Neutron-capture elements record the ordered chemical evolution of the disc over time

Abstract

An ensemble of chemical abundances probing different nucleosynthetic channels can be leveraged to build a comprehensive understanding of the chemical and structural evolution of the Galaxy. Using GALAH DR3 data, we seek to trace the enrichment by the supernovae Ia, supernovae II, asymptotic giant branch stars, and neutron-star mergers and/or collapsars nucleosynthetic sources by studying the [Fe/H], [$\alpha$/Fe], [Ba/Fe], and [Eu/Fe] chemical compositions of $\sim$50,000 red giant stars, respectively. Employing small [Fe/H]-[$\alpha$/Fe] cells, which serve as an effective reference-frame of supernovae contributions, we characterise the abundance-age profiles for [Ba/Fe] and [Eu/Fe]. Our results disclose that these age-abundance relations vary across the [Fe/H]-[$\alpha$/Fe] plane. Within cells, we find negative age-[Ba/Fe] relations and flat age-[Eu/Fe] relations. Across cells, we see the slope of the age-[Ba/Fe] relations evolve smoothly and the [Eu/Fe] relations vary in amplitude. We subsequently model our empirical findings in a theoretical setting using the flexible Chempy Galactic chemical evolution (GCE) code, using the mean [Fe/H], [Mg/Fe], [Ba/Fe], and age values for stellar populations binned in [Fe/H], [Mg/Fe], and age space. We find that within a one-zone framework, an ensemble of GCE model parameters vary to explain the data. Using present day orbits from \textit{Gaia} EDR3 measurements we infer that the GCE model parameters, which set the observed chemical abundance distributions, vary systematically across mean orbital radii. Under our modelling assumptions, the observed chemical abundances are consistent with a small gradient in the high mass end of the initial mass function (IMF) across the disc, where the IMF is more top heavy towards the inner disc and more bottom heavy in the outer disc.

Accepted in MNRAS. 21 pages and 13 Figures

References in corpus (53)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• galpy: A Python Library for Galactic Dynamics
• Origin of the heavy elements in binary neutron-star mergers from a gravitational wave event
• The mass distribution and gravitational potential of the Milky Way
• Galactic chemical evolution: Carbon through Zinc
• A systematic variation of the stellar initial mass function in early-type galaxies
• Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
• Identification of strontium in the merger of two neutron stars
• Kilonova from post-merger ejecta as an optical and near-infrared counterpart of GW170817
• High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
• The GALAH Survey: Observational Overview and Gaia DR1 companion
• Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?
• The age-metallicity structure of the Milky Way disk
• The TESS-HERMES survey Data Release 1: high-resolution spectroscopy of the TESS southern continuous viewing zone
• Origin of chemically distinct discs in the Auriga cosmological simulations
• Intermediate to low-mass stellar content of Westerlund 1
• Enhanced production of barium in low-mass stars: evidence from open clusters
• The SAMI Galaxy Survey: Spatially Resolving the Main Sequence of Star Formation
• Weighing the stellar constituents of the Galactic halo with APOGEE red giant stars
• The SAMI Galaxy Survey: Spatially resolving the environmental quenching of star formation in GAMA galaxies
• The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys
• A radial age gradient in the geometrically thick disk of the Milky Way
• APOGEE DR16: a multi-zone chemical evolution model for the Galactic disc based on MCMC methods
• High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age
• IMF shape constraints from stellar populations and dynamics from CALIFA
• Elevated r-process enrichment in Gaia Sausage and Sequoia
• The GALAH survey: The data reduction pipeline
• High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
• On the need of the Light Elements Primary Process (LEPP)
• The relationship between mono-abundance and mono-age stellar populations in the Milky Way disk
• The age-chemical abundance structure of the Galactic disc II: $\alpha$-dichotomy and thick disc formation
• Abundance-age relations with red clump stars in open clusters
• Testing the universal stellar IMF on the metallicity distribution in the bulges of the Milky Way and M31
• Spatially resolved variations of the IMF mass normalisation in early-type galaxies as probed by molecular gas kinematics
• The origin of stellar populations in the Galactic bulge from chemical abundances
• How Many Elements Matter?
• Stellar Abundance Maps of the Milky Way Disk
• The K2 Galactic Archaeology Program Data Release 3: Age-abundance patterns in C1-C8 and C10-C18
• Origin of $\alpha$-rich young stars: clues from C, N and O
• The homogeneity of the star forming environment of the Milky Way disk over time
• The Gaia-ESO Survey: A new approach to chemically characterising young open clusters II. Abundances of the neutron-capture elements Cu, Sr, Y, Zr, Ba, La, and Ce
• Solar twins and the Barium puzzle
• APOGEE [C/N] Abundances Across the Galaxy: Migration and Infall from Red Giant Ages
• Exploring the s-process history in the Galactic disk: Cerium abundances and gradients in Open Clusters from the OCCAM/APOGEE sample
• Is it possible to reconcile extragalactic IMF variations with a universal Milky Way IMF?
• Binary evolution along the Red Giant Branch with BINSTAR: The barium star perspective
• An [$\alpha$/Fe]-enhanced thick disk in a Milky Way Analogue
• The age distribution of stars in the Milky Way bulge
• First determination of s-process element abundances in pre-main sequence clusters: Y, Zr, La, and Ce in IC 2391, the Argus association and IC 2602
• Heavy element evolution in the inner regions of the Milky Way
• The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data
• Inferring Galactic Parameters from Chemical Abundances: A Multi-Star Approach
• Modelling the chemical evolution of the Milky Way