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Physics Astrophysics

astro-ph Watch Astrophysics

Sunday 16 November

Astrophysics of Galaxies

Made-to-Measure Outperforms Schwarzschild's Method

Richard J. Long

Syer and Tremaine's made-to-measure method and Schwarzschild's orbit superposition method are well-known within the field of stellar dynamical modeling. This research is concerned with assessing and comparing the operational capabilities of the two methods and, in particular, the impact on observable reproduction, orbit classifications and computer elapsed times when using low orbit numbers (8000 orbits) with different observational data sets and initial conditions. Both methods are able to reproduce observed data with mean $\chi^2 \approx 1$ or less. However, the made-to-measure process does so three to five times faster than the orbit superposition method, and this starts to make the made-to-measure process attractive for analyzing galaxy surveys. For a given set of initial conditions, both methods produce similar orbit classifications but the orbits behind the classifications are not the same. Orbits which are common do not have the same weights. Different initial conditions result in different classifications.
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Astrophysics of Galaxies

Examining Turbulence in Galactic Molecular Clouds. II. Turbulence Cascade Beyond the Scale of Giant Molecular Clouds

Yuehui Ma, Miaomiao Zhang, Hongchi Wang et al. (+5 more)

We use $^{12}$CO (J=1–0) data from the MWISP survey to investigate turbulence in a $\sim$kpc-scale segment of the Local Arm. By slicing the position-position-velocity cube into narrow layers that follow the Galactic-rotation trend in the $L$-$V$ diagram, we find that the structure functions (SFs) and spatial power spectra (SPS) of the $^{12}$CO (J=1–0) line velocity and intensity exhibit consistent scaling behaviors across all layers, demonstrating that the molecular gas forms a single, coherent turbulent field with energy cascading from $\sim 200$~pc down to parsec scales. The SPS power-law slopes of both the intensity and velocity fields approach the values expected from turbulence models. Cloud-to-cloud velocity SFs based on the molecular clouds located in the region follow the same extended self-similarity scaling (ESS) as the pixel-based statistics, indicating that inter-cloud motions are part of the same large-scale turbulent cascade. Together, these results provide direct observational evidence that molecular clouds are not dynamically isolated entities but are embedded within a larger-scale turbulent flow that links galactic dynamics to star formation on cloud scales.
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All authors Yuehui Ma, Miaomiao Zhang, Hongchi Wang, Xuepeng Chen, Zhenyi Yue, Suziye He, Xiangyu Ou, Li Sun

Saturday 15 November

Instrumentation and Methods for Astrophysics

The X-$\gamma$ detector onboard the POEMMA-Balloon with Radio payload

Matteo Battisti

The POEMMA-Balloon with Radio (PBR) is a NASA mission designed to study Ultra-High-Energy Cosmic Rays and Very-High-Energy Neutrinos from a balloon platform. Serving as a precursor to the planned POEMMA satellite mission, PBR will be launched aboard a NASA Super Pressure Balloon for a flight at of 33 km altitude in Spring 2027 from Wanaka, New Zealand. The unique conditions of low pressure and high altitude will enable in-situ observations of High-Altitude Horizontal Air Showers (HAHAs), a poorly understood class of nearly horizontal Extensive Air Showers induced by cosmic rays skimming the Earth's atmosphere without reaching the ground. Due to the lower atmospheric grammage at these altitudes, HAHAs develop more gradually compared to typical downward-going EASs, with interaction lengths on the order of 100 km. This slow development allows balloon-borne instruments to probe the early stages of cosmic ray shower evolution. At these early stages, high-energy electrons and positrons from the electromagnetic component of the shower can generate X-rays and gamma rays via synchrotron radiation. The X-$\gamma$ detector onboard PBR is designed to measure these photons across a broad energy range. The instrument consists of four sub-detectors, each optimized for different overlapping energy bandfrom tens of keV to MeV. The current design utilizes CsI(Tl)/NaI(Tl) scintillating crystals coupled with SiPMs for photon detection. To suppress background noise, the detectors are enclosed within an anti-coincidence system to reject charged particle events. The X-$\gamma$ detector is aligned with PBR's primary instruments, the Fluorescence Camera and the Cherenkov Camera, within a 30$^\circ$ field of view, overlapping with both imaging cameras. It will operate in a triggered mode, with the possibility to receive signals from the other instruments to check for simultaneous events.
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High Energy Astrophysical Phenomena

Characterization of type Ibn SNe

D. Farias, C. Gall, V. A. Villar et al. (+29 more)

Type Ibn supernovae (SNe) are characterized by narrow helium (He I) lines from photons produced by the unshocked circumstellar material (CSM). About 80 SNe Ibn have been discovered to date, and only a handful have extensive observational records. Thus, many open questions regarding the progenitor system and the origin of the CSM remain. Here we investigate potential correlations between the spectral features of the prominent He I $\lambda$5876 line and the optical and X-ray light curve properties of SNe Ibn. We compile the largest sample of 61 SNe Ibn to date, of which 24 SNe have photometric and spectroscopic data from the Young Supernova Experiment and 37 SNe have archival data sets. We fit 24 SNe Ibn with sufficient photometric coverage ($B$ to $z$ bands) using semi-analytical models from MOSFiT. We demonstrate that the light curves of SNe Ibn are more diverse than previous analyses suggest, with absolute $r$-band peak magnitudes of $-19.4\pm0.6$~mag and rise (from $-10$ days to peak) and decay-rates (from peak to +10 days) of $-0.08\pm0.06$ and $0.08\pm0.03$ mag/day, respectively. We find that the majority of SNe Ibn in the sub-sample are consistent with a low-energy explosion ($<10^{51}$ erg) of a star with a compact envelope surrounded by $\sim$0.1 M$_{\odot}$ of helium-rich CSM. The inferred ejecta masses are small ($\sim 1$ M$_{\odot}$) and expand with a velocity of $\sim$5000 km/s. Our spectroscopic analysis shows that the mean velocity of the narrow component of the He I lines, associated to the CSM, peaks at $\sim1100$ km/s. The mean CSM and ejecta masses inferred for a sub-sample of SNe Ibn indicate that their progenitors are not massive ($\sim10$ M$_{\odot}$), single stars at the moment of explosion, but are likely binary systems. This agrees with the detection of potential companion stars of SNe Ibn progenitors, and the inferred CSM properties from stellar evolution models.
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All authors D. Farias, C. Gall, V. A. Villar, K. Auchettl, K. M. de Soto, A. Gagliano, W. B. Hoogendam, G. Narayan, A. Sedgewick, S. K. Yadavalli, Y. Zenati, C. R. Angus, K. W. Davis, J. Hjorth, W. V. Jacobson-Galán, D. O. Jones, C. D. Kilpatrick, M. J. Bustamante Rosell, D. A. Coulter, G. Dimitriadis, R. J. Foley, A. Gangopadhyay, H. Gao, M. E. Huber, L. Izzo, J. L. Johnson, A. L. Piro, A. Rest, C. Rojas-Bravo, M. R. Siebert, K. Taggart, S. Tinyanont

