Ho-Sang Chan, Anna Chashkina, Omer Bromberg, Gregory R. Werner, Hayk Hakobyan

Astrophysics of Galaxies

Diffuse Galactic Backgrounds with SPHEREx: A Pilot Study of Background Modeling and Its Impact on Extinction

Wanggi Lim, Jae Hwan Kang, Keunho J. Kim et al. (+1 more)

We present a spectral analysis of diffuse Galactic background emission using SPHEREx data in a pilot Galactic-plane field, where uncertainty in the estimation of the diffuse infrared background is a major source of systematic uncertainty in extinction studies at near- and mid-infrared wavelengths. We construct channel-resolved background maps across the 0.75–5~$\mu$m range using a Large Median Filter approach and then carry the extinction analysis forward only for the cleaner long-wavelength subset at $\lambda \geq 3~\mu$m. In the present field, comparison against an earlier masked-median background model gives a median channel-by-channel background difference of about 6% and a maximum change of $|\Delta\tau_{\rm norm}|\simeq 7.4$ near 3.205~$\mu$m, underscoring the importance of wavelength-dependent background modeling. These results demonstrate that spectral mapping with SPHEREx provides a practical framework for controlling diffuse background systematics and enables improved constraints on dust opacity and extinction in the Galactic plane.
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All authors Wanggi Lim, Jae Hwan Kang, Keunho J. Kim, Young-Jun Kim

Instrumentation and Methods for Astrophysics

The LOFAR Decametre Sky Survey (LoDeSS) I. Survey description and first data release

C.M. Cordun, C. Groeneveld, H. W. Edler et al. (+12 more)

The decametre radio sky ($\sim 10$-$30$ MHz) remains largely unexplored due to strong ionospheric distortions and severe radio-frequency interference. Despite its scientific potential, including access to steep-spectrum synchrotron emission from aged electron populations and coherent radio emission from planetary and stellar magnetospheres, sub-arcminute imaging at these frequencies has only recently become feasible with instruments such as the Low Frequency Array (LOFAR). In this work, we present the first data release (DR1) of the LOFAR decametre Sky Survey (LoDeSS), which maps the northern sky above a declination of $20^\circ$ between 15 and 30 MHz. LoDeSS reaches an angular resolution of $\sim45^{\prime\prime}$ and typical noise levels of $\sim11.5$ mJy beam$^{-1}$ at a central frequency of 23 MHz. Observations were obtained with the LOFAR Low Band Antenna (LBA) system using a multi-beam strategy, with typical integration times of $\sim5$ h per pointing. They were carried out at night to reduce the impact of ionospherically reflected radio-frequency interference. Data quality varies across fields as a result of the ionospheric conditions and the fraction of data flagged due to radio-frequency interference. This first release covers $\sim15\%$ of the full survey area and consists of fields originally selected around exoplanet candidates for radio auroral emission. The products released to the community include primary-beam-corrected images in Stokes I and V, and a source catalogue for fields with reliable flux density scales. This release demonstrates that LOFAR enables sensitive, wide-field imaging in the decametre regime with unprecedented resolution, opening new opportunities for studies of pulsars, exoplanetary systems, galaxy clusters, and other low-frequency phenomena.
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All authors C.M. Cordun, C. Groeneveld, H. W. Edler, H. K. Vedantham, F. de Gasperin, R. J. van Weeren, J. R. Callingham, E. Osinga, F. F. S. van der Tak, M. J. Hardcastle, M. Brüggen, A. Botteon, H. Röttgering, T. W. Shimwell, M. Iacobelli

Solar and Stellar Astrophysics

Measured energy exchange in coronal hole solar wind from its solar origins to the heliosphere

Yeimy J. Rivera, Alin R. Paraschiv, Samuel T. Badman et al. (+33 more)

Coordinated ground- and space-based remote observations are used to provide a comprehensive, multi-perspective view of the solar atmosphere that we connect with in situ measurements in the heliosphere centered around the April 8 2024 Total Solar Eclipse observed across North America. These near-contemporaneous, multi-wavelength datasets are used to directly derive the plasma parameters and compute an energy budget of a solar wind stream at its low-coronal birthplace (at an altitude of 1.05Rsun). The energy budget is also independently computed at and beyond the Alfvén surface from the in situ observations of the same stream. The total wave energy flux dominates the low-coronal budget (11 W m-2 Alfvén, 7 to 23 W m-2 in compressive MHD modes), while enthalpy (13 W m-2) and work done against gravity from 1.0Rsun (2.5 W m-2) make up the remainder. The total coronal energy budget is consistent with the total measured in situ by Parker Solar Probe if and only if compressive energy flux is included and attributed to the fast magnetosonic mode. Nearly all this thermal and wave energy is converted to ion heating, acceleration and gravitational potential energy within the Alfvén surface. The stream evolution is well-described as a thermal-pressure driven wind with additional energy deposited by MHD fluctuations. The observed evolution of the Alfvénic component of these fluctuations follows a near-dissipation-free curve below the Alfvén surface while deviating from it more strongly above this critical surface.
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All authors Yeimy J. Rivera, Alin R. Paraschiv, Samuel T. Badman, Alberto M. Vasquez, Federico A. Nuevo, Ryan J. French, Momchil Molnar, Roberto Susino, Zihao Yang, Marco Romoli, Richard A. Frazin, Michael L. Stevens, Stuart D. Bale, Deborah Baker, Jasper Halekas, Thomas A. Schad, Christopher J. Owen, Philippe Louarn, Jenna Samra, Giuliana de Toma, Daniela A. Lacatus, Giulio Del Zanna, Chad A. Madsen, Enrico Landi, Manolis K. Georgoulis, Amir Caspi, Éric Buchlin, Nour E. Raouafi, Luca Franci, Miho Janvier, Cooper Downs, Roberto Livi, Phyllis Whittlesey, Ali Rahmati, Davin Larson, Nikos Sioulas