KMOS view of the Galactic Centre – II. Metallicity distribution of late-type stars

Feldmeier-Krause, A.; Kerzendorf, Wolfgang; Neumayer, Nadine; Schödel, R.; Nogueras-Lara, F.; Do, Tuan; Zeeuw, P. T. de; Küntschner, H.

doi:10.1093/mnras/stw2339

Cited by 90 publications

(183 citation statements)

References 89 publications

(145 reference statements)

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“…However, few of the coolest observed S-stars can only be explained by super-solar metallicity isochrones. Previous studies have reported observing metal-rich stars in the GC (Cunha et al 2007;Do et al 2015;Feldmeier-Krause et al 2017;Rich et al 2017). Pfuhl et al (2011) and Nishiyama et al (2016) observed similar stars within the NSC and described them as possible outliers due to different extinction or high metallicity.…”

Section: From Deep Spectra To H-r Diagrammentioning

confidence: 99%

Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way

Habibi

Gillessen

Pfuhl

et al. 2019

ApJL

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In a dynamically relaxed cluster around a massive black hole a dense stellar cusp of old stars is expected to form. Previous observations showed a relative paucity of red giant stars within the central 0.5 pc in the Galactic Center. By co-adding spectroscopic observations taken over a decade, we identify new late-type stars, including the first five warm giants (G2-G8III), within the central 1 arcsec 2 (0.04×0.04 pc 2 ) of the Galaxy. Our findings increase the number of late-type stars to 21, of which we present deep spectra for 16. The updated star count, based on individual spectral classification, is used to reconstruct the surface density profile of giant stars. Our study, for the first time, finds a cusp in the surface number density of the spectroscopically identified old (>3 Gyr) giants population (m K <17) within 0.02-0.4 pc described by a single power law with an exponent Γ=0.34±0.04.

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Section: From Deep Spectra To H-r Diagrammentioning

confidence: 99%

Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way

Habibi

Gillessen

Pfuhl

et al. 2019

ApJL

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“…Thus, we work under the assumption that a large fraction of the Milky Way mass inside ∼ 100pc was brought in by infalling globular clusters (Antonini et al 2012). While observations show that in-situ star formation also contributed to the build up of the stellar populations inside ∼ 1pc (e.g., Feldmeier-Krause et al 2017), the relative contribution of the two formation channels (in-situ vs cluster inspirals) remains an open question. Moreover, we assume that the initial density distribution of clusters is proportional to the density distribution of field stars formed at the same epoch.…”

Section: Globular Cluster Formation and Evolutionmentioning

confidence: 99%

Disrupted globular clusters and the gamma-ray excess in the Galactic Centre

Fragione

Antonini

Gnedin

2018

Monthly Notices of the Royal Astronomical Society

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The Fermi Large Area Telescope has provided the most detailed view toward the Galactic Centre (GC) in high-energy gamma rays. Besides the interstellar emission and point-source contributions, the data suggest a residual diffuse gamma-ray excess. The similarity of its spatial distribution with the expected profile of dark matter has led to claims that this may be evidence for dark matter particle annihilation. Here, we investigate an alternative explanation that the signal originates from millisecond pulsars (MSPs) formed in dense globular clusters and deposited at the GC as a consequence of cluster inspiral and tidal disruption. We use a semi-analytical model to calculate the formation, migration, and disruption of globular clusters in the Galaxy. Our model reproduces the mass of the nuclear star cluster and the present-day radial and mass distribution of globular clusters. For the first time, we calculate the evolution of MSPs from disrupted globular clusters throughout the age of the Galaxy and consistently include the effect of the MSP spin-down due to magnetic-dipole breaking. The final gamma-ray amplitude and spatial distribution are in good agreement with the Fermi observations and provide a natural astrophysical explanation for the GC excess.

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“…Our peak metallicity value at the GC is consistent with that from the GC field of APOGEE . A large fraction of super-solar stars has been found by Feldmeier-Krause et al (2017) based on low-resolution spectra in the nuclear star cluster. We will discuss in a forthcoming paper the chemical similarities as well as differences between the nuclear star cluster, the Galactic Center field population and the inner Galactic bulge.…”

Section: Mdfmentioning

confidence: 99%

Chemical characterization of the inner Galactic bulge:North–South symmetry

Nandakumar

Ryde

Schultheis

et al. 2018

Monthly Notices of the Royal Astronomical Society

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While the number of stars in the Galactic bulge with detailed chemical abundance measurements is increasing rapidly, the inner Galactic bulge (|b| < 2 • ) remains poorly studied, due to heavy interstellar absorption and photometric crowding. We have carried out a high-resolution IR spectroscopic study of 72 M giants in the inner bulge using the CRIRES (ESO/VLT) facility. Our spectra cover the wavelength range of 2.0818 -2.1444 µm with the resolution of R∼50,000 and have signal-to-noise ratio of 50-100. Our stars are located along the bulge minor axis at l = 0 • , b = ±0 • , ±1 • , ±2 • and +3 • . Our sample was analysed in a homogeneous way using the most current K-band line list. We clearly detect a bimodal MDF with a metal-rich peak at ∼ 0.3 dex and a metal-poor peak at ∼ −0.5 dex, and no stars with [Fe/H] > +0.6 dex. The Galactic Center field reveals in contrast a mainly metal-rich population with a mean metallicity of 0.3 dex. We derived [Mg/Fe] and [Si/Fe] abundances which are consistent with trends from the outer bulge. We confirm for the supersolar metallicity stars the decreasing trend in [Mg/Fe] and [Si/Fe] as expected from chemical evolution models. With the caveat of a relatively small sample, we do not find significant differences in the chemical abundances between the Northern and the Southern fields, hence the evidence is consistent with symmetry in chemistry between North and South.

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KMOS view of the Galactic Centre – II. Metallicity distribution of late-type stars

Cited by 90 publications

References 89 publications

Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way

Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way

Disrupted globular clusters and the gamma-ray excess in the Galactic Centre

Chemical characterization of the inner Galactic bulge:North–South symmetry

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