The assembly history of the Galactic inner halo inferred from α-element patterns

Emma Fernández-Alvar, Patricia B. Tissera, Leticia Carigi, William J. Schuster, Timothy C. Beers, Vasily A. Belokurov

Resultado de la investigación: Article

4 Citas (Scopus)

Resumen

We explore the origin of the observed decline in [O/Fe] (and [Mg/Fe]) with Galactocentric distance for high-metallicity stars ([Fe/H] > −1.1), based on a sample of halo stars selected within the Apache Point Observatory Galactic Evolution Experiment (APOGEE) fourteenth data release (DR14). We also analyse the characteristics of the [α/Fe] distributions in the inner-halo regions inferred from two zoom-in Milky Way mass-sized galaxies that are taken as case studies. One of them qualitatively reproduces the observed trend to have higher fraction of α-rich star for decreasing galactocentric distance; the other exhibits the opposite trend. We find that stars with [Fe/H] > −1.1 located in the range [15–30] kpc are consistent with formation in two starbursts, with maxima separated by about ∼1 Gyr. We explore the contributions of stellar populations with different origin to the [α/Fe] gradients detected in stars with [Fe/H] > −1.1. Our analysis reveals that the simulated halo that best matches the observed chemical trends is characterized by an accretion history involving low-to intermediate-mass satellite galaxies with a short and intense burst of star formation, and contributions from a more massive satellite with dynamical masses about ∼10 10 M, distributing low [α/Fe] stars at intermediate radius.

Idioma originalEnglish
Páginas (desde-hasta)1745-1756
Número de páginas12
PublicaciónMonthly Notices of the Royal Astronomical Society
Volumen485
N.º2
DOI
EstadoPublished - 15 feb 2019

Huella dactilar

halos
assembly
histories
stars
history
trends
observatory
accretion
galaxies
distributing
galactic evolution
metallicity
trend
star formation
bursts
observatories
experiment
gradients
radii
distribution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Fernández-Alvar, Emma ; Tissera, Patricia B. ; Carigi, Leticia ; Schuster, William J. ; Beers, Timothy C. ; Belokurov, Vasily A. / The assembly history of the Galactic inner halo inferred from α-element patterns. En: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 485, N.º 2. pp. 1745-1756.
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The assembly history of the Galactic inner halo inferred from α-element patterns. / Fernández-Alvar, Emma; Tissera, Patricia B.; Carigi, Leticia; Schuster, William J.; Beers, Timothy C.; Belokurov, Vasily A.

En: Monthly Notices of the Royal Astronomical Society, Vol. 485, N.º 2, 15.02.2019, p. 1745-1756.

Resultado de la investigación: Article

TY - JOUR

T1 - The assembly history of the Galactic inner halo inferred from α-element patterns

AU - Fernández-Alvar, Emma

AU - Tissera, Patricia B.

AU - Carigi, Leticia

AU - Schuster, William J.

AU - Beers, Timothy C.

AU - Belokurov, Vasily A.

PY - 2019/2/15

Y1 - 2019/2/15

N2 - We explore the origin of the observed decline in [O/Fe] (and [Mg/Fe]) with Galactocentric distance for high-metallicity stars ([Fe/H] > −1.1), based on a sample of halo stars selected within the Apache Point Observatory Galactic Evolution Experiment (APOGEE) fourteenth data release (DR14). We also analyse the characteristics of the [α/Fe] distributions in the inner-halo regions inferred from two zoom-in Milky Way mass-sized galaxies that are taken as case studies. One of them qualitatively reproduces the observed trend to have higher fraction of α-rich star for decreasing galactocentric distance; the other exhibits the opposite trend. We find that stars with [Fe/H] > −1.1 located in the range [15–30] kpc are consistent with formation in two starbursts, with maxima separated by about ∼1 Gyr. We explore the contributions of stellar populations with different origin to the [α/Fe] gradients detected in stars with [Fe/H] > −1.1. Our analysis reveals that the simulated halo that best matches the observed chemical trends is characterized by an accretion history involving low-to intermediate-mass satellite galaxies with a short and intense burst of star formation, and contributions from a more massive satellite with dynamical masses about ∼10 10 M, distributing low [α/Fe] stars at intermediate radius.

AB - We explore the origin of the observed decline in [O/Fe] (and [Mg/Fe]) with Galactocentric distance for high-metallicity stars ([Fe/H] > −1.1), based on a sample of halo stars selected within the Apache Point Observatory Galactic Evolution Experiment (APOGEE) fourteenth data release (DR14). We also analyse the characteristics of the [α/Fe] distributions in the inner-halo regions inferred from two zoom-in Milky Way mass-sized galaxies that are taken as case studies. One of them qualitatively reproduces the observed trend to have higher fraction of α-rich star for decreasing galactocentric distance; the other exhibits the opposite trend. We find that stars with [Fe/H] > −1.1 located in the range [15–30] kpc are consistent with formation in two starbursts, with maxima separated by about ∼1 Gyr. We explore the contributions of stellar populations with different origin to the [α/Fe] gradients detected in stars with [Fe/H] > −1.1. Our analysis reveals that the simulated halo that best matches the observed chemical trends is characterized by an accretion history involving low-to intermediate-mass satellite galaxies with a short and intense burst of star formation, and contributions from a more massive satellite with dynamical masses about ∼10 10 M, distributing low [α/Fe] stars at intermediate radius.

KW - Galaxy: abundances

KW - Galaxy: formation

KW - Galaxy: halo

KW - Methods: numerical

KW - Techniques: spectroscopic

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JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

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