Related papers: Cosmic String in the BTZ Black Hole Background wit…
The transition between (non supersymmetric) quantum string states and Schwarzschild black holes is discussed. This transition occurs when the string coupling $g^2$ (which determines Newton's constant) increases beyond a certain critical…
We study the collapse of a fuzzy sphere, that is a spherical membrane built out of D0-branes, in the BFSS model. At weak coupling, as the sphere shrinks, open strings are produced. If the initial radius is large then open string production…
I review some recent work (done in collaboration with G. Veneziano) which clarifies the existence of a correspondence between self-gravitating fundamental string states and Schwarzschild black holes. The main result is a detailed…
We solve dynamical equations of motion to determine the conditions under which an over-dense region in the early universe will lead to collapse to a black hole, starting from horizon crossing of the over-dense region to the point of…
We describe the detailed study and results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. The effect from small loops generated from the…
We investigate the connection between curved spacetime and the emergence of string-instabilities, following the approach developed by Loust\'{o} and S\'{a}nchez for de Sitter and black hole spacetimes. We analyse the linearised equations…
Cosmic strings are expected to form loops. These can act as seeds for accretion of dark matter, leading to the formation of ultracompact minihalos (UCMHs). We perform a detailed study of the accretion of dark matter onto cosmic string loops…
We discuss time-dependent perturbations (induced by matter fields) of a black-hole background in tree-level two-dimensional string theory. We analyse the linearized case and show the possibility of having black-hole solutions with…
In backgrounds with compact dimensions there may exist several phases of black objects including the black-hole and the black-string. The phase transition between them raises puzzles and touches fundamental issues such as topology change,…
The classical Bekenstein entropy of a black hole is argued to arise from configurations of strings with ends which are frozen on the horizon. Quantum corrections to this entropy are probably finite unlike the case in quantum field theory.…
This work presents a generalization of the rotating black hole in two plus one dimensions, in the light of scale--dependent gravitational couplings. In particular, the gravitational coupling $\kappa_0$ and the cosmological term $\Lambda_0$…
Analysing closed string tachyon condensation will improve our understanding of spacetime in string theory. We study the string spectrum on a BTZ black hole spacetime supported by NS-NS flux, which provides a calculable example where we…
The critical formation of low-mass black holes is a historical cornerstone of numerical General Relativity, with important implications in cosmology for censorship conjectures and the production of primordial black holes (PBHs). Concurrent…
In the first part of this talk, I consider some exact string solutions in curved spacetimes. In curved spacetimes with a Killing vector (timelike or spacelike), the string equations of motion and constraints are reduced to the Hamilton…
The interaction of a cosmic string and a maximally charged dilatonic black hole is studied in the low-velocity limit. In particular, the string-black hole scattering at a low velocity is investigated.
Scale dependence at the level of the effective action is a generic result of quantum field theory. Allowing for scale dependence of the gravitational couplings leads to a generalization of the corresponding field equations. In this work,…
We determine the different possible space-time metrics inside an infinite rotating hollow cylinder with given energy density and longitudinal and azimuthal stresses, the metric outside the cylinder being chosen of the spinning cosmic string…
The string-black hole correspondence principle can be investigated in the non-BPS scenario by studying the string configuration and entropy when the string coupling is slowly increased. Through a rigorous analysis, it is shown how an…
The mass function of primordial black holes created through the near-critical gravitational collapse is calculated in a manner fairly independent of the statistical distribution of underlying density fluctuation, assuming that it has a…
String loop vibrations in a central plane of a Schwarzschild black hole are investigated for various string equations of state. We discuss string loop stability and derive frequencies of vibrational modes. Using the vibrating string loop…