VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies

Martin P. Rey; Oscar Agertz; Tjitske K. Starkenburg; Florent Renaud; Gandhali D. Joshi; Andrew Pontzen; Nicolas F. Martin; Diane K. Feuillet; Justin I. Read

doi:10.1093/mnras/stad513

VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies

Martin P. Rey^*, Oscar Agertz, Tjitske K. Starkenburg, Florent Renaud, Gandhali D. Joshi, Andrew Pontzen, Nicolas F. Martin, Diane K. Feuillet, Justin I. Read

^*Corresponding author for this work

CIERA - Center for Interdisciplinary Exploration and Research in Astrophysics

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

We present a new suite of cosmological zoom-in hydrodynamical (≈ 20 pc spatial resolution) simulations of Milky-Way mass galaxies to study how a varying mass ratio for a Gaia-Sausage-Enceladus (GSE) progenitor impacts the z = 0 chemodynamics of halo stars. Using the genetic modification approach, we create five cosmological histories for a Milky-Way-mass dark matter halo (M₂₀₀ ≈ 10¹² M_☉), incrementally increasing the stellar mass ratio of a z ≈ 2 merger from 1:25 to 1:2, while fixing the galaxy’s final dynamical, stellar mass, and large-scale environment. We find markedly different morphologies at z = 0 following this change in early history, with a growing merger resulting in increasingly compact and bulge-dominated galaxies. Despite this structural diversity, all galaxies show a radially biased population of inner halo stars like the Milky-Way’s GSE which, surprisingly, has a similar magnitude, age, [Fe/H], and [α/Fe] distribution whether the z ≈ 2 merger is more minor or major. This arises because a smaller ex-situ population at z ≈ 2 is compensated by a larger population formed in an earlier merger-driven starburst whose contribution to the GES can grow dynamically over time, and with both populations strongly overlapping in the [Fe/H] − [α/Fe] plane. Our study demonstrates that multiple high-redshift histories can lead to similar z = 0 chemodynamical features in the halo, highlighting the need for additional constraints to distinguish them, and the importance of considering the full spectrum of progenitors when interpreting z = 0 data to reconstruct our Galaxy’s past.

Original language	English (US)
Pages (from-to)	995-1012
Number of pages	18
Journal	Monthly Notices of the Royal Astronomical Society
Volume	521
Issue number	1
DOIs	https://doi.org/10.1093/mnras/stad513
State	Published - May 1 2023

Funding

We would like to thank the referee for a constructive review that improved the quality of the manuscript. MR would like to thank Vasily Belokurov, Alyson Brooks, Amina Helmi, Kathryn Johnston, Harley Katz and Sarah Pearson for insightful discussions and comments during the construction of this work. MR is supported by the Beecroft Fellowship funded by Adrian Beecroft. OA and FR acknowledge support from the Knut and Alice Wallenberg Foundation, the Swedish Research Council (grant 2019\u201304659) and the Royal Physiographic Society in Lund. TS is supported by a CIERA Postdoctoral Fellowship. AP is supported by the Royal Society. This project has received funding from the European Union\u2019s Horizon 2020 research and innovation programme under grant agreement No. 818085 GMGalaxies. We acknowledge PRACE for awarding us access to Joliot-Curie at GENCI/CEA, France to perform the simulations presented in this work. Computations presented in this work were in part performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the Tetralith supercomputer, part of the National Supercomputer Centre, Link\u00F6ping University. Development work was carried out on facilities supported by the Research Capital Investment Fund (RCIF) provided by UKRI and partially funded by the UCL Cosmoparticle Initiative. We thank the developers of GENETIC (Stopyra et al. 2021), JUPYTER (Ragan-Kelley et al. 2014), MATPLOTLIB (Hunter 2007), NUMPY (van der Walt, Colbert & Varoquaux 2011), PYNBODY (Pontzen et al. 2013), SCIPY (Virtanen et al. 2020), and TANGOS (Pontzen & Tremmel 2018) for providing open-source softwares used extensively in this work. The Astrophysics Data Service (ADS) and arXiv preprint repository were used in this work. We would like to thank the referee for a constructive review that improved the quality of the manuscript. MR would like to thank Vasily Belokurov, Alyson Brooks, Amina Helmi, Kathryn Johnston, Harley Katz and Sarah Pearson for insightful discussions and comments during the construction of this work. MR is supported by the Beecroft Fellowship funded by Adrian Beecroft. OA and FR acknowledge support from the Knut and Alice Wallenberg Foundation, the Swedish Research Council (grant 2019\u201304659) and the Royal Physiographic Society in Lund. TS is supported by a CIERA Postdoctoral Fellowship. AP is supported by the Royal Society. This project has received funding from the European Union\u2019s Horizon 2020 research and innovation programme under grant agreement No. 818085 GMGalaxies. We acknowledge PRACE for awarding us access to Joliot-Curie at GENCI/CEA, France to perform the simulations presented in this work. Computations presented in this work were in part performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the Tetralith supercomputer, part of the National Supercomputer Centre, Link\u00F6ping University. Development work was carried out on facilities supported by the Research Capital Investment Fund (RCIF) provided by UKRI and partially funded by the UCL Cosmoparticle Initiative.

