scholarly journals Are the globular clusters with significant internal [Fe/H] spreads all former dwarf galaxy nuclei?

2015 ◽  
Vol 11 (S317) ◽  
pp. 110-115 ◽  
Author(s):  
G. S. Da Costa
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Density Profiles ◽  
Cluster Density ◽  
Galactic Globular Clusters ◽  
Metallicity Distribution

AbstractIn this contribution the hypothesis that the Galactic globular clusters with substantial internal [Fe/H] abundance ranges are the former nuclei of disrupted dwarf galaxies is discussed. Evidence considered includes the form of the metallicity distribution function, the occurrence of large diffuse outer envelopes in cluster density profiles, and the presence of ([s-process/Fe], [Fe/H]) correlations. The hypothesis is shown to be plausible but with the caveat that if significantly more than the current nine clusters known to have [Fe/H] spreads are found, then re-evaluation will be required.

The Metallicity Distribution Function of Halo Dwarfs and Globular Clusters

1988 ◽  
Vol 126 ◽  
pp. 517-518
Author(s):  
J. B. Laird ◽  
M. P. Rupin ◽  
B. W. Carney ◽  
D. W. Latham ◽  
R. L. Kurucz
Keyword(s):  
Distribution Function ◽  
Simple Model ◽  
Chemical Evolution ◽  
Globular Clusters ◽  
Dwarf Stars ◽  
Metallicity Distribution

Metallicities have been determined for a chemically unbiased sample of field halo dwarf stars. Their metallicity distribution function is similar to the predictions of a simple model of chemical evolution, but somewhat different from that of globular clusters.

A deep view into the nucleus of the Sagittarius dwarf spheroidal galaxy: M54

2019 ◽  
Vol 14 (S351) ◽  
pp. 47-50
Author(s):  
M. Alfaro-Cuello ◽  
N. Kacharov ◽  
N. Neumayer ◽  
A. Mastrobuono-Battisti ◽  
N. Lützgendorf ◽  
...  
Keyword(s):  
Metal Complex ◽  
Detailed Analysis ◽  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
High Mass ◽  
Data Set

AbstractNuclear star clusters hosted by dwarf galaxies exhibit similar characteristics to high-mass, metal complex globular clusters. This type of globular clusters could, therefore, be former nuclei from accreted galaxies. M54 resides in the photometric center of the Sagittarius dwarf galaxy, at a distance where resolving stars is possible. M54 offers the opportunity to study a nucleus before the stripping of their host by the tidal field effects of the Milky Way. We use a MUSE data set to perform a detailed analysis of over 6600 stars. We characterize the stars by metallicity, age, and kinematics, identifying the presence of three stellar populations: a young metal-rich (YMR), an intermediate-age metal-rich (IMR), and an old metal-poor (OMP). The evidence suggests that the OMP population is the result of accretion of globular clusters in the center of the host, while the YMR population was born in-situ in the center of the OMP population.

scholarly journals Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging

2011 ◽  
Vol 419 (1) ◽  
pp. 14-28 ◽  
Author(s):  
Julio A. Carballo-Bello ◽  
Mark Gieles ◽  
Antonio Sollima ◽  
Sergey Koposov ◽  
David Martínez-Delgado ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Wide Field ◽  
Density Profiles ◽  
Galactic Globular Clusters ◽  
Field Imaging ◽  
Wide Field Imaging

scholarly journals STAR COUNT DENSITY PROFILES AND STRUCTURAL PARAMETERS OF 26 GALACTIC GLOBULAR CLUSTERS

2013 ◽  
Vol 774 (2) ◽  
pp. 151 ◽  
Author(s):  
P. Miocchi ◽  
B. Lanzoni ◽  
F. R. Ferraro ◽  
E. Dalessandro ◽  
E. Vesperini ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Structural Parameters ◽  
Density Profiles ◽  
Count Density ◽  
Star Count ◽  
Galactic Globular Clusters

scholarly journals The dark matter distribution function and halo thermalization from the Eddington equation in galaxies

