Related papers: UCDs - more massive than allowed?
The evidence of the phenomenon for which, in galaxies, the gravitating mass is distributed differently than the luminous mass, increases as new data become available. Furthermore, this discrepancy is well structured and it depends on the…
We use the Hubble Ultra Deep Field (UDF) to study the galaxy luminosity-size (M-Re) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability we identify bias-free regions in…
Two competing theories posit that Ultra Compact Dwarfs (UCDs) form either as the stripped nuclei of dwarf galaxies or as giant globular clusters (GGCs) associated with the largest globular cluster (GC) systems. By focussing on the field and…
We report on the properties of the most massive ultra-compact dwarf galaxy (UCD) in the nearby Virgo Cluster of galaxies using imaging from the Next Generation Virgo Cluster Survey (NGVS) and spectroscopy from Keck/DEIMOS. This object…
We present a photometric search for UCD candidates in the nearby galaxy group NGC 1023 (d=11 Mpc) -- the poorest environment searched for UCDs yet --, based on wide field imaging with CFHT. After photometric and morphological selection, we…
Eleven Ultra-Compact Dwarf (UCD) and 39 extended star cluster candidates are found to be associated with the galaxy NGC 1132. This giant elliptical galaxy is the remnant of a fossil group. UCD and extended star cluster candidates are…
Compact stellar systems such as Ultra-compact dwarfs (UCDs) and Globular Clusters (GCs) around galaxies are known to be the tracers of the merger events that have been forming these galaxies. Therefore, identifying such systems allows to…
In addition to their low stellar densities, ultra-diffuse galaxies (UDGs) have a broad variety of dynamical mass-to-light ratios, ranging from dark matter (DM) dominated systems to objects nearly devoid of DM. To investigate the origin of…
The scaling relation between stellar mass ($M_{*}$) and physical effective radius ($r_{e}$) has been well-studied using wide spectroscopic surveys. However, these surveys suffer from severe surface brightness incompleteness in the dwarf…
The relation between the Ultra Compact Objects (UCOs) recently discovered in the Fornax cluster (Drinkwater et al. 2000, Hilker et al. 1999) and the brightest globular clusters associated with the central galaxy NGC 1399 has been…
We present a statistical analysis of the properties of a large sample of dynamically hot old stellar systems, from globular clusters to giant ellipticals, which was performed in order to investigate the origin of ultra-compact dwarf…
Most globular clusters have half-mass radii of a few pc with no apparent correlation with their masses. This is different from elliptical galaxies, for which the Faber-Jackson relation suggests a strong positive correlation between mass and…
We show that the observed mass-to-light ratio of galaxy clusters increases with cluster temperature as expected from cosmological simulations. Contrary to previous observational suggestions, we find a mild but robust increase of M/L from…
Since 2015 there has been a great deal of interest in a supposed new class of galaxy called Ultra Diffuse Galaxies (UDGs). These are large systems with sizes $> 1.5$ kpc and have surface brightness values which are $\mu > 25$ mag…
The name "Ultra-Compact Dwarf Galaxy" (UCD) was invented for a new type of astronomical object that has been discovered in cores of nearby galaxy clusters a decade ago. UCDs resemble globular clusters, but are up to 100 times more massive…
We point out a strong time-evolution of the mass-to-light conversion factor eta commonly used to estimate masses of unresolved star clusters from observed cluster spectro-photometric measures. We present a series of gas-dynamical models…
The relation between the globular cluster luminosity function (GCLF, dN/dlogL) and globular cluster mass function (GCMF, dN/dlogM) is considered. Due to low-mass star depletion, dissolving GCs have mass-to-light (M/L) ratios that are lower…
We describe a population of compact objects in the centre of the Fornax Cluster which were discovered as part of our 2dF Fornax Spectroscopic Survey. These objects have spectra typical of old stellar systems, but are unresolved on…
The stellar initial mas function (IMF) has been described as being invariant, bottom heavy or top-heavy in extremely dense star burst conditions. To provide usable observable diagnostic we calculate redshift dependent spectral energy…
We explore the mass-to-light ratio in galaxy clusters and its relation to the cluster mass. We study the relations among the optical luminosity ($L_{op}$), the cluster mass ($M_{200}$) and the number of cluster galaxies within $r_{200}$…