Keywords

Galaxy: formation
Galaxy: halo
galaxies: formation
galaxies: kinematics and dynamics
methods: numerical

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1093/mnras/stad513

Cite this

@article{ccba6ea04be94bcea483ea0217ffcf80,

title = "VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies",

abstract = "We present a new suite of cosmological zoom-in hydrodynamical (≈ 20 pc spatial resolution) simulations of Milky-Way mass galaxies to study how a varying mass ratio for a Gaia-Sausage-Enceladus (GSE) progenitor impacts the z = 0 chemodynamics of halo stars. Using the genetic modification approach, we create five cosmological histories for a Milky-Way-mass dark matter halo (M200 ≈ 1012 M☉), incrementally increasing the stellar mass ratio of a z ≈ 2 merger from 1:25 to 1:2, while fixing the galaxy{\textquoteright}s final dynamical, stellar mass, and large-scale environment. We find markedly different morphologies at z = 0 following this change in early history, with a growing merger resulting in increasingly compact and bulge-dominated galaxies. Despite this structural diversity, all galaxies show a radially biased population of inner halo stars like the Milky-Way{\textquoteright}s GSE which, surprisingly, has a similar magnitude, age, [Fe/H], and [α/Fe] distribution whether the z ≈ 2 merger is more minor or major. This arises because a smaller ex-situ population at z ≈ 2 is compensated by a larger population formed in an earlier merger-driven starburst whose contribution to the GES can grow dynamically over time, and with both populations strongly overlapping in the [Fe/H] − [α/Fe] plane. Our study demonstrates that multiple high-redshift histories can lead to similar z = 0 chemodynamical features in the halo, highlighting the need for additional constraints to distinguish them, and the importance of considering the full spectrum of progenitors when interpreting z = 0 data to reconstruct our Galaxy{\textquoteright}s past.",

keywords = "Galaxy: formation, Galaxy: halo, galaxies: formation, galaxies: kinematics and dynamics, methods: numerical",

author = "Rey, {Martin P.} and Oscar Agertz and Starkenburg, {Tjitske K.} and Florent Renaud and Joshi, {Gandhali D.} and Andrew Pontzen and Martin, {Nicolas F.} and Feuillet, {Diane K.} and Read, {Justin I.}",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s).",

year = "2023",

month = may,

day = "1",

doi = "10.1093/mnras/stad513",

language = "English (US)",

volume = "521",

pages = "995--1012",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "1",

}

TY - JOUR

T1 - VINTERGATAN-GM

T2 - The cosmological imprints of early mergers on Milky-Way-mass galaxies

AU - Rey, Martin P.

