Related papers: Nuclear Star Clusters and Black Holes
Close encounters and physical collisions between stars in young dense clusters can result in new channels for stellar evolution, and may lead to the formation of very massive stars and black holes via runaway merging. We present some…
Massive stellar clumps in high redshift galaxies interact and migrate to the center to form a bulge and exponential disk in <1 Gyr. Here we consider the fate of intermediate mass black holes (BHs) that might form by massive-star coalescence…
Cosmological simulations of structure formation predict that galaxies are dramatically modified by galaxy harassment during the assembly of galaxy clusters, losing a substantial fraction of their stellar mass which today must be in the form…
Nucleation is a common phenomenon in all types of galaxies and at least 70% of them host nuclear star clusters (NSCs) in their centres. Many of the NSCs co-habit with super-massive black holes and follow similar scaling relations with host…
Current theoretical models predict a mass gap with a dearth of stellar black holes (BHs) between roughly $50\,M_\odot$ and $100\,M_\odot$, while, above the range accessible through massive star evolution, intermediate-mass BHs (IMBHs) still…
We estimate the rate of gravitational microlensing events of cluster stars due to black holes (BHs) in the globular cluster NGC 5139 ($\omega Cen$). Theory and observations both indicate that $\omega Cen$ may contain thousands of BHs, but…
Recent high-resolution X-ray imaging studies have discovered possible candidates of intermediate-mass black holes with masses of $M_\bullet \sim 10^{2-4} \MO$ in circumnuclear regions of many (disk) galaxies. It is known that a large number…
The history of star formation in the strong gravitational potential of the Galactic center has been of much interest, recently. We propose that the sub-parsec-scale disk of massive stars orbiting the massive black hole at the Galactic…
Globular clusters contain multiple stellar populations, with some previous generation of stars polluting the current stars with heavier elements. Understanding the history of globular clusters is helpful in understanding how galaxies merged…
The ACS Virgo cluster survey by Cote' and collaborators shows the presence of compact nuclei at the photocenters of many early-type galaxies. It is argued that they are the low-mass counterparts of nuclei hosting Super Massive Black Holes…
Nuclear Clusters (NCs) are common stellar systems in the centres of galaxies. Yet, the physical mechanisms involved in their formation are still debated. Using a parsec-resolution hydrodynamical simulation of a dwarf galaxy, we propose an…
We present high-resolution seeing limited and AO NIR imaging observations of the stellar cluster within about one parsec of Sgr A*, the massive black hole at the centre of the Milky Way. Stellar number counts and the diffuse background…
Black holes exceeding a billion solar masses have been detected at redshifts greater than six. The rapid formation of these objects may suggest a massive early seed or a period of growth faster than Eddington. Here we suggest a new…
Active galaxies are often associated with starbursts, which are possible sources of fuelling for the nuclear black holes. By means of optical (3500-7500 A) spectroscopic and narrow-band photometric data (H_alpha+[NII]6548,6583 and…
We present the results of several surveys for supernovae (SNe) in galaxy clusters. SNe discovered in deep, archival HST images were used to measure the cluster SN Ia rate to z=1. A search for SNe in nearby (0.06 < z < 0.2) Abell galaxy…
Among the most explored directions in the study of dense stellar systems is the investigation of the effects of the retention of supernova remnants, especially that of the massive stellar remnant black holes (BHs), in star clusters. By…
We present 3D kinematic observations of stars within the central 0.5 pc of the Milky Way nuclear star cluster using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a…
Due to its proximity, the Milky Way nuclear star cluster provides us with a wealth of data not available in other galactic nuclei. In particular, with adaptive optics, we can observe the detailed properties of individual stars, which can…
This paper presents new results from a photometric study of the main-sequence stars in M4, the closest globular cluster to the sun. Multi-field, multi-epoch observations at approximately 1, 2, and 6 core-radii were obtained with the WFPC2…
The existence of compact stellar remnants in the mass range $2-5\,M_{\odot}$ has long been debated. This so-called lower mass gap was initially suggested by the lack of low-mass X-ray binary observations with accretors about…