Locally authored papers of the past 5 days

In the hierarchical paradigm of galaxy formation, central massive black holes (MBHs) are expected to coalesce after the merger of their host galaxies. One of the main goals of the Laser Interferometer Space Antenna (LISA) is to constrain the origin and growth of MBHs through their merger rates and mass distribution. Predicting MBH merger rates requires not only tracing their statistical population from large to small physical scales (kpc to sub-pc) but also modelling their formation, accretion, dynamics, mergers, and their galactic physical processes across cosmic time. This project is the result of a large collaborative effort undertaken by the LISA Astrophysics Working Group, bringing together its collective expertise on MBH formation, evolution, and modelling, to build a comprehensive understanding of MBH merger rates across cosmic time. The project compares various theoretical predictions of MBH merger rates, quantifies the spread, and evaluates the global astrophysical uncertainties of the LISA event rates. To build a unique and complete view, our work is based on about 20 semi-analytical models and cosmological simulations from the literature, all employing distinct approaches to modelling MBH and galaxy physics. To compute the merger rates, we also incorporate delays arising from the dynamical phase of MBH hardening to coalescence. We present the expected LISA merger rates given current galaxy formation models and discuss how the merger rate depends on model assumptions, such as the seeding model and the resolution of cosmological simulations.

Fast radio bursts (FRBs), highly polarized, mostly have a nearly constant polarization position angle (PA) during each burst. Their PAs are observed to vary from burst to burst, with the statistical properties remaining stable across different observation sessions. We found that the intrinsic PAs of repeating FRBs are approximately Gaussian distributed, suggesting that the emission likely originates from a localized region within the neutron star's magnetosphere. A periodicity search of the PA time series using the Lomb-Scargle periodogram reveals no credible periodic signal in the period range from 10 ms to $10^7$ ms, and similar analyses of several active observations also yield null detections. We interpret these properties by extending the rotating vector model to include a dynamically evolving magnetosphere, in which the effective magnetic axis varies from burst to burst due to stochastic perturbations. In this framework, the observed PA distributions can naturally arise from geometric projection effects, and the absence of periodicity reflects the random wandering of the magnetic axis within a confined region. This scenario provides a natural explanation for both repeating and apparently non-repeating FRBs.

Large surveys of galaxies in the local and high-redshift Universe have, traditionally, relied on the intensity of rest-optical emission lines from metal ions in the Interstellar Medium (ISM) to indirectly estimate the O/H abundance in the gas. However, these optical strong line diagnostics are also sensitive to the electron gas temperature ($T_e$), resulting in large systematic uncertainties that inherently limit their utility as metallicity tracers, especially in dust-obscured and metal-rich environments. To this end, we provide the first empirical calibration of Ne$_{23}$, a novel abundance diagnostic using the mid-infrared (MIR) $T_e$-insensitive [Ne II]$\lambda$12.81$\mu$m and [Ne III]$\lambda$15.56$\mu$m fine-structure lines. We present new JWST/MIRI MRS observations of ten H II regions with optical measurements of $T_e$ and O/H from the CHAOS project, and we analyze MIRI observations of eight low-metallicity galaxies with similarly high-fidelity direct O/H. We measure Ne$_{23}$ from 1D MIR spectra extracted from apertures matched to the ground-based spectroscopy used to obtain O/H, a method that is unfeasible from MIR spectra acquired on prior space-based observatories. From these nebulae, Ne$_{23}$ is strongly correlated with O/H over 1.5 dex in 12+log(O/H). We calibrate the O/H-Ne$_{23}$ relation from the empirical data, finding a scatter of just 0.06 dex in O/H at fixed Ne$_{23}$. The O/H-Ne$_{23}$ relation presented here provides a means to reliably estimate 12+log(O/H) from JWST/MIRI MRS observations of ionized nebulae out to z$\approx$0.8, enabling new chemical abundance surveys of highly-attenuated regions and in the metal-rich ISM.