AU - Agertz, Oscar

AU - Starkenburg, Tjitske K.

AU - Renaud, Florent

AU - Joshi, Gandhali D.

AU - Pontzen, Andrew

AU - Martin, Nicolas F.

AU - Feuillet, Diane K.

AU - Read, Justin I.

PY - 2023/5/1

Y1 - 2023/5/1

N2 - We present a new suite of cosmological zoom-in hydrodynamical (≈ 20 pc spatial resolution) simulations of Milky-Way mass galaxies to study how a varying mass ratio for a Gaia-Sausage-Enceladus (GSE) progenitor impacts the z = 0 chemodynamics of halo stars. Using the genetic modification approach, we create five cosmological histories for a Milky-Way-mass dark matter halo (M200 ≈ 1012 M☉), incrementally increasing the stellar mass ratio of a z ≈ 2 merger from 1:25 to 1:2, while fixing the galaxy’s final dynamical, stellar mass, and large-scale environment. We find markedly different morphologies at z = 0 following this change in early history, with a growing merger resulting in increasingly compact and bulge-dominated galaxies. Despite this structural diversity, all galaxies show a radially biased population of inner halo stars like the Milky-Way’s GSE which, surprisingly, has a similar magnitude, age, [Fe/H], and [α/Fe] distribution whether the z ≈ 2 merger is more minor or major. This arises because a smaller ex-situ population at z ≈ 2 is compensated by a larger population formed in an earlier merger-driven starburst whose contribution to the GES can grow dynamically over time, and with both populations strongly overlapping in the [Fe/H] − [α/Fe] plane. Our study demonstrates that multiple high-redshift histories can lead to similar z = 0 chemodynamical features in the halo, highlighting the need for additional constraints to distinguish them, and the importance of considering the full spectrum of progenitors when interpreting z = 0 data to reconstruct our Galaxy’s past.

AB - We present a new suite of cosmological zoom-in hydrodynamical (≈ 20 pc spatial resolution) simulations of Milky-Way mass galaxies to study how a varying mass ratio for a Gaia-Sausage-Enceladus (GSE) progenitor impacts the z = 0 chemodynamics of halo stars. Using the genetic modification approach, we create five cosmological histories for a Milky-Way-mass dark matter halo (M200 ≈ 1012 M☉), incrementally increasing the stellar mass ratio of a z ≈ 2 merger from 1:25 to 1:2, while fixing the galaxy’s final dynamical, stellar mass, and large-scale environment. We find markedly different morphologies at z = 0 following this change in early history, with a growing merger resulting in increasingly compact and bulge-dominated galaxies. Despite this structural diversity, all galaxies show a radially biased population of inner halo stars like the Milky-Way’s GSE which, surprisingly, has a similar magnitude, age, [Fe/H], and [α/Fe] distribution whether the z ≈ 2 merger is more minor or major. This arises because a smaller ex-situ population at z ≈ 2 is compensated by a larger population formed in an earlier merger-driven starburst whose contribution to the GES can grow dynamically over time, and with both populations strongly overlapping in the [Fe/H] − [α/Fe] plane. Our study demonstrates that multiple high-redshift histories can lead to similar z = 0 chemodynamical features in the halo, highlighting the need for additional constraints to distinguish them, and the importance of considering the full spectrum of progenitors when interpreting z = 0 data to reconstruct our Galaxy’s past.

KW - Galaxy: formation

KW - Galaxy: halo

KW - galaxies: formation

KW - galaxies: kinematics and dynamics

KW - methods: numerical

UR - http://www.scopus.com/inward/record.url?scp=85161604592&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85161604592&partnerID=8YFLogxK

U2 - 10.1093/mnras/stad513

DO - 10.1093/mnras/stad513

M3 - Article

AN - SCOPUS:85161604592

SN - 0035-8711

VL - 521

SP - 995

EP - 1012

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

VINTERGATAN-GM: The cosmological imprints of early mergers on Milky-Way-mass galaxies

Abstract

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this