Gas-phase metallicity gradients of TNG50 star-forming galaxies

Abstract

We present the radial gas-phase, mass-weighted metallicity profiles and gradients of the TNG50 star-forming galaxy population measured at redshifts z = 0–3. We investigate the redshift evolution of gradients and examine relations between gradient (negative) steepness and galaxy properties. We find that TNG50 gradients are predominantly negative at all redshifts, although we observe significant diversity among these negative gradients. We determine that the gradients of all galaxies grow more negative with redshift at a roughly constant rate of approximately −0.02 dex kpc−1/Δz. This rate does not vary significantly with galaxy mass. We observe a weak negative correlation between gradient (negative) steepness and galaxy stellar mass at z < 2. However, when we normalize gradients by a characteristic radius defined by the galactic star formation distribution, we find that these normalized gradients do not vary significantly with either stellar mass or redshift. We place our results in the context of previous simulations and show that TNG50 high-redshift gradients are more negative than those of models featuring burstier feedback, which may further highlight high-redshift gradients as important discriminators of galaxy formation models. We also find that z = 0 and z = 0.5 TNG50 gradients are consistent with the gradients observed in galaxies at these redshifts, although the preference for flat gradients observed in redshift z ≳ 1 galaxies is not present in TNG50. If future JWST and ELT observations validate these flat gradients, it may indicate a need for simulation models to implement more powerful radial gas mixing within the ISM, possibly via turbulence and/or stronger winds.

The Fornax3D project: The environmental impact on gas metallicity gradients in Fornax cluster galaxies

“…In contrast with Hemler et al (2021) and Ma et al (2017), and to be consistent with our observational data, our gas metallicity gradients are normalized to the R e of each subhalo. An individual inspection to each gradient shows that fitting data out to 2 R e results in reliable fits.…”

“…Once our sample is constrained, we estimated gas metallicity gradients as done in Hemler et al (2021) and Ma et al (2017). First, the center of each galaxy is defined as the position of the particle (of any type) at the minimum potential, and we define the origin of the coordinate system in this position.…”

The resolved chemical abundance properties within the interstellar medium of star-forming galaxies at $\mathbf{ \textit{z} \approx 1.5}$

“…To analyse this correlation in the KURVS-CDFS sample, in Figure 9 we correlate the intrinsic annuli-based metallicity gradients with the galaxies stellar mass. We also show comparison samples from the SAMI survey at 𝑧 < 0.1 (Poetrodjojo et al 2021), the analytical model of Sharda et al (2021a) and results from the TNG hydrodynamical simulations at redshift snapshots 𝑧 = 0, 1, 2 (Hemler et al 2021). The intrinsic metallicity gradients of the KURVS-CDFS galaxies exhibit a similar correlation to the comparison samples, with flatter (or inverted) metallicity gradients at higher stellar mass.…”

“…Recent studies have indicated connections between a galaxies gasphase metallicity gradient and its fundamental properties such as stellar mass and stellar continuum half-light radius (e.g. Hemler et al 2021;Sharda et al 2021a,c,b;Boardman et al 2021;Franchetto et al 2021). To analyse this correlation in the KURVS-CDFS sample, in Figure 9 we correlate the intrinsic annuli-based metallicity gradients with the galaxies stellar mass.…”

“…Left: The beam-smear corrected annuli-based metallicity gradient as a function of the galaxies stellar mass. We also show comparison samples from the SAMI survey at 𝑧 < 0.1(Poetrodjojo et al 2021), the analytical model ofSharda et al (2021a) and results from the TNG hydrodynamical simulations at redshift snapshots 𝑧 = 1, 2, 3(Hemler et al 2021). The size of theHemler et al (2021) data points reflect the number of galaxies in each stellar mass bin.…”