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We present the final configuration chosen to be build for the Columbia Stellarator eXperiment (CSX), a new stellartor experiment at Columbia University. In a recent publication, Baillod et al. (NF, 2025) discussed in detail the different objectives, constraints, and optimization algorithms used to find an optimal configuration for CSX. In this paper, we build upon this first publication and find a configuration that satisfies all the constraints. We describe this final configuration including discussion of the coil finite build effects, sensitivity analyses, and the plasma neoclassical physics properties using the SFINCS code. These post-processing calculations provide a confirmation that the experimental goals of CSX can be achieved with the presented configuration.

This work presents the compact experimental negative triangularity reactor (CENTAUR), a low overnight cost, high-field tokamak, breakeven reactor design, achieving a predicted total fusion power of 40MW and scientific energy gain of 1.3. Ballooning stability calculations confirm that the device's pedestal is within the first stability regime, which is consistent with the expected ELM-free operation associated with negative triangularity (NT) plasmas. The geometry of the NT divertor allows for high fraction of radiated power (13.5\\(\\%\\)) between the separatrix and plasma facing components. Heat transport modeling based on simulations of the edge region show heat loads into plasma facing components well below material limits. The magnet system employs rare-earth barium copper oxide (REBCO) high-temperature superconductors in 18 toroidal field coils, an hourglass-shaped central solenoid, and six poloidal field coils to support high-field (\\(B_0=10.9\\) T) plasma confinement, shaping, and current drive. Neutronics analysis shows that a 12 cm \\(B_4C\\) shield keeps superconducting magnet heating below the 33~K quench limit during 10 s, 40 MW DT pulses. With this shielding, the modeled fluence indicates HTS components can survive more than ten times the 3000-pulse design lifetime. Iteration of economic analysis in tandem with the technical design process allows CENTAUR to achieve its overnight cost goal of$\\$ $2B determined using a custom costing model that predicts a total overnight cost of \\(1.6\\)B\\(0.2\\)B.

Detecting the first generation of stars, Population III (Pop III), has been a long-standing goal in astrophysics, yet they remain elusive even in the JWST era. Here we present a novel NIRCam-based selection method for Pop III galaxies, and carefully validate it through completeness and contamination simulations. We systematically search ≃ 500 arcmin2 across JWST legacy fields for Pop III candidates, including GLIMPSE, which, assisted by gravitational lensing, has produced JWST’s deepest NIRCam imaging thus far. We discover one promising Pop III galaxy candidate (GLIMPSE-16043) at z=6.50−0.24+0.03 , a moderately lensed galaxy ( μ=2.9−0.2+0.1 ) with an intrinsic UV magnitude of MUV=−15.89−0.14+0.12 . It exhibits key Pop III features: strong Hα emission (rest-frame EW 2810 ± 550 Å); a Balmer jump; no dust (UV slope β = −2.34 ± 0.36); and undetectable metal lines (e.g., [O iii]; [O iii]/Hβ < 0.44), implying a gas-phase metallicity of Zgas/Z⊙ < 0.5%. These properties indicate the presence of a nascent, metal-deficient young stellar population (<5 Myr) with a stellar mass of ≃105 M⊙. Intriguingly, this source deviates significantly from the extrapolated UV–metallicity relation derived from recent JWST observations at z = 4–10, consistent with UV enhancement by a top-heavy Pop III initial mass function or the presence of an extremely metal-poor active galactic nucleus. We also derive the first observational constraints on the Pop III UV luminosity function at z ≃ 6–7. The volume density of GLIMPSE-16043 (≈10−4 cMpc−3) is in excellent agreement with theoretical predictions, independently reinforcing its plausibility. This study demonstrates the power of our novel NIRCam method to finally reveal distant galaxies even more pristine than the Milky Way’s most metal-poor satellites, thereby promising to bring us closer to the first generation of stars than we have ever been before.

