scholarly journals Globular Cluster Subpopulations in Early-Type Galaxies: Insights into Galaxy Formation

2002 ◽  
Vol 207 ◽  
pp. 218-228
Author(s):  
Jean P. Brodie
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Morphological Type ◽  
Host Galaxy ◽  
Early Type ◽  
Distant Galaxies ◽  
Nearby Galaxies ◽  
Distant Sample ◽  
Multiple Episodes

New and archival HST images of the globular cluster systems of 17 relatively nearby galaxies and 6 more distant galaxies have been used to establish the characteristics of GC subpopulations over a range of host galaxy morphological type from E5 to Sa. GC color/metallicity, size and luminosity distributions have been examined in the nearby galaxies and color distributions have been determined for the more distant sample. Correlations with parent galaxy properties and trends with galactocentric radius have been explored. Supplemented with Keck spectroscopy, our results are best explained by an in situ formation scenario in which both GC subpopulations formed at early times within the potential well of the protogalaxy, in multiple episodes of star formation. We have also discovered a third population of clusters, fundamentally distinct from the compact red and blue clusters common in early type galaxies.

scholarly journals Using GAMA and H-ATLAS data to explore the cold dust properties of early-type galaxies

2011 ◽  
Vol 7 (S284) ◽  
pp. 262-264
Author(s):  
Nicola K. Agius ◽  
Anne E. Sansom ◽  
Cristina C. Popescu
Keyword(s):  
Galaxy Formation ◽  
Concentration Index ◽  
Elliptical Galaxies ◽  
Host Galaxy ◽  
Early Type ◽  
Large Dataset ◽  
Atlas Data ◽  
Multi Wavelength ◽  
Cold Dust

AbstractHierarchical galaxy formation models predict the development of elliptical galaxies through a combination of the mergers and interactions of smaller galaxies. We are carrying out a study of Early-Type Galaxies (ETGs) using GAMA multi-wavelength and Herschel-ATLAS sub-mm data to understand their intrinsic dust properties. The dust in some ETGs may be a relic of past interactions and mergers of galaxies, or may be produced within the galaxies themselves. With this large dataset we will probe the properties of the dust and its relation to host galaxy properties. This paper presents our criteria for selecting ETGs and explores the usefulness of proxies for their morphology, including optical colour, Sérsic index and Concentration index. We find that a combination of criteria including r band Concentration index, ellipticity and apparent sizes is needed to select a robust sample. Optical and sub-mm parameter diagnostics are examined for the selected ETG sample, and the sub-mm data are fitted with modified Planck functions giving initial estimates for the cold dust temperatures and masses.

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 The age structure of globular cluster systems in early-type galaxies and its dependence on host galaxy properties

2006 ◽  
Vol 463 (2) ◽  
pp. 493-502 ◽  
Author(s):  
M. Hempel ◽  
M. Kissler-Patig ◽  
T. H. Puzia ◽  
M. Hilker
Keyword(s):  
Age Structure ◽  
Globular Cluster ◽  
Host Galaxy ◽  
Early Type ◽  
Cluster Systems

scholarly journals Elliptical Galaxies: Darkly Cloaked or Scantily Clad?

2004 ◽  
Vol 220 ◽  
pp. 165-170
Author(s):  
A. J. Romanowsky ◽  
N. G. Douglas ◽  
K. Kuijken ◽  
M. R. Merrifield ◽  
M. Arnaboldi ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Velocity Dispersion ◽  
Elliptical Galaxies ◽  
Small Sample ◽  
Early Type ◽  
Dynamical Models ◽  
Show Evidence ◽  
Major Merger ◽  
Nearby Galaxies ◽  
Ab Initio Models

Planetary nebulae (PNe) may be the most promising tracers in the halos of early-type galaxies. We have used multi-object spectrographs on the WHT and the VLT, and the new Planetary Nebula Spectrograph on the WHT, to obtain hundreds of PN velocities in a small sample of nearby galaxies. These ellipticals show weak halo rotation, which may be consistent with ab initio models of galaxy formation, but not with more detailed major merger simulations. the galaxies near L* show evidence of a universal declining velocity dispersion profile, and dynamical models indicate the presence of little dark matter within 5 Reff—implying halos either not as massive or not as centrally concentrated as CDM predicts.

