scholarly journals A discrete chemo-dynamical model of M87’s globular clusters: Kinematics extending to ∼400 kpc

2020 ◽  
Vol 492 (2) ◽  
pp. 2775-2795
Author(s):  
Chao Li ◽  
Ling Zhu ◽  
R J Long ◽  
Shude Mao ◽  
Eric W Peng ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Tangential Velocity ◽  
Major Axis ◽  
Main Galaxy ◽  
Luminous Matter ◽  
Best Fitting ◽  
Field Unit ◽  
Varying Mass

ABSTRACT We study the mass distribution and kinematics of the giant elliptical galaxy M87 (NGC 4486) using discrete chemo-dynamical, axisymmetric Jeans equation modelling. Our catalogue comprises 894 globular clusters (GCs) extending to a projected radius of ∼430 kpc with line-of-sight velocities and colours, and Multi Unit Spectroscopic Explorer integral field unit data within the central 2.4 kpc of the main galaxy. The gravitational potential for our models is a combination of a luminous matter potential with a varying mass-to-light ratio for the main galaxy, a supermassive black hole and a dark matter (DM) potential with a cusped or cored DM halo. The best-fitting models with either a cusped or a cored DM halo show no significant differences and both are acceptable. We obtain a total mass of $(2.16 \pm 0.38) \times 10^{13} \, \mathrm{M}_{\odot }$ within ∼400 kpc. By including the stellar mass-to-light ratio gradient, the DM fraction increases from ∼26 per cent (with no gradient) to ∼73 per cent within $1\, R_e^{\rm maj}$ (major axis of half-light isophote, 14.2 kpc), and from ∼84 per cent to ∼94 per cent within $5\, R_e^{\rm maj}$ (71.2 kpc). Red GCs have moderate rotation with Vmax/σ ∼ 0.4, and blue GCs have weak rotation with Vmax/σ ∼ 0.1. Red GCs have tangential velocity dispersion anisotropy, while blue GCs are consistent with being nearly isotropic. Our results suggest that red GCs are more likely to be born in situ, while blue GCs are more likely to be accreted.

scholarly journals Anisotropic Distribution Functions for the Elliptical Galaxy NGC 1600

1996 ◽  
Vol 171 ◽  
pp. 413-413
Author(s):  
Michael Matthias ◽  
Ortwin Gerhard
Keyword(s):  
Perturbation Theory ◽  
Elliptical Galaxy ◽  
Major Axis ◽  
Distribution Functions ◽  
Minor Axis ◽  
Dynamical Models ◽  
Ccd Photometry ◽  
Radial Anisotropy ◽  
Best Fitting ◽  
Integral Distribution

Three-integral (3I) dynamical models for NGC 1600 were constructed as follows: (i) Lucy-inversion of CCD photometry and gravitational potential as in Binney, Davies, Illingworth (ApJ 361, 78, 1990), assuming axisymmetry. (ii) Third integral by perturbation theory as in Gerhard & Saha (MN 261, 311, 1991). (iii) Two- and three-integral distribution functions as in Dehnen & Gerhard (MN 261, 311, 1993), assuming various anisotropy patterns. The kinematic results from these models are presented in Fig. 1. The best-fitting 3I model (solid line, right panels) has outward-increasing radial anisotropy on the major axis and is nearly isotropic on the minor axis. The M/L of the various 3I-models varies only slightly around M/L=6.2.

scholarly journals A Complete Sample of Globular Clusters in NGC 5128

1988 ◽  
Vol 126 ◽  
pp. 545-546
Author(s):  
Ray Sharples
Keyword(s):  
Power Law ◽  
Density Profile ◽  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Major Axis ◽  
Cluster System ◽  
Radial Velocities ◽  
Complete Sample ◽  
The Core ◽  
The Galaxy

We present the results of an unbiased survey to search for globular clusters around the nearby elliptical galaxy NGC 5128. A total of 44 clusters has been identified on the basis of radial velocities alone. The cluster system appears to be flattened towards the major axis of the galaxy but does not show any dynamically significant rotation. There is a deficit of clusters in the core when compared with the power law density profile seen at large radii.

scholarly journals Globular Clusters and Planetary Nebula Kinematics in NGC 5128 (Cen A)

2002 ◽  
Vol 207 ◽  
pp. 312-314
Author(s):  
Eric W. Peng ◽  
Holland C. Ford ◽  
Kenneth C. Freeman
Keyword(s):  
Angular Momentum ◽  
Globular Cluster ◽  
Planetary Nebula ◽  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Major Axis ◽  
Wide Field ◽  
List Type ◽  
Type Number

We have conducted a wide-field optical survey of NGC 5128 (Cen A), the nearest large elliptical galaxy (3.5 Mpc). From UBVRI imaging and spectroscopic follow-up, we have identified and obtained kinematics for 125 new globular clusters out to a projected radius of 40 kpc. We also extend our survey of field star kinematics in NGC 5128, and now possess a total of 736 radial velocities for planetary nebulae out to a projected radius of 80 kpc.•The PNe sample along the photometric major axis shows significant rotational support out to 80 kpc.•The blue globular clusters seem to possess little or no angular momentum.•The kinematics of the red globular cluster sample show some evidence for rotation around an axis common to that of the field stars.