As observations have yet to constrain the ionizing properties of the faintest (MUV ≳ −16) galaxies, their contribution to cosmic reionization remains unclear. The rest-frame ultraviolet (UV) continuum slope (β) is a powerful diagnostic of stellar populations and one of the few feasible indicators of the escape fraction of ionizing photons (fesc) for such faint galaxies at high redshift. Leveraging ultradeep JWST/NIRCam GLIMPSE imaging of the strong lensing field Abell S1063, we estimate the UV continuum slopes of 553 galaxies at z > 6 with absolute magnitudes down to MUV ≃ −12.5. We find a modest evolution of β with redshift and a flattening in the β–MUV relation such that galaxies fainter than MUV ∼ −16.5 no longer exhibit the bluest UV slopes. The 136 ultrafaint galaxies with MUV > −16 are a diverse population encompassing dusty (30%), old (15%), and low-mass (50%) galaxies. We apply the empirical β–fesc relation from local Lyman continuum leakers, finding the mean fesc peaks at ∼20% at MUV = −16.5 and declines towards fainter galaxies, while remaining consistent with fesc = 14% within the uncertainties, in agreement with recent radiative transfer simulations. Incorporating GLIMPSE constraints on the UV luminosity function, ionizing photon production efficiency, and escape fractions produces a reionization history consistent with independent observational constraints. Our results indicate galaxies with an MUV between −18 and −14 supplied ∼60% of the ionizing photons to cosmic reionization, while the lower fesc of fainter galaxies produces a natural cutoff in the ionizing photon production rate density.

Urban biodiversity offers important benefits to residents and may be crucial to reaching global biodiversity conservation targets, but little research has been conducted on how cities actually plan for biodiversity. In this study, we conducted a mixed methods content analysis of biodiversity plans by 39 cities around the world to determine whether they measured their actions, how they did so (via quantitative indicators and qualitative outputs), and what topics these actions and measures covered. We based our analytical framework on the Singapore Index on Cities' Biodiversity (also known as the City Biodiversity Index), a widely applied 23-indicator index that helps cities track their progress in biodiversity planning. The Singapore Index groups its indicators into the following three core components: native biodiversity, ecosystem services, and governance and management. For actions and measures not classifiable by the Singapore Index, we inductively derived additional categories. Across all plans, we identified 2,231 actions, 346 indicators, and 444 outputs. We found that all of the plans included actions, while 82% included measures (67% included indicators and 72% included outputs). Only 29% of actions were associated with a measure. Overall, the plans covered all of the categories in the Singapore Index, particularly within the core components of native biodiversity and governance and management, though some plans had a narrower focus. The 20 additional urban biodiversity topics that were not covered by the Singapore Index framework included socioeconomic considerations, data collection, genetic diversity, urban agriculture and forestry, green infrastructure, human-wildlife conflicts, indigenous concerns, and citizen science. Indicators were the most common measures for native biodiversity and ecosystem service topics, while outputs were the most common measures for governance and management. Our results may inform the revision and development of urban biodiversity indicators in the post-2020 framework and of other initiatives that guide cities in contributing to local and global biodiversity goals.

We report the discovery of two galaxy candidates at redshifts between 15.7 < z < 16.4 in James Webb Space Telescope (JWST) observations from the GLIMPSE survey. These robust sources were identified using a combination of Lyman break selection and photometric redshift estimates. The ultradeep NIRCam imaging from GLIMPSE, combined with the strong gravitational lensing of the AS1063 galaxy cluster, allows us to probe an intrinsically fainter population (down to MUV = −17.0 mag) than previously achievable. These galaxies have absolute magnitudes ranging from MUV = −17.0 to −17.2 mag, with blue (β ≃ −2.87) ultraviolet (UV) continuum slopes, consistent with young, dust-free stellar populations. The number density of these objects, log10(ϕ/[Mpc−3 mag−1]) = −3.47−0.10+0.13 at MUV = −17, is in clear tension with pre-JWST theoretical predictions, extending the overabundance of galaxies from z ∼ 10 to z ∼ 17. These results, together with the scarcity of brighter galaxies in other public surveys, suggest a steep decline in the bright end of the UV luminosity function at z ∼ 16, implying efficient star formation and possibly a close connection to the halo mass function at these redshifts. Testing a variety of star formation histories suggests that these sources are plausible progenitors of the unusually UV-bright galaxies that JWST now routinely uncovers at z = 10–14. Overall, our results indicate that the luminosity distribution of the earliest star-forming galaxies could be shifting toward fainter luminosities, implying that future surveys of cosmic dawn will need to explore this faint luminosity regime.

