We present measurements of the [N II]/Hα ratio as a probe of gas-phase oxygen abundance for a sample of 419 star-forming galaxies at z = 0.6 − 2.7 from the KMOS 3D near-IR multi-IFU survey. The mass-metallicity relation (MZR) is determined consistently with the same sample selection, metallicity tracer, and methodology over the wide redshift range probed by the survey. We find good agreement with long-slit surveys in the literature, except for the low-mass slope of the relation at z ∼ 2.3, where this sample is less biased than previous samples based on optical spectroscopic redshifts. In this regime we measure a steeper slope than some literature results. Excluding the AGN contribution from the MZR reduces sensitivity at the high mass end, but produces otherwise consistent results. There is no significant dependence of the [N II]/Hα ratio on SFR or environment at fixed redshift and stellar mass. The IFU data allow spatially resolved measurements of [N II]/Hα, from which we can infer abundance gradients for 180 galaxies, thus tripling the current sample in the literature. The observed gradients are on average flat, with only 15 gradients statistically offset from zero at > 3σ. We have modelled the effect of beam-smearing, assuming a smooth intrinsic radial gradient and known seeing, inclination and effective radius for each galaxy. Our seeing-limited observations can recover up to 70% of the intrinsic gradient for the largest, face-on disks, but only 30% for the smaller, more inclined galaxies. We do not find significant trends between observed or corrected gradients and any stellar population, dynamical or structural galaxy parameters, mostly in agreement with existing studies with much smaller sample sizes. In cosmological simulations, strong feedback is generally required to produce flat gradients at high redshift.

We analyze orbits of stars and dark matter out to three effective radii for 42 galaxies formed in cosmological zoom simulations. Box orbits always dominate at the centers and z-tubes become important at larger radii. We connect the orbital structure to the formation histories and specific features (e.g. disk, counter-rotating core, minor axis rotation) in two-dimensional kinematic maps. Globally, fast rotating galaxies with significant recent in situ star formation are dominated by z-tubes. Slow rotators with recent mergers have significant box orbit and x-tube components. Rotation, quantified by the λ R -parameter often originates from streaming motion of stars on z-tubes but sometimes from figure rotation. The observed anti-correlation of h 3 and V 0 /σ in rotating galaxies can be connected to a dissipative formation history leading to high z-tube fractions. For galaxies with recent mergers in situ formed stars, accreted stars and dark matter particles populate similar orbits. Dark matter particles have isotropic velocity dispersions. Accreted stars are typically radially biased (β ≈ 0.2 − 0.4). In situ stars become tangentially biased (as low as β ≈ −1.0) if dissipation was relevant during the late assembly of the galaxy. We discuss the relevance of our analysis for integral field surveys and for constraining galaxy formation models.

We present an analysis of the origin and properties of the circumgalactic medium (CGM) in a suite of 11 cosmological zoom simulations resembling present-day spiral galaxies. On average the galaxies retain about 50 per cent of the cosmic fraction in baryons, almost equally divided into disc (interstellar medium) gas, cool CGM gas and warm-hot CGM gas. At radii smaller than 50 kpc the CGM is dominated by recycled warm-hot gas injected from the central galaxy, while at larger radii it is dominated by cool gas accreted on to the halo. The recycled gas typically accounts for one-third of the CGM mass. We introduce the novel publicly available analysis tool pygad to compute ion abundances and mock absorption spectra. For Lyman α absorption, we find good agreement of the simulated equivalent width (EW) distribution and observations out to large radii. Disc galaxies with quiescent assembly histories show significantly more absorption along the disc major axis. By comparing the EW and H i column densities, we find that CGM Lyman α absorbers are best represented by an effective line width b ≈ 50–70 km s−1 that increases mildly with halo mass, larger than typically assumed.

Abstract. Recent neutron star observations set new constraints for the equation of state of baryonic matter. A chiral effective field theory approach is used for the description of neutron-dominated nuclear matter present in the outer core of neutron stars. Possible hybrid stars with quark matter in the inner core are discussed using a three-flavor NambuJona-Lasinio model.