Accretion process onto super-spinning objects (2009)
Bambi, Cosimo, Freese, Katherine, Harada, Tomohiro, Takahashi, Rohta, Yoshida, Naoki
The accretion process onto spinning objects in Kerr spacetimes is studied with numerical simulations. Our results show that accretion onto compact objects with Kerr parameter (characterizing the...
Is the Carter-Israel conjecture correct? (2009)
Bambi, Cosimo, Freese, Katherine, Takahashi, Rohta
According to the Carter-Israel conjecture, the end-state of the gravitational collapse of matter is a Kerr-Newman black hole. Nevertheless, neither the theory nor observations can confirm that. In...
Axion braneworld cosmology (2009)
Bambi, Cosimo, Kawasaki, Masahiro, Urban, Federico R.
We study axion cosmology in a 5D Universe, in the case of flat and warped extra dimension. The comparison between theoretical predictions and observations constrains the 5D axion decay constant and...
Bambi, Cosimo, Freese, Katherine
We reply to the comment "A note on the innocuous implications of a minimum length in quantum gravity" by P.H. Frampton [Class. Quantum Grav. 26 (2009) 018001, arXiv:arXiv:0808.0283] on our paper...
Apparent shape of super-spinning black holes (2008)
Bambi, Cosimo, Freese, Katherine
We consider the possibility that astrophysical Black Holes (BHs) can violate the Kerr bound; i.e., they can have angular momentum greater than BH mass, $J > M$. We discuss implications on the BH...
Bambi, Cosimo, Spolyar, Douglas, Dolgov, Alexander D., Freese, Katherine, Volonteri, Marta
If the cosmological dark matter has a component made of small primordial black holes, they may have a significant impact on the physics of the first stars and on the subsequent formation of massive...
Gravitational production of KK states (2008)
Bambi, Cosimo, Urban, Federico R.
Gravitational particle production in the context of braneworlds is considered from a phenomenological point of view. The production of KK modes for bulk fields is discussed and their abundances...
Black holes as antimatter factories (2008)
Bambi, Cosimo, Dolgov, Alexander D., Petrov, Alexey A.
We consider accretion of matter onto a low mass black hole surrounded by ionized medium. We show that, because of higher mobility of protons than electrons, the black hole would acquire positive...
A revision of the Generalized Uncertainty Principle (2008)
The Generalized Uncertainty Principle arises from the Heisenberg Uncertainty Principle when gravity is taken into account, so the leading order correction to the standard formula is expected to be...
A note on the black hole information paradox in de Sitter spacetimes (2008)
The possibility of stable or quasi--stable Planck mass black hole remnants as solution to the black hole information paradox is commonly believed phenomenologically unacceptable: since we have to...
Dangerous implications of a minimum length in quantum gravity (2008)
Bambi, Cosimo, Freese, Katherine
The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this...
Primordial black holes and the observed Galactic 511 keV line (2008)
Bambi, Cosimo, Dolgov, Alexander D., Petrov, Alexey A.
The observed 511 keV line from the Galactic Bulge is a real challenge for theoretical astrophysics: despite a lot of suggested mechanisms, there is still no convincing explanation and the origin of...
Dangerous implications of a minimum length in quantum gravity (2008)
Bambi, Cosimo, Freese, Katherine
"The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this...
Gravitomagnetism in superconductors and compact stars (2007)
There are three experimentally observed effects in rotating superconductors that are so far unexplained. Some authors have tried to interpret such a phenomena as possible new gravitational properties...
Rare Decays in Theories with LGS (2007)
Gravitational decays in particle physics are expected to violate the B and L quantum numbers. In the standard theory, where gravity is weak because of the huge value of Planck mass, the observation...
Primordial antimatter in the contemporary universe (2007)
In some baryogenesis scenarios, the universe acquires a non-vanishing average baryonic charge, but the baryon to photon ratio is not spatially constant and can be even negative in some space regions....
Strange stars and the cosmological constant problem (2007)
The cosmological constant problem represents an evident tension between our present description of gravity and particle physics. Many solutions have been proposed, but experimental tests are always...
Dark Energy and the mass of galaxy clusters (2007)
Up to now, Dark Energy evidences are based on the dynamics of the universe on very large scales, above 1 Gpc. Assuming it continues to behave like a cosmological constant $\Lambda$ on much smaller...