Metallicity gradients in disks - Do galaxies form inside-out?

By K. Pilkington, C. G. Few, Bradley K Gibson, F. Calura, L. Michel-Dansac, R. Thacker, M. Molla, F. Matteucci, A. Rahimi, Daisuke Kawata and 6 more. 2012

146 citations recorded by the source corpus.

Aims. We examine radial and vertical metallicity gradients using a suite of disk galaxy hydrodynamical simulations, supplemented with two classic chemical evolution approaches. We determine the rate of change of gradient slope and reconcile the differences existing between extant models and observations within the canonical “inside-out” disk growth paradigm. Methods. A suite of 25 cosmological disks is used to examine the evolution of metallicity gradients; this consists of 19 galaxies selected from the RaDES (Ramses Disk Environment Study) sample, realised with the adaptive mesh refinement code ramses ,i ncluding eight drawn from the “field” and six from “loose group” environments. Four disks are selected from the MUGS (McMaster Unbiased Galaxy Simulations) sample, generated with the smoothed particle hydrodynamics (SPH) code gasoline. Two chemical evolution models of inside-out disk growth were employed to contrast the temporal evolution of their radial gradients with those of the simulations. Results. We first show that generically flatter gradients are observed at redshift zero when comparing older stars with those forming today, consistent with expectations of kinematically hot simulations, but counter to that observed in the Milky Way. The vertical abundance gradients at ∼1−3 disk scalelengths are comparable to those observed in the thick disk of the Milky Way, but significantly shallower than those seen in the thin disk. Most importantly, we find that systematic differences exist between the predicted evolution of radial abundance gradients in the RaDES and chemical evolution models, compared with the MUGS sample; specifically, the MUGS simulations are systematically steeper at high-redshift, and present much more rapid evolution in their gradients. Conclusions. We find that the majority of the models predict radial gradients today which are consistent with those observed in late-type disks, but they evolve to this self-similarity in different fashions, despite each adhering to classical “inside-out” growth. We find that radial dependence of the efficiency with which stars form as a function of time drives the differences seen in the gradients; systematic differences in the sub-grid physics between the various codes are responsible for setting these gradients. Recent, albeit limited, data at redshift z ∼ 1.5 are consistent with the steeper gradients seen in our SPH sample, suggesting a modest revision of the classical chemical evolution models may be required.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0949df60f946253d7b0d5ad0a103dcf5aad4395a

