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1. Generalized T _e ([O iii ])– T _e (He i ) Discrepancies in Ionized Nebulae: Possible Evidence of Case B Deviations and Temperature Inhomogeneities

   https://doi.org/10.3847/1538-4357/adc67a  

   Méndez-Delgado, J E; Skillman, E D; Aver, E; Morisset, C; Esteban, C; García-Rojas, J; Kreckel, K; Rogers, N_S J; Rosales-Ortega, F F; Arellano-Córdova, K Z; et al (June 2025, The Astrophysical Journal)

   Abstract The physics of recombination lines in the Heisinglet system is expected to be relatively simple, supported by accurate atomic models. We examine the intensities of Heisingletsλ3614, λ3965, λ5016, λ6678, and λ7281 and the triplet Heiλ5876 in various types of ionized nebulae and compare them with theoretical predictions to test the validity of the “Case B” recombination scenario and the assumption of thermal homogeneity. Our analysis includes 85 spectra from Galactic and extragalactic Hiiregions, 90 from star-forming galaxies, and 218 from planetary nebulae, all compiled by the Deep Spectra of Ionized Regions Database Extended (DESIRED-E) project. By evaluating the ratios Heiλ7281/λ6678 and Heiλ7281/λ5876, we determineT_e(Hei) and compare it with direct measurements ofT_e([Oiii]λ4363/λ5007). We find thatT_e(Hei) is systematically lower thanT_e([Oiii]) across most objects and nebula types. Additionally, we identify a correlation between the abundance discrepancy factor (ADF(O²⁺)) and the differenceT_e([Oiii]) –T_e(Hei) for planetary nebulae. We explore two potential explanations: photon loss fromn¹P → 1¹Stransitions and temperature inhomogeneities. Deviations from “Case B” may indicate photon absorption by Hirather than Heiand/or generalized ionizing photon escape, highlighting the need for detailed consideration of radiative transfer effects. If temperature inhomogeneities are widespread, identifying a common physical phenomenon affecting all ionized nebulae is crucial. Our results suggest that both scenarios can contribute to the observed discrepancies. 

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2. A Quasar-anchored Protocluster at z = 6.6 in the ASPIRE Survey. I. Properties of [O iii ] Emitters in a 10 Mpc Overdensity Structure

   https://doi.org/10.3847/1538-4357/adb1bd  

   Champagne, Jaclyn B; Wang, Feige; Zhang_张, Haowen 昊文; Yang, Jinyi; Fan, Xiaohui; Hennawi, Joseph F; Sun, Fengwu; Bañados, Eduardo; Bosman, Sarah_E I; Costa, Tiago; et al (March 2025, The Astrophysical Journal)

   Abstract A SPectroscopic survey of bIased halos in the Reionization Era is a quasar legacy survey primarily using JWST to target a sample of 25z > 6 quasars with NIRCam slitless spectroscopy and imaging. The first study in this series found evidence of a strong overdensity of galaxies around J0305−3150, a luminous quasar atz= 6.61, within a single NIRCam pointing obtained in JWST Cycle 1. Here we present the first results of a JWST Cycle 2 mosaic that covers 35 arcmin²with NIRCam imaging/wide-field slitless spectroscopy of the same field to investigate the spatial extent of the putative protocluster. The F356W grism data target [Oiii]+Hβat 5.3 < z < 7 and reveal a population of 124 line emitters down to a flux limit of 1.2 × 10⁻¹⁸erg s⁻¹cm⁻². Fifty-three of these galaxies lie at 6.5 < z < 6.8 spanning 10 cMpc on the sky, corresponding to an overdensity within a 2500 cMpc³volume of 12.5 ± 2.6, anchored by the quasar. Comparing to the [Oiii] luminosity function from the Emission line galaxies and Intergalactic Gas in the Epoch of Reionization project, we find a dearth of faint [Oiii] emitters at log(L/erg s⁻¹) < 42.3, which we suggest is consistent with either bursty star formation causing galaxies to scatter around the grism detection limit or modest suppression from quasar feedback. While we find a strong filamentary overdensity of [Oiii] emitters consistent with a protocluster, we suggest that we could be insensitive to a population of older, more massive Lyman break galaxies with weak nebular emission on scales >​​​​​​10 cMpc. 

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3. EELG1002: A Record-breaking [O iii ]+H β EW ∼ 3700 Å Galaxy at z  ∼ 0.8—Analog of Early Galaxies?

   https://doi.org/10.3847/1538-4357/ae0330  

   Khostovan, Ali Ahmad; Kartaltepe, Jeyhan S; Brinch, Malte; Casey, Caitlin; Faisst, Andreas; Harish, Santosh; Gozaliasl, Ghassem; Onodera, Masato; Yabe, Kiyoto (November 2025, The Astrophysical Journal)