2016 ◽  
Vol 31 (13) ◽  
pp. 1650073 ◽  
Author(s):  
H. J. de Vega ◽  
N. G. Sanchez
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Equation Of State ◽  
Globular Clusters ◽  
Boltzmann Distribution ◽  
Distribution Functions ◽  
Local Thermal Equilibrium ◽  
Density Profiles ◽  
Starting Point ◽  
Analytic Expressions

We find the distribution function [Formula: see text] for dark matter (DM) halos in galaxies and the corresponding equation of state from the (empirical) DM density profiles derived from observations. We solve for DM in galaxies the analogous of the Eddington equation originally used for the gas of stars in globular clusters. The observed density profiles are a good realistic starting point and the distribution functions derived from them are realistic. We do not make any assumption about the DM nature, the methods developed here apply to any DM kind, though all results are consistent with warm dark matter (WDM). With these methods we find: (i) Cored density profiles behaving quadratically for small distances [Formula: see text] produce distribution functions which are finite and positive at the halo center while cusped density profiles always produce divergent distribution functions at the center. (ii) Cored density profiles produce approximate thermal Boltzmann distribution functions for [Formula: see text] where [Formula: see text] is the halo radius. (iii) Analytic expressions for the dispersion velocity and the pressure are derived yielding at each halo point an ideal DM gas equation of state with local temperature [Formula: see text]. [Formula: see text] turns out to be constant in the same region where the distribution function is thermal and exhibits the same temperature within the percent. The self-gravitating DM gas can thermalize despite being collisionless because it is an ergodic system. (iv) The DM halo can be consistently considered at local thermal equilibrium with: (a) a constant temperature [Formula: see text] for [Formula: see text], (b) a space dependent temperature [Formula: see text] for [Formula: see text], which slowly decreases with [Formula: see text]. That is, the DM halo is realistically a collisionless self-gravitating thermal gas for [Formula: see text]. (v) [Formula: see text] outside the halo radius nicely follows the decrease of the circular velocity squared.

scholarly journals The Effect of Dwarf Galaxies on the Tidal Tails of Globular Clusters

2021 ◽  
Author(s):  
Nada El-Falou ◽  
Jeremy J Webb
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxies ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Size And Shape ◽  
The Galaxy ◽  
Galaxy Model ◽  
Galactic Globular Clusters ◽  
Tidal Tails

Abstract The tidal tails of globular clusters have been shown to be sensitive to the external tidal field. We investigate how Galactic globular clusters with observed tails are affected by satellite dwarf galaxies by simulating tails in galaxy models with and without dwarf galaxies. The simulations indicate that tidal tails can be subdivided into into three categories based on how they are affected by dwarf galaxies: 1) dwarf galaxies perturb the progenitor cluster’s orbit (NGC 4590, Pal 1, Pal 5), 2) dwarf galaxies perturb the progenitor cluster’s orbit and individual tail stars (NGC 362, NGC 1851, NGC 4147, NGC 5466, NGC 7492, Pal 14, Pal 15), and 3) dwarf galaxies negligibly affect tidal tails (NGC 288, NGC 5139, NGC 5904, Eridanus). Perturbations to a cluster’s orbit occur when dwarf galaxies pass within its orbit, altering the size and shape of the orbital and tail path. Direct interactions between one or more dwarf galaxies and tail stars lead to kinks and spurs, however we find that features are more difficult to observe in projection. We further find that the tails of Pal 5 are shorter in the galaxy model with dwarf galaxies as it is closer to apocentre, which results in the tails being compressed. Additional simulations reveal that differences between tidal tails in the two galaxy models are primarily due to the Large Magellanic Cloud. Understanding how dwarf galaxies affect tidal tails allows for tails to be used to map the distribution of matter in dwarf galaxies and the Milky Way.

scholarly journals Blanco DECam Bulge Survey (BDBS) II: project performance, data analysis, and early science results

2020 ◽  
Vol 499 (2) ◽  
pp. 2357-2379
Author(s):  
Christian I Johnson ◽  
Robert Michael Rich ◽  
Michael D Young ◽  
Iulia T Simion ◽  
William I Clarkson ◽  
...  
Keyword(s):  
Distribution Function ◽  
Dark Energy ◽  
Globular Clusters ◽  
Gaussian Mixture Models ◽  
Gaussian Mixture ◽  
Project Performance ◽  
Point Spread ◽  
Spread Function ◽  
Red Clump ◽  
Metallicity Distribution

