317 citations · 1.3k across the 22 of their papers we have counts for
22 papers
Hair is complicated: Gravitational waves from stable and unstable boson-star mergers
Bo-Xuan Ge, Eugene A. Lim, Ulrich Sperhake +5
We explore the gravitational-wave emission from head-on collisions of equal-mass solitonic boson-star binaries from simulations spanning a two-dimensional parameter space, consisti…
Waveform Modelling for the Laser Interferometer Space Antenna
LISA Consortium Waveform Working Group, Niayesh Afshordi, Sarp Akçay +144
LISA, the Laser Interferometer Space Antenna, will usher in a new era in gravitational-wave astronomy. As the first anticipated space-based gravitational-wave detector, it will exp…
GRDzhadzha: A code for evolving relativistic matter on analytic metric backgrounds
Josu C. Aurrekoetxea, Jamie Bamber, Sam E. Brady +5
GRDzhadzha is an open-source code for relativistic simulations of matter fields on curved spacetimes that admit an analytic description (e.g. stationary black holes). It is based o…
Relativistic drag forces on black holes from scalar dark matter clouds of all sizes
Dina Traykova, Rodrigo Vicente, Katy Clough +4
We use numerical simulations of scalar field dark matter evolving on a moving black hole background to confirm the regime of validity of (semi-)analytic expressions derived from fi…
Unequal-mass boson-star binaries: Initial data and merger dynamics
Tamara Evstafyeva, Ulrich Sperhake, Thomas Helfer +4
We present a generalization of the curative initial data construction derived for equal-mass compact binaries in Helfer {\it et al} (2019 Phys. Rev. D 99 044046; 2022 Class. Quantu…
Nonlinear effects in black hole ringdown
Mark Ho-Yeuk Cheung, Vishal Baibhav, Emanuele Berti +8
We report evidence for nonlinear modes in the ringdown stage of the gravitational waveform produced by the merger of two comparable-mass black holes. We consider both the coalescen…
The Gravitational Afterglow of Boson Stars
Robin Croft, Thomas Helfer, Bo-Xuan Ge +5
In this work we study the long-lived post-merger gravitational wave signature of a boson-star binary coalescence. We use full numerical relativity to simulate the post-merger and t…
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…
The problem with Proca: ghost instabilities in self-interacting vector fields
Katy Clough, Thomas Helfer, Helvi Witek +1
Massive vector fields feature in several areas of particle physics, e.g., as carriers of weak interactions, dark matter candidates, or as an effective description of photons in a p…
GRChombo: An adaptable numerical relativity code for fundamental physics
Tomas Andrade, Llibert Areste Salo, Josu C. Aurrekoetxea +29
GRChombo is an open-source code for performing Numerical Relativity time evolutions, built on top of the publicly available Chombo software for the solution of PDEs. Whilst GRChomb…
Superradiance in massive vector fields with spatially varying mass
Zipeng Wang, Thomas Helfer, Katy Clough +1
Superradiance is a process by which massive bosonic particles can extract energy from spinning black holes, leading to the build up of a "cloud" if the particle has a Compton wavel…
Lessons for adaptive mesh refinement in numerical relativity
Miren Radia, Ulrich Sperhake, Amelia Drew +7
We demonstrate the flexibility and utility of the Berger-Rigoutsos Adaptive Mesh Refinement (AMR) algorithm used in the open-source numerical relativity code GRChombo for generatin…
Hunting intermediate-mass black holes with LISA binary radial velocity measurements
Vladimir Strokov, Giacomo Fragione, Kaze W. K. Wong +2
Despite their potential role as massive seeds for quasars, in dwarf galaxy feedback, and in tidal disruption events, the observational evidence for intermediate-mass black holes (I…
Malaise and remedy of binary boson-star initial data
Thomas Helfer, Ulrich Sperhake, Robin Croft +3
Through numerical simulations of boson-star head-on collisions, we explore the quality of binary initial data obtained from the superposition of single-star spacetimes. Our results…
Dynamical friction from scalar dark matter in the relativistic regime
Dina Traykova, Katy Clough, Thomas Helfer +3
Light bosonic scalars (e.g. axions) may form clouds around black holes via superradiant instabilities, or via accretion if they form some component of the dark matter. It has been…
The mass gap, the spin gap, and the origin of merging binary black holes
Vishal Baibhav, Davide Gerosa, Emanuele Berti +3
Two of the dominant channels to produce the black-hole binary mergers observed by LIGO and Virgo are believed to be the isolated evolution of stellar binaries in the field and dyna…
Coherent Gravitational Waveforms and Memory from Cosmic String Loops
Josu C. Aurrekoetxea, Thomas Helfer, Eugene A. Lim
We construct, for the first time, the time-domain gravitational wave strain waveform from the collapse of a strongly gravitating Abelian Higgs cosmic string loop in full general re…
Black hole formation in relativistic Oscillaton collisions
James Y. Widdicombe, Thomas Helfer, Eugene A. Lim
We investigate the physics of black hole formation from the head-on collisions of boosted equal mass Oscillatons (OS) in full numerical relativity, for both the cases where the OS…
Cosmic String Loop Collapse in Full General Relativity
Thomas Helfer, Josu C. Aurrekoetxea, Eugene A. Lim
We present the first fully general relativistic dynamical simulations of Abelian Higgs cosmic strings using 3+1D numerical relativity. Focusing on cosmic string loops, we show that…
Formation of Relativistic Axion Stars
James Y. Widdicombe, Thomas Helfer, David J. E. Marsh +1
Axions and axion-like particles are compelling candidates for the missing dark matter of the universe. As they undergo gravitational collapse, they can form compact objects such as…
Gravitational Wave Emission from Collisions of Compact Scalar Solitons
Thomas Helfer, Eugene A. Lim, Marcos A. G. Garcia +1
We numerically investigate the gravitational waves generated by the head-on collision of equal-mass, self-gravitating, real scalar field solitons (oscillatons) as a function of the…
Black hole formation from axion stars
Thomas Helfer, David J. E. Marsh, Katy Clough +3
The classical equations of motion for an axion with potential possess quasi-stable, localized, oscillating solutions, which we refer to as "axion…