scholarly journals Stellar halos and the link to galaxy formation

2015 ◽  
Vol 11 (S317) ◽  
pp. 228-234
Author(s):  
Amina Helmi
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Galaxy Formation ◽  
Globular Cluster ◽  
Milky Way ◽  
Cluster System ◽  
Host Galaxy ◽  
Globular Cluster System

AbstractI present a brief overview of how stellar halos may be used to constrain the process of galaxy formation. In particular, streams and substructure in stellar halos trace merger events but can also be used to determine the mass distribution of the host galaxy and hence put constraints on the nature of dark matter. Much of the focus of this contribution is on the Milky Way, but I also present an attempt to understand the kinematics of the globular cluster system of M31.

scholarly journals Early-type galaxies in low-density environments: NGC 6876 explored through its globular cluster system

2019 ◽  
Vol 488 (1) ◽  
pp. 770-781 ◽  
Author(s):  
Ana I Ennis ◽  
Lilia P Bassino ◽  
Juan P Caso ◽  
Bruno J De Bórtoli
Keyword(s):  
Globular Cluster ◽  
Galaxy Cluster ◽  
Host Galaxy ◽  
Distance Modulus ◽  
Early Type ◽  
The Galaxy ◽  
Colour Distribution ◽  
Poor Group ◽  
Early Type Galaxy ◽  
Massive Galaxy

ABSTRACT We present the results of a photometric study of the early-type galaxy NGC 6876 and the surrounding globular cluster (GC) system. The host galaxy is a massive elliptical, the brightest of this type in the Pavo Group. According to its intrinsic brightness (Mv ∼ −22.7), it is expected to belong to a galaxy cluster instead of a poor group. Observational material consists of g′, r′, i′ images obtained with the Gemini/GMOS camera. The selected GC candidates present a clear bimodal colour distribution at different galactocentric radii, with mean colours and dispersions for the metal-poor (‘blue’) and metal-rich (‘red’) typical of old GCs. The red subpopulation dominates close to the galaxy centre, in addition to the radial projected distribution showing that they are more concentrated towards the galaxy centre. The azimuthal projected distribution shows an overdensity in the red subpopulation in the direction of a trail observed in X-ray that could be evidence of interactions with its spiral neighbour NGC 6872. The turnover of the luminosity function gives an estimated distance modulus (m − M) ≈ 33.5 and the total population amounts to 9400 GCs, i.e. a quite populous system. The halo mass obtained using the number ratio (i.e. the number of GCs with respect to the baryonic and dark mass) gives a total of ∼1013, meaning it is a very massive galaxy, given the environment.

scholarly journals A census of ultraluminous X-ray sources in the local Universe

2020 ◽  
Vol 498 (4) ◽  
pp. 4790-4810
Author(s):  
K Kovlakas ◽  
A Zezas ◽  
J J Andrews ◽  
A Basu-Zych ◽  
T Fragos ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Morphological Type ◽  
Star Formation History ◽  
Early Type ◽  
Local Universe ◽  
X Ray ◽  
Star Forming ◽  
Bona Fide ◽  
Nearby Galaxies

ABSTRACT Using the Chandra Source Catalog 2.0 and a newly compiled catalogue of galaxies in the local Universe, we deliver a census of ultraluminous X-ray source (ULX) populations in nearby galaxies. We find 629 ULX candidates in 309 galaxies with distance smaller than 40 Mpc. The foreground/background contamination is $\sim \! 20{{\ \rm per\ cent}}$. The ULX populations in bona fide star-forming galaxies scale on average with star formation rate and stellar mass (M⋆) such that the number of ULXs per galaxy is $0.45^{+0.06}_{-0.09}\times \frac{\rm SFR}{\rm M_\odot \, yr^{-1}}{+}3.3^{+3.8}_{-3.2}\times \frac{M_\star }{\rm M_\odot }$. The scaling depends strongly on the morphological type. This analysis shows that early spiral galaxies contain an additional population of ULXs that scales with M⋆. We also confirm the strong anticorrelation of the ULX rate with the host galaxy’s metallicity. In the case of early-type galaxies, we find that there is a non-linear dependence of the number of ULXs with M⋆, which is interpreted as the result of star formation history differences. Taking into account age and metallicity effects, we find that the predictions from X-ray binary population synthesis models are consistent with the observed ULX rates in early-type galaxies, as well as spiral/irregular galaxies.

