Maria Koller

A majority of JWST/NIRSpec/IFU studies at high redshifts to date have focused on UV-bright or massive objects, while our understanding of low-mass galaxies at early cosmic times remains limited. In this work, we present NIRSpec/IFS high-resolution observations of two low-mass (M* < 109 M⊙), low-metallicity ([12 + log (O/H)] < 8) galaxies at z ∼ 7.66, one of which we identify as hosting a Type-II AGN. We measure flat strong-line metallicity gradients, suggestive of ISM redistribution by outflows or past merging, but also identify tension with the direct-Te metallicity gradient in one galaxy. We find the ionised gas phase in both galaxies to be dispersion-dominated, consistent with previous observations of lower rotational support at early cosmic times. We identify broad kinematical components decoupled from galactic rotation with velocities of ∼250 − 500 km s−1and argue these components trace outflows, for which we infer mass outflow rates of ∼8 − 14 M⊙ yr−1. We compare our findings to results from the new large-volume Aesopica simulations, which fully incorporate different models of black hole growth and AGN feedback. We find that our observationally-measured ratios of outflow to escape velocity are consistent with those of the simulated dwarf AGN population, hinting that AGN-driven feedback may contribute to quenching in early low-mass galaxies such as our targets. This novel study illustrates the necessity of deep IFU observations to decompose the complex kinematics and morphology of high-z galaxies, trace outflows, and constrain the effects of feedback in the early Universe.

Aims. Star formation rates (SFRs), gas-phase metallicities, and stellar masses are crucial for studying galaxy evolution. The different relations resulting from these properties give insights into the complex interplay of gas inside galaxies and their evolutionary trajectory and current characteristics. We aim to characterize these relations at z ∼ 0.3, corresponding to a 3–4 Gyr lookback time, to gather insight into the galaxies’ redshift evolution. Methods. We utilized optical integral field spectroscopy data from 65 emission-line galaxies from the MUSE large program MAGPI at a redshift of 0.28 < z < 0.35 (average redshift of z ∼ 0.3) and spanning a total stellar mass range of 8.2 < log(M_*/M_⊙) < 11.4. We measured emission line fluxes and stellar masses, allowing us to determine spatially resolved SFRs, gas-phase metallicities, and stellar mass surface densities. We derived the resolved star formation main sequence (rSFMS), resolved mass metallicity relation (rMZR), and resolved fundamental metallicity relation (rFMR) at z ∼ 0.3, and compared them to results for the local Universe. Results. We find a relatively shallow rSFMS slope of ∼0.425 ± 0.014 compared to the expected slope at this redshift for an ordinary least square (OLS) fitting routine. For an orthogonal distance regression (ODR) routine, a much steeper slope of ∼1.162 ± 0.022 is measured. We confirm the existence of an rMZR at z ∼ 0.3 with an average metallicity located ∼0.03 dex above the local Universe’s metallicity. Via partial correlation coefficients, evidence is found that the local metallicity is predominantly determined by the stellar mass surface density and has a weak secondary (inverse) dependence on the SFR surface density Σ_SFR. Additionally, a significant dependence of the local metallicity on the total stellar mass M_* is found. Furthermore, we find that the stellar mass surface density Σ_* and M_* have a significant influence in determining the strength with which Σ_SFR correlates with the local metallicity. We observe that at lower stellar masses, there is a tighter correlation between Σ_SFR and the gas-phase metallicity, resulting in a more pronounced rFMR.

Our Sun lies within 300 pc of the 2.7-kpc-long sinusoidal chain of dense gas clouds known as the Radcliffe Wave.¹ The structure’s wave-like shape was discovered using 3D dust mapping, but initial kinematic searches for oscillatory motion were inconclusive.^2–7 Here we present evidence that the Radcliffe Wave is oscillating through the Galactic plane while also drifting radially away from the Galactic Center. We use measurements of line-of-sight velocity⁸ for ¹²CO and 3D velocities of young stellar clusters to show that the most massive star-forming regions spatially associated with the Radcliffe Wave (including Orion, Cepheus, North America, and Cygnus X) move as if they are part of an oscillating wave driven by the gravitational acceleration of the Galactic potential. By treating the Radcliffe Wave as a coherently oscillating structure, we can derive its motion independently of the local Galactic mass distribution, and directly measure local properties of the Galactic potential as well as the Sun’s vertical oscillation period. In addition, the measured drift of the Radcliffe Wave radially outward from the Galactic Center suggests that the cluster whose supernovae ultimately created today’s expanding Local Bubble⁹ may have been born in the Radcliffe Wave.