742 citations · 2.6k across the 34 of their papers we have counts for
22 papers · 1 filter
Is a black hole shadow a reliable test of the no-hair theorem?
Kostas Glampedakis, George Pappas
Capturing the image of the shadow cast by the event horizon of an illuminated black hole is, at the most basic level, an experiment of extreme light deflection in a strongly curved…
New Horizons for Fundamental Physics with LISA
K. G. Arun, Enis Belgacem, Robert Benkel +138
The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitatio…
Can supermassive black hole shadows test the Kerr metric?
Kostas Glampedakis, George Pappas
The unprecedented image of the M87* supermassive black hole has sparked some controversy over its usefulness as a test of the general relativistic Kerr metric. The criticism is mai…
Prospects for Fundamental Physics with LISA
Enrico Barausse, Emanuele Berti, Thomas Hertog +318
In this paper, which is of programmatic rather than quantitative nature, we aim to further delineate and sharpen the future potential of the LISA mission in the area of fundamental…
Multipole moments and universal relations for scalarized neutron stars
George Pappas, Daniela D. Doneva, Thomas P. Sotiriou +2
In recent years there has been a surge of interest in what has come to be known as the `universal relations' between various global properties of neutron stars. These universal rel…
The modification of photon trapping orbits as a diagnostic of non-Kerr spacetimes
Kostas Glampedakis, George Pappas
Photon circular orbits, an extreme case of light deflection, are among the hallmarks of black holes and are known to play a central role in a variety of phenomena related to these…
Black holes, gravitational waves and fundamental physics: a roadmap
Leor Barack, Vitor Cardoso, Samaya Nissanke +203
The grand challenges of contemporary fundamental physics---dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem-…
On the connection of spacetime separability and spherical photon orbits
George Pappas, Kostas Glampedakis
The notion of non-equatorial spherical photon orbits is among the very special properties of the Kerr spacetime of rotating black holes and is one that leaves a clear mark on the e…
How well can ultracompact bodies imitate black hole ringdowns?
Kostas Glampedakis, George Pappas
The ongoing observations of merging black holes by the instruments of the fledging gravitational wave astronomy has opened the way for testing the general relativistic Kerr black h…
Universal Relations and Alternative Gravity Theories
Daniela D. Doneva, George Pappas
This is a review with the ambitious goal of covering the recent progress in: 1) universal relations (in general relativity and alternative theories of gravity), and 2) neutron star…
Post-Kerr black hole spectroscopy
Kostas Glampedakis, George Pappas, Hector O. Silva +1
One of the central goals of the newborn field of gravitational wave astronomy is to test gravity in the highly nonlinear, strong field regime characterizing the spacetime of black…
An accurate metric for the spacetime around neutron stars
George Pappas
The problem of having an accurate description of the spacetime around neutron stars is of great astrophysical interest. For astrophysical applications, one needs to have a metric t…
Astrophysical applications of the post-Tolman-Oppenheimer-Volkoff formalism
Kostas Glampedakis, George Pappas, Hector O. Silva +1
The bulk properties of spherically symmetric stars in general relativity can be obtained by integrating the Tolman-Oppenheimer-Volkoff (TOV) equations. In previous work we develope…
Geodesic properties in terms of multipole moments in scalar-tensor theories of gravity
George Pappas, Thomas P. Sotiriou
The formalism for describing a metric and the corresponding scalar in terms of multipole moments has recently been developed for scalar-tensor theories. We take advantage of this f…
Multipole moments in scalar-tensor theory of gravity
George Pappas, Thomas P. Sotiriou
Stationary, asymptotically flat spacetimes in general relativity can be characterized by their multipole moments. The moments have proved to be very useful tools for extracting inf…
Why I-Love-Q
Kent Yagi, Leo C. Stein, George Pappas +2
Black holes are said to have no hair because all of their multipole moments can be expressed in terms of just their mass, charge and spin angular momentum. The recent discovery of…
Effective No-Hair Relations for Neutron Stars and Quark Stars: Relativistic Results
Kent Yagi, Koutarou Kyutoku, George Pappas +2
Astrophysical charge-free black holes are known to satisfy no-hair relations through which all multipole moments can be specified in terms of just their mass and spin angular momen…
Effectively universal behavior of rotating neutron stars in general relativity makes them even simpler than their Newtonian counterparts
George Pappas, Theocharis A. Apostolatos
Recently it was shown that slowly rotating neutron stars exhibit an interesting correlation between their moment of inertia , their quadrupole moment , and their tidal deform…
Multipole Moments of numerical spacetimes
George Pappas, Theocharis A Apostolatos
In this article we present some recent results on identifying correctly the relativistic multipole moments of numerically constructed spacetimes, and the consequences that this cor…
An all-purpose metric for the exterior of any kind of rotating neutron star
George Pappas, Theocharis A. Apostolatos
We have tested the appropriateness of two-soliton analytic metric to describe the exterior of all types of neutron stars, no matter what their equation of state or rotation rate is…
Revising the multipole moments of numerical spacetimes, and its consequences
George Pappas, Theocharis A. Apostolatos
Identifying the relativistic multipole moments of a spacetime of an astrophysical object that has been constructed numerically is of major interest, both because the multipole mome…
Matching of analytical and numerical solutions for neutron stars of arbitrary rotation
George Pappas
We demonstrate the results of an attempt to match the two-soliton analytical solution with the numerically produced solutions of the Einstein field equations, that describe the spa…