Instrumentation and Methods for Astrophysics

QuaRT: A toolkit for the exploration of quantum methods for radiation transport

Rasmit Devkota and John H. Wise

QuaRT is a Python library for quantum simulation of radiative transfer in astrophysical and cosmological problems. It features a novel angular redistribution methodology for lattice Boltzmann methods which improves the isotropy of simulations of objects such as stars in non-scattering media.
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Instrumentation and Methods for Astrophysics

AstroMLab 5: Structured Summaries and Concept Extraction for 400,000 Astrophysics Papers

Yuan-Sen Ting, Alberto Accomazzi, Tirthankar Ghosal et al. (+4 more)

We present a dataset of 408,590 astrophysics papers from arXiv (astro-ph), spanning 1992 through July 2025. Each paper has been processed through a multi-stage pipeline to produce: (1) structured summaries organized into six semantic sections (Background, Motivation, Methodology, Results, Interpretation, Implication), and (2) concept extraction yielding 9,999 unique concepts with detailed descriptions. The dataset contains 3.8 million paper-concept associations and includes semantic embeddings for all concepts. Comparison with traditional ADS keywords reveals that the concepts provide denser coverage and more uniform distribution, while analysis of embedding space structure demonstrates that concepts are semantically dispersed within papers-enabling discovery through multiple diverse entry points. Concept vocabulary and embeddings are publicly released at https://github.com/tingyuansen/astro-ph_knowledge_graph.
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All authors Yuan-Sen Ting, Alberto Accomazzi, Tirthankar Ghosal, Tuan Dung Nguyen, Rui Pan, Zechang Sun, Tijmen de Haan

Cosmology and Nongalactic Astrophysics

Clustering effects on the Dark Siren determination of $H_0$: A simulation study

Marios Kalomenopoulos, Riccardo Barbieri, Sadegh Khochfar et al. (+2 more)

We investigate the cosmological power of gravitational wave (GWs) events without electromagnetic counterparts using high-resolution, cosmological simulations that include realistic clustering. We assume a near-future detector network (LVK + LIGO India in O5), with sky localisation and distance uncertainty capabilities for binary black holes, of the order of $60$ deg. squared and $10\%$ respectively, and with a range of about $1600$ Mpc/h. We find that clustering leads to increased convergence of the $H_0$ posteriors, with clear recovery of the input value as early as $N_{\rm gw}=40$ events (a very conservative estimate for O5, which expects thousands of BBHs/year). In contrast, even with $N_{\rm gw}=100$ events in uniform catalogues, the posterior remains largely unconstrained. Additionally, we quantify the role of catalogue completeness and show that levels as low as $f=25\%$ can be competitive with fully complete catalogues, confirming the impact of clustering. Completeness levels of $f=50\%$ perform statistically similar to complete catalogues with as few as $N_{\rm gw}=40$ events. We conclude that improving GWs detection capabilities yields better results than more complete galaxy catalogues.Finally, we find that 1) physical weights do not provide significant additional constraining power on top of clustering, 2) luminosity distance errors contribute more for small cone openings, 3) the $H_0$ prior range does not introduce any biases in the $H_0$ posterior, 4) closer events ($\lesssim 100$ Mpc/h) yield about two times better precision than more distant events ($\lesssim 1600$ Mpc/h), and 5) our method is robust to different modelling choices.
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All authors Marios Kalomenopoulos, Riccardo Barbieri, Sadegh Khochfar, Jonathan Gair, Robert J. McGibbon

Solar and Stellar Astrophysics

Pre-Supernova Multiple Giant Eruptions in Massive Stars

Bhawna Mukhija and Amit Kashi

Massive stars can exhibit giant eruptions with high mass loss shortly before their explosion as a core-collapse Supernova. These multiple giant eruptions (MGEs) may have a commutative effect that brings the star to a different state, possible one that favors the explosion. To address this problem, we evolve a 100 solar mass star and initiate a series of three giant eruptions lasting one year each, testing different mass loss rates and different metallicities. Following each eruption, we track the recovery phase to examine the post-eruption behavior of the star and its recovery timescale. The MGEs lead to a decrease in luminosity, accompanied by a slight increase in temperature. Later, during the recovery phases as the star starts to retain its equilibrium state, its luminosity increases. The recovery time-scale varies significantly after each eruption for independent on the mass loss rate, but it is shorter for lower metallicities. For the higher mass-loss rates during the recovery phase, the outer layers of the star exhibit oscillations and undergo compression at higher metallicity. These oscillations are most likely a consequence of thermal imbalance in the outer envelope. This behavior at higher mass-loss rates also suggests that the thermal readjustments during recovery may create favorable conditions for a subsequent eruption of the star.
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Instrumentation and Methods for Astrophysics

