Constraining sub-grid physics with high-redshift spatially-resolved metallicity distributions

Abstract

Aims. We examine the role of energy feedback in shaping the distribution of metals within cosmological hydrodynamical simulations of L * disc galaxies. While negative abundance gradients today provide a boundary condition for galaxy evolution models, in support of inside-out disc growth, empirical evidence as to whether abundance gradients steepen or flatten with time remains highly contradictory. Methods. We made use of a suite of L * discs, realised with and without "enhanced" feedback. All the simulations were produced using the smoothed particle hydrodynamics code Gasoline, and their in situ gas-phase metallicity gradients traced from redshift z ∼ 2 to the present-day. Present-day age-metallicity relations and metallicity distribution functions were derived for each system. Results. The "enhanced" feedback models, which have been shown to be in agreement with a broad range of empirical scaling relations, distribute energy and re-cycled ISM material over large scales and predict the existence of relatively "flat" and temporally invariant abundance gradients. Enhanced feedback schemes reduce significantly the scatter in the local stellar age-metallicity relation and, especially, the Conclusions. Our results with "enhanced" feedback are inconsistent with our earlier generation of simulations realised with "conservative" feedback. We conclude that spatially-resolved metallicity distributions, particularly at high-redshift, offer a unique and under-utilised constraint on the uncertain nature of stellar feedback processes.

A relationship between specific star formation rate and metallicity gradient within z ∼ 1 galaxies from KMOS-HiZELS

“…Marcon-Uchida et al 2010;Stinson et al 2010;Gibson et al 2013). Alternatively, flattened and positive gradients have been interpreted as suggesting an inflow of metal-poor gas to their central regions.…”

“…Marcon-Uchida, Matteucci & Costa 2010;Stinson et al 2010;Gibson et al 2013). Observational support for this has been claimed, as Jones et al (2013) find a small subset of their z = 2 galaxies that possess significantly steeper negative abundance gradients than local galaxies.…”

Mild evolution of the stellar metallicity gradients of disc galaxies

“…In an inside-out scenario for disc formation, gas-phase metallicity profiles with negative gradients are a natural outcome if star formation is driven mainly by the gas density in the discs. Supernova (SN) feedback can regulate the star formation activity and modulate the metallicity content of galaxies if mass-loaded galactic winds are triggered (Gibson et al 2013;Tissera et al 2016b). …”

“…Pilkington et al (2012) carried out a comparison of the metallicity gradients in the ISM (traced by young SPs) obtained by different numerical and analytical models. Gibson et al (2013) analysed different models of SN feedback schemes reporting different evolution for the gas-phase metallicity gradients. No evolution was reported when an enhanced SN model was used.…”

The evolution of the oxygen abundance radial gradient in the Milky Way Galaxy disk

“…In left panels the gradient is calculated using the whole radial range that we run our MWG model, while in the right ones we use only regions within the optical radius. Top panel results are compared with our old model MD05, cosmological simulations by Gibson et al (2013) and recent data as labelled, including Jones et al (2013) and Cresci et al (2010) for high redshift galaxies. …”