A5033447763- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Cosmology and Gravitation Theories
- Advanced Numerical Methods in Computational Mathematics
- Ionosphere and magnetosphere dynamics
- Relativity and Gravitational Theory
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Computational Fluid Dynamics and Aerodynamics
- Meteorological Phenomena and Simulations
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Geophysics and Sensor Technology
- Galaxies: Formation, Evolution, Phenomena
- Matrix Theory and Algorithms
- History and Theory of Mathematics
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Numerical methods for differential equations
- Mechanics and Biomechanics Studies
- History and Developments in Astronomy
Oak Ridge National Laboratory
2020-2023
Rochester Institute of Technology
2017-2021
Universitat de València
2014-2016
We present the first magnetohydrodynamic simulation in which a circumbinary disk around relativistic binary black hole feeds mass to individual accretion disks ("mini-disks") each hole. Mass flow through streams linking mini-disks is modulated quasi-periodically by streams' interaction with nonlinear $m=1$ density feature, or "lump", at inner edge of disk: stream supplying mini-disk comes into phase lump frequency $0.74$ times orbital frequency. Because relativistic, tidal truncation radii...
Abstract The origins of the various outbursts hard X-rays from magnetars (highly magnetized neutron stars) are still unknown. We identify instabilities in relativistic magnetospheres that can explain a range X-ray flare luminosities. Crustal surface motions twist magnetar magnetosphere by shifting frozen-in footpoints magnetic field lines current-carrying flux bundles. Axisymmetric (2D) exhibit strong eruptive dynamics, i.e., catastrophic lateral triggered critical footpoint displacement ψ...
We present the first exploration of relativistic gas dynamics in immediate vicinity binary black holes as system inspirals close to merger gravitational radiation-driven regime. focus on 2D hydrodynamical studies comparable-mass, non-spinning systems. Relativistic effects alter this environment several ways. Because potential between two becomes shallower than Newtonian regime, mini-disks stretch toward L1 point and amount passing back forth increases sharply with decreasing separation. This...
We present SphericalNR, a new framework for the publicly available Einstein Toolkit that numerically solves field equations coupled to of general relativistic magnetohydrodynamics (GRMHD) in 3+1 split spacetime spherical coordinates without symmetry assumptions. The evolution is performed using reference-metric versions either Baumgarte-Shapiro-Shibata-Nakamura or fully covariant and conformal Z4 system with constraint damping. have developed version Valencia formulation GRMHD vector...
Abstract We present the first relativistic prediction of electromagnetic emission from surrounding gas a supermassive binary black hole system approaching merger. Using ray-tracing code to post-process data general 3D magnetohydrodynamic simulation, we generate images and spectra, analyze viewing angle dependence light emitted. When accretion rate is relatively high, circumbinary disk, streams, mini-disks combine emit in UV/extreme-UV bands. posit thermal Compton hard X-ray spectrum for...
Accreting supermassive black hole binaries are powerful multimessenger sources emitting both gravitational and electromagnetic (EM) radiation. Understanding the accretion dynamics of these systems predicting their distinctive EM signals is crucial to informing guiding upcoming efforts aimed at detecting waves produced by binaries. To this end, accurate numerical modeling required describe spacetime magnetized gas around holes. In paper, we present two key advances in field research. First,...
Recent work has shown that scalar fields around black holes can form long-lived, quasistationary configurations surviving for cosmological time scales. Scalar thus cannot be discarded as viable candidates dark matter halo models in galaxies central supermassive (SMBHs). One hypothesized formation scenario of most SMBHs at high redshift is the gravitational collapse stars (SMSs) with masses $\ensuremath{\sim}{10}^{5}\text{ }\text{ }{\mathrm{M}}_{\ensuremath{\bigodot}}$. Any such field must...
Numerical relativity codes that do not make assumptions on spatial symmetries most commonly adopt Cartesian coordinates. While these coordinates have many attractive features, spherical are much better suited to take advantage of approximate in a number astrophysical objects, including single stars, black holes, and accretion disks. the appearance coordinate singularities often spoils numerical simulations coordinates, especially absence any symmetry assumptions, it has recently been...
In this work we present 3D numerical relativity simulations of thick accretion disks around tilted Kerr BH. We investigate the evolution three different initial disk models with a range black hole spin magnitudes and tilt angles. For all disk-to-black mass ratios considered (0.044-0.16) observe significant precession nutation during evolution. This indicates that for such ratios, neglecting self-gravity by evolving them in fixed background spacetime is not justified. find two more massive...