Implications of Mini-EUSO measurements for a space-based observation of UHECRs

Mario Bertaina, Matteo Battisti and JEM-EUSO collaboration

Mini–EUSO (Multiwavelength Imaging New Instrument for the Extreme Universe Space Observatory, known as UV atmosphere in the Russian Space Program) is the first mission of the JEM-EUSO program on board the International Space Station. It was launched in August 2019 and it is operating since October 2019 being located in the Russian section (Zvezda module) of the station and viewing our planet from a nadir-facing UV-transparent window. The instrument is based on the concept of the original JEM-EUSO mission and consists of an optical system employing two Fresnel lenses of 25 cm each and a focal surface composed of 36 Multi-Anode Photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity and an overall field of view of 44$^\circ \times $44$^\circ$. Mini-EUSO can map the night-time Earth in the near UV range (predominantly between 290 nm and 430 nm), with a spatial resolution of about 6~km and different temporal resolutions of 2.5~$\mu$s, 320~$\mu$s and 41 ms. Mini-EUSO observations are extremely important to better assess the potential of a space-based detector in studying Ultra-High Energy Cosmic Rays (UHECRs) such as K-EUSO and POEMMA. In this contribution we focus the attention on the results of the UV measurements and we place them in the context of UHECR observations from space, namely the estimation of exposure for the planned M-EUSO (Multi-messenger Extreme Universe Space Observatory) mission.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Quintessence: Quadratic potentials

Artur Alho and Claes Uggla

Arguably one can use a canonical scalar field $\varphi$, minimally coupled to gravity, with quadratic potentials $V = \Lambda \pm \frac12 m^2\varphi^2$ to explore some general features of slow-roll and hilltop thawing quintessence, respectively. For each of these two potentials, and pressure-free matter, we introduce a regular unconstrained dynamical system on a compact state space, where the formulation for the hilltop case is new. Together with a derivation of monotonic functions in the two global state space settings, this enables us to obtain global results and to introduce figures that illustrate the global solution spaces of these models, in which we situate the observationally viable quintessence solutions.
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Astrophysics of Galaxies

Metallicity Effects on Machine Learning Classification of Dusty Stellar Sources in the Magellanic Clouds

Sepideh Ghaziasgar, Mahdi Abdollahi, Atefeh Javadi et al. (+4 more)

Differences in metallicity between the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) offer an opportunity to examine whether environmental metallicity affects the performance of machine learning models in classifying dusty stellar sources. The five stellar classes studied include young stellar objects (YSOs), red supergiants (RSGs), post-asymptotic giant branch stars (PAGBs), and oxygen- and carbon-rich asymptotic giant branch stars (OAGBs and CAGBs), which are key phases of stellar evolution involved in dust production. Using spectroscopically labeled data from the Surveying the Agents of Galaxy Evolution (SAGE) project, we trained and evaluated a probabilistic random forest (PRF) classifier with four approaches: (1) separate training on LMC and SMC, including all five classes, (2) excluding the underpopulated PAGB class, (3) combined LMC and SMC datasets, and (4) cross-galaxy training and testing. The model achieved 93% accuracy on the SMC and 88% on the LMC across all five classes. In the SMC, PAGB sources were misclassified as YSOs, mainly because of their small sample size (4 objects). When PAGB was excluded, both the LMC and the SMC reached 92% accuracy. A combined dataset produced the same accuracy, and cross-galaxy training yielded similar results, indicating that metallicity does not significantly impact model performance. A comparison of absolute CMDs for the LMC and SMC confirms their similarity in stellar populations. These findings suggest that environmental metallicity has little effect on ML-based classification of dusty stellar sources, supporting the use of combined datasets and cross-galaxy models in low-metallicity environments.
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All authors Sepideh Ghaziasgar, Mahdi Abdollahi, Atefeh Javadi, Jacco Th. van Loon, Iain McDonald, Joana Oliveira, Habib G. Khosroshahi

Instrumentation and Methods for Astrophysics

High-impact Scientific Software in Astronomy and its creators

Johannes Buchner

In the last decades, scientific software has graduated from a hidden side-product to a first-class member of the astrophysics literature. We aim to quantify the activity and impact of software development for astronomy, using a systematic survey. Starting from the Astrophysics Source Code Library and the Journal of Open Source Software, we analyse 3432 public git-based scientific software packages. Paper abstract text analysis suggests seven dominant themes: cosmology, data reduction pipelines, exoplanets, hydrodynamic simulations, radiative transfer spectra simulation, statistical inference and galaxies. We present key individual software contributors, their affiliated institutes and countries of high-impact software in astronomy & astrophysics. We consider the number of citations to papers using the software and the number of person-days from their git repositories, as proxies for impact and complexity, respectively. We find that half of the mapped development is through US-affiliated institutes, and a large number of high-impact projects are led by a single person. Our results indicate that there are currently over 200 people active on any given day to improve software in astronomy.
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Solar and Stellar Astrophysics

Doppler imaging combined with high-cadence photometry. I. Revisiting the surface of a pre-main-sequence flare star

Sanghee Lee, Engin Bahar, Hakan Volkan Şenavc{\i} et al. (+11 more)