Fluid equations are nonlinear, dissipative, and non-Hamiltonian, which makes their relation to Schrödinger evolution and quantum algorithms nontrivial. We derive an exact Eulerian Cole-Hopf-type reformulation of isothermal compressible Navier-Stokes (NS) flow in Schrödinger-type amplitude variables. To our knowledge, this gives the first exact Cole-Hopf-type Schrödinger-variable reformulation of compressible NS flow. In two dimensions, a Helmholtz decomposition separates the velocity into compressive and vortical potentials, whose logarithmic transforms yield two scalar imaginary-time Schrödinger-type equations with nonlinear self-consistent potentials. We show that the mixed density-compressive amplitude $\Psi_\alpha=\rho^\alpha\Theta^{1-2\alpha}$, where $\rho$ is the density, $\Theta$ is the compressive amplitude, and $\alpha\neq 0,\,1/2$, satisfies a nonlinear Schrödinger-type equation with a vector-potential-coupled Laplacian. The transformed system is exactly equivalent to compressible NS and is nonlocal only through Helmholtz and Poisson projections. In three dimensions, the density-carrying equation retains the same vector-potential-coupled structure, while the solenoidal sector admits a compressible analogue of Ohkitani's incompressible NS Cole-Hopf formulation. Unlike unitary hydrodynamic Schrödinger-flow representations, the present equations are imaginary-time heat or drift-diffusion equations with self-consistent potentials, but they remain an exact change of variables for compressible NS. A two-dimensional Kelvin-Helmholtz unstable shear-layer calculation verifies the transformed equations against a direct compressible NS simulation. The formulation exposes operator structures that may be useful for reduced flow descriptions, quantum algorithms for operator evolution, and quantum partial differential equation solvers.

We report the confirmation and characterization of four transiting giant planets orbiting early-M dwarfs discovered by the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey: TOI-7189 b, TOI-7265B b, TOI-7393 b, and TOI-7394B b. Joint modeling of TESS and ground-based photometry with precision radial velocities from the Habitable-zone Planet Finder and NEID spectrographs yields self-consistent orbital and physical parameters for all systems. The planets have short orbital periods ($P = 1.25-4.17$ days), masses spanning from $0.5\,M_{\rm J}$ to $2.1\,M_{\rm J}$, and radii comparable to Jupiter ($0.95\,R_{\rm J} < R_p < 1.02\,R_{\rm J}$). TOI-7189 b ($0.50\,M_{\rm J}$), TOI-7265B b ($0.71\,M_{\rm J}$), and TOI-7393 b ($0.61\,M_{\rm J}$) are Saturn-like in mass and density, whereas TOI-7394B b is a dense super-Jupiter ($2.10\,M_{\rm J}$, $\rho_p \approx 2.4$ g cm$^{-3}$) on a 1.25-day orbit. All hosts are early-M dwarfs with a narrow range of stellar properties, enabling a controlled comparison of giant-planet outcomes around low-mass stars. Three systems orbit super-solar metallicity stars, while TOI-7393 ($\mathrm{[Fe/H]} = -0.35 \pm 0.16$) is the most metal-poor GEMS host identified to date, and exhibits kinematics consistent with the thin/thick-disk transition, suggestive of an older stellar population. Together, these systems reveal substantial diversity in the masses and bulk properties of short-period giant planets orbiting early-M dwarfs, demonstrating that markedly different planetary outcomes can arise around stars with otherwise similar fundamental properties.

Winds and jets are symbiotic when the accretion rate is low, according to black hole accretion theory. Both components are potentially important for active galactic nucleus (AGN) feedback, but previous works typically include only jets with free parameters. We perform hydrodynamical simulations of an isolated elliptical galaxy with both jets and winds included. The key features discriminating our simulations from others are that our simulations resolve the Bondi radius for reliable black hole accretion rate calculation and use parameters from GRMHD simulations. By selectively activating jets and winds, we examine their individual and combined effects. We find that effective AGN feedback, which is capable of generating strong turbulence and subsequently increasing central gas entropy and suppressing cool gas condensation and star formation, occurs only when both jets and winds operate simultaneously. The physical mechanism is the interaction between winds and jets: this interaction produces strong shear at their interface, leading to turbulence via the Kelvin-Helmholtz instability. In contrast, neither jets nor winds alone can generate strong turbulence due to the insufficient shear. The turbulence produced by wind-jet interaction is predominantly solenoidal in nature, giving rise to a broad energy spectrum approximately following a Kolmogorov-like power law and a dissipation rate $\sim 10^{-27}\,\mathrm{erg\,cm^{-3}\,s^{-1}}$ in the interstellar medium, consistent with observations. Our findings highlight the importance of simultaneously considering both jets and winds in studying the effects of AGN feedback in the evolution of elliptical galaxies.