ABSTRACT The Blanco DECam Bulge Survey (BDBS) imaged more than 200 sq deg of the Southern Galactic bulge using the ugrizY filters of the Dark Energy Camera, and produced point spread function photometry of approximately 250 million unique sources. In this paper, we present details regarding the construction and collation of survey catalogues, and also discuss the adopted calibration and dereddening procedures. Early science results are presented with a particular emphasis on the bulge metallicity distribution function and globular clusters. A key result is the strong correlation (σ ∼ 0.2 dex) between (u − i)o and [Fe/H] for bulge red clump giants. We utilized this relation to find that interior bulge fields may be well described by simple closed box enrichment models, but fields exterior to b ∼ −6° seem to require a secondary metal-poor component. Applying scaled versions of the closed box model to the outer bulge fields is shown to significantly reduce the strengths of any additional metal-poor components when compared to Gaussian mixture models. Additional results include: a confirmation that the u band splits the subgiant branch in M22 as a function of metallicity, the detection of possible extratidal stars along the orbits of M 22 and FSR 1758, and additional evidence that NGC 6569 may have a small but discrete He spread, as evidenced by red clump luminosity variations in the reddest bands. We do not confirm previous claims that FSR 1758 is part of a larger extended structure.

scholarly journals Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters

2020 ◽  
Vol 634 ◽  
pp. A53 ◽  
Author(s):  
Katja Fahrion ◽  
Oliver Müller ◽  
Marina Rejkuba ◽  
Michael Hilker ◽  
Mariya Lyubenova ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Main Body ◽  
Host Galaxies ◽  
Low Mass ◽  
The Masses

Studies of nucleated dwarf galaxies can constrain the scenarios for the formation and evolution of nuclear star clusters (NSC) in low-mass galaxies and give us insights on the origin of ultra compact dwarf galaxies (UCDs). We report the discovery of a NSC in the dwarf galaxy KKs58 and investigate its properties together with those of another NSC in KK197. Both NSCs are hosted by dwarf elliptical galaxies of the Centaurus group. Combining ESO VLT MUSE data with photometry from VLT FORS2, CTIO Blanco DECam, and HST ACS, as well as high-resolution spectroscopy from VLT UVES, we analyse the photometric, kinematic and stellar population properties of the NSCs and their host galaxies. We confirm membership of the NSCs based on their radial velocities and location close to the galaxy centres. We also confirm the membership of two globular clusters (GCs) and detect oblate rotation in the main body of KK197. Based on high signal-to-noise spectra taken with MUSE of the NSCs of both KKs58 and KK197 we measure low metallicities, [Fe/H] = −1.75 ± 0.06 dex and [Fe/H] = −1.84 ± 0.05 dex, and stellar masses of 7.3 × 105 M⊙ and 1.0 × 106 M⊙, respectively. Both NSCs are more metal-poor than their hosts that have metallicities of −1.35 ± 0.23 dex (KKs58) and −0.84 ± 0.12 dex (KK197). This can be interpreted as NSC formation via the in-spiral of GCs. The masses, sizes and metallicities of the two NSCs place them among other NSCs, but also among the known UCDs of the Centaurus group. This indicates that NSCs might constitute the progenitors of a part of the low-mass UCDs, although their properties are almost indistinguishable from typical GCs.

scholarly journals The Faint Globular Cluster in the Dwarf Galaxy Andromeda I

2017 ◽  
Vol 34 ◽  
Author(s):  
Nelson Caldwell ◽  
Jay Strader ◽  
David J. Sand ◽  
Beth Willman ◽  
Anil C. Seth
Keyword(s):  
Dark Matter ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Dark Matter Halos ◽  
History Of ◽  
Low Mass ◽  
Growing Population

AbstractObservations of globular clusters in dwarf galaxies can be used to study a variety of topics, including the structure of dark matter halos and the history of vigorous star formation in low-mass galaxies. We report on the properties of the faint globular cluster (MV ~ −3.4) in the M31 dwarf galaxy Andromeda I. This object adds to the growing population of low-luminosity Local Group galaxies that host single globular clusters.

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