The characteristic initial value problem has been successfully implemented as a robust computational algorithm (the PITT NULL CODE) to evolve 4-dimensional vacuum spacetimes. It has been applied to the calculation of gravitational waveforms emitted by black holes and to the event horizon structure in the merger of black holes. The characteristic code also has potential application to the binary...

We have analyzed spectra of the Galactic black hole GX 339−4 obtained through simultaneous 76 ksec XMMNewton/EPIC-pn and 9 ksec RXTE observations during a bright phase of its 2002–2003 outburst. An extremely skewed, relativistic Fe Kα emission line and ionized disk reflection spectrum are revealed in these spectra. Selfconsistent models for the Fe Kα emission line profile and disk reflection sp...

My main expertise is in numerical simulations of the Einstein equations in the fully non-linear regime. In particular, I am working on simulations of binary black hole systems. I have experience in both the time evolution of such systems and also in the construction of realistic initial data. Modeling the inspiral and merger phase of black hole binaries is one of the major challenges in gravita...

or Does the 2D black hole have tachyonic or W–hair? Abstract We solve the equations of motion of the tachyon and the discrete states in the background of Witten's semiclassical black hole and in the exact 2D dilaton-graviton background of Dijkgraaf et al. We find the exact solutions for weak fields, leading to conclusions in disagreement with previous studies of tachyons in the black hole. Dema...

Classical black holes are defined by the property that things can go in, but don’t come out. However, Stephen Hawking calculated that black holes actually radiate quantum mechanical particles. The two important ingredients that result in back hole evaporation are (1) the spacetime geometry, in particular the black hole horizon, and (2) the fact that the notion of a “particle” is not an invarian...

It has been proposed that a black hole horizon should generate Hawking radiation. In order to test this theory, we have created a narrow, low density, very low temperature atomic Bose-Einstein condensate, containing an analog black hole horizon and an inner horizon, as in a charged black hole. We observe Hawking radiation emitted by the black hole. This is the output of the black hole laser. We...

We show that the Abelian Higgs field equations in the background of the four dimensional AdS-Schwarzschild black hole have a vortex line solution. This solution, which has axial symmetry, is a generalization of the AdS spacetime Nielsen-Olesen string. By a numerical study of the field equations, we show that black hole could support the Abelian Higgs field as its Abelian hair. Also, we conside ...

Using the Mathisson-Papapetrou-Dixon equations together with Tulczyjew spin-supplementary condition, we study circular orbits of a spinning test particle moving in equatorial plane quantum improved Rotating Black Hole (RBH) spacetime. This background metric incorporates position-dependent gravitational constant $G(r)$ and its behavior determines corrections to properties Innermost Stable Circul...

The quantum string emission by Black Holes is computed in the framework of the ‘string analogue model’ (or thermodynamical approach), which is well suited to combine quantum field theory (QFT) and string theory in curved backgrounds (particulary here, as black holes and strings posses intrinsic thermal features and temperatures). String theory properly describes black-hole evaporation. The blac...