386 citations · 817 across the 23 of their papers we have counts for
23 papers
Approaching a dynamical extreme black hole horizon
Achilleas P. Porfyriadis, Christopher Rosen, Georgios Tsaraktsidis
We give an explicit closed form description of the late-time near-horizon approach to dynamical extreme Reissner-Nordstrom (DERN) black holes. These are spherically symmetric dynam…
Holographic shear correlators at low temperatures, and quantum
Alexandros Kanargias, Elias Kiritsis, Sameer Murthy +2
The strongly-coupled 3-dimensional theory, holographically dual to black branes at fixed chemical potential $\muext$ and temperature is considered in AdS Einstein-Max…
Scalar field scattering in a Schwarzschild-de Sitter geometry
Marco de Cesare, Marcello Miranda, Achilleas P. Porfyriadis
We solve analytically the low-frequency s-wave dynamics of a massless scalar field propagating on a Schwarzschild-de Sitter black hole background. A rigorous application of the met…
Connecting Gravitational Perturbations: from Bertotti-Robinson to Extreme Reissner-Nordstrom
Marco de Cesare, Roberto Oliveri, Achilleas P. Porfyriadis
We study spherically symmetric spacetime perturbations induced by a neutral scalar in the near-horizon region of extreme Reissner-Nordstrom black holes. For the unperturbed black h…
Accidental Symmetry Near Extreme Spinning Black Holes
Avik Banerjee, Achilleas P. Porfyriadis, Grant N. Remmen
Near the horizon of extremal charged black holes, an accidental symmetry is known to act on zero-temperature perturbations, transforming them into finite-temperature ones. In this…
Charged Dilatonic Spacetimes in String Theory
Achilleas P. Porfyriadis, Grant N. Remmen
We construct and study general static, spherically symmetric, magnetically charged solutions in Einstein-Maxwell-dilaton gravity in four dimensions. That is, taking Einstein gravit…
Large Diffeomorphisms and Accidental Symmetry of the Extremal Horizon
Achilleas P. Porfyriadis, Grant N. Remmen
We uncover a symmetry of the linear Einstein equations near extremal horizons. Specifically, acting with a spherically symmetric linearized diffeomorphism on the perturbative solut…
Horizon Acoustics of the GHS Black Hole and the Spectrum of
Achilleas P. Porfyriadis, Grant N. Remmen
We uncover a novel structure in Einstein-Maxwell-dilaton gravity: an solution in string frame, which can be obtained by a near-horizon limit of the extreme…
Extreme Black Hole Anabasis
Shahar Hadar, Alexandru Lupsasca, Achilleas P. Porfyriadis
We study the transformation properties of spherically symmetric perturbations of the Bertotti-Robinson universe and identify an invariant that characterizes th…
Near- perturbations and the connection with near-extreme Reissner-Nordstrom
Achilleas P. Porfyriadis
The geometry very near the horizon of a near-extreme Reissner-Nordstrom black hole is described by the direct product of a near- spacetime with a two-sphere. While near-$AdS…
Scattering of gravitational and electromagnetic waves off in extreme Reissner-Nordstrom
Achilleas P. Porfyriadis
The direct product of two-dimensional anti-de Sitter spacetime with a two-sphere is an exact solution of four-dimensional Einstein-Maxwell theory without a cosmological constant. I…
Critical Emission from a High-Spin Black Hole
Alexandru Lupsasca, Achilleas P. Porfyriadis, Yichen Shi
We consider a rapidly spinning black hole surrounded by an equatorial, geometrically thin, slowly accreting disk that is stationary and axisymmetric. We analytically compute the br…
Logarithmic corrections to black hole entropy from Kerr/CFT
Abhishek Pathak, Achilleas P. Porfyriadis, Andrew Strominger +1
It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They theref…
Whirling orbits around twirling black holes from conformal symmetry
Shahar Hadar, Achilleas P. Porfyriadis
Dynamics in the throat of rapidly rotating Kerr black holes is governed by an emergent near-horizon conformal symmetry. The throat contains unstable circular orbits at radii extend…
Photon Emission Near Extreme Kerr Black Holes
Achilleas P. Porfyriadis, Yichen Shi, Andrew Strominger
Ongoing astronomical efforts extract physical properties of black holes from electromagnetic emissions in their near-vicinity. This requires finding the null geodesics which extend…
Particle on the Innermost Stable Circular Orbit of a Rapidly Spinning Black Hole
Samuel E. Gralla, Achilleas P. Porfyriadis, Niels Warburton
We compute the radiation emitted by a particle on the innermost stable circular orbit of a rapidly spinning black hole both (a) analytically, working to leading order in the deviat…
Fast plunges into Kerr black holes
Shahar Hadar, Achilleas P. Porfyriadis, Andrew Strominger
Most extreme-mass-ratio-inspirals of small compact objects into supermassive black holes end with a fast plunge from an eccentric last stable orbit. For rapidly rotating black hole…
New Symmetries of Massless QED
Temple He, Prahar Mitra, Achilleas P. Porfyriadis +1
An infinite number of physically nontrivial symmetries are found for abelian gauge theories with massless charged particles. They are generated by large gauge transformation…
Gravity Waves from Extreme-Mass-Ratio Plunges into Kerr Black Holes
Shahar Hadar, Achilleas P. Porfyriadis, Andrew Strominger
Massive objects orbiting a near-extreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be rela…
Gravity Waves from Kerr/CFT
Achilleas P. Porfyriadis, Andrew Strominger
Dynamics at large redshift near the horizon of an extreme Kerr black hole are governed by an infinite-dimensional conformal symmetry. This symmetry may be exploited to analytically…
Effective Action, Boundary Conditions, and Virasoro Algebra for AdS
Achilleas P. Porfyriadis, Frank Wilczek
We construct, to second order, the effective action of General Relativity for small excitations generated by a vector field and use it to study conformal symmetry in the boundary o…
Anomalies and Hawking fluxes from the black holes of topologically massive gravity
Achilleas P. Porfyriadis
The anomaly cancelation method proposed by Wilczek et al. is applied to the black holes of topologically massive gravity (TMG) and topologically massive gravito-electrodynamics (TM…
Hawking radiation via anomaly cancelation for the black holes of five-dimensional minimal gauged supergravity
Achilleas P. Porfyriadis
The anomaly cancelation method proposed by Wilczek et al. is applied to the general charged rotating black holes in five-dimensional minimal gauged supergravity. Thus Hawking tempe…