Latitude distribution of stellar magnetic activity is not well constrained by observations, despite its importance for a better understanding of stellar dynamos. We aim to obtain an accurate reconstruction of the surface spot distribution on the young, rapidly rotating K2 star PW And by combining spectroscopic and photometric diagnostics. In particular, we seek to assess how the inclusion of continuous high-precision TESS photometry in parallel with high-resolution spectroscopy improves latitude recovery of starspots, especially at low latitudes and in the southern hemisphere, which are poorly constrained by Doppler imaging (DI) alone. We explore the spatial origins of the observed white-light flares. We performed simultaneous Doppler imaging and light curve inversion (DI+LCI) using contemporaneous high-resolution GAOES-RV spectra from the 3.8 m Seimei telescope (R~65000) and high-precision TESS light curves. Surface reconstructions employ the SpotDIPy code to model both line profiles and continuum brightness variations. We compare DI+LCI maps with DI-only solutions, conduct artificial-spot simulations to evaluate the effects of latitude, phase coverage, and S/N on reconstruction reliability. We also investigate the spatial correlation between the DI+LCI reconstructed map and flares detected in the TESS data. The DI+LCI reconstruction reveals significant spot features at mid-to-low latitudes, equatorial regions, and even in the southern hemisphere. Simulations show that DI+LCI provides more accurate reconstructions than DI-only, especially under conditions of incomplete phase coverage and low S/N, by better recovering both spot latitudes and filling factors. A comparison between the DI+LCI map and the TESS flare timings also suggests potential association between flare occurrence and reconstructed spot longitudes.
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All authors Sanghee Lee, Engin Bahar, Hakan Volkan Şenavc{\i}, Emre Iş{\i}k, Kai Ikuta, Kosuke Namekata, Haruhi Nagata, Kiyoe Kawauchi, Masashi Omiya, Hideyuki Izumiura, Akito Tajitsu, Bun'ei Sato, Satoshi Honda, Daisaku Nogami

Astrophysics of Galaxies

Chemically primitive dwarf accretion reignites the inner disk assembly of Malin 1

Manish Kataria and Kanak Saha

We present a detailed kinematic and stellar population analysis of the inner disk of Malin 1, a giant low surface brightness (GLSB) galaxy with a prominent SB0-type central morphology. AstroSat far-UV imaging reveals clumpy emission features indicating recent star formation. Using MUSE integral field spectroscopy, we identify four star-forming complexes (SFCs) within the inner 10 kpc, each associated with localized ionized gas emission in distinct H$\alpha$ velocity channels. Two of the SFCs, including a far-UV clump, appear on the blue-shifted side ($V_{H\alpha}=-230~\mathrm{kms^{-1}}$), while the other two are redshifted. The far-UV clump shows a strong velocity offset ($\sim150~\mathrm{kms^{-1}}$) and high gas dispersion ($\sim250~\mathrm{kms^{-1}}$), indicating that it is kinematically decoupled from the rotating disk. The spatial and velocity isolation of these features in the channel map confirms they do not follow regular disk rotation. The far-UV clump hosts young (250-500 Myr), extremely metal-poor ([M/H]$\simeq$ -1.69) and $\alpha$-enriched ($[\alpha/Fe] \sim 0.5$) stellar populations, sharply contrasting with the surrounding super-solar gas-phase metallicity. The young stellar populations in each SFC are chemically distinct (similar to the far-UV clump) from the enriched central ISM, indicating rapid, local star formation from primitive gas before efficient mixing with the enriched ISM. Their spatial and velocity segregation, age synchronicity, and chemical homogeneity suggest an origin of gas delivered by a disrupted, gas-rich dwarf on a high-inclination (off-plane) orbit. These results suggest that the central HSB within $\rm \sim 9^{\prime\prime} (14\ kpc)$ radius component of Malin 1 has grown through discrete, externally driven accretion, contributing to its complex, hybrid disk morphology.
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Astrophysics of Galaxies

3D extinction maps of the Milky Way disc from Gaia GSP-Spec parameters

M. Barbillon, A. Recio-Blanco, P. de Laverny et al. (+1 more)

3D maps of interstellar dust are crucial for understanding the structure of the Milky Way interstellar medium to apply correction to astrophysical observations affected by dust. We aim at providing new extinction estimates in the Gaia BP/RP bands to study the dust distribution in the disc, to provide new views of the spatial distribution of extinction and to compare it with tracers of the Galactic spiral arms. We use a highly homogeneous method based on the spectral chemo-physical parametrisation of stars from Gaia General Stellar Parametriser-Spectroscopy (GSP-Spec). This catalogue of 5.6 million stars in DR3, presents the advantage of estimating the stellar atmospheric parameters independently of extinction. The extinction is calculated by comparing the observed stellar (BP-RP) colours in the Gaia bands with the theoretical ones assuming a theoretical Teff-log(g)-[M/H] relation, from the GSP-Spec parameters. Publicly available, 3D high-resolution maps around the Sun are produced through the computation of differential extinction by discretising the dataset into spherical coordinates. Our large scale map covers a region of 4x4x0.8 kpc centred on the Sun with a discretisation of (dr,d{\theta},d{\phi})=(40pc,1{\deg},1{\deg}). To exploit the higher number of stars in the Sun proximity, we created a smaller scale map focused on the Local Bubble area, with a volume of 1x1x0.8 kpc and a finer discretisation of (dr,d{\theta},d{\phi})=(30pc,1{\deg},1{\deg}). The produced extinction maps exhibit a strong spatial correlation with molecular clouds and the spiral arms. Interestingly, several regions of the map are consistently present in different tracers as density of gas, of young stars and the chemical pattern of the spiral arms. Our study unveils the link between the distribution of dust, gas, and stars governing the chemical and dynamical evolution of the spiral arms in the Galactic framework.
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All authors M. Barbillon, A. Recio-Blanco, P. de Laverny, P.A. Palicio

Instrumentation and Methods for Astrophysics · Cross-listed from math.HO

The Engineering and Programming Methods Used in Manufacture of Astrolabes and Errors Resulting

Duaa Abdullah

In this study, we first reviewed the traditional astrolabe design methods and identified potential sources of manufacturing error. We then proposed an analytical approach using computer assistance to develop designs for the astrolabe components. This approach marks a pioneering step toward designing and producing a physical astrolabe model aided by computer technology. Our goal was to revive this significant heritage instrument while leveraging modern techniques and software to produce astrolabe models free from traditional manufacturing inaccuracies.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Spin precession effects in the phasing formula of eccentric compact binary inspirals up to the second post-Newtonian order

