scholarly journals Globular cluster clustering around ultra compact dwarf galaxies in the halo of NGC 1399

2015 ◽  
Vol 11 (S317) ◽  
pp. 365-366 ◽  
Author(s):  
Karina Voggel ◽  
Michael Hilker ◽  
Tom Richtler
Keyword(s):  
Spatial Distribution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Star Cluster ◽  
Host Galaxy ◽  
Cluster Complex ◽  
Fornax Cluster

AbstractWe tested the spatial distribution of UCDs and GCs in the halo of NGC 1399 in the Fornax cluster. In particular we tried to find out if globular clusters are more abundant in the vicinity of UCDs than what is expected from their global distribution. A local overabundance of globular clusters was found around UCDs on a scale of 1 kpc compared to what is expected from the large scale distribution of globulars in the host galaxy. This effect is stronger for the metal-poor blue GCs and weaker for the red GCs. An explanation for these clustered globulars is either that they are the remains of a GC system of an ancestor dwarf galaxy before it was stripped to its nucleus, which appears as UCD today. Alternatively these clustered GCs could have been originally part of a super star cluster complex.

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.

scholarly journals The Mass Distribution of the Milky Way Deduced from Globular Cluster Dynamics

1996 ◽  
Vol 169 ◽  
pp. 697-702 ◽  
Author(s):  
B. Dauphole ◽  
J. Colin ◽  
M. Geffert ◽  
M. Odenkirchen ◽  
H.-J. Tucholke
Keyword(s):  
Spatial Distribution ◽  
Mass Distribution ◽  
Globular Cluster ◽  
Total Mass ◽  
Globular Clusters ◽  
Large Scale ◽  
Milky Way ◽  
Proper Motions ◽  
Orbital Parameters ◽  
Galactic Potential

We present here a new analytical Galactic potential. We used the constraint of galactic globular cluster dynamics compared to their spatial distribution. This was done with the help of the globular clusters' proper motions. The result for the clusters dynamics show a better agreement between orbital parameters and statistical distribution of the studied globular clusters than in previous published potentials. The globular cluster dynamics constrain the mass distribution on a large scale, until 40 kpc from the centre. In this model, the total mass for the Milky Way is 7.9 1011 M⊙.

scholarly journals The major merger origin of the Andromeda II kinematics

2018 ◽  
Vol 14 (S344) ◽  
pp. 62-65
Author(s):  
Ivana Ebrová ◽  
Ewa L. Łokas ◽  
Sylvain Fouquet ◽  
Andrés del Pino
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Equal Mass ◽  
Star Formation History ◽  
Host Galaxy ◽  
Tidal Forces ◽  
Radial Orbit ◽  
Major Merger

AbstractProlate rotation (i.e. rotation around the long axis) has been reported for two Local Group dwarf galaxies: Andromeda II, a dwarf spheroidal satellite of M31, and Phoenix, a transition type dwarf galaxy. The prolate rotation may be an exceptional indicator of a past major merger between dwarf galaxies. We showed that this type of rotation cannot be obtained in the tidal stirring scenario, in which the satellite is transformed from disky to spheroidal by tidal forces of the host galaxy. However, we successfully reproduced the observed Andromeda II kinematics in controlled, self-consistent simulations of mergers between equal-mass disky dwarf galaxies on a radial or close-to-radial orbit. In simulations including gas dynamics, star formation and ram pressure stripping, we are able to reproduce more of the observed properties of Andromeda II: the unusual rotation, the bimodal star formation history and the spatial distribution of the two stellar populations, as well as the lack of gas. We support this scenario by demonstrating the merger origin of prolate rotation in the cosmological context for sufficiently resolved galaxies in the Illustris large-scale cosmological hydrodynamical simulation.

scholarly journals A Search for Globular Clusters in the Surroundings of Dwarf Galaxies in Fornax: Intracluster Globulars?

2002 ◽  
Vol 207 ◽  
pp. 345-347
Author(s):  
Lilia P. Bassino ◽  
Sergio A. Cellone ◽  
Juan C. Forte
Keyword(s):  
Density Distribution ◽  
Globular Cluster ◽  
Surface Density ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Color Distribution ◽  
Low Surface Brightness ◽  
Fornax Cluster

We present the results of a search for globular clusters in the surroundings of 15 low surface brightness dwarf galaxies in the Fornax cluster, on CCD images in the C and T1 bands. Globular cluster candidates show a clear bimodal color distribution. Their surface density distribution shows no concentration towards the respective dwarf galaxies but it does show concentration towards the center of the Fornax cluster. We suggest that the potential globular clusters might not be bound to the dwarf galaxies, but might instead belong to the intra-cluster medium.

scholarly journals The accreted nuclear clusters of the Milky Way

2020 ◽  
Vol 500 (2) ◽  
pp. 2514-2524
Author(s):  
Joel Pfeffer ◽  
Carmela Lardo ◽  
Nate Bastian ◽  
Sara Saracino ◽  
Sebastian Kamann
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
Host Galaxy ◽  
The Galaxy ◽  
Nuclear Clusters ◽  
The Common ◽  
Massive Clusters ◽  
Peculiar Case

