Related papers: Donald Lynden-Bell: A Biographical Memoir
Observations reveal that mature spiral galaxies consist of stars, gases and plasma approximately distributed in a thin disk of circular shape, usually with a central bulge. The rotation velocities quickly increase from the galactic center…
I present an elementary primer of black hole physics, including its general relativity basis, all peppered with astrophysical illustrations. Following a brief review of the process stellar collapse to a black hole, I discuss the…
The statistical mechanical investigation of Violent Relaxation of phase space elements of different densities first derived by Lynden-Bell (1967) is re-examined. It is found that the mass independence of the equations of motion of Violent…
Tidal torque theory (TTT) predicts that galaxy angular momenta are imprinted by the early tidal field acting on their proto-structures, which are preserved through cosmic evolution and provide the potentially most precise measurement of the…
The accretion disks that fuel active galactic nuclei (AGN) may house numerous stars and compact objects, formed in situ or captured from nearby star clusters. Embedded neutron stars and black holes may form binaries and eventually merge,…
We consider the orbital evolution of the S-stars, the young main-sequence stars near the supermassive black hole (SBH) at the Galactic center (GC), and put constraints on competing models for their origin. Our analysis includes for the…
This study presents a new framework to explore the fundamental relationship between gravity and quantum mechanics, with particular emphasis on the fundamental role of primordial black holes (PBHs) in cosmology. Through the concept of…
MOND theory explains the rotation curves of the galaxies. Verlinde's ideas establishes an entropic origin for gravitational forces and Tsallis principle generalizes the theory of Boltzman-Gibbs. In this work we have promoted a connection…
This thesis embraces several aspects of theoretical stellar dynamics in clusters, both analytically and numerically. We try to elucidate the phenomena currently observed in all types of galaxies, including AGNs and quasars, some of the most…
A review of the present observational and theoretical status of elliptical galaxies is presented with the aim to clarify whether the monolithic or the hierarchical, is a more viable scenario for the origin of these structures. We describe…
This paper is the third in a series presenting the results of direct numerical integrations of the Fokker-Planck equation for stars orbiting a supermassive black hole (SBH) at the center of a galaxy. The algorithm of Paper II included…
We have investigated the 2-D stellar distribution in the outer parts of three nearby open clusters: NGC 2287 (=M41), NGC 2516, and NGC 2548 (=M48). Wide-field star counts have been performed in two colours on pairs of digitized ESO and SRC…
Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and…
Observational astronomy of tidal disruption events (TDEs) began with the detection of X-ray flares from quiescent galaxies during the ROSAT all-sky survey of 1990-1991. The flares complied with theoretical expectations, having high peak…
The first mechanism invoked to explain the existence of the thick disk in the Milky Way Galaxy, were the spiral arms. Up-to-date work summon several other possibilities that together seem to better explain this component of our Galaxy. All…
This is an invited commentary on the Nobel Prize in Physics 2020 which was awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity," and Reinhard Genzel and Andrea…
In previous works, we have shown that stars in the Orion and the Lagoon Nebula Clusters, and simulations of collapsing clouds, exhibit constant velocity dispersion as a function of mass, a result described by Lynden-Bell 50 years ago as an…
We solve the Klein-Gordon equation for a scalar field, in the background geometry of a dust cloud collapsing to form a black hole, everywhere in the (1+1) spacetime: that is, both inside and outside the event horizon and arbitrarily close…
Light received from a cosmological source is redshifted with an apparent loss of energy, a problem first pointed out by Edwin Hubble in 1936. A new type of energy called Hubble Energy is introduced to restore the principle of energy…
Active galactic nuclei (AGNs) are occasionally seen in pairs, suggesting that tidal encounters are responsible for the accretion of material by both central supermassive black holes (BHs). In Paper I of this series, we selected a sample of…