In this paper we continue the first ever study of magnetized mini-disks coupled to circumbinary accretion in a supermassive binary black hole (SMBBH) approaching merger reported Bowen et al. 2018. We extend simulation from 3 12 orbital periods. find that relativistic SMBBH acts as resonant cavity, where quasi-periodic oscillations tied frequency at which hole's phase matches non-linear $m=1$ density feature, or ``lump'', disk permeate system. The rate mass onto each around holes is modulated...
General relativistic force-free electrodynamics is one possible plasma-limit employed to analyze energetic outflows in which strong magnetic fields are dominant over all inertial phenomena. The amazing images of black hole (BH) shadows from the Galactic Center and M87 galaxy provide a first direct glimpse into physics accretion flows most extreme environments universe. efficient extraction energy form collimated or jets rotating BH directly linked topology surrounding field. We aim at...
Scientific codes are an indispensable link between theory and experiment; in (astro-)plasma physics, such numerical tools one window into the universe’s most extreme flows of energy. The discretization Maxwell’s equations – needed to make highly magnetized (astro)physical plasma amenable its modeling introduces diffusion. It acts as a source dissipation independent system’s physical constituents. Understanding diffusion scientific is key classifying their reliability. gives specific limits...
We present results from three-dimensional, numerical relativity simulations of a tilted black hole-thick accretion disc system. The are analysed using tracer particles in the which advected with flow. Such tracers, we employ these new for first time, provide powerful means to analyse detail complex dynamics hole–torus systems. show how its use helps gain insight into overall system, discussing origin observed hole precession and development global non-axisymmetric m = 1 mode disc. Our...
We perform binary neutron star (BNS) merger simulations in full dynamical general relativity with IllinoisGRMHD, on a Cartesian grid adaptive-mesh refinement. After the remnant black hole has become nearly stationary, evolution of surrounding accretion disk grids over long timescales (1s) is suboptimal, as coordinates over-resolve angular at large distances, and accreting plasma flows obliquely across coordinate lines dissipating momentum artificially from disk. To address this, we present...
This work establishes a relation between chiral anomalies in curved spacetimes and the radiative content of gravitational field. In particular, we show that flux circularly polarized waves triggers spontaneous creation photons with net circular polarization from quantum vacuum. Using waveform catalogs, identify precessing binary black holes as astrophysical configurations emit such radiation then solve fully nonlinear Einstein's equations numerical relativity to evaluate effect. The...
Numerical simulations of merging compact objects and their remnants form the theoretical foundation for gravitational wave multimessenger astronomy. While Cartesian-coordinate-based adaptive mesh refinement is commonly used simulations, spherical-like coordinates are more suitable nearly spherical azimuthal flows due to lower numerical dissipation in evolution fluid angular momentum, as well requiring fewer numbers computational cells. However, use numerically solve hyperbolic partial...
We show that the so-called flat-space rotational Killing vector method for measuring Cartesian components of a black hole spin can be derived from surface integral Weinberg's pseudotensor over apparent horizon when using Gaussian normal coordinates in integration. Moreover, integration this gauge yields Komar angular momentum foliation adapted to axisymmetry spacetime. As result, does not explicitly depend on evolved lapse $\ensuremath{\alpha}$ and shift ${\ensuremath{\beta}}^{i}$ respective...
Supermassive black hole binaries are likely to accrete interstellar gas through a circumbinary disk. Shortly before merger, the inner portions of this disk subject general relativistic effects. To study regime, we approximate spacetime metric close orbiting holes by superimposing two boosted Kerr-Schild terms. After demonstrating quality approximation, carry out very long-term magnetohydrodynamic simulations We consider with spin dimensionless parameters magnitude 0.9, in one simulation...
The origins of the various outbursts hard X-rays from magnetars (highly magnetized neutron stars) are still unknown. We identify instabilities in relativistic magnetospheres that can explain a range X-ray flare luminosities. Crustal surface motions twist magnetar magnetosphere by shifting frozen-in footpoints magnetic field lines current-carrying flux bundles. Axisymmetric (2D) exhibit strong eruptive dynamics, as to say, catastrophic lateral triggered critical footpoint displacement $ψ_{\rm...