ABSTRACT A number of the massive clusters in the halo, bulge, and disc of the Galaxy are not genuine globular clusters (GCs) but instead are different beasts altogether. They are the remnant nuclear star clusters (NSCs) of ancient galaxies since accreted by the Milky Way. While some clusters are readily identifiable as NSCs and can be readily traced back to their host galaxy (e.g. M54 and the Sagittarius Dwarf galaxy), others have proven more elusive. Here, we combine a number of independent constraints, focusing on their internal abundances and overall kinematics, to find NSCs accreted by the Galaxy and trace them to their accretion event. We find that the true NSCs accreted by the Galaxy are: M54 from the Sagittarius Dwarf, ω Centari from Gaia-Enceladus/Sausage, NGC 6273 from Kraken, and (potentially) NGC 6934 from the Helmi Streams. These NSCs are prime candidates for searches of intermediate-mass black holes (BHs) within star clusters, given the common occurrence of galaxies hosting both NSCs and central massive BHs. No NSC appears to be associated with Sequoia or other minor accretion events. Other claimed NSCs are shown not to be such. We also discuss the peculiar case of Terzan 5, which may represent a unique case of a cluster–cluster merger.

An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750

2019 ◽  
Vol 15 (S356) ◽  
pp. 376-376
Author(s):  
Ingyin Zaw
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Host Galaxy ◽  
Scaling Relations ◽  
Host Galaxies ◽  
Seed Formation ◽  
Maser Emission ◽  
Water Masers

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.

scholarly journals The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 300-300
Author(s):  
R.O. Amorín ◽  
J.A.L. Aguerri ◽  
L.M. Cairós ◽  
N. Caon ◽  
C. Muñoz-Tuñón
Keyword(s):  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Structural Parameters ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Galaxy Formation And Evolution ◽  
Radial Profiles ◽  
Low Surface Brightness ◽  
Formation And Evolution

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.

scholarly journals Central Dynamics of Globular Clusters: the Case for a Black Hole in ω Centauri

2007 ◽  
Vol 3 (S246) ◽  
pp. 341-345
Author(s):  
Eva Noyola ◽  
Karl Gebhardt ◽  
Marcel Bergmann
Keyword(s):  
Black Hole ◽  
Relaxation Time ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Dwarf Galaxy ◽  
Kinematic Data ◽  
The Core ◽  
Galactic System ◽  
Interesting Candidate ◽  
Radial Anisotropy

AbstractThe globular cluster ω Centauri is one of the largest and most massive members of the Galactic system. Its classification as a globular cluster has been challenged making it a candidate for being the stripped core of an accreted dwarf galaxy; this and the fact that it has one of the largest velocity dispersions for star clusters in our galaxy makes it an interesting candidate for harboring an intermediate mass black hole. We measure the surface brightness profile from integrated light on an HST/ACS image, and find a central power-law cusp of logarithmic slope -0.08. We also analyze Gemini GMOS-IFU kinematic data for a 5”x5” field centered on the nucleus of the cluster, as well as for a field 14″ away. We detect a clear rise in the velocity dispersion from 18.6 kms−1 at 14″ to 23 kms−1 in the center. Given the very large core in ω Cen (2.58'), an increase in the dispersion in the central 10″ is difficult to attribute to stellar remnants, since it requires too many dark remnants and the implied configuration would dissolve quickly given the relaxation time in the core. However, the increase could be consistent with the existence of a central black hole. Assuming a constant M/L for the stars within the core, the dispersion profile from these data and data at larger radii implies a black hole mass of 4.0+0.75−1.0×104M⊙. We have also run flattened, orbit-based models and find a similar mass. In addition, the no black hole case for the orbit model requires an extreme amount of radial anisotropy, which is difficult to preserve given the short relaxation time of the cluster.

scholarly journals The Ghosts of Galaxies: Tidal Debris in Clusters

2004 ◽  
Vol 217 ◽  
pp. 70-76
Author(s):  
Michael D. Gregg ◽  
Michael J. West
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
X Ray ◽  
Cluster Evolution ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Formation And Evolution

Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby Coma and Centaurus clusters both have striking examples of galaxy ghosts, in the form of 100 kpc-long plumes of intergalactic debris. By searching HST archival images, we have found numerous other examples of galaxy ghosts in rich clusters at low redshift, evidence that galaxy destruction and recycling are ubiquitous, important in cluster formation and evolution, and continue to mold clusters at the present epoch. Many ghosts appear in X-ray bright clusters, perhaps signaling a connection with energetic subcluster mergers.The fate of such material has important ramifications for cluster evolution. Our new HST WFPC2 V & I images of a portion of the Centaurus plume reveal that it contains an excess of discrete objects with −12 < MV < −6, consistent with being globular clusters or smaller dwarf galaxies. This tidally liberated material is being recycled directly into the intracluster population of stars, dwarf galaxies, globular clusters, and gas, which may have been built largely from a multitude of similar events over the life of the cluster.

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