3.7k citations · 4.4k across the 13 of their papers we have counts for
14 papers
Gravitational Wave Energy Emitted in the Head-On Collision of Two Black Holes
Nesibe Derin Sivrioglu, Robert R. Caldwell
What is the spectrum of gravitational radiation produced by the head-on collision of two equal-mass black holes? The emission is dominated by low frequency bremsstrahlung, producin…
Null Impact of the Null Energy Condition in Current Cosmology
Robert R. Caldwell, Eric V. Linder
We clarify the role of the oft-misunderstood Null Energy Condition (NEC) in the context of the current cosmological data. In particular, the NEC implies the sum of the total energy…
The Persistence of Nonlinear Gravitational Wave Memory
Robert R. Caldwell
Nonlinear gravitational wave memory is a surprise of theoretical physics. Whereas it is understood that a gravitational wave induces oscillatory squeezing and stretching motion in…
Cold Dark Matter Based on an Analogy with Superconductivity
Guanming Liang, Robert R. Caldwell
We present a novel candidate for cold dark matter consisting of condensed Cooper pairs in a theory of interacting fermions with broken chiral symmetry. Establishing the thermal his…
Massive black hole binaries in LISA: constraining cosmological parameters at high redshifts
Alberto Mangiagli, Chiara Caprini, Sylvain Marsat +3
One of the scientific objectives of the Laser Interferometer Space Antenna (LISA) is to probe the expansion of the Universe using gravitational wave observations. Indeed, as gravit…
Inflation: Theory and Observations
Ana Achúcarro, Matteo Biagetti, Matteo Braglia +19
Cosmic inflation provides a window to the highest energy densities accessible in nature, far beyond those achievable in any realistic terrestrial experiment. Theoretical insights i…
Gravitational-wave cosmology across 29 decades in frequency
Paul D. Lasky, Chiara M. F. Mingarelli, Tristan L. Smith +24
Quantum fluctuations of the gravitational field in the early Universe, amplified by inflation, produce a primordial gravitational-wave background across a broad frequency band. We…
Spectral Distortion in a Radially Inhomogeneous Cosmology
R. R. Caldwell, N. A. Maksimova
The spectral distortion of the cosmic microwave background blackbody spectrum in a radially inhomogeneous spacetime, designed to exactly reproduce a LambdaCDM expansion history alo…
Effects of the Sound Speed of Quintessence on the Microwave Background and Large Scale Structure
Simon DeDeo, R. R. Caldwell, Paul J. Steinhardt
We consider how quintessence models in which the sound speed differs from the speed of light and varies with time affect the cosmic microwave background and the fluctuation power s…
Measuring the Speed of Sound of Quintessence
Joel K. Erickson, R. R. Caldwell, Paul J. Steinhardt +2
Quintessence, a time-varying energy component that may account for the accelerated expansion of the universe, can be characterized by its equation of state and sound speed. In this…
The Imprint of Gravitational Waves in Models Dominated by a Dynamical Cosmic Scalar Field
R. R. Caldwell, Paul J. Steinhardt
An alternative to the standard cold dark matter model has been recently proposed in which a significant fraction of the energy density of the universe is due to a dynamical scalar…
Cosmological Imprint of an Energy Component with General Equation of State
R. R. Caldwell, Rahul Dave, Paul J. Steinhardt
We examine the possibility that a significant component of the energy density of the universe has an equation-of-state different from that of matter, radiation or cosmological cons…
Green's function for gravitational waves in FRW spacetimes
R. R. Caldwell
A method for calculating the retarded Green's function for the gravitational wave equation in Friedmann-Roberson-Walker spacetimes, within the formalism of linearized Einstein grav…
Constraints on Cosmic Strings due to Black Holes Formed from Collapsed Cosmic String Loops
R. R. Caldwell, E. Gates
The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are…