TIDAL STRIPPING OF GLOBULAR CLUSTERS IN A SIMULATED GALAXY CLUSTER

AbstractAt the center of the nearest galaxy cluster, the Virgo cluster, lies the massive cD galaxy, M87 (NGC 4486). Using data from the Next Generation Virgo Cluster Survey, we investigate the relationship between M87, its globular clusters (GCs), and satellite dwarf galaxies. We find that the kinematics of GCs and ultra-compact dwarfs (UCDs) are different, indicating that UCDs are not simply massive GCs. We also identify a morphological sequence of envelope fraction around UCDs correlated with cluster-centric distance that suggest UCDs are the result of tidal stripping. Lastly, we find that the [α/Fe] abundance ratios of low-mass early-type galaxies in Virgo exhibit a strong negative gradient within ~ 400 kpc of M87, where the galaxies closest to M87 have the highest values. These satellite galaxies are likely the surviving counterparts of accreted dwarfs that contribute stars to the metal-poor, α-rich stellar halos of massive galaxies. Together, these results describe a dense environment that has had a strong and continuing impact on the evolution of its low-mass neighbors.

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Globular Cluster Systems in the Hydra I Galaxy Cluster

Symposium - International Astronomical Union ◽

10.1017/s0074180900223863 ◽

2002 ◽

Vol 207 ◽

pp. 281-286

Author(s):

Michael Hilker

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Dwarf Galaxies ◽

Star Clusters ◽

Galaxy Cluster ◽

Cluster Center ◽

Early Type ◽

Cluster Systems ◽

First Results ◽

Globular Cluster System

In this contribution, first results of deep VLT (V,I) photometry in the central region of the Hydra I galaxy cluster are presented. Many star clusters have been identified not only around several early-type galaxies, but also in the intra-cluster field, as far as 250 kpc from the cluster center. Outside the bulges of the central galaxies NGC 3311 and NGC 3309, the intra-cluster globular cluster system is dominated by blue clusters whose spatial distribution is similar to that of the (newly discovered) dwarf galaxies in Hydra I. The color distributions of globular clusters around NGC 3311 and NGC 3309 are multimodal, with a sharp blue peak and a slightly broader distribution of the red cluster population.

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THEHST/ACS COMA CLUSTER SURVEY. IV. INTERGALACTIC GLOBULAR CLUSTERS AND THE MASSIVE GLOBULAR CLUSTER SYSTEM AT THE CORE OF THE COMA GALAXY CLUSTER

The Astrophysical Journal ◽

10.1088/0004-637x/730/1/23 ◽

2011 ◽

Vol 730 (1) ◽

pp. 23 ◽

Cited By ~ 71

Author(s):

Eric W. Peng ◽

Henry C. Ferguson ◽

Paul Goudfrooij ◽

Derek Hammer ◽

John R. Lucey ◽

...

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Galaxy Cluster ◽

Cluster System ◽

Coma Cluster ◽

Cluster Survey ◽

The Core ◽

Globular Cluster System

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Globular Clusters in NGC 1399 and Background Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900240989 ◽

1990 ◽

Vol 139 ◽

pp. 377-378

Author(s):

Rainer Madejsky ◽

Ralf Bender

Keyword(s):

Globular Clusters ◽

Gaussian Model ◽

Galaxy Cluster ◽

Central Field ◽

Number Magnitude ◽

The Difference ◽

Comparison Field ◽

Image Position ◽

Number Counts ◽

Peak Luminosity

NGC 1399, the central galaxy of the Fornax cluster, is known to have an overabundance of globular clusters (Hanes and Harris, 1986). In order to determine the luminosity function of these globular clusters, two fields near NGC 1399 were observed in the B, V, and R band. One field was chosen near the center of NGC 1399 and the second field 20′ east of the galaxy center. The second field is supposed to contain no globular clusters and is used for comparison. Both fields were reduced with DAOPHOT (Stetson, 1987) to determine the number-magnitude relation for all detected objects (see Figure 1). The differential number counts give log N (m) = 0.84 mB for the comparison field while the differential number counts for the central field (background galaxies and globular clusters) cannot be described by this simple law. Figure 2 shows the number-magnitude relation of the excess objects in the central field (difference between all counts in the central and in the comparison field). The differential number counts N (m) of the excess objects can be represented by the superposition of three populations, each following approximately a Gaussian distribution. The population with the brightest peak luminosity (mB = 22.1 mag) is due to a galaxy cluster with an estimated redshift z = 0.3–0.4. Figure 1.The differential number counts of the central field (upper line) and the comparison field (lower line) are displayed for the band until 0.5 mag short of the limiting magnitude. The differential number counts of the comparison field can be described by a simple exponential law; this function is displayed as a dotted line. The differential number counts of the central field cannot be approximated by a simple exponential function.Figure 2.The difference among all detected objects between both fields (Ncent(m) - Ncomp(m)) is shown for the B band. The excess objects in the central field can be represented by the superposition of three populations. This three-component Gaussian model is indicated by the dotted line. The most abundant population (N > 250) with peak luminosity mB = 24.8 mag is identified with globular clusters belonging to NGC 1399.

