We investigate the environmental dependence of the mass-metallicity relation at z = 2 with MOSFIRE/Keck as part of the ZFIRE survey. Here, we present the chemical abundance of a Virgo-like progenitor at z = 2.095 that has an established red sequence. We identified 43 cluster (< z >= 2.095 ± 0.004) and 74 field galaxies (< z >= 2.195 ± 0.083) for which we can measure metallicities. For the first time, we show that there is no discernible difference between the mass-metallicity relation of field and cluster galaxies to within 0.02dex. Both our field and cluster galaxy mass-metallicity relations are consistent with recent field galaxy studies at z ∼ 2. We present hydrodynamical simulations for which we derive mass-metallicity relations for field and cluster galaxies. We find at most a 0.1dex offset towards more metal-rich simulated cluster galaxies. Our results from both simulations and observations are suggestive that environmental effects, if present, are small and are secondary to the ongoing inflow and outflow processes that are governed by galaxy halo mass.

The reactions CH n D 4−n + OH → P and CH 4 + OD → CH 3 + HOD as a test of current direct dynamics computational methods to determine variational transition-state rate constants. I.The pulsed laser photolysis/pulsed laser-induced fluorescence technique has been applied to obtain rate coefficients for OHϩCH 3 C͑O͒CH 3 and CD 3 C͑O͒CD 3 of k H (298-832 K)ϭ(3.99Ϯ0.40) ϫ10 Ϫ24 T 4.00 exp(453Ϯ44)/T and k D (298-710 K)ϭ(1.94Ϯ0.31)ϫ10 Ϫ21 T 3.17 exp(Ϫ529Ϯ68)/ T cm 3 molecule Ϫ1 s Ϫ1 , respectively. Three pathways were characterized via the CBS-QB3 ab initio method to obtain complete basis set limits for coupled-cluster theory. Addition to form CH 3 C͑O͒͑OH͒CH 3 , followed by dissociation to CH 3 ϩCH 3 C͑O͒OH, is negligibly slow. Variational transition state theory reveals that the dominant products are CH 3 C͑O͒CH 2 ϩH 2 O formed by direct abstraction at higher temperatures and via a hydrogen-bonded complex below about 450 K. Inclusion of tunneling gives good accord with the observed kinetic isotope effect down to about 250 K.

During the first three observing runs of the Advanced gravitational-wave detector network, the LIGO/Virgo collaboration detected several black hole binary (BHBH) mergers. As the population of detected BHBH mergers grows, it will become possible to constrain different channels for their formation. Here we consider the chemically homogeneous evolution (CHE) channel in close binaries, by performing population synthesis simulations that combine realistic binary models with detailed cosmological calculations of the chemical and star-formation history of the Universe. This allows us to constrain population properties, as well as cosmological and aLIGO/aVirgo detection rates of BHBH mergers formed through this pathway. We predict a BHBH merger rate at redshift zero of $5.8 \rm {Gpc}^{-3} \rm {yr}^{-1}$ through the CHE channel, to be compared with aLIGO/aVirgo’s measured rate of ${53.2}_{-28.2}^{+55.8} \text{Gpc}^{-3}\text{yr}^{-1}$, and find that eventual merger systems have BH masses in the range $17 - 43 \rm {M}_{\odot }$ below the pair-instability supernova (PISN) gap, and $&gt;124 \rm {M}_{\odot }$ above the PISN gap. We investigate effects of momentum kicks during black hole formation, and calculate cosmological and magnitude limited PISN rates. We also study the effects of high-redshift deviations in the star formation rate. We find that momentum kicks tend to increase delay times of BHBH systems, and our magnitude limited PISN rate estimates indicate that current deep surveys should be able to detect such events. Lastly, we find that our cosmological merger rate estimates change by at most $\sim 8\%$ for mild deviations of the star formation rate in the early Universe, and by up to $\sim 40\%$ for extreme deviations.