Soham Bhattacharyya and Omkar Sridhar

Compact binary systems emitting gravitational waves (GWs) can exhibit orbital eccentricity, along with generic spin orientations, leading to the precession of the orbital angular momentum, individual spins, and the orbital plane. While eccentric binaries with aligned spins are well studied, closed form post Newtonian (PN) expressions that simultaneously include eccentricity and precessing spin effects have remained unavailable. Eccentricity complicates orbital evolution because solving the coupled differential equations typically requires numerical integration, which slows down the generation of waveforms. We exploit the separation of timescales between orbital motion, spin precession, and radiation reaction, applying the precession averaging method of Morras et al. (2025) to remove explicit time dependence from the spin orbit and spin spin dynamics through the second PN order. Using this framework, we derive analytic phasing formulae from the evolution equations for orbital frequency and eccentricity, treating eccentricity as a small parameter. Closed form solutions for the eccentricity evolution and GW phase are obtained up to eighth order in the initial eccentricity. We also generalize the TaylorT2 approximant to include spin precession effects and compute the orbital phase in both time and frequency domains. To improve accuracy for moderate to high initial eccentricities, we perform a resummation of the TaylorT2 phasing. These results offer efficient, closed form phasing expressions that capture the coupled dynamics of eccentricity and precession, enabling more accurate and computationally tractable GW waveform modeling for data analysis.
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Astrophysics of Galaxies

Dual core system candidates: a sample of objects with large velocity offset between absorption and narrow emission lines

Zheng Qi, Zhang Xueguang and Yuan Qirong

We present a sample of 28 objects at z<0.3 from Data Release 16 of the Sloan Digital Sky Survey (SDSS DR16) with large velocity offset (> 200 km/s) of narrow H$\beta$ and H$\alpha$ emission lines relative to absorption lines. Diagnostic classification via the Baldwin-Phillips-Terlevich diagram indicates that the sample comprises 12 AGNs, 12 composite galaxies, 3 Hii galaxies, and 1 object of uncertain classification. A strong correlation is found between stellar mass and velocity dispersion. We examine the asymmetries of the narrow H$\beta$ and find that the correlation between velocity offset and narrow H$\beta$ skewness is negligible in both blue-shifted and red-shifted systems, suggesting that the rotating disk model may not fully explain the observed kinematics. The sample exhibits an asymmetric velocity offset distribution, with more red-shifted (17) than blue-shifted (11) objects. No significant correlation is observed between velocity offset and line width in blue-shifted systems, while red-shifted systems show a weak anti-correlation for narrow H$\alpha$, which is inconsistent with the outflow model. The similarity in velocity offset between narrow emission lines supports the dual core system. Furthermore, the SDSS photometric images reveal eight objects with two cores and two with merger features. Based on the narrow emission line properties, the objects in our sample represent strong candidates for dual core systems exhibiting velocity offset. Extending this property to higher-redshift populations in the near future may facilitate the identification of merging supermassive black hole pairs at earlier cosmic epochs, providing critical constraints on their formation and evolution.
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Cosmology and Nongalactic Astrophysics

Gravitational wave standard sirens from GWTC-3 combined with DESI DR2 and DESY5: A late-universe probe of the Hubble constant and dark energy

Ji-Yu Song, Guo-Hong Du, Tian-Nuo Li et al. (+4 more)

Recently, the combination of the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) baryon acoustic oscillation (BAO) data and the Planck cosmic microwave background (CMB) measurements has shown a $\sim$3$\sigma$ preference for a dynamical dark energy model with a phantom-crossing behavior. However, such a phantom-crossing dark energy evolution further exacerbates the already severe Hubble tension in the $\Lambda$CDM model. Moreover, there exists a $\sim2\sigma$ tension between the DESI DR2 BAO and CMB datasets. Therefore, it is essential to measure the Hubble constant and dark-energy equation-of-state (EoS) parameters using only late-universe observations. In this work, we investigate a novel late-universe data combination: gravitational-wave (GW) standard sirens, BAO, and Type Ia supernovae (SNe Ia). This combination provides a fully distance-ladder- and CMB-independent determination of the Hubble constant and the dark-energy EoS. Using 47 GW standard sirens from the third Gravitational-Wave Transient Catalog, the DESI DR2 BAO data, and DESY5 SNe Ia data, in the $w_0w_a$CDM model, we obtain $H_0=74.8^{+6.3}_{-8.9}$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_{\rm m}=0.320^{+0.015}_{-0.012}$, $w_0=-0.775^{+0.072}_{-0.074}$, and $w_a=-0.80\pm0.47$, indicating a mild phantom-crossing behavior within the $1\sigma$ credible interval with an $H_0$ value consistent with the distance ladder measurements. Our analysis demonstrates the power of GW standard sirens in breaking parameter degeneracies, and this novel data combination provides joint constraints on the Hubble constant and the dark-energy EoS parameters.
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All authors Ji-Yu Song, Guo-Hong Du, Tian-Nuo Li, Ling-Feng Wang, Jing-Zhao Qi, Jing-Fei Zhang, Xin Zhang

Astrophysics of Galaxies

The Impact of Orbital Anisotropy Assumptions in Lensing-Dynamics Modeling

Yan Liang, Dandan Xu, Anowar J. Shajib et al. (+2 more)

We investigate potential systematic biases introduced by assumptions regarding stellar orbital anisotropy in joint lensing-dynamics modeling. Our study employs the massive early-type galaxies from the TNG100 simulation at redshifts z = 0.2, 0.5, and 0.7. Based on the simulated galaxies, we generate a self-consistent mock dataset containing both lensing and stellar kinematic observables. This is achieved through taking the potential composed of both dark matter and baryons of the simulated galaxies, plus the radial variation of the stellar orbit anisotropy depicted by a logistic function. By integrating constraints from both lensing and stellar kinematics, we separate the contributions of stars and dark matter inside the galaxies. Under three commonly adopted stellar anisotropy assumptions (isotropic orbits, constant anisotropy, and the Osipkov-Merritt profile), the model inferences suggest that the systematic biases in the total stellar mass and central dark matter fraction are not significant. Specifically, the total stellar mass on average is underestimated by less than $0.03\pm0.10$ $\rm dex$ while the dark matter fraction experiences only a statistically insignificant increase of less than $2\%\pm10\%$ at the population level. The dark matter inner density slope in our tests is over-predicted by $0.15\pm0.2$. Additionally, these lacks of significant biases are insensitive to the discrepancies between the assumed anisotropy in modeling and the ground truth orbital anisotropy of mock sample. Our results suggest that conventional assumptions regarding orbital anisotropy, such as an isotropic profile or the Osipkov-Merritt model, would not introduce a significant systematic bias when inferring galaxy mass density distribution at the population level.
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All authors Yan Liang, Dandan Xu, Anowar J. Shajib, Yiping Shu, Ran Li