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From a star cluster ensemble to its formation history

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315008923 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 263-264

Author(s):

Christine Schulz ◽

Michael Hilker

Keyword(s):

Globular Clusters ◽

Dwarf Galaxies ◽

Star Formation Rate ◽

Formation Rate ◽

Galaxy Cluster ◽

Mass Function ◽

Star Cluster ◽

Upper Limit ◽

Formation History ◽

Individual Star

AbstractThe present-day sample of ultra-compact dwarf galaxies (UCDs) and globular clusters (GCs) around NGC 1399 is interpreted to be composed of individual star cluster (SC) populations. It is assumed that such an SC population forms at a constant star-formation rate (SFR), and its mass distribution is described by the embedded cluster mass function (ECMF) up to the upper limit Mmax. The GCs and UCDs probably formed in interactions of the progenitor galaxies during the assembly of the central Fornax galaxy cluster which is why we use them as tracers of those events. After some corrections, the overall GC/UCD mass function is decomposed into separate SC populations, each described by an ECMF. Mmax of each ECMF is converted to an SFR according to the SFR-Mmax relation, revealing the SFRs reached during the assembly of galaxies in the central Fornax galaxy cluster.

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Intra-cluster GC-LMXB in the Fornax galaxy cluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319007890 ◽

2019 ◽

Vol 14 (S351) ◽

pp. 151-154

Author(s):

G. Riccio ◽

M. Paolillo ◽

R. D’Abrusco ◽

M. Cantiello ◽

X. Jin ◽

...

Keyword(s):

Globular Clusters ◽

Galaxy Cluster ◽

Stellar Systems ◽

X Ray ◽

Low Mass ◽

Fornax Cluster ◽

X Ray Binaries

AbstractThe formation of Low mass X-ray binaries (LMXB) is favored within dense stellar systems such as Globular Clusters (GCs). The connection between LMXB and Globular Clusters has been extensively studied in the literature, but these studies have always been restricted to the innermost regions of galaxies. We present a study of LMXB in GCs within the central 1.5 deg2 of the Fornax cluster with the aim of confirming the existence of a population of LMXB in intra-cluster GCs and understand if their properties are related to the host GCs, to the environment or/and to different formation channels.

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The X-ray emissivity of low-density stellar populations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa194 ◽

2020 ◽

Vol 492 (4) ◽

pp. 5684-5708 ◽

Cited By ~ 2

Author(s):

C O Heinke ◽

M G Ivanov ◽

E W Koch ◽

R Andrews ◽

L Chomiuk ◽

...

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Dwarf Galaxy ◽

Open Cluster ◽

Strong Dependence ◽

Galaxy Cluster ◽

Stellar Populations ◽

Low Density ◽

X Ray ◽

X Ray Binaries

ABSTRACT The dynamical production of low-mass X-ray binaries and brighter cataclysmic variables (CVs) in dense globular clusters is well-established. We investigate how the X-ray emissivity of fainter X-ray binaries (principally CVs and coronally active binaries) varies between different environments. We compile calculations (largely from the literature) of the X-ray emissivity of old stellar populations, including open and globular clusters and several galaxies. We investigate three literature claims of unusual X-ray sources in low-density stellar populations. We show that a suggested quiescent neutron star in the open cluster NGC 6819 is a foreground M dwarf. We show that the suggested diffuse X-ray emission from an old nova shell in the globular cluster NGC 6366 is actually a background galaxy cluster. And we show that a suggested population of quiescent X-ray binaries in the Sculptor Dwarf Galaxy is mostly (perhaps entirely) background galaxies. We find that above densities of 104 M⊙ pc−3, the X-ray emissivity of globular clusters increases, due to dynamical production of X-ray emitting systems. Below this density, globular clusters have lower X-ray emissivity than the other populations, and we do not see a strong dependence of X-ray emissivity due to density effects. We find significant correlations between X-ray emissivity and binary fraction, metallicity, and density. Sampling these fits via bootstrap techniques gives less significant correlations, but confirms the effect of metallicity on low-density populations, and that of density on the full globular cluster sample.

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Dust and star formation in the centre of NGC 3311

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037932 ◽

2020 ◽

Vol 643 ◽

pp. A119 ◽

Cited By ~ 1

Author(s):

T. Richtler ◽

M. Hilker ◽

M. Arnaboldi ◽

C. E. Barbosa

Keyword(s):

Star Formation ◽

Emission Line ◽

Globular Clusters ◽

Stellar Population ◽

Line Emission ◽

Galaxy Cluster ◽

Emission Lines ◽

Strong Line ◽

Rotating Disc ◽

Neutral Gas

Context. NGC 3311 is the central galaxy of the Hydra I galaxy cluster. It has a hot interstellar medium and hosts a central dust lane with emission lines. These dust lanes are frequent in elliptical galaxies, but the case of NGC 3311 might be particularly interesting for problems of dust lifetime and the role of cool gas in the central parts. Aims. We aim to use archival HST images and MUSE data to investigate the central dust structure of NGC 3311. Methods. We used the tool PyParadise to model the stellar population and extract the emission lines. Results. The HST/ACS colour map reveals the known dust structures, but also blue spots, which are places of strong line emission. A dusty “mini-jet” emanates from the centre. The distribution of the emission line gas matches the dust silhouette almost exactly. Close to the brightest Hα emission, the ratio [NII]/Hα resembles that of HII-regions; in the outer parts, [NII] gets stronger and is similar to LINERLow-ionization nuclear emission-line region -like spectra. The gas kinematics is consistent with that of a rotating disc. The Doppler shifts of the strongest line emissions, which indicate the areas of highest star formation activity, smoothly fit into the disc symmetry. The metallicity is supersolar. The presence of neutral gas is indicated by the fit residuals of the stellar NaI D absorption line, which we interpret as interstellar absorption. We estimate the mass of the neutral gas to be of the order of the X-ray mass. The dynamical mass infers a stellar population of intermediate age, whose globular clusters have already been identified. Conclusions. Our findings can be harmonised in a scenario in which the star formation is triggered by the accretion of cold gas onto a pre-existing gas/dust disc or ring. Newly produced dust then contributes to the longevity of the dust.

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