The Chemical Enrichment of the Milky Way Disk Evaluated Using Conditional Abundances

Ratcliffe, Bridget L.; Ness, Melissa

doi:10.3847/1538-4357/aca8a1

Cited by 8 publications

(7 citation statements)

References 97 publications

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“…The majority of α, light odd-Z, and Fepeak elements (the elements observed by APOGEE) are dominantly produced by K = 2 sources, with one being a prompt process or mix of prompt processes and one being a delayed process or mix of delayed processes. This is substantiated by theoretical yields (e.g., Rybizki et al 2017;Anderson 2019) and past successful data-driven models (e.g., Ness et al 2019;G22;Ting & Weinberg 2022;W22;Ratcliffe & Ness 2023). In this paper, we therefore assume that K 2, though KPM could in principle be implemented with K = 1.…”

Section: The K-process Modelmentioning

confidence: 85%

“…These works, as well as Ting & Weinberg (2022) and Ratcliffe & Ness (2023), find that the Milky Way stellar abundances are well fit by two components, grounded in [Fe/H] and [Mg/Fe], down to residuals of 0.01-0.03 dex for the most precisely measured elements and 0.05-0.1 dex for elements (such as Na, C, and Ce) with large measurement errors. Simultaneously, Frankel et al (2018) and Ness et al (2022) have found that disk abundances are also well described by a two-component model of birth radius and age.…”

Section: Introductionmentioning

confidence: 90%

“…In our fiducial model, we adopt K = 2 with the two processes representing prompt, CCSN-like enrichment and delayed, SN-Ia-like enrichment. While a K = 2 model can well describe the stellar abundances (e.g., Figures 2 and 3), the abundance residuals cannot be explained by observational noise alone and hold information about the intrinsic variations from a K = 2 model (Ness et al 2019;G22;Ting & Weinberg 2022;W22;Ratcliffe & Ness 2023). Potential sources of such scatter include metallicity-dependent SN yields with a bursty star formation history, environmental variations in the IMF, stochastic sampling of the IMF, and more than two distinct processes (e.g., AGB stars, merging neutron stars, and unique classes of SNe Ia) with different time delays for enrichment (e.g., Belokurov & Kravtsov 2022;.…”

Section: Increasing the Number Of Processesmentioning

confidence: 97%

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KPM: A Flexible and Data-driven K-process Model for Nucleosynthesis

Griffith,

Hogg,

Dalcanton

et al. 2024

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The element abundance pattern found in Milky Way disk stars is close to two-dimensional, dominated by production from one prompt process and one delayed process. This simplicity is remarkable, since the elements are produced by a multitude of nucleosynthesis mechanisms operating in stars with a wide range of progenitor masses. We fit the abundances of 14 elements for 48,659 red-giant stars from APOGEE Data Release 17 using a flexible, data-driven K-process model—dubbed KPM. In our fiducial model, with K = 2, each abundance in each star is described as the sum of a prompt and a delayed process contribution. We find that KPM with K = 2 is able to explain the abundances well, recover the observed abundance bimodality, and detect the bimodality over a greater range in metallicity than has previously been possible. We compare to prior work by Weinberg et al., finding that KPM produces similar results, but that KPM better predicts stellar abundances, especially for the elements C+N and Mn and for stars at supersolar metallicities. The model fixes the relative contribution of the prompt and delayed processes to two elements to break degeneracies and improve interpretability; we find that some of the nucleosynthetic implications are dependent upon these detailed choices. We find that moving to four processes adds flexibility and improves the model’s ability to predict the stellar abundances, but does not qualitatively change the story. The results of KPM will help us to interpret and constrain the formation of the Galaxy disk, the relationship between abundances and ages, and the physics of nucleosynthesis.