This is the fourth paper of our series investigating the effects of active galactic nucleus (AGN) feedback in the evolution of an elliptical galaxy using the {\it MACER} framework. While previous works considered only AGN radiation and wind, we now add jet feedback. The values of the jet parameters are taken from small-scale general relativity MHD simulations of black hole accretion. We run three models: {\tt FullFeedback}, {\tt JetOnly}, and {\tt WindOnly}. Time-averaged star formation rates are $10^{-1}$, $10^{-2}$, and $10^{-3} \mathrm{M}_\odot\,\mathrm{yr}^{-1}$ in {\tt JetOnly}, {\tt WindOnly}, and {\tt FullFeedback}, respectively. Despite the higher jet power, jet feedback is less efficient than wind due to a small opening angle and low momentum flux. The much lower star formation rate in {\tt FullFeedback} indicates nonlinear coupling between jet and wind, with stronger suppression than the linear sum. The AGN energy dissipation efficiency values (fraction of injected kinetic energy dissipated via turbulence and shock) are 0.64 ({\tt FullFeedback}), 0.48 ({\tt WindOnly}), and 0.26 ({\tt JetOnly}). In the {\tt FullFeedback} model the wind-jet shear results in Kelvin-Helmholtz instability, driving stronger turbulence that effectively converts AGN kinetic energy into heating.

We present a comprehensive analysis of the 21 cm intensity mapping (IM) data from the Tianlai Cylinder Pathfinder Array (TCPA), focusing on multi-scale foreground mitigation and three-dimensional power spectrum estimation. Utilizing 20 days of drift-scan observations (714.4-781.7 MHz, corresponding to HI emission at redshift $z \approx 0.82-0.99$), we reconstruct high-fidelity sky maps by incorporating a high-precision, drone-measured primary beam model. This in-situ calibration significantly enhances reconstruction accuracy over previous analytical approximations. To address astrophysical foregrounds, which exceed the cosmological signal by approximately five orders of magnitude, we implement a robust multi-scale subtraction strategy--mPCA-UWTS--which combines an isotropic Undecimated Wavelet Transform on the Sphere (UWTS) with independent Principal Component Analysis (PCA) within each wavelet domain. We subsequently estimate the 3D power spectrum via Spherical Fourier-Bessel (SFB) decomposition, providing a mathematically rigorous treatment of wide-angle and line-of-sight curvature effects inherent in wide-field surveys. Our analysis demonstrates that the SFB framework effectively isolates systematic contaminants and recovers the clustering signal without the biases introduced by conventional flat-sky approximations. This work represents the first application of the SFB formalism to observational 21 cm IM data, establishing it as a computationally efficient and scalable diagnostic tool for the next generation of wide-field 21 cm surveys, including the Square Kilometre Array (SKA) and the full Tianlai array.

We present an extensive X-ray spectral variability study of the TeV photon-emitting high-energy-peaked BL Lacertae object PG 1553+113, using the data from EPIC-PN camera of XMM-Newton, which observed the source during its operational period from Sep 2001 to Nov 2024. X-ray spectra in this energy range, $0.6-7.0$ keV, were fitted with absorbed Power-law (PL) and absorbed Log-Parabola (LP) models. We found with 99$\%$ confidence that 14 of them were fit well by LP models having parameters in the range $\alpha\simeq2.13-2.80$, and $\beta\simeq0.04-0.18$, one spectrum favours a LP model with $\beta<0$, while simple PL models with $\Gamma\simeq2.53-2.69$ were sufficient to describe the X-ray spectra of the remaining 15. Two of these 30 observations showed strong signatures of an additional inverse Compton component, while one showed weaker indications. On fitting joint Optical Monitor and EPIC-PN data with LP models, we found synchrotron peaks in the energy range of $\nu_s\simeq4.59-48.61$ eV. This indicates that the spectral evolution is probably caused by variations in particle acceleration or cooling conditions within the jet.

