A path towards constraining the evolution of the interstellar medium and outflows in the Milky Way using APOGEE

Monthly Notices of the Royal Astronomical Society, vol. 532, pp. 1–21

Abstract

ABSTRACT In recent years, the study of the Milky Way has significantly advanced due to extensive spectroscopic surveys of its stars, complemented by astroseismic and astrometric data. However, it remains disjoint from recent advancements in understanding the physics of the Galactic interstellar medium (ISM). This paper introduces a new model for the chemical evolution of the Milky Way that can be constrained on stellar data, because it combines a state-of-the-art ISM model with a Milky Way stellar disc model. Utilizing a data set of red clump stars from APOGEE, known for their precise ages and metallicities, we concentrate on the last 6 billion years – a period marked by Milky Way’s secular evolution. We examine the oxygen abundance in the low-$\alpha$ disc stars relative to their ages and birth radii, validating or constraining critical ISM parameters that remain largely unexplored in extragalactic observations. The models that successfully reproduce the radius–metallicity distribution and the age–metallicity distribution of stars without violating existing ISM observations indicate a need for modest differential oxygen enrichment in Galactic outflows, meaning that the oxygen abundance of outflows is higher than the local ISM abundance, irrespective of outflow mass loading. The models also suggest somewhat elevated ISM gas velocity dispersion levels over the past 6 billion years compared to galaxies of similar mass. The extra turbulence necessary could result from energy from gas accretion onto the Galaxy, supernovae clustering in the ISM, or increased star formation efficiency per freefall time. This work provides a novel approach to constraining the Galactic ISM and outflows, leveraging the detailed insights available from contemporary Milky Way surveys.

Authors 3

1. Piyush Sharda corresponding Aachen Leiden Observatory

   Leiden University · Australian National University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University , PO Box 9513, NL-2300 RA Leiden , the Netherlands

   Research School of Astronomy & Astrophysics, Australian National University, Canberra 2611, Australia

2. Yuan-Sen Ting corresponding

   The Ohio State University · Australian National University

   Affiliation as printed

   Center for Cosmology and AstroParticle Physics, The Ohio State University , Columbus, OH 43210 , USA

   Department of Astronomy, The Ohio State University , Columbus, OH 43210 , USA

   Research School of Astronomy & Astrophysics, Australian National University , Canberra 2611 , Australia

   School of Computing, Australian National University , Acton, ACT 2601 , Australia

3. Neige Frankel corresponding

   University of Toronto · Canadian Institute for Theoretical Astrophysics

   Affiliation as printed

   Canadian Institute of Theoretical Astrophysics, University of Toronto , Toronto, ON M5S 3H8 , Canada

   Department of Astronomy & Astrophysics, University of Toronto , Toronto, ON M5S 3H4 , Canada