scholarly journals Creation/destruction of ultra-wide binaries in tidal streams

2020 ◽  
Author(s):  
Jorge Peñarrubia
Keyword(s):  
Globular Clusters ◽  
Galactic Halo ◽  
Local Density ◽  
Formation Rate ◽  
Semimajor Axis ◽  
Major Axis ◽  
Binding Energies ◽  
Semi Major Axis ◽  
The Mean ◽  
Tidal Streams

Abstract This paper uses statistical and N-body methods to explore a new mechanism to form binary stars with extremely large separations (≳ 0.1 pc), whose origin is poorly understood. Here, ultra-wide binaries arise via chance entrapment of unrelated stars in tidal streams of disrupting clusters. It is shown that (i) the formation of ultra-wide binaries is not limited to the lifetime of a cluster, but continues after the progenitor is fully disrupted, (ii) the formation rate is proportional to the local phase-space density of the tidal tails, (iii) the semimajor axis distribution scales as p(a)da ∼ a1/2da at a ≪ D, where D is the mean interstellar distance, and (vi) the eccentricity distribution is close to thermal, p(e)de = 2ede. Owing to their low binding energies, ultra-wide binaries can be disrupted by both the smooth tidal field and passing substructures. The time-scale on which tidal fluctuations dominate over the mean field is inversely proportional to the local density of compact substructures. Monte-Carlo experiments show that binaries subject to tidal evaporation follow p(a)da ∼ a−1da at a ≳ apeak, known as Öpik’s law, with a peak semi-major axis that contracts with time as apeak ∼ t−3/4. In contrast, a smooth Galactic potential introduces a sharp truncation at the tidal radius, p(a) ∼ 0 at a ≳ rt. The scaling relations of young clusters suggest that most ultra-wide binaries arise from the disruption of low-mass systems. Streams of globular clusters may be the birthplace of hundreds of ultra-wide binaries, making them ideal laboratories to probe clumpiness in the Galactic halo.

scholarly journals Assembly Histories and Observational Properties of Simulated Early-type Galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 354-357
Author(s):  
Peter H. Johansson
Keyword(s):  
Star Formation ◽  
Initial Growth ◽  
Early Type ◽  
Massive Galaxies ◽  
Main Galaxy ◽  
Two Phases ◽  
Late Growth ◽  
Kinematic Properties

AbstractWe demonstrate that massive simulated galaxies assemble in two phases, with the initial growth dominated by compact in situ star formation, whereas the late growth is dominated by accretion of old stars formed in subunits outside the main galaxy. We also show that 1) gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy colour bimodality that 2) the observed galaxy downsizing can be explained naturally in the two-phased model and finally that 3) the details of the assembly histories of massive galaxies are directly connected to their observed kinematic properties.

scholarly journals The WAGGS project-III. Discrepant mass-to-light ratios of Galactic globular clusters at high metallicity

2020 ◽  
Vol 492 (3) ◽  
pp. 3859-3871 ◽  
Author(s):  
H Dalgleish ◽  
S Kamann ◽  
C Usher ◽  
H Baumgardt ◽  
N Bastian ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Milky Way ◽  
Population Models ◽  
Theoretical Predictions ◽  
Field Unit ◽  
Stellar Masses ◽  
Kinematic Information ◽  
High Metallicity ◽  
Integral Field

ABSTRACT Observed mass-to-light ratios (M/L) of metal-rich globular clusters (GCs) disagree with theoretical predictions. This discrepancy is of fundamental importance since stellar population models provide the stellar masses that underpin most of extragalactic astronomy, near and far. We have derived radial velocities for 1622 stars located in the centres of 59 Milky Way GCs – 12 of which have no previous kinematic information – using integral-field unit data from the WAGGS project. Using N-body models, we determine dynamical masses and M/LV for the studied clusters. Our sample includes NGC 6528 and NGC 6553, which extend the metallicity range of GCs with measured M/L up to [Fe/H] ∼ −0.1 dex. We find that metal-rich clusters have M/LV more than two times lower than what is predicted by simple stellar population models. This confirms that the discrepant M/L–[Fe/H] relation remains a serious concern. We explore how our findings relate to previous observations, and the potential causes for the divergence, which we conclude is most likely due to dynamical effects.

scholarly journals A Spiral-Like Disk of Ionized Gas in IC 1459: Signature of a Merging Collision?

