Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy

Danny Horta; Ricardo P. Schiavon; J. Ted MacKereth; Joel Pfeffer; Andrew C. Mason; Shobhit Kisku; Francesca Fragkoudi; Carlos Allende Prieto; Katia Cunha; Sten Hasselquist; Jon Holtzman; Steven R. Majewski; David Nataf; Robert W. Oconnell; Mathias Schultheis; Verne V. Smith

doi:10.1093/mnras/staa2987

Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy

Danny Horta, Ricardo P. Schiavon, J. Ted MacKereth, Joel Pfeffer, Andrew C. Mason, Shobhit Kisku, Francesca Fragkoudi, Carlos Allende Prieto, Katia Cunha, Sten Hasselquist, Jon Holtzman, Steven R. Majewski, David Nataf, Robert W. Oconnell, Mathias Schultheis, Verne V. Smith

Steward Observatory

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

128 Scopus citations

Abstract

We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] <-0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

Original language	English (US)
Pages (from-to)	1385-1403
Number of pages	19
Journal	Monthly Notices of the Royal Astronomical Society
Volume	500
Issue number	1
DOIs	https://doi.org/10.1093/mnras/staa2987
State	Published - Jan 1 2021

Keywords

Galaxy: Abundances
Galaxy: evolution
Galaxy: formation
Galaxy: halo
Galaxy: kinematics and dynamics
Galaxy: structure

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/mnras/staa2987

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Horta, D., Schiavon, R. P., MacKereth, J. T., Pfeffer, J., Mason, A. C., Kisku, S., Fragkoudi, F., Allende Prieto, C., Cunha, K., Hasselquist, S., Holtzman, J., Majewski, S. R., Nataf, D., Oconnell, R. W., Schultheis, M., & Smith, V. V. (2021). Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy. Monthly Notices of the Royal Astronomical Society, 500(1), 1385-1403. https://doi.org/10.1093/mnras/staa2987

Horta, D, Schiavon, RP, MacKereth, JT, Pfeffer, J, Mason, AC, Kisku, S, Fragkoudi, F, Allende Prieto, C, Cunha, K, Hasselquist, S, Holtzman, J, Majewski, SR, Nataf, D, Oconnell, RW, Schultheis, M & Smith, VV 2021, 'Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy', Monthly Notices of the Royal Astronomical Society, vol. 500, no. 1, pp. 1385-1403. https://doi.org/10.1093/mnras/staa2987

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abstract = "We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] <-0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.",

keywords = "Galaxy: Abundances, Galaxy: evolution, Galaxy: formation, Galaxy: halo, Galaxy: kinematics and dynamics, Galaxy: structure",

author = "Danny Horta and Schiavon, {Ricardo P.} and MacKereth, {J. Ted} and Joel Pfeffer and Mason, {Andrew C.} and Shobhit Kisku and Francesca Fragkoudi and {Allende Prieto}, Carlos and Katia Cunha and Sten Hasselquist and Jon Holtzman and Majewski, {Steven R.} and David Nataf and Oconnell, {Robert W.} and Mathias Schultheis and Smith, {Verne V.}",

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doi = "10.1093/mnras/staa2987",

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AU - Horta, Danny

AU - Schiavon, Ricardo P.

AU - MacKereth, J. Ted

AU - Pfeffer, Joel

AU - Mason, Andrew C.

AU - Kisku, Shobhit

AU - Fragkoudi, Francesca

AU - Allende Prieto, Carlos

AU - Cunha, Katia

AU - Hasselquist, Sten

AU - Holtzman, Jon

AU - Majewski, Steven R.

AU - Nataf, David

AU - Oconnell, Robert W.

AU - Schultheis, Mathias

AU - Smith, Verne V.

PY - 2021/1/1

Y1 - 2021/1/1

N2 - We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] <-0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

AB - We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] <-0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

KW - Galaxy: Abundances

KW - Galaxy: evolution

KW - Galaxy: formation

KW - Galaxy: halo

KW - Galaxy: kinematics and dynamics

KW - Galaxy: structure

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Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy

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Keywords

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