The decade-long debate over the existence of apsidal clustering in the outer solar system is poised for reignition given the plethora of distant trans-Neptunian object (TNO) discoveries expected from the forthcoming Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). Here, we present a new conditional-likelihood method to measure apsidal clustering that is insensitive to uneven survey footprints. We calculate the long-term orbital stability of distant TNOs, which allows us to expand the known sample of relevant objects from 21 to 25. We apply our new method to this up-to-date sample, showing that the significance of the apsidal clustering in the outer solar system has fallen from $2.7\sigma$ to $1.9\sigma$, and that the direction of clustering is not well constrained. This new method is suitable for application to the growing sample of known TNOs, and the results will reveal whether the evidence for a hypothetical Planet X from apsidal clustering is real or spurious.

The enigmatic population of ``Little Red Dots'' (LRDs) sit at the center of some of the largest debates in extragalactic astronomy today. The source(s) of ionizing emission and the physical scale over which it governs is still largely unknown. We show for the first time spectroscopic variability in a z ~ 7 LRD. Comparing a recently obtained 10.2 hr JWST/NIRSpec F290LP/G395M spectrum via the C3PO survey to an 8.4 hr F290LP/G395M spectrum taken 99 days earlier (~13 rest-days) via the THRILS survey, we find a ~30% $ difference in the continuum and broad-line flux, and a 42% difference between [OIII]5008 flux in the two epochs. Through rigorous testing, we confirm that such differences are not the result of differing MSA slit placements on source nor merely flux calibration offsets. These results are further corroborated by both a similar continuum and [OIII]5008 flux differences found in NIRSpec prism/clear observations of the source at an epoch taken approximately a year earlier than the THRILS observations via RUBIES and an additional observation fortuitously taken during the THRILS epoch (within a rest-day) via the CAPERS survey. Assuming LRDs are a type of accreting black hole system, this implies direct sight-lines must exist from the accretion disk to the surrounding nebular gas on scales beyond the broad-line region, and thus any high-density gas interpretations must allow for covering fractions < 100%. Furthermore, these results show the [OIII] line emission is likely not galaxy process-dominated, with a significant population of the narrow-line emitting gas closest to the broad-line region being directly ionized by the LRD. Finally, these results highlight the need for new approaches in inferring black hole properties of these systems, accounting for the lack of significant ionization via star formation, and/or exploring more exotic host-galaxy conditions at these early epochs.

We demonstrate that ultra-relativistic black hole encounters reveal a new regime of the two-body interaction in general relativity. Evolving equal-mass, nonspinning black holes with initial center-of-mass Lorentz factors up to $\gamma\approx 5.1$ using numerical relativity, we find that the resulting waveforms defy the standard expectation of a post-Newtonian description followed by a smooth transition to a prompt Kerr ringdown. Instead, at nonzero impact parameter, the system can exhibit prolonged, highly irregular emission and significant horizon absorption, even without coalescence. We show these phenomena are driven by transient null trapping and repeated lensing of radiation in the binary interaction region. Furthermore, our simulations indicate that over $65\%$ of the initial ADM energy can be radiated as gravitational waves at $\gamma\approx 5.1$, which is substantially larger than previously estimated by extrapolating from lower boost data.

