scholarly journals Ultradiffuse galaxies in the IC 1459 group from the VEGAS survey

2020 ◽  
Vol 494 (4) ◽  
pp. 5293-5297
Author(s):  
Duncan A Forbes ◽  
Bililign T Dullo ◽  
Jonah Gannon ◽  
Warrick J Couch ◽  
Enrichetta Iodice ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Compact Objects ◽  
Early Type ◽  
Group Members ◽  
Measurement Uncertainties ◽  
Stellar Masses ◽  
Double Nucleus ◽  
Early Type Galaxy

ABSTRACT Using deep g, r, i imaging from the VST Early-type GAlaxy Survey (VEGAS), we have searched for ultradiffuse galaxies (UDGs) in the IC 1459 group. Assuming they are group members, we identify nine galaxies with physical sizes and surface brightnesses that match the UDG criteria within our measurement uncertainties. They have mean colours of g − i = 0.6 and stellar masses of ∼108 M⊙. Several galaxies appear to have associated systems of compact objects, e.g. globular clusters. Two UDGs contain a central bright nucleus, with a third UDG revealing a remarkable double nucleus. This appears to be the first reported detection of a double nucleus in a UDG – its origin is currently unclear.

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.

scholarly journals Study of gravitational fields and globular cluster systems of early-type galaxies

2019 ◽  
Vol 625 ◽  
pp. A32 ◽  
Author(s):  
M. Bílek ◽  
S. Samurović ◽  
F. Renaud
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Globular Clusters ◽  
Mass Relation ◽  
Early Type ◽  
Radial Acceleration ◽  
Galaxy Interactions ◽  
Gravitational Fields ◽  
Stellar Masses ◽  
Best Fit

Context.Gravitational fields at the outskirts of early-type galaxies (ETGs) are difficult to constrain observationally. It thus remains poorly explored how well the ΛCDM and MOND hypotheses agree with ETGs.Aims.The dearth of studies on this topic motivated us to gather a large sample of ETGs and examine homogeneously which dark matter halos they occupy, whether the halos follow the theoretically predicted stellar-to-halo mass relation (SHMR) and the halo mass-concentration relation (HMCR), whether ETGs obey MOND and the radial acceleration relation (RAR) observed for late-type galaxies (LTGs), and finally whether ΛCDM or MOND perform better in ETGs.Methods.We employed Jeans analysis of radial velocities of globular clusters (GCs). We analysed nearly all ETGs having more than about 100 archival GC radial velocity measurements available. The GC systems of our 17 ETGs extend mostly over ten effective radii. A ΛCDM simulation of GC formation helped us to interpret the results.Results.Successful ΛCDM fits are found for all galaxies, but compared to the theoretical HMCR and SHMR, the best-fit halos usually have concentrations that are too low and stellar masses that are too high for their masses. This might be because of tidal stripping of the halos or because ETGs and LTGs occupy different halos. Most galaxies can be fitted by the MOND models successfully as well, but for some of the galaxies, especially those in centers of galaxy clusters, the observed GC velocity dispersions are too high. This might be a manifestation of the additional dark matter that MOND requires in galaxy clusters. Additionally, we find many signs that the GC systems were perturbed by galaxy interactions. Formal statistical criteria prefer the best-fit ΛCDM models over the MOND models, but this might be due to the higher flexibility of the ΛCDM models. The MOND approach can predict the GC velocity dispersion profiles better.

scholarly journals CHEMICAL ABUNDANCE EVIDENCE OF ENDURING HIGH STAR FORMATION RATES IN AN EARLY-TYPE GALAXY: HIGH [Ca/Fe] IN NGC 5128 GLOBULAR CLUSTERS

2013 ◽  
Vol 773 (2) ◽  
pp. L36 ◽  
Author(s):  
Janet E. Colucci ◽  
María Fernanda Durán ◽  
Rebecca A. Bernstein ◽  
Andrew McWilliam
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Early Type ◽  
Chemical Abundance ◽  
Early Type Galaxy

scholarly journals A Wide-field Photometric Survey of Globular Clusters in the Peculiar Early-type Galaxy M85

2019 ◽  
Vol 872 (2) ◽  
pp. 202 ◽  
Author(s):  
Youkyung Ko ◽  
Myung Gyoon Lee ◽  
Hong Soo Park ◽  
Sungsoon Lim ◽  
Jubee Sohn ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Wide Field ◽  
Early Type ◽  
Early Type Galaxy

scholarly journals The total mass of the early-type galaxy NGC 4649 (M60)