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Section: The K-process Modelmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 90%

Section: Increasing the Number Of Processesmentioning

confidence: 97%

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KPM: A Flexible and Data-driven K-process Model for Nucleosynthesis

Griffith,

Hogg,

Dalcanton

et al. 2024

Self Cite

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“…2e). Furthermore, at the early stage (8-11 Gyr) of Milky Way, there is a quick steepening in [Fe/H] and [O/Fe] gradient, linked to the effect of the GSE merger event [22,24], slighter later (by ∼ 0.5 Gyr, see Fig. A4) than the epoch based on the LAMOST [27,28] and APOGEE [29,30] data [22,23].…”

Section: Temporal Evolution Of Radial Abundance Gradientmentioning

confidence: 95%

“…The oxygen enrichment and metallicity depletion ([Fe/H]) strongly suggest that Sgr have influenced the evolution of our Galaxy in the past few billion years. Previous studies on the Gaia-Enceladus/Sausage (GSE) have highlighted the significant role of massive mergers in shaping the Galactic disc and altering the radial metallicity gradient in the past 8-11 Gyr [21][22][23][24]. To study the influence of minor merger events (Sgr accretion) on the radial metallicity gradient during the later stages of Galaxy evolution.…”

Section: Temporal Evolution Of Radial Abundance Gradientmentioning

confidence: 99%

Imprints of Sagittarius accretion event: Young O-rich stars and discontinuous chemical evolution in Milky Way disc

Bi,

Sun,

Chen

et al. 2023

Preprint

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The Milky Way has undergone significant transformations in its early history, characterised by violent mergers and the accretion of satellite galaxies. Among these events, the infall of the satellite galaxy Gaia-Enceladus/Sausage is recognised as the last major merger event, fundamentally altering the evolution of the Milky Way and shaping its chemo-dynamical structure. However, recent observational evidence suggests that the Milky Way remains undergone notable events of star formation in the past 4 Gyr, which is thought to be triggered by the perturbations from Sagittarius dwarf galaxy (Sgr). Here we report chemical signatures of the Sgr accretion event in the past 4 Gyr, using the [Fe/H] and [O/Fe] ratios in the thin disc, which is reported for the first time. It reveals that the previously discovered V-shape structure of age-[Fe/H] relation varies across different Galactic locations and has rich substructures. Interestingly, we discovery a discontinuous structure at zmax < 0.3 kpc, interrupted by a recent burst of star formation from 4 Gyr to 2 Gyr ago. In this episode, we find a significant rise in oxygen abundance leading to a distinct [O/Fe] gradient, contributing to the formation of young O-rich stars. Combined with the simulated star formation history and chemical abundance of Sgr, we suggest that the Sgr is an important actor in the discontinuous chemical evolution of the Milky Way disc.

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Unveiling the time evolution of chemical abundances across the Milky Way disc with APOGEE

Ratcliffe

Minchev

Anders

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Chemical abundances are an essential tool in untangling the Milky Way’s enrichment history. However, the evolution of the interstellar medium abundance gradient with cosmic time is lost as a result of radial mixing processes. For the first time, we quantify the evolution of many observational abundances across the Galactic disk as a function of lookback time and birth radius, $\rm \text{R}_\text{birth}$. Using an empirical approach, we derive $\rm \text{R}_\text{birth}$ estimates for 145,447 APOGEE DR17 red giant disk stars, based solely on their ages and $\rm [Fe/H]$. We explore the detailed evolution of 6 abundances (Mg, Ca (α), Mn (iron-peak), Al, C (light), Ce (s-process)) across the Milky Way disk using 87,426 APOGEE DR17 red giant stars. We discover that the interstellar medium had three fluctuations in the metallicity gradient ∼9, ∼6, and ∼4 Gyr ago. The first coincides with the end of high-α sequence formation around the time of the Gaia-Sausage-Enceladus disruption, while the others are likely related to passages of the Sagittarius dwarf galaxy. A clear distinction is found between present-day observed radial gradients with age and the evolution with lookback time for both [X/Fe] and [X/H], resulting from the significant flattening and inversion in old populations due to radial migration. We find the $\rm [Fe/H]$–$\rm [\alpha /Fe]$ bimodality is also seen as a separation in the $\rm \text{R}_\text{birth}$–$\rm [X/Fe]$ plane for the light and α-elements. Our results recover the chemical enrichment of the Galactic disk over the past 12 Gyr, providing tight constraints on Galactic disk chemical evolution models.

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The Chemical Enrichment of the Milky Way Disk Evaluated Using Conditional Abundances

Cited by 8 publications

References 97 publications

KPM: A Flexible and Data-driven K-process Model for Nucleosynthesis

KPM: A Flexible and Data-driven K-process Model for Nucleosynthesis

Imprints of Sagittarius accretion event: Young O-rich stars and discontinuous chemical evolution in Milky Way disc

Unveiling the time evolution of chemical abundances across the Milky Way disc with APOGEE

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