Magnetic reconnection is a fundamental physical process that can drive rapid conversion of magnetic energy into plasma bulk flows, thermal heating, and particle acceleration in space and astrophysical plasmas. Classical reconnection theory predicts that the Alfvenic reconnection exhausts are bounded by pairs of slow-mode shocks. However, identifying and characterizing these shocks through in situ spacecraft observations remains a challenge. Here we report Parker Solar Probe (PSP) observations of a reconnection exhaust embedded in the heliospheric current sheet (HCS) at a heliocentric distance of 12.2 R_O. The reconnection exhaust is bounded on both boundaries by compound magnetic structures rather than a pair of pure slow shocks. Each boundary consists of a rapidly evolving, steep inner slow shock, whose Mach numbers and shock-normal angles change significantly within several minutes, and an outer, gradual compound structure which comprises a slow shock and a rotational discontinuity. These slow shocks are quasi-perpendicular and are accompanied by enhanced proton perpendicular heating. Deep within the reconnection exhaust, high perpendicular temperature together with large plasma beta trigger mirror instability and generate mirror-mode structures. These observations provide new insights into the structure of reconnection exhaust boundaries and their role in energy conversion in the near-Sun plasma.

The Euclid Wide Survey (EWS) will cover the majority of the extragalactic sky with a resolution similar to the Hubble Space Telescope. This unprecedented data set will introduce a new era of precision cosmology. However, systematic effects need to be controlled better than ever. One of the sources of systematic uncertainties in weak gravitational lensing are biases introduced during the shear measurement. Determining these biases precisely allows the calibration of cosmological measurements to within Euclid's required accuracy. The simulations that are used to determine such biases, need to resemble the real observations. In this work, we aim to learn distributions of galaxy shape parameters from real Euclid data and use the new information to augment the morphological information in the Flagship galaxy mock catalogue. The morphology is extracted using single and double-Sérsic model fits to the real data, for which we use SourceXtractor++. We train our pipeline on deep Euclid observations of a field with rich auxiliary data and then use it to simulate EWS-like data. In these simulations we compare the multiplicative bias between the morphology from the Flagship catalogue, the trained single-Sérsic morphology, and the trained double-Sérsic morphology. We find that the image simulations with the updated morphology result in a percent-level change in the multiplicative shear bias compared to the original morphology from Flagship. This bias exceeds Euclid's tight error budget by a factor of five and underlines the need for this work. Furthermore, we study the sensitivity of the multiplicative bias to key morphological parameters and show that our approach satisfies the requirements for the cosmology analysis with the first data release of Euclid.

Using high-resolution data from the Chashan Broadband Solar radio spectrometer at meter wavelengths (CBSm) of the Chinese Meridian Project-Phase II (CMP-II), Li et al. (2025) identified a novel fine spectral structure of solar radio bursts, termed periodic beaded stripes, and proposed a generation mechanism. Here we report additional events and develop a quantitative method to determine the physical conditions in the emission region. Periodic stripes tend to occur in the post-phase of flares and are associated with complex magnetic configurations. They repeat on sub-second timescales and show $\sim$0.1 s bead-like modulations, often accompanied by low-frequency absorptions. Modeling the chained stripes with linear kinetic theory of the double plasma resonance (DPR) instability constrains the source-region magnetic field to 0.2-1.7 G and the plasma density to (1-7) $\times 10^8$ cm $^{-3}$. The former follows the drift of individual stripes, and the latter tracks the overall trend. This study summarizes the key properties of periodic beaded stripes and establishes a quantitative DPR-based framework for coronal diagnostics.

In this paper, we introduce Mujic{\Lambda} (Mapping the Universe with Jax-based Initial Condition Reconstr{\Lambda}ction), an optimization-based framework for reconstructing initial conditions from realistic galaxy spectroscopic redshift surveys. Unlike standard optimization-based approaches, Mujic{\Lambda} augments the L-BFGS algorithm with a projection operator and rank-order matching to enforce Gaussianity of the initial conditions and substantially improve robustness to incomplete survey geometries. We validate Mujic{\Lambda} on a mock lightcone catalog derived from semi-analytic models applied to the Millennium simulation. We construct a differentiable forward model that incorporates a fast particle-mesh simulation at megaparsec resolution and a comprehensive treatment of observational effects and survey incompleteness. Mujic{\Lambda} reaches good agreement with the true density field down to the scale of the forward model, while maintaining consistency with the Gaussian prior through the projection step. It also broadly recovers the cosmic web classification, underscoring its value for deciphering environmental information in galaxy evolution studies. Beyond its key role in next-generation constrained simulations, the methodology offers a practical way to generate initial guesses and speed up field-level inference, especially for upcoming large-scale galaxy surveys.