1990 ◽  
Vol 124 ◽  
pp. 215-219
Author(s):  
Paul Goudfrooij ◽  
H.U. Nørgaard-Nielsen ◽  
H.E. Jørgensen ◽  
L. Hansen ◽  
T. de Jong
Keyword(s):  
Spiral Structure ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
Major Axis ◽  
Colour Index ◽  
Line Flux ◽  
Ionized Gas ◽  
The Galaxy ◽  
Merger Event ◽  
Stellar Body

AbstractWe report the discovery of a large (15 kpc diameter) Hα+[NII] emission-line disk in the elliptical galaxy IC 1459, showing weak spiral structure. The line flux peaks strongly at the nucleus and is more concentrated than the stellar continuum. The major axis of the disk of ionized gas coincides with that of the stellar body of the galaxy. The mass of the ionized gas is estimated to be ~ 1 105 M⊙, less than 1% of the total mass of gas present in IC 1459. The total gas mass of 4 107 M⊙ has been estimated from the dust mass derived from a broad-band colour index image and the IRAS data. We speculate that the presence of dust and gas in IC 1459 is a signature of a merger event.

scholarly journals Ultraluminous Infrared Galaxies

1999 ◽  
Vol 186 ◽  
pp. 289-294 ◽  
Author(s):  
D.B. Sanders ◽  
J.A. Surace ◽  
C.M. Ishida
Keyword(s):  
Globular Clusters ◽  
Elliptical Galaxy ◽  
Seyfert Galaxies ◽  
Infrared Galaxies ◽  
Primary Stage ◽  
Massive Black Holes ◽  
Bolometric Luminosity ◽  
Ultraluminous Infrared Galaxies ◽  
Supernova Explosions ◽  
Galaxy Cores

At luminosities above ~ 1011L⊙, infrared galaxies become the dominant population of extragalactic objects in the local Universe (z < 0.5), being more numerous than optically selected starburst and Seyfert galaxies, and QSOs at comparable bolometric luminosity. At the highest luminosities, ultraluminous infrared galaxies (ULIGs: Lir > 1012L⊙), outnumber optically selected QSOs by a factor of ~ 1.5–2. All of the nearest ULIGs (z <0.1) appear to be advanced mergers that are powered by both a circumnuclear starburst and AGN, both of which are fueled by an enormous concentration of molecular gas (~ 1010M⊙) that has been funneled into the merger nucleus. ULIGs may represent a primary stage in the formation of massive black holes and elliptical galaxy cores. The intense circumnuclear starburst that accompanies the ULIG phase may also represent a primary stage in the formation of globular clusters, and the metal enrichment of the intergalactic medium by gas and dust expelled from the nucleus due to the combined forces of supernova explosions and powerful stellar winds.

scholarly journals Light element variations within the different age-metallicity populations in the nucleus of the Sagittarius dwarf

2019 ◽  
Vol 490 (1) ◽  
pp. L67-L70 ◽  
Author(s):  
Alison Sills ◽  
Emanuele Dalessandro ◽  
Mario Cadelano ◽  
Mayte Alfaro-Cuello ◽  
J M Diederik Kruijssen
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Star Clusters ◽  
Light Element ◽  
Iron Complex ◽  
Star Cluster ◽  
Chromosome Maps ◽  
Insight Into ◽  
Poor Population

ABSTRACT The cluster M54 lies at the centre of the Sagittarius dwarf spheroidal galaxy, and therefore may be the closest example of a nuclear star cluster. Either in situ star formation, inspiralling globular clusters, or a combination have been invoked to explain the wide variety of stellar sub-populations in nuclear star clusters. Globular clusters are known to exhibit light element variations, which can be identified using the photometric construct called a chromosome map. In this letter, we create chromosome maps for three distinct age-metallicity sub-populations in the vicinity of M54. We find that the old, metal-poor population shows the signature of light element variations, while the young and intermediate-age metal rich populations do not. We conclude that the nucleus of Sagittarius formed through a combination of in situ star formation and globular cluster accretion. This letter demonstrates that properly constructed chromosome maps of iron-complex globular clusters can provide insight into the formation locations of the different stellar populations.

scholarly journals Using MUSE-AO observations to constrain the formation of the large nuclear star cluster in FCC 47

2019 ◽  
Vol 14 (S351) ◽  
pp. 108-111
Author(s):  
Katja Fahrion ◽  
Mariya Lyubenova ◽  
Glenn van de Ven ◽  
Michael Hilker
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Host Galaxy ◽  
Wide Field ◽  
Early Type ◽  
Gas Reservoir ◽  
External Galaxies ◽  
Integral Field ◽  
Early Type Galaxy

AbstractNuclear star clusters (NSCs) are found in at least 70% of all galaxies, but their formation path is still unclear. In the most common scenarios, NSCs form in-situ from the galaxy’s central gas reservoir, through merging of globular clusters (GCs), or through a combination of the two. As the scenarios pose different expectations for angular momentum and stellar population properties of the NSC in comparison to the host galaxy and the GC system, it is necessary to characterise the stellar light, NSC, and GCs simultaneously. Wide-field observations with modern integral field units such as the Multi Unit Spectroscopic Explorer (MUSE) allow to perform such studies. However, at large distances, NSCs usually are not resolved in MUSE observations. The particularly large NSC (Reff ∼ 66 pc) of the early-type galaxy FCC 47 at distance of ∼20 Mpc is an exception and is therefore an ideal laboratory to constrain NSC formation of external galaxies.

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