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We present updated cosmological constraints from measurements of the gas mass fractions ($f_{gas}$) of massive, dynamically relaxed galaxy clusters. Our new data set has greater leverage on models of dark energy, thanks to the addition of…
We explore the reliability and robustness in measuring the age, metallicity and mass of a sample of old Milky Way globular clusters (GCs) from their integrated light, setting the stage for using GCs as cosmic clocks at high redshift. We…
We compare the sizes and luminosities of 307 faint z=6-8 sources revealed by the Hubble Frontier Fields (HFF) program with sources in the nearby universe. Making use of the latest lensing models and data from the first four HFF clusters…
Groups and clusters of galaxies occupy a special position in the hierarchy of large-scale cosmic structures because they are the largest and the most massive (from ~10^13 Msun to over 10^15 Msun) objects in the universe that have had time…
Galaxy clusters are the most massive gravitationally bound structures in the universe and serve as tracers of the assembly of large-scale structure. Studying their progenitors, proto-clusters, sheds light on the earliest stages of cluster…
Context. The Sagittarius (Sgr) dwarf galaxy is merging with the Milky Way, and the study of its globular clusters (GCs) is important to understand the history and outcome of this ongoing process. Aims. Our main goal is to characterize the…
The baryon fraction of galaxy clusters is a powerful tool to inform on the cosmological parameters while the hot-gas fraction provides indications on the physics of the intracluster plasma and its interplay with the processes driving galaxy…
The spatial distribution of known globular clusters (GCs) in the Milky Way shows that the current census of GCs is incomplete in the direction of the Galactic plane. We present the discovery of two new GCs located close to the Galactic…
The progenitors of high-mass stars and clusters are still challenging to recognise. Only unbiased surveys, sensitive to compact regions of high dust column density, can unambiguously reveal such a small population of particularly massive…
Using new and published data, we construct a sample of 160 brightest cluster galaxies (BCGs) spanning the redshift interval 0.03 < z < 1.63. We use this sample, which covers 70% of the history of the universe, to measure the growth in the…
Metal-poor globular clusters (GCs) are both numerous and ancient, which indicates that they may be important contributors to ionizing radiation in the reionization era. Starting from the observed number density and stellar mass function of…
We use high-precision photometry of red-giant-branch (RGB) stars in 57 Galactic globular clusters (GCs), mostly from the `Hubble Space Telescope (HST) UV Legacy Survey of Galactic globular clusters', to identify and characterize their…
Globular clusters (GCs) are some of the oldest bound structures in the Universe, holding clues to the earliest epochs of star formation and galaxy assembly. However, accurate age measurements of ancient clusters are challenging due to the…
We study the gas and stellar mass content of galaxy groups and clusters in the FABLE suite of cosmological hydrodynamical simulations, including the evolution of their central brightest cluster galaxies (BCGs), satellite galaxies and…
Nearby Compact Groups of Galaxies (CGs) are very complex systems, tracing their history is a challenge (e.g. Stephan's Quintet). The presence of a diffuse X-rays emission that often peaks in the center of CGs shows that CGs are bound…
We have identified 335 galaxy cluster and group candidates, 106 of which are at z > 1, using a 4.5 um selected sample of objects from a 7.25 deg^2 region in the Spitzer Infrared Array Camera (IRAC) Shallow Survey. Clusters were identified…
Fifty-seven nearby low surface brightness dwarf galaxies were searched for globular cluster candidates (GCCs) using Hubble Space Telescope WFPC2 imaging in V and I. The sample consists of 18 dwarf spheroidal (dSph), 36 irregular (dIrr), and…
Brightest Cluster Galaxies (BCGs) are typically massive ellipticals at the centers of clusters. They are believed to experience strong environmental processing, and their mass assembly and star formation history are still debated. We have…
Two generations of stars, G1 and G2, typically populate Galactic globular clusters (GCs). The origin of G2 stars is unclear. We uncover two empirical dependencies between GC characteristics, which can be explained by the formation of G2…
By means of three-dimensional hydrodynamical simulations, we investigate the formation of second generation (SG) stars in young globular clusters of different masses. We consider clusters with a first generation of asymptotic giant branch…