We present \texttt{ORCHARD}, a publicly available planetary evolution code based on the gas giant evolution code, \texttt{APPLE}, capable of modeling the evolution and structures of terrestrial, super-Earth, sub-Neptune, Neptune, and gas giant planets and exoplanets from 0.5 M$_\oplus$ to 10 M$_J$. It supports not only the inhomogeneous and non-adiabatic evolution of gas giants and sub-Neptunes, but also the solidification of the mantles and cores of terrestrial planets, sub-Neptunes, and super-Earths. \texttt{ORCHARD} incorporates a state-of-the-art hydrogen-helium equation of state, ``metal" equations of state (water, ice mixtures, enstatite/perovskite, olivine/forsterite, iron), and atmospheric boundary conditions ranging from detailed non-gray radiative transfer models for Solar System giants to irradiated sub-Neptune atmospheres and bare rocky surfaces. The purpose of \texttt{ORCHARD} is to provide the scientific community with a flexible, unified tool for modeling planetary structures and evolution across the entire mass continuum of general astrophysical and planetary interest.

The Euclid Ecliptic Survey was conducted during the calibration phase of the mission, 23-31 December 2023, as a campaign to study Solar System objects. We used data from this survey to analyse more than 23 000 appeareances of 2321 known asteroids. Due to their high apparent angular motion relative to the background stars (5-$60^{\prime\prime}\,\mathrm{h}^{-1}$), these objects appear as streaks in VIS long-exposure images. We set out to estimate their spin periods, since only $7\%$ of them have periods published in the literature. We used multiple apertures along each streak to increase the time resolution of our light curves. Our method combines a Lomb-Scargle approach with a Markov chain Monte Carlo (MCMC) algorithm to characterise the posterior distributions. Some asteroids show multimodality in the MCMC search, indicating period aliases; in these cases, we report all aliases and their likelihoods. We validate our pipeline by comparing our fitted periods with 48 published periods, including period harmonics. We find that $44\%$ of our periods are within $1\%$ of those published and $98\%$ are within $15\%$, and we establish that with $98\%$ confidence the best solution can be found among the first three aliases. All reliable periods reported agree with our current understanding of the spin-period distribution for asteroids. We find 16 periods below the spin barrier of 2.2 h with absolute magnitudes below 19, and thus 16 candidate super-fast rotators. We provide light curves for all 2321 objects observed and 889 high-quality periods in an open-access catalogue. The asteroids with reported periods include five Mars crossers, four Cybeles, four Hildas, three Hungarias, and 877 asteroids in other regions of the main belt. Our results represent the first batch of spin periods extracted from Euclid light curves and include the first-ever period measurements for $93\%$ of the objects.

The \textit{Euclid} satellite will deliver a catalogue of optically-selected galaxy clusters spanning from around $2000$ deg$^2$ in Data Release (DR) 1 to around $14\,000$ deg$^2$ in DR3. We assess the validity of cluster clustering (CC) models for template-fitting, which complements the full-shape methodology in providing cosmological information from the anisotropy of the redshift-space two-point correlation function (2PCF). Both will be used to analyse the cluster 2PCF multipoles in \textit{Euclid}. We analyse the multipoles of the two-point redshift-space clustering of galaxy clusters simulated with the semi-analytic \code{PINOCCHIO} code using third-order Lagrangian perturbation theory, assuming a \textit{Euclid} DR1-like footprint of 500 deg$^2$ in the Northern Hemisphere and 1400 deg$^2$ in the Southern Hemisphere. We estimate the first three even multipoles of the 2PCF and associated covariance matrix from 1000 DR1-like synthetic catalogues. We study the impact of the modelling of nonlinearities, halo bias, and photometric redshift uncertainties on the 2PCF. We apply three clustering models to the mock catalogues at $0<z<2$ and virial mass $M_{\rm vir}>10^{14}\;h^{-1}\,M_\odot$ under realistic and optimistic photometric redshift uncertainty scenarios. We formulate a set of permissive and conservative criteria that should be fulfilled by the multipole cut-off scales and validate against 100 mock catalogues via inference of the growth rate times the matter power spectrum normalisation parameter, $f\sigma_8$. We test the dispersion, Scoccimarro, and Taruya--Nishimichi--Saito models. We find that the simplest of the three -- the dispersion model -- yields unbiased inferences on $f\sigma_8$ from CC down to $10$ $h^{-1}$ Mpc in a DR1-like setting. All clustering models provide very similar goodness-of-fit metrics in the presence of DR1-like cluster redshift uncertainties.