2008 ◽  
pp. 1-7
Author(s):  
S. Samurovic ◽  
M.M. Cirkovic
Keyword(s):  
Dark Matter ◽  
Total Mass ◽  
Globular Clusters ◽  
X Rays ◽  
Early Type ◽  
X Ray ◽  
Modified Newtonian Dynamics ◽  
Newtonian Dynamics ◽  
Early Type Galaxy

In this paper the problem of the total mass and the total mass-to-light ratio of the early-type galaxy NGC 4649 (M60) is analyzed. Use is made of two independent techniques: the X-ray methodology which is based on the temperature of the X-ray halo of NGC 4649 and the tracer mass estimator (TME) which uses globular clusters (GCs) observed in this galaxy. The mass is calculated in Newtonian and Modified Newtonian Dynamics (MOND) approaches and it is found that inside 3 effective radii (Re ) there is no need for large amounts of dark matter. Beyond 3Re the dark matter starts to play important dynamical role. The possible reasons for the discrepancy between the estimates of the total mass based on X-rays and TME in the outer regions of NGC 4649 are also discussed.

scholarly journals Low dark matter content of the nearby early-type galaxy NGC 821

2014 ◽  
pp. 29-36 ◽  
Author(s):  
S. Samurovic ◽  
A. Vudragovic ◽  
M. Jovanovic ◽  
M.M. Cirkovic
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Planetary Nebulae ◽  
Matter Content ◽  
Kinematics And Dynamics ◽  
Constant Mass ◽  
Early Type ◽  
Kinematic Data ◽  
Early Type Galaxy ◽  
Dynamical Modelling

In this paper we analyze the kinematics and dynamics of the nearby early-type galaxy NGC 821 based on its globular clusters (GCs) and planetary nebulae (PNe). We use PNe and GCs to extract the kinematics of NGC 821 which is then used for the dynamical modelling based on the Jeans equation. We apply the Jeans equation using the Newtonian mass-follows-light approach assuming constant mass-to-light ratio and find that using such an approach we can successfully fit the kinematic data. The inferred constant mass-to-light ratio, 4:2 < M=LB < 12:4 present throughout the whole galaxy, implies the lack of significant amount of dark matter. We also used three different MOND approaches and found that we can fit the kinematic data without the need for additional, dark, component.

scholarly journals New Constraints on Early-type Galaxy Assembly from Spectroscopic Metallicities of Globular Clusters in M87

2019 ◽  
Vol 879 (1) ◽  
pp. 45 ◽  
Author(s):  
Alexa Villaume ◽  
Aaron J. Romanowsky ◽  
Jean Brodie ◽  
Jay Strader
Keyword(s):  
Globular Clusters ◽  
Early Type ◽  
Galaxy Assembly ◽  
Early Type Galaxy

scholarly journals The first detection of ultra-diffuse galaxies in the Hydra I cluster from the VEGAS survey

2020 ◽  
Vol 642 ◽  
pp. A48
Author(s):  
E. Iodice ◽  
M. Cantiello ◽  
M. Hilker ◽  
M. Rejkuba ◽  
M. Arnaboldi ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Total Population ◽  
Matter Content ◽  
Early Type ◽  
Low Surface Brightness ◽  
Colour Distribution ◽  
Specific Frequency ◽  
Stellar Masses ◽  
Low Surface Brightness Galaxies ◽  
Early Type Galaxy

In this paper, we report the discovery of 27 low-surface brightness galaxies, of which 12 are candidates for ultra-diffuse galaxies (UDG) in the Hydra I cluster, based on deep observations taken as part of the VST Early-type Galaxy Survey (VEGAS). This first sample of UDG candidates in the Hydra I cluster represents an important step in our project that aims to enlarge the number of confirmed UDGs and, through study of statistically relevant samples, constrain the nature and formation of UDGs. This study presents the main properties of this class of galaxies in the Hydra I cluster. For all UDGs, we analysed the light and colour distribution, and we provide a census of the globular cluster (GC) systems around them. Given the limitations of a reliable GC selection based on two relatively close optical bands only, we find that half of the UDG candidates have a total GC population consistent with zero. Of the other half, two galaxies have a total population larger than zero at 2σ level. We estimate the stellar mass, the total number of GCs, and the GC specific frequency (SN). Most of the candidates span a range of stellar masses of 107 − 108 M⊙. Based on the GC population of these newly discovered UDGs, we conclude that most of these galaxies have a standard or low dark matter content, with a halo mass of ≤1010 M⊙.

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