scholarly journals Molecular clouds in a Milky Way progenitor at z = 1

2019 ◽  
Vol 15 (S352) ◽  
pp. 269-273
Author(s):  
Miroslava Dessauges-Zavadsky ◽  
Johan Richard ◽  
Françoise Combes ◽  
Daniel Schaerer ◽  
Wiphu Rujopakarn ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Milky Way ◽  
High Redshift ◽  
Galaxy Cluster ◽  
Host Galaxy ◽  
Giant Molecular Clouds ◽  
Distant Galaxies ◽  
First Time ◽  
Massive Galaxy

AbstractThanks to the remarkable ALMA capabilities and the unique configuration of the Cosmic Snake galaxy behind a massive galaxy cluster, we could resolve molecular clouds down to 30 pc linear physical scales in a typical Milky Way progenitor at z = 1.036, through CO(4–3) observations performed at the ∼ 0.2″ angular resolution. We identified 17 individual giant molecular clouds. These high-redshift molecular clouds are clearly different from their local analogues, with 10–100 times higher masses, densities, and internal turbulence. They are offset from the Larson scaling relations. We argue that the molecular cloud physical properties are dependent on the ambient interstellar conditions particular to the host galaxy. We find these high-redshift clouds in virial equilibrium, and derive, for the first time, the CO-to-H2 conversion factor from the kinematics of independent molecular clouds at z = 1. The measured large clouds gas masses demonstrate the existence of parent gas clouds with masses high enough to allow the in-situ formation of similarly massive stellar clumps seen in the Cosmic Snake galaxy in comparable numbers. Our results support the formation of molecular clouds by fragmentation of turbulent galactic gas disks, which then become the stellar clumps observed in distant galaxies.

scholarly journals Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC 47

2019 ◽  
Vol 628 ◽  
pp. A92 ◽  
Author(s):  
Katja Fahrion ◽  
Mariya Lyubenova ◽  
Glenn van de Ven ◽  
Ryan Leaman ◽  
Michael Hilker ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
High Mass ◽  
Host Galaxy ◽  
Main Body ◽  
Early Type ◽  
Cluster Galaxy ◽  
The Galaxy ◽  
Poor Population

Context. Nuclear 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 the merging of globular clusters (GCs), or through a combination of both. Aims. 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. The large NSC (reff = 66 pc) and rich GC system of the early-type Fornax cluster galaxy FCC 47 (NGC 1336) render this galaxy an ideal laboratory to constrain NSC formation. Methods. Using Multi Unit Spectroscopic Explorer science verification data assisted by adaptive optics, we obtained maps for the stellar kinematics and stellar-population properties of FCC 47. We extracted the spectra of the central NSC and determined line-of-sight velocities of 24 GCs and metallicities of five. Results. The galaxy shows the following kinematically decoupled components (KDCs): a disk and a NSC. Our orbit-based dynamical Schwarzschild model revealed that the NSC is a distinct kinematic feature and it constitutes the peak of metallicity and old ages in FCC 47. The main body consists of two counter-rotating populations and is dominated by a more metal-poor population. The GC system is bimodal with a dominant metal-poor population and the total GC system mass is ∼17% of the NSC mass (∼7 × 108 M⊙). Conclusions. The rotation, high metallicity, and high mass of the NSC cannot be explained by GC-inspiral alone. It most likely requires additional, quickly quenched, in-situ formation. The presence of two KDCs likely are evidence of a major merger that has significantly altered the structure of FCC 47, indicating the important role of galaxy mergers in forming the complex kinematics in the galaxy-NSC system.

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