Solar and Stellar Astrophysics

He-star donor pathway for the hypervelocity star D6-2

Abinaya Swaruba Rajamuthukumar, Ruediger Pakmor, Stephen Justham et al. (+2 more)

Type Ia supernovae are thermonuclear explosions of white dwarfs, yet the nature of their progenitor systems remains uncertain. Recent discoveries of hypervelocity stars provide unique constraints, as these stars likely represent the surviving companions of such explosions. Using detailed binary evolution models computed with MESA and population synthesis with MSE, we investigate the outcomes of hot subdwarf + white dwarf binaries undergoing helium accretion. We find that donors can nearly exhaust their helium and form compact, C/O cores before explosion. The predicted ejection velocities span a broad distribution reaching up to $\sim 1000\,\mathrm{km\,s^{-1}}$, with D6-2 representing the extreme high-velocity tail of this population. We estimate analytically that the thin residual helium envelope can be stripped by the supernova ejecta, producing a C/O-rich surface composition consistent with the observed spectrum. The Type Ia supernova rate from this channel is ${\sim}(1.69\pm0.06)\times10^{-5}\,\mathrm{M_\odot^{-1}}$, consistent with 1% of the observed Type Ia supernova rate. Hot subdwarf + white dwarf binaries containing nearly exhausted He-star donors can therefore naturally explain the velocity and composition of D6-2 while providing a quantitatively consistent contribution to the observed Type Ia supernova rate. Our models predict a distribution of surviving donor remnants with various core He fractions and with ejection velocities extending down to $\sim 450\,\mathrm{ km\,s^{-1}}$. The orbital velocities of donor stars in this progenitor channel naturally yield orbital velocities consistent with US 708, LP 40-365 stars, and D6-2, indicating that a single class of thermonuclear supernova progenitors can account for their entire range of ejection velocities.
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All authors Abinaya Swaruba Rajamuthukumar, Ruediger Pakmor, Stephen Justham, Aakash Bhat, Ken J Shen

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

Upper Bound on the Cosmic Baryon Chemical Potential from Lepton-Flavor Asymmetry

Francesco Di Clemente, Alessandro Drago, Lorenzo Formaggio et al. (+3 more)

We study the early Universe trajectory around the QCD transition in lepton-flavor-asymmetric cases with small total lepton asymmetry ($|\ell|\lesssim 10^{-2}$), while allowing large individual lepton asymmetries. For each temperature, we find an upper bound on the baryon chemical potential $\mu_{\mathrm B}(T)$: $\tau$–$\mu$ asymmetric cases exhibit a local maximum, whereas $\mu$–$e$ cases approach a limiting curve. Thus, even extreme lepton-flavor asymmetry alone cannot reach a first-order region, unless the critical point is moved to a substantially lower $\mu_\mathrm{B}/T$ because of the nonzero $\mu_\mathrm{Q}$. Therefore, we constrain the QCD-era relic to the standard scenario of a chiral crossover transition.
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All authors Francesco Di Clemente, Alessandro Drago, Lorenzo Formaggio, Claudia Ratti, Volodymyr Vovchenko, Geetika Yadav

Astrophysics of Galaxies

First Light And Reionisation Epoch Simulations (FLARES) XX: Comparing semi-analytic models at high-redshift

Louise T. C. Seeyave, Carlton M. Baugh, Angel Chandro-Gomez et al. (+13 more)

We explore how the choice of galaxy formation model affects the predicted properties of high-redshift galaxies. Using the FLARES zoom resimulation strategy, we compare the EAGLE hydrodynamics model and the GALFORM, L-Galaxies, SC-SAM and SHARK semi-analytic models (SAMs) at $5\leq z \leq 12$. The first part of our analysis examines the stellar mass functions, stellar-to-halo mass relations, star formation rates, and supermassive black hole (SMBH) properties predicted by the different models. Comparisons are made with observations, where relevant. We find general agreement between the range of predicted and observed stellar mass functions. The model predictions differ considerably when it comes to SMBH properties, with GALFORM and SHARK predicting between 1.5-3 dex more massive SMBHs ($M_{\rm BH}>10^6\ {\rm M_\odot}$) than L-Galaxies and SC-SAM, depending on redshift. The second half of our analysis focuses on passive galaxies. We show that in L-Galaxies and SC-SAM, environmental quenching of satellites is the prevalent quenching mechanism, with active galactic nuclei (AGN) feedback having little effect at the redshifts probed. On the other hand, $\sim40\%$ of passive galaxies predicted by GALFORM and SHARK are quenched by AGN feedback at $z=5$. The SAMs are an interesting contrast to the EAGLE model, in which AGN feedback is essential for the formation of passive galaxies, in both satellites and centrals, even at high redshift.
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All authors Louise T. C. Seeyave, Carlton M. Baugh, Angel Chandro-Gomez, Claudia del P. Lagos, Robert M. Yates, L. Y. Aaron Yung, Rachel S. Somerville, Stephen M. Wilkins, Christopher C. Lovell, William J. Roper, Aswin P. Vijayan, Cedric G. Lacey, Chris Power, Shihong Liao, Maxwell G. A. Maltz, Jack C. Turner

Astrophysics of Galaxies

Formation of Close Binaries through Massive Black Hole Perturbations and Chaotic Tides

