Chemodynamical Simulations of the Milky Way Galaxy

Kobayashi, Chiaki; Nakasato, Nobukazu

doi:10.1088/0004-637x/729/1/16

Cited by 233 publications

(332 citation statements)

References 99 publications

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“…This behaviour is compatible with an intense star-formation rate in the Galactic bulge, which is assumed in most chemical evolution models (e.g. Matteucci & Brocato 1990;Ballero et al 2007;Grieco et al 2012;Kobayashi & Nakasato 2011;Cavichia et al 2014).…”

Section: Introductionsupporting

confidence: 82%

“…6b, the [O/Mg] ratio, as extensively discussed by McWilliam (2016), shows a drop in [O/Mg] for super-metalrich stars, which is not expected and could be due to selective winds in massive stars, as proposed by McWilliam (2016, and references therein), and regarded as a possibility by Kobayashi & Nakasato (2011), with the other possibility being some process that would change the C/O ratio. The present models include metallicity-dependent yields from stellar winds but do not discriminate among different elements.…”

Section: Comparison With Literature Oxygen Abundancesmentioning

confidence: 83%

“…Their bulge component seems to be larger than the Galactic bulge, and should correspond better to the M31 bulge; in general, their calculations are applicable to the Galactic bulge. In Kobayashi & Nakasato (2011;their Fig. 17), there is a transition at [Fe/H] ∼ −0.1 to +0.3 that corresponds to a fast SFR.…”

Section: Discussionmentioning

confidence: 99%

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Tracing the evolution of the Galactic bulge with chemodynamical modelling of alpha-elements

Friaça

Barbuy

2017

A&A

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Context. Galactic bulge abundances can be best understood as indicators of bulge formation and nucleosynthesis processes by comparing them with chemo-dynamical evolution models. Aims. The aim of this work is to study the abundances of alpha-elements in the Galactic bulge, including a revision of the oxygen abundance in a sample of 56 bulge red giants. Methods. Literature abundances for O, Mg, Si, Ca and Ti in Galactic bulge stars are compared with chemical evolution models. For oxygen in particular, we reanalysed high-resolution spectra obtained using FLAMES+UVES on the Very Large Telescope, now taking each star's carbon abundances, derived from CI and C 2 lines, into account simultaneously.Results. We present a chemical evolution model of alpha-element enrichment in a massive spheroid that represents a typical classical bulge evolution. The code includes multi-zone chemical evolution coupled with hydrodynamics of the gas. Comparisons between the model predictions and the abundance data suggest a typical bulge formation timescale of 1-2 Gyr. The main constraint on the bulge evolution is provided by the O data from analyses that have taken the C abundance and dissociative equilibrium into account. Mg, Si, Ca and Ti trends are well reproduced, whereas the level of overabundance critically depends on the adopted nucleosynthesis prescriptions.

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Section: Introductionsupporting

confidence: 82%

Section: Comparison With Literature Oxygen Abundancesmentioning

confidence: 83%

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Tracing the evolution of the Galactic bulge with chemodynamical modelling of alpha-elements

Friaça

Barbuy

2017

A&A

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“…Note that the mass loss from low-mass stars has been included since Kobayashi (2004). The effects of hypernovae are included with a metal-dependent hypernova fraction as in Kobayashi & Nakasato (2011). The progenitor model of Type Ia supernovae (SNe Ia) is very important for predicting [α/Fe] of galaxies because SNe Ia produce more iron than α elements (O, Mg, Si, S, and Ca).…”

Section: Stellar Physicsmentioning

confidence: 99%

The effects of AGN feedback on present-day galaxy properties in cosmological simulations

Taylor

Kobayashi

2015

Monthly Notices of the Royal Astronomical Society

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We show that feedback from active galactic nuclei (AGN) plays an essential role in reproducing the down-sizing phenomena, namely: the colour-magnitude relation; specific star formation rates; and the α enhancement of early type galaxies. In our AGN model, black holes originate from Population iii stars, in contrast to the merging scenario of previous works. In this paper, we show how the properties of present-day galaxies in cosmological chemo-hydrodynamical simulations change when we include our model for AGN feedback. Massive galaxies become redder, older, less massive, less compact, and show greater α enhancement than their counterparts without AGN. Since we reproduce the black hole mass and galaxy mass relation, smaller galaxies do not host a supermassive black hole and their star formation history is affected very little, but they can get external enrichment from nearby AGN depending on their environment. Nonetheless, the metallicity change is negligible, and the mass-metallicity relations, which are mainly generated by supernova feedback at the first star burst, are preserved.

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“…Our simulations use the GADGET-3 code (Springel 2005) augmented with physical processes relevant to galaxy formation and evolution: star formation (Kobayashi et al 2007), energy feedback and chemical enrichment from Type II and Ia SNe (Kobayashi 2004;Kobayashi & Nomoto 2009) and hypernovae (Kobayashi et al 2006;Kobayashi & Nakasato 2011); BH formation, growth through gas accretion and mergers, and energy feedback (TK14); heating from a uniform, evolving UV background; radiative gas cooling. The simulation box is 25 h −1 Mpc on a side, with initial conditions for 2 × 240 3 particles that produce a central cluster by the present day (see Taylor & Kobayashi 2015 for more details).…”

Section: E F I N I T I O N O F O U T F L Ow Smentioning

confidence: 99%