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Citations in the corpus

• Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, methodology): “For example, depending on the choice of initial conditions, the ISM metallicity gradient flattens with time in Prantzos & Aubert (1995), Pilkington et al. (2012), and in the pure thin-disk model of Chiappini (2009) (used in MCM13), while it steepens with time in Chiappini et al. (2001) and Cescutti…”
• Measuring Radial Orbit Migration in the Galactic Disk (2018, background): “But the gradient itself could evolve with time, as pointed out in Minchev et al. (2018), Pilkington et al. (2012), and Wuyts et al. (2016).”
• TRACING CHEMICAL EVOLUTION OVER THE EXTENT OF THE MILKY WAY'S DISK WITH APOGEE RED CLUMP STARS (2014, background): “Conservative feedback prescriptions predict initially steep gradients that flatten over time, while models with ’enhanced’ feedback physics create flatter gradients at early times that subsequently steepen (Pilkington et al. 2012; Gibson et al. 2013).”
• THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). I. SURVEY OVERVIEW AND FIRST DATA RELEASE (2015, methodology): “Cosmological simulations coupled with chemical evolution models can reproduce these data, but various models predict different behavior at earlier times (e.g., Pilkington et al. 2012; Gibson et al. 2013).”
• The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, background): “…to understanding these abundance observations in the context of cosmological galaxy evolution with effects such as insideout formation scenarios (Pilkington et al. 2012), migration (Kubryk et al. 2015, Kubryk et al. 2015, Minchev et al. 2014), spiral arm influence (Grand et al. 2016), and…”
• SDSS IV MaNGA – metallicity and nitrogen abundance gradients in local galaxies (2017, background): “Recent progress in semi-analytical modelling (Fu et al. 2009) and hydrodynamical simulations performed in a cosmological context (Pilkington et al. 2012a; Gibson et al. 2013) have demonstrated the fundamental role that metal recycling via galactic fountains has on the metallicity gradient.”
• Metallicity gradients in local field star-forming galaxies: insights on inflows, outflows, and the coevolution of gas, stars and metals (2015, background): “However, some models predict that metallicity gradients steepen with time (e.g., Chiappini et al. 1997, 2001; see alsoMott et al. 2013who included radial inflow), while others predict the opposite (e.g.,Molla et al. 1997; Prantzos & Boissier 2000; Fu et al. 2009; Pilkington et al. 2012).”
• The SINS/zC-SINF Survey of z ∼ 2 Galaxy Kinematics: SINFONI Adaptive Optics–assisted Data and Kiloparsec-scale Emission-line Properties (2018, result): “…2012), and in line with predictions from theoretical models and simulations (e.g., Rahimi et al. 2011; Kobayashi & Nakasato 2011; Few et al. 2012; Pilkington et al. 2012; Torrey et al. 2012; Gibson et al. 2013; Mott et al. 2013), these findings have been interpreted as resulting from…”
• Numerical simulation of a possible origin of the positive radial metallicity gradient of the thick disk (2013, unknown): “Using a suite of self-consistent cosmological simulations, Pilkington et al. (2012) examined the evolution of metallicity gradients finding most models predict radial gradients consistent with those observed in late-type disks at the present day.”
• Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient (2016, background): “…radial metallicity gradient in star forming disk especially at a high redshift when strong feedback could flatten the radial metallicity gradient (Pilkington et al. 2012; Gibson et al. 2013). ably sized bar for the Milky Way, and including the gas, star formation and chemical evolution, Grand et…”
• Metallicity evolution, metallicity gradients, and gas fractions at z ~ 3.4 (2013, background): “…at z∼3.4 from the FMR may be associated with an increased rate of mergers, which destabilize low metallicity gas in galaxy outskirts and drive it towards the central, active regions as suggested by some models (e.g. Rupke et al. 2010; Perez et al. 2011; Pilkington et al. 2012; Torrey et al. 2012).”
• Theoretical Challenges in Galaxy Formation (2016, background): “…et al. 2014). systems the enriched gas is kept within the halo (in a galactic fountain) and is accreted back onto the galaxy later on with metallicity enhanced, sometimes repeatedly (Brook et al. 2014, Genel et al. 2015, Oppenheimer & Davé 2008, Oppenheimer et al. 2010, Pilkington et al. 2012).”
• INSIDE OUT AND UPSIDE DOWN: TRACING THE ASSEMBLY OF A SIMULATED DISK GALAXY USING MONO-AGE STELLAR POPULATIONS (2013, background): “The resulting shape of the radial abundance gradient early in a galaxy’s evolution can therefore directly constrain feedback models (Pilkington et al. 2012; Gibson et al. 2013).”
• Towards a more realistic population of bright spiral galaxies in cosmological simulations (2013, background): “It is interesting that Pilkington et al. (2012) found steeper gradients in a set of cosmological simulations with AMR and SPH codes.”
• Europium production: neutron star mergers versus core-collapse supernovae (2013, methodology): “This mechanism was suggested by Matteucci & François (1989) and proven to be valid also in semi-analytical models (e.g. Pilkington et al. 2012).”
• Stellar population gradients in galaxy discs from the CALIFA survey - The influence of bars (2014, methodology): “Pilkington et al. (2012) analysed the metallicity gradient and its evolution with time in a suite of 25 cosmological simulations of disc galaxies with similar properties to the Milky Way finding that, whilst the majority of the models predict radial gradients today which are consistent with those…”
• The GLASS-JWST Early Release Science Program. I. Survey Design and Release Plans (2022, background): “Tension is highest at low masses ( *Mlog 8), especially at z> 2 (Pilkington et al. 2012; Pillepich et al. 2018; Wang et al. 2017, 2020).”
• The CALIFA survey across the Hubble sequence: Spatially resolved stellar population properties in galaxies (2015, background): “…galaxies can constrain the complex interplay between gas infall, outflows, stellar migration, radial gas flows, and star formation efficiency, in driving the inside-out growth of galactic disks (Brook et al. 2012; Gibson et al. 2013; Few et al. 2012; Pilkington et al. 2012a; Minchev et al. 2014).”