Related papers: Scalar Tsunamis from Black Hole Formation
In scalar-tensor theories, spontaneous scalarization is a phase transition that can occur in ultra-dense environments such as neutron stars. The scalar field develops a non-trivial configuration once the stars exceeds a compactness…
An analogue of the Oppenheimer-Synder collapsing model is treated analytically, where the matter source is a scalar field with an exponential potential. An exact solution is derived followed by matching to a suitable exterior geometry, and…
Binary neutron star mergers provide a laboratory for probing fundamental physics through their gravitational-wave emission and electromagnetic counterparts. In particular, they may allow us to explore signatures of physics beyond the…
We consider stationary axially symmetric black holes with the background scalar field and test particles that can interact with this field directly. Then, particle collision near a black hole can lead to the unbounded energy $% E_{c.m.}$ in…
When two stars collide and merge they form a new star that can stand out against the background population in a starcluster as a blue straggler. In so called collision runaways many stars can merge and may form a very massive star that…
Motivated by novel results in the theory of wave dynamics in black-hole spacetimes, we analyze the dynamics of a massive scalar field surrounding a rapidly rotating Kerr black hole. In particular, we report on the existence of stationary…
Recent gravitational wave observations include possible detections of black hole - neutron star binary mergers. As with binary black hole mergers, numerical simulations help characterize the sources. For binary systems with neutron star…
We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established…
There is compelling evidence that supermassive black holes exist. Yet the origin of these objects, or their seeds, is still unknown. We discuss several plausible scenarios for forming the seeds of supermassive black holes. These include the…
The compact remnants of core collapse supernovae - neutron stars and black holes - have properties that reflect both the structure of their stellar progenitors and the physics of the explosion. In particular, the masses of these remnants…
Recent work has shown that scalar fields around black holes can form long-lived, quasistationary configurations surviving for cosmological timescales. With this requirement, scalar fields cannot be discarded as viable candidates for dark…
Supersymmetric extensions of the standard model generically predict that in the early universe a scalar condensate can form and fragment into Q-balls before decaying. If the Q-balls dominate the energy density for some period of time, the…
Precise measurements of the S-stars orbiting SgrA* have set strong constraints on the nature of the compact object at the centre of the Milky Way. The presence of a black hole in that region is well established, but its neighboring…
Black holes provide a natural laboratory to study particle physics and astrophysics. When black holes are surrounded by matter fields, there will be plenty of phenomena which can have observational consequences, from which we can learn…
Hypothetical light scalar particles trigger the superradiant instability around spinning black holes (BHs), causing clouds of scalars to grow around the BH. In the presence of sufficiently strong particle self-interactions (characterized by…
Using axisymmetric simulations coupling special relativistic MHD, an approximate post-Newtonian gravitational potential and two-moment neutrino transport, we show different paths for the formation of either protomagnetars or stellar mass…
Mergers of neutron stars with black holes have been suggested as candidates for short gamma-ray bursts. They have also been studied for their potential as gravitational wave sources observable with ground-based detectors. For these…
The most massive black holes, lurking at the centers of large galaxies, must have formed less than a billion years after the big bang, as they are visible today in the form of bright quasars at redshift larger than six. Their early…
The accretion of ~ 0.1 -- 1 M_o of material by a neutron star through Roche lobe overflow of its companion or through white-dwarf/neutron-star coalescence in a low mass binary system could be enough to exceed the critical mass of a neutron…
We present preliminary results of the application of a new sophisticated code which allows high precision integration of orbits of stars belonging to a dense stellar system moving in the vicinity of a massive black hole. This mimics the…