The Dynamics of Debris Disk Creation in Neutron Star Mergers
Year: 2024
Type: article
Abstract: The detection of GW170817/AT2017gfo inaugurated an era of multimessenger astrophysics, in which gravitational-wave and multiwavelength photon observations complement one another to provide unique insight into astrophysical systems. A broad theoretical consensus exists, in which the photon phenomenology of neutron star mergers largely rests upon the evolution of the small amount of matter left on bound orbits around the black hole or massive neutron star remaining after the merger. Because this accretion disk is far from inflow equilibrium, its subsequent evolution depends very strongly on its initial state, yet very little is known about how this state is determined. Using both snapshot and tracer particle data from a numerical relativity/MHD simulation of an equal-mass neutron star merger that collapses to a black hole, we show how gravitational forces arising in a nonaxisymmetric, dynamical spacetime supplement hydrodynamical effects in shaping the initial structure of the bound debris disk. The work done by hydrodynamical forces is ∼10 times greater than that due to time-dependent gravity. Although gravitational torques prior to remnant relaxation are an order of magnitude larger than hydrodynamical torques, their intrinsic sign symmetry leads to strong cancellation; as a result, hydrodynamical and gravitational torques have a comparable effect. We also show that the debris disk’s initial specific angular momentum distribution is sharply peaked at roughly the specific angular momentum of the merged neutron star’s outer layers, a few r g c, and identify the regulating mechanism.
Source: The Astrophysical Journal
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: G1011805105, G1187630603, G1216115535, G127156130, G2873784832, G3987227970, Boosting Algorithmic Efficiency: Numerical Relativity in Dynamical, Curvilinear Coordinates, THE L3 LASER INTERFEROMETER SPACE ANTENNA (LISA" AN ESA-NASA COLLABORATIVE MISSION) MAY PROVIDE OUR RST DETECTIONS OF GRAVITATIONAL WAVES (GWS) FROM MASSIVE BINARY BLACK HOLES (MBBHS). UNLIKE STELLAR-MASS BINARY BLACK HOLES OBSERVED BY LIGO/VIRGO MBBHS ARE THOUGHT TO INTERACT WITH THE SURROUNDING PLASMA AND GENERATE POTENTIALLY DETECTABLE ELECTROMAGNETIC (EM) EMISSION IN COINCIDENCE WITH THE GWS. A COINCIDENT GW AND EM DETECTION FROM MBBHS MAY YIELD UNPRECEDENTED INSIGHTS INTO HOW BLACK HOLES FORM AND IMPACT THEIR ENVIRONMENTS. HOWEVER UNLESS A CONSISTENT THEORETICAL FRAMEWORK CAN BE BUILT CONNECTING OBSERVED EM AND GW SIGNALS TO THE UNDERLYING PHYSICAL PROCESSES GENERATING THEM THE SCIENCE PRODUCT FROM SUCH HARD-FOUGHT OBSERVATIONS MAY BE TRAGICALLY UNDERWHELMING. SUCH A THEORETICAL FRAMEWORK DOES NOT YET EXIST. WHILE IT IS POSSIBLE TO SEPARATELY MODEL PLASMA OWS AND EM PARTICLE (PHOTON) MOTION NEAR BLACK HOLES WITH TWO SEPARATE PIECES OF SOFTWARE A SELF-CONSISTENT MODEL INCORPORATING PHOTON{PLASMA INTERACTIONS WOULD REQUIRE THAT THE TWO PIECES OF SOFTWARE BE MERGED INTO ONE. WEST VIRGINIA UNIVERSITY SUBCONTRACT PI Z. ETIENNE IS A COMPUTATIONAL ASTROPHYSICIST WHO AUTHORED AND MAINTAINS ILLINOISGRMHD A SUPERCOMPUTER-GRADE PIECE OF SOFTWARE CAPABLE OF FULLY GENERAL RELATIVISTIC COMPUTATIONAL MODELING OF MAGNETIZED PLASMA OWS AROUND BLACK HOLES. J. SCHNITTMAN AT NASA GSFC AUTHORED AND MAINTAINS PANDURATA SOFTWARE THAT TRACKS PHOTONS IN BLACK HOLE SPACETIMES. THIS PROPOSAL PROVIDES FUNDING THAT WILL ENABLE ETIENNE TO CONTINUE HIS WORK WITH SCHNITTMAN TO MERGE ILLINOISGRMHD AND PANDURATA INTO A PIECE OF SOFTWARE CAPABLE OF MODELING PHOTON{PLASMA INTERACTIONS IN A FULLY SELF-CONSISTENT WAY AND IN CONTINUED COLLABORATION WITH GSFC ASTROPHYSICISTS J. BAKER AND B. KELLY PRODUCE THE RST SELF-CONSISTENT THEORETICAL PREDICTIONS OF COINCIDENT GW AND EM SIGNALS FROM MBBH MERGERS. WE ADOPT A SYSTEMATIC APPROACH WHEREBY STATE-OF-THE-ART THEORETICAL PREDICTIONS CAN BE PRODUCED WHILE THE SOFTWARE MERGER IS IN PROGRESS., G6293982872, G6757593912, Collaborative Research: Frameworks: The Einstein Toolkit ecosystem: Enabling fundamental research in the era of multi-messenger astrophysics, Boosting Algorithmic Efficiency: Numerical Relativity in Dynamical, Curvilinear Coordinates
OpenAlex ID: W4401375252