   Abstract Extreme emission line galaxies (EELGs) are powerful low-zanalogs of high-zgalaxies that can provide us valuable insights of early Universe conditions. We present a detailed analysis of EELG1002: az= 0.8275 EELG identified within archival Gemini/GMOS spectroscopy as part of the ongoing COSMOS Spectroscopic Archive. We find EELG1002 is a low-mass (∼10⁸M_⊙), compact (∼530 pc), bursty star-forming galaxy with a ∼15–35 Myr mass doubling timescale. EELG1002 has record-breaking rest-frame [Oiii]+HβEW ∼3100–3700 Å; ∼32–36× higher than typicalz ∼ 0.8 [Oiii] emitters with similar stellar mass; and higher than typicalz > 5 galaxies. We find no clear evidence of an active galactic nucleus suggesting the emission lines are star formation driven. EELG1002 is chemically unevolved (directT_e; $12+{\log }_{10}\left(\mathrm{O/H}\right)\sim 7.52$ consistent withz > 5 galaxies at fixed stellar mass) and may be undergoing a first intense, bursty star formation phase analogous to conditions expected of galaxies in the early Universe. We find evidence for a highly energetic interstellar medium ([Oiii]/[Oii] ∼ 9) and hard ionizing radiation field (elevated [Neiii]/[Oii] at fixed [Oiii]/[Oii]). Coupled with its compact, metal-poor, and actively star-forming nature, EELG1002 is found to efficiently produce ionizing photons (ξ_ion ∼ 10^25.74erg⁻¹Hz) and may have ∼10%–20% Lyman Continuum (LyC) escape suggesting such sources may be important analogs of galaxies responsible for reionization. We find a dynamical mass of ∼10⁹M_⊙suggesting copious amounts of gas to support intense star formation as also suggested by identified Illustris-TNG analogs. EELG1002 may be an ideal low-zlaboratory of galaxies in the early Universe and demonstrates how archival data sets can support high-zscience and next-generation surveys planned with Euclid and Roman. 

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4. A GLIMPSE into the very faint end of the H β +[O III] λλ 4960,5008 luminosity function at z ∼ 7 – 9 behind Abell S1063

   https://doi.org/10.1051/0004-6361/202556868  

   Korber, Damien; Chemerynska, Iryna; Furtak, Lukas J; Atek, Hakim; Endsley, Ryan; Schaerer, Daniel; Chisholm, John; Kokorev, Vasily; Saldana-Lopez, Alberto; Adamo, Angela; et al (April 2026, Astronomy & Astrophysics)

   We used the ultra-deep GLIMPSE JWST/NIRCam survey to constrain the faint end of the [O III]+Hβluminosity function (LF) down to 10³⁹erg s⁻¹atz ∼ 7 − 9 behind the lensed Hubble Frontier Field galaxy cluster Abell S1063. We applied a spectral energy distribution fitting on a Lyman-break galaxy selected sample of 164 lensed galaxies and measured their combined Hβ+[O III]λλ4960, 5008 flux to build the emission line LF. We found a [O III]+HβLF with a faint-end slope (α= −1.78^+0.06_−0.06forz = 7 − 8 andα= −1.55^+0.11_−0.11forz = 8 − 9), which is flatter than the UV LF at similar redshifts (α ≤ −2) and suggests a lower number density of weak [O III]+Hβemitting galaxies at fixedM_UV. We analysed several possible explanations: (i) a decrease in the [O III]+Hβ-to-UV ratio due to bursty star formation histories (SFHs), (ii) the effect of metallicity on the [O III]-to-Hβratio, or (iii) signs of a faint-end turnover in the UV LF. Under the assumption of an evolving [O III]-to-Hβratio, we separated the contribution of [O III]λ5008 and Hβand obtained a flatter [O III]λ5008 LF (α= −1.66^+0.05_−0.05forz = 7 − 8 andα= −1.45^+0.09_−0.10forz = 8 − 9) but steeper HβLF ($$ \alpha=-1.95_{-0.08}^{+0.08} $$ forz = 7 − 8 andα= −1.68^+0.13_−0.14forz = 8 − 9). The combination of a decreasing metallicity and bursty SFH can reconcile the observed differences between the UV and [O III]+HβLF. By converting this LF into the ionising photon-production rateṄ_ion, we show that galaxies withL_Hα ≥ 10³⁹erg s⁻¹, that is, with a star formation rate (SFR) (Hα)  ≥  5 × 10⁻³M_⊙yr⁻¹) cause 31%−90% and 46%−156% of the ionising photon budget (at 7 < z < 8 and 8 < z < 9), when we assume a constant escape fraction of Lyman-continuum photon (f_esc = 0.14). The shape of the LF further shows the negligible contribution of faint galaxies to theṄ_ion. Additionally, we derived the cosmic star formation rate density (SFRD), finding results consistent with previous estimates. However, the sensitivity of GLIMPSE to lower SFRs reinforces the conclusion that very faint galaxies contribute very little toṄ_ionand the SFRD. Our results suggests that GLIMPSE has detected the bulk of the total [O III]+Hβemission from star-forming galaxies, and that galaxies below our detection limits are likely minor contributors to cosmic re-ionisation. 

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5. Exploring sulfur donor atom coordination chemistry with La( ii ), Nd( ii ), and Tm( ii ) using a terphenylthiolate ligand

   https://doi.org/10.1039/d4cc01037j  

   Gilbert-Bass, Kito; Stennett, Cary R.; Grotjahn, Robin; Ziller, Joseph W.; Furche, Filipp; Evans, William J. (April 2024, Chemical Communications)

   To expand the range of donor atoms known to stabilize 4fⁿ5d¹Ln(ii) ions beyond C, N, and O first row main group donor atoms, the Ln(iii) terphenylthiolate iodides, Ln^III(SAr^iPr6)₂I (Ar^iPr6= C₆H₃-2,6-(C₆H₂-2,4,6-ⁱPr₃)₂, Ln = La, Nd) were reduced to Ln^II(SAr^iPr6)₂complexes. 

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