Large-scale spectroscopic surveys have collectively observed millions of stars across the Milky Way, but each derives stellar labels using independent pipelines with distinct modelling assumptions, introducing systematic offsets that obscure signals in chemical space and hinder large-scale Galactic archaeology. We present a unified deep-learning framework that delivers atmospheric parameters, chemical abundances for 20 elements, distances, and ages -- all on a single, self-consistent scale -- for an arbitrary number of spectroscopic surveys simultaneously. Our approach uses a Transformer model that ingests spectra of arbitrary wavelength range and resolution, trained end-to-end as a single model across all surveys, eliminating the need for post-hoc recalibration. We apply this framework to spectra from APOGEE DR17, GALAH DR3, DESI DR1, and $\textit{Gaia}$ RVS DR3, spanning resolutions from R ~ 2,000 to 28,000 and wavelengths from the optical to the near-infrared. On high-resolution APOGEE spectra the model achieves precisions of $18~$K in $\textrm{T}_{\rm eff}$, $0.04~$dex in $\textrm{log}\,\textit{g}$, $0.015~$dex in [Fe/H], and ${<}\,0.03~$dex across all abundances; on lower-resolution DESI spectra, typical precisions are $51~$K, $0.09~$dex, $0.04~$dex, and ${\sim}\,0.06~$dex, respectively. Cross-survey comparisons demonstrate that labels for the same stars observed by different surveys are consistent within model uncertainties; we further validate against external distance catalogs and open cluster metallicities and ages. The resulting homogeneous catalog enables Galactic archaeology at unprecedented scale and consistency, and the framework is readily extensible to forthcoming spectroscopic surveys such as SDSS-V, WEAVE, and 4MOST. The catalog is publicly available at this https URL.

Nitrogen-bearing molecules are more difficult to observe than oxygen-bearing ones, mainly due to the lower abundance of nitrogen in the interstellar medium. Therefore, the formation pathways of many of these species is still under debate. Studies prior to the launch of the JWST did not have the sensitivity to observe ices toward the youngest and most deeply embedded Class 0 objects. Here we will focus on OCN$^-$, CH$_3$CN, C$_2$H$_5$CN, NO, and N$_2$O in ices to better understand their formation. We use the data from the JOYS+ program to study 8 Class 0 and 11 Class I objects with JWST. We firmly detect OCN$^-$ in ices for all these objects, tentatively detect CH$_3$CN, C$_2$H$_5$CN, and N$_2$O toward three sources, and find upper limits on the NO abundance in ices. The OCN$^-$/CO$_2$ ratios are found to be larger by a factor of ~2-3 for the objects that have a visible CO$_2$ double peak (a sign of ice thermal processing) pointing to the moderate effect of temperature on OCN$^-$ production. Relation of H$_2$O, CO$_2$, and OCN$^-$ with $A_{\rm V}$ indicates that OCN$^-$ may tentatively form at a later stage than H$_2$O and CO$_2$. We find that the ratios of CH$_3$CN, C$_2$H$_5$CN, and N$_2$O with respect to OCN$^-$ are relatively constant within one order of magnitude across our objects, likely suggesting that they have similar ice environments. The upper limit abundances of NO are ~1 order of magnitude lower than what was previously predicted in ices of a mature protoplanetary disk. This indicates that the detected gas-phase NO in that disk may be a product of another molecule (e.g. N$_2$O) in the ices. We conclude that OCN$^-$ can get enhanced at higher temperatures by only a factor of ~2-3 and thus OCN$^-$ detection alone does not imply ice heating. Large-sample studies of OCN$^-$ toward pre-stellar cores will be useful to further confirm the formation timeline of this molecule.