Howard Hao-Tse Huang and Wenbin Lu

Hills breakup of binary systems allows massive black holes (MBH) to produce hyper-velocity stars (HVSs) and tightly bound stars. The long timescale of orbital relaxation means that binaries must spend numerous orbits around the MBH before they are tidally broken apart. Repeated MBH tidal perturbations over multiple pericenter passages can perturb the binary inner orbit to high eccentricities, leading to strong tidal interactions between the stars. In this work, we develop a physical model of the MBH-binary system, taking into account outer orbital relaxation, MBH tidal perturbations, and tidal interactions between the binaries in the form of dynamical tides. We show that when the inner orbit reaches high eccentricities such that the pericenter radius is only a few times stellar radii ($R_*$), the stellar oscillation modes can grow chaotically and rapidly harden the binaries to semi-major axes $a_b\lesssim 10\,R_*$. We find that a significant fraction (up to 50%) of initially wide binaries that are in the empty loss-cone regime ($a_b\sim 1.0\,{\rm AU}$) do not undergo Hills breakup as wide binaries, but instead experience chaotic growth of tides and become close binaries. These tidally hardened binaries provide a new channel for the production of the fastest HVSs, and are connected to other nuclear transients such as repeating partial tidal disruption events and quasi-periodic eruptions.
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Earth and Planetary Astrophysics

Functionality of Ice Line Latitudinal EBM Tenacity (FILLET). Protocol Version 1.1

Rory Barnes, Russell Deitrick, Jacob Haqq-Misra et al. (+5 more)

The Functionality of Ice Line Latitudinal EBM Tenacity (FILLET) project is a CUISINES exoplanet model intercomparison project (exo-MIP) that compares various energy balance models (EBMs) through a series of numerical experiments. The objective is to establish rigorous protocols that enable the identification of intrinsic differences among EBMs that could lead to model-dependent results for past, current, and future EBM studies. Such efforts also provide the community with an EBM ensemble average and standard deviation, rather than a single model prediction, on benchmark cases typically used by EBM studies. These experiments include Earth-like planets at different obliquity, instellation, and carbon dioxide abundance. Here we update the v1.0 protocol (Deitrick et al., 2023) to accommodate the requirements of previously untested community models. In particular, we expand the range of carbon dioxide abundances for Experiment 4 to ensure any code will capture both snowball and ice-free end states. Additionally, participants are now required to report two ice edge latitudes per hemisphere to fully distinguish all climate states (snowball, ice caps, ice belts, and ice-free). The outputs described in FILLET protocol version 1.0 have also now been revised to include the maximum and minimum ice extent, in latitude, for each hemisphere, as well as the diffusion coefficient and outgoing longwave radiative flux.
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All authors Rory Barnes, Russell Deitrick, Jacob Haqq-Misra, Shintaro Kadoya, Ramses Ramirez, Paolo Simonetti, Vidya Venkatesan, Thomas J. Fauchez

Friday 14 November

Solar and Stellar Astrophysics · Cross-listed from physics.plasm-ph

On the Theory of Bulk Viscosity of Cold Plasmas and Thermodynamics of Alkali-Noble Gas Cocktails

Albert M. Varonov and Todor M. Mishonov

By solving the kinetic equation for ionization-recombination processes in cold plasmas for temperatures much lower than the first ionization potentials, we derive an explicit expression for the complex polytropic index, as well as bulk viscosity. The obtained result for the ionization-recombination relaxation time reveals that the Mandelstam-Leontovich approximation for the frequency dependence of the bulk viscosity is actually an exact solution in the case of cold plasmas. We systemize also explicit general formulae for the thermodynamics of the alkali-noble cocktails in the same low temperature plasma approximation, allowing the Schwarzschild criterion on convectional instability to be derived, too. All these general results are applicable for cold stellar, interstellar and laboratory plasmas. Additionally, the wave heating of the inner solar atmosphere up to the solar transition region is studied thoroughly, and it is found that the magnetic diffusivity, heat conductivity, shear- and bulk viscosities all play an almost equally important part in the wave damping, therefore none of them can be omitted in realistic considerations of heating of the solar atmosphere.
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Cosmology and Nongalactic Astrophysics

Source REconstruction of Arcs behind Cluster Halos (SourceREACH): A New Source Reconstruction Algorithm Optimized for Giant Arcs and Galaxy Cluster Lenses

Lana Eid and Charles Keeton

We introduce a new algorithm designed for use with extended lensed images, specifically giant arcs lensed by galaxy clusters. These highly magnified images contain important information about both the mass distribution of the cluster and the properties of the background source, but modeling them requires significant computational effort. Our new source reconstruction methodology is designed to be accurate and efficient for high-resolution observations in which point spread function effects are not significant. The overall process deconvolves the observed image by the point spread function, de-lenses the image pixels, and uses interpolation or regression with smoothing to determine the model source. By working with de-lensed points, the method accounts for varying resolution across the source plane. We evaluate the speed and accuracy of different interpolation and regression methods using both mock data and real data for the giant arc in Abell 370. We find that utilizing K Nearest Neighbor Regression results in the best balance of noise smoothing and preservation of compact detail in the source.
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Astrophysics of Galaxies

Euclid Quick Data Release (Q1): Identification of massive galaxy candidates at the end of the Epoch of Reionisation

Euclid Collaboration: R. Navarro-Carrera, K. I. Caputi, C. J. R. McPartland et al. (+294 more)

