Understanding the Variability of Accreting Supermassive Binary Black Hole Systems, and the Post-Merger Evolution of Binary Neutron Star Collisions
Abstract
Binaries of supermassive black holes are thought to arise naturally from cosmic structure formation and galactic mergers. Once they grow close, their gravitational wave emission will be heard over large redshifts by future gravitational wave detectors such as LISA and pulsar timing arrays (PTAs). However, these systems are still mysterious: all purported binaries are separated by too much distance to be detectable by LISA or PTAs. Our theoretical understanding of their electromagnetic appearance is nascent, which hinders present-day conventional astronomical searches. We present our latest results in simulating the accretion of magnetized gas onto binary black holes using GRMHD techniques and dynamic GR, focusing on the circumbinary disk's evolution. We report on how a persistent azimuthal asymmetry in the mass density of the circumbinary (aka the "lump") acts to resonantly modulate the accretion rate and light curve of the system. We will quantify how this modulation varies with mass ratio and properties of the disk, providing insight into the genesis and strength of the lump. On the other hand, multi-messenger sources of LIGO events, i.e. those involving neutron stars such as the GW/GRB170817 event, offer a great opportunity to learn about short gamma-ray bursts and nuclear processes in the strong-field regime of gravity. We will provide a short glimpse into the current state of our efforts to model the post-merger evolution of binary neutron star merger debris. The aim is to perform long-term GRMHD simulations with a neutrino leakage scheme and predict the resultant nucleosynthetic yield and multi-band kilonova light curve.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23525301N