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1. A Massive H i -absorption-selected Galaxy at z  ≈ 2.356

   https://doi.org/10.3847/2041-8213/adb83d  

   Kaur, B; Kanekar, N; Neeleman, M; Zhu, Y; Prochaska, J X; Rafelski, M; Becker, G (March 2025, The Astrophysical Journal Letters)

   Abstract We use the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array to detect CO(1–0), CO(3–2), and rest-frame 349 GHz continuum emission from an Hi-selected galaxy, DLA1020+2733g, atz ≈ 2.3568 in the field of thez= 2.3553 damped Lyαabsorber (DLA) toward QSO J1020+2733. The VLA CO(1–0) detection yields a molecular gas mass of (2.84 ± 0.42) × 10¹¹ × (α_CO/4.36)M_⊙, the largest ever measured in an Hi-selected galaxy. The DLA metallicity is +0.28 ± 0.16, from the Zniiλ2026 absorption line detected in a Keck Echellette Spectrograph and Imager spectrum. This continues the trend of high-metallicity DLAs being frequently associated with massive galaxies. We obtain a star formation rate (SFR) of ≲400M_⊙yr⁻¹from the rest-frame 349 GHz continuum emission and a relatively long molecular gas depletion timescale of ≳0.6 Gyr. The excitation of theJ= 3 rotational level is subthermal, with $r_{31}\equiv L{\prime }_{\mathrm{CO}(3-2)}/L{\prime }_{\mathrm{CO}(1-0)}=0.513\pm 0.081$, suggesting that DLA1020+2733g has a low SFR surface density. The large velocity spread of the CO lines, ≈500 km s⁻¹, and the long molecular gas depletion timescale suggest that DLA1020+2733g is likely to be a cold rotating-disk galaxy. 

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2. A Complete Triad of Zero‐Valent 17‐Electron Monoradicals of Group 7 Elements Stabilized by m ‐Terphenyl Isocyanides

   https://doi.org/10.1002/anie.202300254  

   Salsi, Federico; Wang, Shuai; Teutloff, Christian; Busse, Marvin; Neville, Michael L.; Hagenbach, Adelheid; Bittl, Robert; Figueroa, Joshua S.; Abram, Ulrich (April 2023, Angewandte Chemie International Edition)

   Abstract The first consistent series of mononuclear 17‐electron complexes of three Group 7 elements has been isolated in crystalline form and studied by X‐ray diffraction and spectroscopic methods. The paramagnetic compounds have a composition of [M⁰(CO)(CNp‐F‐Ar^DArF2)₄] (M=Mn, Tc, Re; Ar^DArF2=2,6‐(3,5‐(CF₃)₂C₆H₃)₂C₆H₂F) and are stabilized by four sterically encumbering isocyanides, which prevent the metalloradicals from dimerization. They have a square pyramidal structure with the carbonyl ligands as apexes. The frozen‐solution EPR spectra of the rhenium and technetium compounds are clearly anisotropic with large⁹⁹Tc and^185,187Re hyperfine interactions for one component. High‐field EPR (Q band and W band) has been applied for the elucidation of the EPR parameters of the manganese(0) complex. 

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3. A rare isocyanide derived from an unprecedented neutral yttrium( ii ) bis(amide) complex

   https://doi.org/10.1039/d3sc00171g  

   Jena, Rashmi; Benner, Florian; Delano, Francis; Holmes, Daniel; McCracken, John; Demir, Selvan; Odom, Aaron L. (April 2023, Chemical Science)

   A room temperature stable Y(ii)bis(amide) has been prepared and fully characterized. The complex reacts withtert-butylisocyanide to make a rare example of a transition metal isocyanide, CN–Y(NHAr*)₂. 

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4. The Qz5 Survey. I. How the H i Mass Density of the Universe Evolves with Cosmic Time

   https://doi.org/10.3847/1538-4357/adb430  

   Oyarzún, Grecco A; Rafelski, Marc; Christensen, Lise; Ozyurt, Fiona; Jorgenson, Regina A; Neeleman, M; Fumagalli, Michele; Prochaska, J Xavier; Worseck, G; Wisz, M E; et al (April 2025, The Astrophysical Journal)

   Abstract We report that the neutral hydrogen (Hi) mass density of the Universe (ρ_Hi) increases with cosmic time sincez ∼ 5, peaks atz ∼ 3, and then decreases towardz ∼ 0. This is the first result of Qz5, our spectroscopic survey of 63 quasars atz ≳ 5 with VLT/X-SHOOTER and Keck/ESI aimed at characterizing intervening Higas absorbers atz ∼ 5. The main feature of Qz5 is the high resolution (R ∼ 7000–9000) of the spectra, which allows us to (1) accurately detect high column density Higas absorbers in an increasingly neutral intergalactic medium atz ∼ 5 and (2) determine the reliability of previousρ_Himeasurements derived with lower resolution spectroscopy. We find five intervening damped Lyαabsorbers (DLAs) atz > 4.5, which corresponds to the lowest DLA incidence rate ( $0.034_{0.02}^{0.05}$) atz ≳ 2. We also measure the lowestρ_Hiatz ≳ 2 from our sample of DLAs and subDLAs, corresponding toρ_Hi $=0.56_{0.31}^{0.82}\times 10^8{M}_{\odot }$Mpc⁻³atz ∼ 5. Taking into account our measurements atz ∼ 5 and systematic biases in the DLA detection rate at lower spectral resolutions, we conclude thatρ_Hidoubles fromz ∼ 5 toz ∼ 3. From these results emerges a qualitative agreement between how the cosmic densities of Higas mass, molecular gas mass, and star formation rate build up with cosmic time. 

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5. A [C ii ] 158 μ m Survey of Damped Lyα Absorber Galaxies at z  ∼ 4: Observations of Dense and Metal-enriched Neutral Gas within the Circumgalactic Medium of Star-forming Galaxies

   https://doi.org/10.3847/1538-4357/adbbd1  

   Neeleman, Marcel; Kanekar, Nissim; Prochaska, J Xavier; Rafelski, Marc A; Kahinga, Lordrick A (April 2025, The Astrophysical Journal)

   Abstract We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Lyαabsorbers (DLAs) atz ≈ 4.1–4.5, using the [Cii] 158μm ([Cii]) line. We detect seven [Cii]-emitting galaxies in the fields of five DLAs, all of which have absorption metallicity [M/H] > −1.5. We find that the detectability of these Hi-selected galaxies with ALMA is a strong function of DLA metallicity, with a detection rate of $71_{-20}^{+11}$% for DLAs with [M/H] > −1.5 and 0⁺¹⁸% for DLAs with [M/H] < −1.5. The identified DLA galaxies have far-IR properties similar to those of typical star-forming galaxies atz ∼ 4, with estimated obscured star formation rates ranging from ≲6M_⊙yr⁻¹to 110M_⊙yr⁻¹. High-metallicity DLAs therefore provide an efficient way to identify and study samples of high-redshift, star-forming galaxies, without preselecting the galaxies by their emission properties. The agreement between the velocities of the metal absorption lines of the DLA and the [Cii] emission line of the DLA galaxy indicates that the metals within the DLA originated in the galaxy. With observed impact parameters between 14 and 59 kpc, this indicates that star-forming galaxies atz ∼ 4 have a substantial reservoir of dense, cold, neutral gas within their circumgalactic medium that has been enriched with metals from the galaxy. 

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