Probing the presence and properties of massive galaxies at high redshift is one of the most critical tests for galaxy formation models. In this work, we search for galaxies with stellar masses M* > 10^10.25 Msun at z in [5,7], i.e., towards the end of the Epoch of Reionisation, over a total of ~23 deg^2 in two of the Euclid Quick Data Release (Q1) fields: the Euclid Deep Field North and Fornax (EDF-N and EDF-F). In addition to the Euclid photometry, we incorporate Spitzer Infrared Camera (IRAC) and ground-based optical data to perform spectral energy distribution (SED) fitting, obtaining photometric redshifts and derived physical parameters. After applying rigorous selection criteria, we identify a conservative sample of 145 candidate massive galaxies with M* > 10^10.25 Msun at z in [5,7], including 5 objects with M* > 10^11 Msun. This makes for a surface density of about 6.3 deg^-2 at z in [5,7], which should be considered a lower limit because of the current depth of the Euclid data (H_E < 24, 5 sigma in Q1). We find that the inferred stellar masses are consistent with galaxy formation models with standard star-formation efficiencies. These massive galaxies have colour excess E(B-V) values up to 0.75, indicating significant dust attenuation in some of them. In addition, half of the massive galaxies have best-fit ages comparable to the age of the Universe at those redshifts, which suggests that their progenitors were formed very early in cosmic time. About 78% of the massive galaxies lie on the star-forming main sequence (MS) in the SFR-M* plane, ~12% are found in the starburst region, and 10% in the transition zone between the MS and starbursts. We find no significant evidence for outshining or AGN contamination that could account for the elevated specific star-formation rates (sSFR) observed in the ~12% of galaxies classified as starbursts.
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All authors Euclid Collaboration: R. Navarro-Carrera, K. I. Caputi, C. J. R. McPartland, J. R. Weaver, D. B. Sanders, G. Desprez, A. A. Tumborang, A. Biviano, C. J. Conselice, Y. Fu, G. Girardi, V. Le Brun, C. C. Lovell, G. Rodighiero, J. Schaye, R. G. Varadaraj, S. M. Wilkins, G. Zamorani, K. Jahnke, D. Scott, M. Siudek, F. Shankar, J. G. Sorce, F. Tarsitano, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, E. Branchini, M. Brescia, J. Brinchmann, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, A. M. Di Giorgio, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, R. C. Nichol, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, S. Pires, G. Polenta, M. Poncet, L. A. Popa, L. Pozzetti, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, D. Sapone, M. Schirmer, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, A. Veropalumbo, Y. Wang, J. Weller, E. Zucca, M. Ballardini, M. Bolzonella, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, J. A. Escartin Vigo, L. Gabarra, W. G. Hartley, M. Huertas-Company, R. Maoli, J. Martín-Fleitas, S. Matthew, M. Maturi, N. Mauri, R. B. Metcalf, A. Pezzotta, M. Pöntinen, C. Porciani, I. Risso, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, D. Bertacca, M. Bethermin, L. Bisigello, A. Blanchard, L. Blot, M. Bonici, S. Borgani, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, T. Contini, A. R. Cooray, O. Cucciati, A. Díaz-Sánchez, J. J. Diaz, S. Di Domizio, J. M. Diego, P.-A. Duc, M. Y. Elkhashab, A. Enia, Y. Fang, A. G. Ferrari, A. Finoguenov, A. Fontana, F. Fontanot, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, K. Kiiveri, J. Kim, C. C. Kirkpatrick, S. Kruk, L. Legrand, M. Lembo, F. Lepori, G. Leroy, G. F. Lesci, J. Lesgourgues, T. I. Liaudat, S. J. Liu, J. Macias-Perez, G. Maggio, M. Magliocchetti, F. Mannucci, C. J. A. P. Martins, L. Maurin, M. Miluzio, P. Monaco, C. Moretti, G. Morgante, K. Naidoo, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, L. Patrizii, A. Pisani, D. Potter, S. Quai, M. Radovich, S. Sacquegna, M. Sahlén, E. Sarpa, A. Schneider, D. Sciotti, E. Sellentin, L. C. Smith, K. Tanidis, C. Tao, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, N. A. Walton

High Energy Astrophysical Phenomena

Through the Heliospheric Lens: Directional Deflection of High-Energy Cosmic-Ray Electrons and Positrons

Stefano Profumo, Aria Koul, Anika Malladi et al. (+1 more)

We investigate how the large-scale heliosphere alters the arrival directions of high-energy cosmic-ray electrons and positrons and ask if and when this "heliospheric lens" can be ignored for anisotropy and source-association studies - an especially timely topic given, for instance, the persistent cosmic-ray positron fraction and its unknown origin. Using a modular back-tracing framework, we explore a set of widely used magnetic-field descriptions-from a Parker spiral baseline to more structured configurations that include latitudinal wind contrasts, Smith-Bieber-type azimuthal strengthening, and tilted or wavy heliospheric current sheets. We model the deterministic deflections of high-energy cosmic-ray electrons and positrons (CREs) induced by large-scale heliospheric magnetic-field structures using a back-tracing approach. Our results apply to CREs above tens of GeV, where diffusion, convection, and adiabatic energy losses play a subdominant role; these processes are neglected in the present study and will be addressed in future work. Across these models the picture is consistent: most bending is accumulated within the inner tens of astronomical units and decreases rapidly with energy. Field choices and solar-cycle geometry set the overall normalization, with stronger spiral winding or a more highly tilted current sheet producing larger deflections at the same energy. Differences between electrons and positrons are most apparent at lower energies, where drift histories and current-sheet encounters diverge, and become increasingly small at multi-TeV energies. [...]
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All authors Stefano Profumo, Aria Koul, Anika Malladi, Ben Schmitt

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Symmetric Bimetric Cosmology: A Minimal Extension of {\Lambda}CDM

Ghani Imadouchene

We construct and analyze a symmetric bimetric cosmological model connecting Anti-de Sitter (AdS) and de Sitter (dS) regimes through a coupled scalar field. Starting from a Lagrangian with Einstein-Hilbert terms for two FLRW metrics and an inter-metric potential, we derive modified Friedmann and Klein-Gordon equations governing their evolution. In the symmetric effective-fluid limit, the model reproduces the main phenomenology of the $\Lambda$CDM cosmology with a small dynamical correction proportional to $(1+z)^{-3}$, and naturally satisfies local-gravity constraints through Vainshtein screening. This article outlines the theoretical structure and calibration of the model within a dual-geometry cosmological setting.
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