JWST has revealed an abundance of supermassive black holes (BHs) in the early Universe, and yet the lowest mass seed BHs that gave rise to these populations remain elusive. Here, we present a systematic search for broad-line active galactic nuclei (AGNs) in some of the faintest high-z galaxies surveyed yet by combining ultra-deep JWST/NIRSpec G395M spectroscopy with the strong lensing aid in AS1063. By employing the profile of the [O iii]λ5007 emission lines as a template for narrow-line components and carefully cross-validating with mock observations, we identify a sample of 10 broad-line AGNs at 4.5 < z < 7.0 (eight secure, two tentative). The inferred BH masses from the broad Hα line explore the intermediate BH mass regime down to ∼105.5 M⊙. The stellar mass (M*) is estimated with a galaxy+AGN composite model, and we find the BH to stellar mass ratio spans down to MBH/M* ≲ 0.1%, unveiling populations on the empirical MBH–M* relation observed in the local Universe. We also derive the BH mass function and investigate its low-mass end at this epoch. While we confirm the agreement of our results with previous studies at MBH ≳ 106.5M⊙, we find the mass range of ∼105.5 M⊙ features an enhanced abundance with respect to the extrapolated best-fit Schechter function. Comparison with theoretical models suggests that a possible origin for this enhanced abundance is the direct-collapse BH formation, supporting the scenario that the direct collapse of massive gas clouds is a significant pathway for the earliest supermassive BHs.

We present the discovery of extreme nitrogen enrichment by Wolf Rayet nitrogen (WN) stars in the metal-poor (∼10%Z⊙), lensed, compact (Reff ∼ 20 pc) galaxy RXCJ2248 at z = 6.1, revealed by unprecedentedly deep JWST/NIRSpec medium-resolution spectroscopy from the GLIMPSE-D Survey. The exquisite signal-to-noise ratio reveals multiple high-ionization nebular lines and broad Balmer and [O iii] components (FWHM ∼700–3000 km s−1). We detect broadened He ii λ1640 and λ4687 (FWHM ∼ 530 km s−1) and strong N iii λ4642 emission consistent with a population of WN stars, making RXCJ2248 the most distant galaxy with confirmed Wolf Rayet (WR) features to date. We measure the multiphase nebular density across five ions, the direct-method metallicity ( 12+log(O/H)=7.753±0.025 ), and a nonuniform elemental enrichment pattern of extreme N/O enhancement ( log(N/O)=−0.391±0.037 from N+, N+2, and N+3) but suppressed C/O relative to empirical C/N trends. We show that this abundance pattern can be explained by enrichment from a dual-burst with a low WR carbon/WN ratio, as expected at low metallicities. Crucially, these signatures can only arise during a brief, rare evolutionary window shortly after a burst (∼3–6 Myr), when WN stars dominate chemical feedback but before dilution by later yields (e.g., supernovae). The observed frequency of strong N emitters at high−z implies a ∼50 Myr burst duty cycle, suggesting that N/O outliers may represent a brief but ubiquitous phase in the evolution of highly star-forming early galaxies. The WN detection in RXCJ2248, therefore, provides the first direct evidence of WR-driven nitrogen enrichment in the first billion years of the Universe and a novel timing argument for the bursty star formation cycles that shaped galaxies at cosmic dawn.

The detection of strong Balmer breaks and absorption features in Little Red Dots (LRDs) suggests they host active galactic nuclei embedded within dense gas envelopes, potentially powered by super-Eddington accretion. We present GLIMPSE-17775, a luminous (Lbol ∼ 1045 erg s−1) LRD at z = 3.501 behind Abell S1063 (μ ∼ 2), observed with deep JWST/NIRCam and a ∼20 hr (80 hr delensed) NIRSpec G395M spectrum. The data reveal over 40 emission and absorption features, including a rich forest of low-ionization Fe ii lines and numerous broad hydrogen recombination transitions. We use this depth to test the dense-gas interpretation through five independent diagnostics. Nearly all permitted lines show exponential wings with consistent FWHM, a signature of Thomson scattering requiring ne ≳ 108 cm−3. Adopting this width yields MBH ∼ 106.7M⊙, a factor of 10 lower than Gaussian fits, and λEdd ∼ 1.8. Additional diagnostics support the same picture: a pronounced Balmer break (fν,4050/fν,3670 = 2.0 ± 0.1), enhanced He i λ7065 and λ10830 with P-Cygni absorption, Bowen-fluorescent O i λ8446–λ11290 emission requiring Lyβ pumping, and 16 Fe ii lines matching fluorescence models. These features indicate a dense (n ∼ 108 cm−3), partially ionized cocoon where scattering and fluorescence dominate line formation, providing strong evidence that at least some LRDs are powered by super-Eddington black hole growth in the early Universe.