Clay weekly context brief for the Astro category (ISO week 2026-W38). Clay tracks publications from the Astro feed list. Below are recent items from this category, each with its source and a short description of what the publication covers when one is available in the source feed. Recent publications: 1. Aletheia: Emulating the halo mass function with evolution mapping Source: astro-ph.CO (Cosmology and Nongalactic Astrophysics) Link: https://arxiv.org/abs/2609.10665 We present an emulator of the halo mass function (HMF) based on Gaussian-process regression, that exploits the evolution mapping framework. 2. Sorting a mess I: Addressing velocity-axis correlation of cross-correlation functions. A census of atomic and ionised species in KELT-9b's atmosphere Source: astro-ph.EP (Earth and Planetary Astrophysics) Link: https://arxiv.org/abs/2609.10695 Ultra-hot Jupiters (UHJs) are the most extreme class of close-in gas giants. 3. Probing dynamics of extreme galaxies I. Dark matter content in ultra-diffuse galaxies Source: astro-ph.GA (Astrophysics of Galaxies) Link: https://arxiv.org/abs/2609.10700 We investigate the internal structure of two galaxies from the LEWIS sample: the ultra-diffuse galaxy UDG-1 and the extended dwarf LSB-6. 4. Detection of hard X-ray pulsations in non-ULX X-ray pulsar 3X J0042 in M31 Source: astro-ph.HE (High Energy Astrophysical Phenomena) Link: https://arxiv.org/abs/2609.10699 We report the detection of hard X-ray pulsations from the M31 accreting non-ULX X-ray pulsar 3X J0042 (3XMM J004232.1+411314) using archival NuSTAR observations. 5. Cycle Variation in the Occurrence of Great Soft X-ray Solar Flares Source: astro-ph.SR (Solar and Stellar Astrophysics) Link: https://arxiv.org/abs/2609.09435 Powerful nonstationary processes such as flares and coronal mass ejections are detected mainly near the solar cycle maxima. 6. A Content-Addressed Workflow for Reproducible DANTE Gravitational-Wave Anomaly Analysis Source: astro-ph.IM (Instrumentation and Methods for Astrophysics) Link: https://arxiv.org/abs/2609.08695 Unsupervised analysis of gravitational-wave detector data combines expensive scientific stages with data acquisition, provenance checks, statistical calibration, follow-up products, and reporting. 7. The relevance of the cosmic microwave background for cosmology Source: astro-ph.CO (Cosmology and Nongalactic Astrophysics) Link: https://arxiv.org/abs/2609.10672 Within the Hot Big Bang picture, as usually interpreted in the standard LCDM framework and its hierarchical scenario for elliptical galaxy assembly, the cosmic microwave background (CMB) is associated with photon decoupling near z = 1100, and the Planck angular power spectra are taken to constrain primordial 10^{-5}-level fluctuations that seeded later structure formation. 8. WASP-43b TESS Phase Curve Mapping: Evidence for a Hot Interior Source: astro-ph.EP (Earth and Planetary Astrophysics) Link: https://arxiv.org/abs/2609.10719 Phase-curve mapping probes various atmospheric properties depending on wavelength: thermal phase curves are dominated by atmospheric emission, while visible and near-infrared phase curves include reflected light. 9. Predictions for astrometric microlensing in Gaia Source: astro-ph.GA (Astrophysics of Galaxies) Link: https://arxiv.org/abs/2609.10705 ESA's astrometric space mission Gaia is uniquely positioned for microlensing studies thanks to its all-sky coverage and simultaneous astrometric and photometric observations. 10. Teglon: A Pixel-Level Pipeline for Galaxy-Informed Gravitational-Wave Follow-up Planning and Efficiency Analysis Source: astro-ph.HE (High Energy Astrophysical Phenomena) Link: https://arxiv.org/abs/2609.10736 We describe Teglon, an open-source database and analysis pipeline engineered to optimize the search for electromagnetic (EM) counterparts to gravitational wave (GW) sources. 11. Planetary Nebula Central Stars as Tracers of Planetary Nebula-Star Cluster Associations in the Galaxy Source: astro-ph.SR (Solar and Stellar Astrophysics) Link: https://arxiv.org/abs/2609.09618 Planetary nebulae (PNe) that are physically associated with star clusters are rare but crucial for stellar evolution studies because they allow their initial and final stellar properties to be determined independently, contributing to constraints on the initial-to-final-mass relation (IFMR), which traces stellar mass loss. 12. A Missing Tool for Calculating Auto/Cross-correlation Function under Nonuniform Sampling Observations Source: astro-ph.IM (Instrumentation and Methods for Astrophysics) Link: https://arxiv.org/abs/2609.08604 Nonuniform sampling presents a long-standing challenge in astrophysical time-domain analysis, invalidating the standard autocorrelation and cross-correlation functions and forcing researchers to adopt ad-hoc methods like interpolation or binning, which introduce unquantified biases and lack rigorous error estimation. 13. PBH runaway during reheating Source: astro-ph.CO (Cosmology and Nongalactic Astrophysics) Link: https://arxiv.org/abs/2609.10696 The growth of primordial black holes through the absorption of the surrounding plasma has recently been shown to exhibit a critical behavior during radiation domination. 