1.8k citations · 2.8k across the 45 of their papers we have counts for
50 papers
Systematic Effects of Hydrogen and Helium Atmosphere Mismatch on Radius Inference in PSR~J0740+6620-like Synthetic NICER Data
Isiah M. Holt, M. Coleman Miller, Alexander J. Dittmann +1
Constraints on neutron star radii provide insight into the properties of the cold, dense matter in their interiors. Previous studies using synthetic Neutron star Interior Compositi…
Magnetized accretion onto rapidly spinning binary black holes: mini-disk thermodynamics, magnetic transport, and dual jets
Luciano Combi, Manuela Campanelli, Sean M. Ressler +2
Supermassive binary black holes embedded in gas-rich environments are promising multi-messenger sources for pulsar timing arrays and future space-borne gravitational-wave interfero…
The Radius of the Neutron Star PSR J0614-3329 from NICER Data
M. C. Miller, A. J. Dittmann, I. M. Holt +14
Neutron star radius measurements, particularly using X-ray data collected with the Neutron star Interior Composition Explorer (NICER), have provided invaluable information for mode…
Signatures of Compact Object Mergers Inside Stars in AGN Disks
Matteo Cantiello, Alexander J. Dittmann, Saavik Ford +4
Disks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational in…
Finite-Solid-Angle Boltzmann Radiation Transport on Dynamical Spacetimes in AthenaK
Hengrui Zhu, Alexander J. Dittmann, Lizhong Zhang +3
We extend the finite-solid-angle general relativistic radiation transport method of C. J. White et al. (2023) to time-dependent spacetimes represented in ADM form. This Valencia-ty…
Extreme-Mass-Ratio Inspirals in Gaseous Disks
Alexander J. Dittmann, Abhishek Hegade K. R., Callum W. Fairbairn
Gravitational waves from extreme mass ratio inspirals (EMRIs) are precise probes of the environment of the supermassive black holes (SMBHs) they orbit. If an SMBH is actively accre…
The Effects of Accretion Feedback on Stellar Evolution in AGN Disks
Alexander J. Dittmann, Matteo Cantiello
Stars embedded in the accretion disks of active galactic nuclei (AGN) can accrete rapidly from their surroundings, dramatically altering their structure and evolution. However, fee…
A More Rigorous Test Problem For Viscous Hydrodynamics Codes
Alexander J. Dittmann, Geoffrey Ryan
We advocate for a more stringent test problem for codes that aim to solve the equations of viscous hydrodynamics. Specifically, we discuss a nonuniform-density version of the commo…
Eccentric Binaries Accreting from Thin Disks: Orbital Evolution
Alexander J. Dittmann, Geoffrey Ryan, Luciano Combi
Circumbinary disks crucially affect the orbital and electromagnetic properties of binary systems across the universe, from stars in our galactic neighborhood to supermassive black…
The LISA Astrophysics "Disc-IMRI" Code Comparison Project: Intermediate-Mass-Ratio Binaries in AGN-Like Discs
Andrea Derdzinski, Alexander J. Dittmann, Alessia Franchini +16
Upcoming space-based gravitational wave detectors such as LISA, the Laser Interferometer Space Antenna, will be sensitive to extreme- and intermediate-mass-ratio inspirals (EMRIs a…
The Radius of PSR J0437-4715 from NICER Data
M. C. Miller, A. J. Dittmann, I. M. Holt +12
Neutron star Interior Composition Explorer (NICER) data have been used to estimate the masses and radii of the rotation-powered millisecond pulsars PSR J00300451, PSR J074066…
An Investigation of Systematic Effects from Background Priors on PSR J07406620 Radius Estimates using Synthetic NICER and XMM-Newton Data
Isiah M. Holt, M. Coleman Miller, Alexander J. Dittmann +1
Accurate and precise measurements of neutron star radii provide invaluable information about the cold, dense matter in neutron star cores. Analyses of synthetic X-ray pulse wavefor…
Indirect forces in disc-planet interaction
Roman R. Rafikov, Nicolas P. Cimerman, Callum W. Fairbairn +1
Gravitational coupling between a protoplanetary disc and an embedded planet is often studied in a frame attached to a central star. This frame is non-inertial because of the stella…
Pushing the limits of eccentricity in planet-disc interactions
Callum W. Fairbairn, Alexander J. Dittmann
Modelling the gravitational interaction between an eccentric perturber and a differentially shearing gas disc is a longstanding problem with various astrophysical applications, ran…
The Multiple Paths to Merger of Unequal-Mass Black Hole Binaries in the Disks of Active Galactic Nuclei
Alexander J. Dittmann, Adam M. Dempsey, Hui Li
The accretion disks that power active galactic nuclei (AGN) are thought to house populations of stars and compact objects; after forming binaries these compact objects may merge, b…
The SHMS 11 GeV/c Spectrometer in Hall C at Jefferson Lab
S. Ali, A. Ahmidouch, G. R. Ambrose +72
The Super High Momentum Spectrometer (SHMS) has been built for Hall C at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). With a momentum capability reaching 11…
Multi-Point Hermite Methods for the N-Body Problem
Alexander J. Dittmann
Numerical integration methods are central to the study of self-gravitating systems, particularly those comprised of many bodies or otherwise beyond the reach of analytical methods.…
A Semi-Analytical Model for Stellar Evolution in AGN Disks
Alexander J. Dittmann, Matteo Cantiello
Disks of gas accreting onto supermassive black holes may host numerous stellar-mass objects, formed within the disk or captured from a nuclear star cluster. We present a simplified…
Mapping the Outcomes of Stellar Evolution in the Disks of Active Galactic Nuclei
Gaia Fabj, Alexander J. Dittmann, Matteo Cantiello +2
The disks of Active Galactic Nuclei (AGNs) are expected to be populated by numerous stars, either formed in the outer regions of the disk via gravitational instability, or captured…
A More Precise Measurement of the Radius of PSR J0740+6620 Using Updated NICER Data
Alexander J. Dittmann, M. Coleman Miller, Frederick K. Lamb +9
PSR J0740+6620 is the neutron star with the highest precisely determined mass, inferred from radio observations to be . Measurements of its radius therefo…
Exploring Waveform Variations among Neutron Star Ray-tracing Codes for Complex Emission Geometries
Devarshi Choudhury, Anna L. Watts, Alexander J. Dittmann +8
Pulse Profile Modeling (PPM), the technique used to infer mass, radius and geometric parameters for rotation-powered millisecond pulsars using data from the Neutron Star Interior C…
The Effects of Cooling on Boundary Layer Accretion
Alexander J. Dittmann
In many cases accretion proceeds from disks onto planets, stars, white dwarfs, and neutron stars via a boundary layer, a region of intense shear where gas transitions from a near-K…
Notes on the Practical Application of Nested Sampling: MultiNest, (Non)convergence, and Rectification
Alexander J. Dittmann
Nested sampling is a promising tool for Bayesian statistical analysis because it simultaneously performs parameter estimation and facilitates model comparison. MultiNest is one of…
The Santa Barbara Binary-Disk Code Comparison
Paul C. Duffell, Alexander J. Dittmann, Daniel J. D'Orazio +13
We have performed numerical calculations of a binary interacting with a gas disk, using eleven different numerical methods and a standard binary-disk setup. The goal of this study…