Postdoctoral Researcher · ISTA

David
O'Neill

Supermassive black hole binaries do not merge in vacuum. They are embedded in the dense environments of galactic centers, exchanging energy and momentum with the surrounding stars and gas until they spiral together in a gravitational wave-driven merger. Those waves carry the imprint of the environment that shaped them — a signal the upcoming Laser Interferometer Space Antenna (LISA) will detect directly. My research predicts these fingerprints and the physical processes behind them.

Institute of Science and Technology Austria
Haiman Group · Klosterneuburg
01

Research

Circumbinary disk simulations

Polar Circumbinary Disks

Three-dimensional polar-aligned disk. A circumbinary disk settled into a polar configuration, orbiting perpendicular to the binary plane. Shown in three orthogonal projections.

Circumbinary disk simulations

Retrograde Circumbinary Disks

Left: retrograde and prograde disks side by side, showing the cleared cavity of the prograde case against the direct intrabinary flow of the retrograde one. Right: a retrograde disk around an eccentric binary, with the shocked bridge structure between the black holes.

Linear perturbation theory

Dynamical Friction

Density response of a gaseous medium to a moving perturber. These play as you scroll.

Eccentric binaries
Subsonic The density wake generated by a circular, subsonic binary moving through a gaseous medium.
Transonic The density wake generated by an eccentric, transonic binary moving through a gaseous medium.
Supersonic The density wake generated by an eccentric, supersonic binary moving through a gaseous medium.
Hyperbolic encounters
Extracted wake A supersonic hyperbolic encounter where both perturbers "escape" the density wake generated during the pericenter approach.
Hyperbolic passage A supersonic hyperbolic encounter where the Mach cone "engulfs" the two perturbers after pericenter
Asymptotic regime A transonic hyperbolic encounter, where the acceleration near pericenter causes the perturbers to cross the sound barrier.
03

Publications

Full list on NASA ADS and ORCID.

2024
Gaseous Dynamical Friction on Elliptical Keplerian Orbits
D. O'Neill, D. J. D'Orazio, J. Samsing, M. Pessah
ApJ 974, 216
IOP
2025
Gaseous Dynamical Friction on Hyperbolic Scatterings
D. O'Neill, D. J. D'Orazio, M. Pessah
ApJ 1000, 212
IOP
2025
Gravitational Wave Decoupling in Retrograde Circumbinary Disks
D. O'Neill, C. Tiede, D. J. D'Orazio, Z. Haiman, A. MacFadyen
ApJ 993, 206
IOP
2026
Dynamics and Detectability of Long-lived Nonaccretion Phases for Massive Black Hole Binaries in Cold Thermally Regulating Disks
C. Tiede, D. O'Neill, D. J. D'Orazio
ApJ 1008, 26
IOP
2026
Amplified capture rate of dark matter in compact binaries and constraints on bosonic dark matter from GW170817
J. Takátsy, L. Zwick, D. O'Neill, J. Samsing
PRD 113, 023027
APS
2025
Bridging the micro-Hz gravitational wave gap via Doppler tracking with the Uranus Orbiter and Probe mission: Massive black hole binaries, early Universe signals, and ultralight dark matter
L. Zwick, D. Soyeur, D.J D'Orazio, D. O'Neill, A. Derdzinski, P. Saha, D. Blas, A. Jenkins, L.Z. Kelley
PRD 112, 083029
APS
2025
Dissecting environmental effects with eccentric gravitational wave sources
L. Zwick, K. Henriks, D. O'Neill, J. Takátsy, P. Kirkeberg, C. Tiede, J. Stegmann, J. Samsing, D.J. D'Orazio
PRD 112, 063005
APS
2025
Gravitational wave memory imprints on the CMB from populations of massive black hole mergers
Z. Lorenz, D. O'Neill, K. Hendriks, P. Kirkeberg, M. Miravet-Tenés
A&A 694, A95
EDP
04

About

I'm a postdoctoral researcher at the Institute of Science and Technology Austria, working with Zoltán Haiman on circumbinary disk dynamics and gravitational wave source modelling.

I completed my PhD at the Niels Bohr Institute, University of Copenhagen, with earlier study at NUI Maynooth. My work sits at the intersection between computational and analytical hydrodynamics with gravitational wave astrophysics, with the aim of predicting the dynamics and signatures of black hole binary mergers.

David O'Neill
05

Contact

Email
david.oneill@ist.ac.at
Institution
ISTA
Am Campus 1
3400 Klosterneuburg, Austria
Profiles
ORCID · ADS · GitHub
Group
Haiman Group at ISTA