14. Fast and Furious: Long-term orbit integrations with collocation integrator Lobbie Source: astro-ph.EP (Earth and Planetary Astrophysics) Link: https://arxiv.org/abs/2609.10809 Efficient and accurate numerical integration methods are fundamental to studying long-term solar system dynamics, where numerical errors can accumulate over billions of orbital periods. 15. BIND (Baryonic INpainting with Deep learning): A Field-level Emulator for Galaxy Groups and Clusters Source: astro-ph.GA (Astrophysics of Galaxies) Link: https://arxiv.org/abs/2609.10709 Baryonic feedback is a dominant source of systematic uncertainty for upcoming weak-lensing surveys, but current tools for modeling its effect rely on spherical approximations and density profiles calibrated almost entirely on two-point statistics. 16. Low-Mass Magnetic Monopoles in the Galaxy: Simulations and Comparison with Ultra-High-Energy Cosmic-Ray Data Source: astro-ph.HE (High Energy Astrophysical Phenomena) Link: https://arxiv.org/abs/2609.10784 Origin and composition of ultra-high energy cosmic rays are still uncertain, particularly the rare events exceeding the Greisen-Zatsepin-Kuzmin cutoff and whose apparent arrival directions point to the Local Void. 17. The FU Ori outburst of PR Ori B Source: astro-ph.SR (Solar and Stellar Astrophysics) Link: https://arxiv.org/abs/2609.09722 We report the discovery of a nearby FU Ori-type outburst (FUor), PR Ori B, in the L1641 cluster of the Orion star-forming region. 18. CTree: Branch-wise compatible merger tree builder Source: astro-ph.IM (Instrumentation and Methods for Astrophysics) Link: https://arxiv.org/abs/2609.08086 We introduce a merger tree builder, CTree. 19. BINDing the lightcone: A suite of astrophysical ray-traced weak lensing and SZ maps Source: astro-ph.CO (Cosmology and Nongalactic Astrophysics) Link: https://arxiv.org/abs/2609.10710 Recent multiwavelength observations of galaxy group and cluster gas suggest stronger baryonic feedback than our best-calibrated hydrodynamical simulations produce, while modeling this feedback remains a primary source of uncertainty in Stage-IV weak-lensing (WL) analyses. 20. Constraining Tidal Migration with the Hot Jupiter Population Source: astro-ph.EP (Earth and Planetary Astrophysics) Link: https://arxiv.org/abs/2609.10850 Hot Jupiters with orbital periods shorter than a few days have probably been affected by tidal orbital migration. 21. A Novel Approach to 3D Dust Mapping of the Central Molecular Zone Source: astro-ph.GA (Astrophysics of Galaxies) Link: https://arxiv.org/abs/2609.10782 The 3D distribution of dust and gas in the Milky Way's Central Molecular Zone (CMZ) is key to understanding gas inflows toward the Galactic Centre (GC), the process of star formation in this extreme environment, and the propagation of energetic cosmic rays originating from Sgr A*. 22. XRISM observations of the Perseus cluster along two arms: Chaotic ICM motions probed by resonant scattering Source: astro-ph.HE (High Energy Astrophysical Phenomena) Link: https://arxiv.org/abs/2609.10845 XRISM has mapped gas velocities across the core of the Perseus cluster, separating the kinematic effects of mergers and AGN feedback. 23. Connecting Dynamo Theory with DNS Data: A Computational Analysis of {\alpha} and \b{eta} Effects Source: astro-ph.SR (Solar and Stellar Astrophysics) Link: https://arxiv.org/abs/2609.09767 We investigate the influence of current helicity on the turbulent magnetic diffusivity $\beta$ using three complementary derivations of the $\alpha$ and $\beta$ coefficients, based on the large-scale magnetic field $\overline{\mathbf{B}}$, the turbulent velocity $\mathbf{u}$, and the turbulent magnetic field $\mathbf{b}$. 24. Neural Posterior Estimation for Tomographic Weak Lensing Mass Mapping Source: astro-ph.IM (Instrumentation and Methods for Astrophysics) Link: https://arxiv.org/abs/2609.07833 Weak gravitational lensing shear and convergence trace the distribution of baryonic and dark matter across space, making them a powerful probe of cosmic structure. 25. $w_0w_a$ or $bc$: DESI constraints on relative baryon-CDM perturbations Source: astro-ph.CO (Cosmology and Nongalactic Astrophysics) Link: https://arxiv.org/abs/2609.10794 We carry out a search for the relative baryon-cold dark matter (CDM) density and velocity modes in the DESI full-shape (FS) data, and investigate whether DESI's preference for evolving dark energy can be affected by these relative perturbations, which are a known contaminant of the baryon acoustic oscillations. 26. Lava Tube Exploration with LunarLeaper Source: astro-ph.EP (Earth and Planetary Astrophysics) Link: https://arxiv.org/abs/2609.11453 Lunar pits, some of which are interpreted as collapse features into underlying lava tubes, expose otherwise inaccessible stratigraphy and may provide entry points to subsurface voids that preserve records of lunar volcanism and offer potential sites for future human exploration. 27. The THRILS Factor: Investigating the properties of Little Red Dots (LRDs) at 3