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1. Fine-structure Transitions of Ne ⁺ , Ar ⁺ , Ne ²⁺ , and Ar ²⁺ Induced by Collisions with Atomic Hydrogen

   https://doi.org/10.3847/1538-4357/ad0e77  

   Yan, Pei-Gen; Babb, James F (January 2024, The Astrophysical Journal)

   Abstract We calculate cross sections for fine-structure transitions of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with atomic hydrogen by using quantum-mechanical methods. Relaxation rate coefficients are calculated for temperatures up to 10,000 K. The temperature-dependent critical densities for the relaxation of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with H have been determined and compared to the critical densities for collisions with electrons. The present calculations will be useful for studies utilizing the infrared lines [Neii] 12.8, [Neiii] 15.6, [Neiii] 36.0, [Arii] 6.99, [Ariii] 8.99, and [Ariii] 21.8μm as diagnostics of, for example, planetary nebulae and star formation. 

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2. Reaction landscape of a mononuclear Mn ^III –hydroxo complex with hydrogen peroxide

   https://doi.org/10.1039/D3DT02672H  

   Grotemeyer, Elizabeth N; Parham, Joshua D; Jackson, Timothy A (October 2023, Dalton Transactions)

   The reaction of a mononuclear Mn^III–hydroxo complex with hydrogen peroxide under different reaction conditions yields bis(μ-oxo)dimanganese(iii,iv), Mn^III–hydroperoxo, and Mn^III–peroxo intermediates. 

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3. The CGM ² Survey: Quenching and the Transformation of the Circumgalactic Medium

   https://doi.org/10.3847/1538-4357/acc86a  

   Tchernyshyov, Kirill; Werk, Jessica K.; Wilde, Matthew C.; Prochaska, J. Xavier; Tripp, Todd M.; Burchett, Joseph N.; Bordoloi, Rongmon; Howk, J. Christopher; Lehner, Nicolas; O’Meara, John M.; et al (May 2023, The Astrophysical Journal)

   Abstract This study addresses how the incidence rate of strong Oviabsorbers in a galaxy’s circumgalactic medium (CGM) depends on galaxy mass and, independently, on the amount of star formation in the galaxy. We use Hubble Space Telescope/Cosmic Origins Spectrograph absorption spectroscopy of quasars to measure Oviabsorption within 400 projected kpc and 300 km s⁻¹of 52 galaxies withM_*∼ 3 × 10¹⁰M_⊙. The galaxies have redshifts 0.12 <z< 0.6, stellar masses 10^10.1M_⊙<M_*< 10^10.9M_⊙, and spectroscopic classifications as star-forming or passive. We compare the incidence rates of high column density Oviabsorption (N_OVI≥ 10^14.3cm⁻²) near star-forming and passive galaxies in two narrow ranges of stellar mass and, separately, in a matched range of halo mass. In all three mass ranges, the Ovicovering fraction within 150 kpc is higher around star-forming galaxies than around passive galaxies with greater than 3σ-equivalent statistical significance. On average, the CGM of star-forming galaxies withM_*∼ 3 × 10¹⁰M_⊙contains more Ovithan the CGM of passive galaxies with the same mass. This difference is evidence for a CGM transformation that happens together with galaxy quenching and is not driven primarily by halo mass. 

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4. An Fe( ii ) complex detects hydrogen peroxide with ¹ H and ¹⁹ F magnetic resonance imaging responses

   https://doi.org/10.1039/D5CC04066C  

   Karbalaei, Sana; Franke, Alicja; Zahl, Achim; Pokkuluri, P Raj; Beyers, Ronald J; Ivanović-Burmazović, Ivana; Goldsmith, Christian R (October 2025, Chemical Communications)

   A highly air- and water-stable Fe(ii) complex with a fluorinated ligand has a strong¹⁹F MRI signal but is a poorT₁-weighted¹H MRI contrast agent. Upon oxidation by H₂O₂, the¹⁹F MRI signal decays as the relaxivity for¹H MRI markedly improves. 

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5. The CGM ² Survey: Circumgalactic O vi from Dwarf to Massive Star-forming Galaxies

   https://doi.org/10.3847/1538-4357/ac450c  

   Tchernyshyov, Kirill; Werk, Jessica K.; Wilde, Matthew C.; Prochaska, J. Xavier; Tripp, Todd M.; Burchett, Joseph N.; Bordoloi, Rongmon; Howk, J. Christopher; Lehner, Nicolas; O’Meara, John M.; et al (March 2022, The Astrophysical Journal)

   Abstract We combine 126 new galaxy-Oviabsorber pairs from the CGM²survey with 123 pairs drawn from the literature to examine the simultaneous dependence of the column density of Oviabsorbers (N_OVI) on galaxy stellar mass, star-formation rate, and impact parameter. The combined sample consists of 249 galaxy-Oviabsorber pairs coveringz= 0–0.6, with host galaxy stellar massesM_*= 10^7.8–10^11.2M_⊙and galaxy-absorber impact parametersR_⊥= 0–400 proper kiloparsecs. In this work, we focus on the variation ofN_OVIwith galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the averageN_OVIwithin one virial radius of a star-forming galaxy is greatest for star-forming galaxies withM_*= 10^9.2–10¹⁰M_⊙. Star-forming galaxies withM_*between 10⁸and 10^11.2M_⊙can explain most Ovisystems with column densities greater than 10^13.5cm⁻². Sixty percent of the Ovimass associated with a star-forming galaxy is found within one virial radius, and 35% is found between one and two virial radii. In general, we find that some departure from hydrostatic equilibrium in the CGM is necessary to reproduce the observed Oviamount, galaxy mass dependence, and extent. Our measurements serve as a test set for CGM models over a broad range of host galaxy masses. 

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