Accreting Neutron Stars in 3D General-relativistic Magnetohydrodynamic Simulations: Jets, Magnetic Polarity, and the Interchange Slingshot
Year: 2024
Type: article
Abstract: Accreting neutron stars differ from black holes by the presence of the star’s own magnetic field, whose interaction with the accretion flow is a central component in understanding these systems’ disk structure, outflows, jets, and spin evolution. It also introduces an additional degree of freedom, as the stellar dipole can have any orientation relative to the inner disk’s magnetic field. We present a suite of 3D general-relativistic magnetohydrodynamic simulations in which we investigate the two extreme polarities, with the dipole field being either parallel or antiparallel to the initial disk field, in both the accreting and propeller states. When the magnetosphere truncates the disk near or beyond the corotation radius, most of the system’s properties, including the relativistic jet power, are independent of the star–disk relative polarity. However, when the disk extends well inside the corotation radius, in the parallel orientation the jet power is suppressed and the inner disk is less dense and more strongly magnetized. We suggest a physical mechanism that may account for this behavior—the interchange slingshot—and discuss its astrophysical implications. When the star is in the rapidly accreting regime, which in most cases will be associated with strong spin-up, we expect large observational differences between the two magnetic orientations. This may be reflected in increased variability as the accretion flow drags in successive magnetic structures of varying polarity.
Source: The Astrophysical Journal
Authors: Kyle Parfrey, Alexander Tchekhovskoy
Institutions: Princeton Plasma Physics Laboratory, Northwestern University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: Collaborative Research: Tidal Disruption of Stars by Massive Black Holes, G3486320892, G3492253450, G3950215619, Collaborative Research: WoU-MMA: Multi-scale and multi-messenger modeling of jets in active galactic nuclei, WE PROPOSE TO USE STATE-OF-THE ART NUMERICAL SIMULATIONS OF NSBH AND NSNS MERGERS AND OF THEIR POST-MERGER REMNANTS TO INFORM OBSERVATIONS OF THESE SYSTEMS. WE WILL FOCUS ON PREDICTING THE PROPERTIES OF THE EJECTED MATERIAL A CRITICAL STEP IN THE MODELING OF KILONOVAE AND IN THE DETERMINATION OF THE IMPACT OF MERGERS ON THE ENRICHMENT OF THE UNIVERSE IN HEAVY ELEMENTS. A BIG CHALLENGE IN MODELING THESE OUTFLOWS IS THAT THEY ARE PRODUCED OVER A WIDE RANGE OF TIME SCALES. MATERIAL IS FIRST EJECTED DYNAMICALLY DURING THE MERGER (OVER A FEW MILLISECONDS) THEN THROUGH POWERFUL DISK WINDS (OVER 100 MS) AND FINALLY THROUGH THE VISCOUS EVOLUTION OF THE REMNANT ACCRETION DISK (OVER 10 S). WE WILL PERFORM FOR THE FIRST TIME 3D SIMULATIONS CAPABLE OF CAPTURING ALL THREE COMPONENTS OF THE EJECTA WITH SELF-CONSISTENT EVOLUTION FROM BEFORE THE MERGER UNTIL MASS OUTFLOWS BECOMES NEGLIGIBLE., G5964487840, Collaborative Research: Short Gamma-Ray Bursts Arising From Misaligned Structured Jets in the Dawn of Gravitational Wave Astronomy, Frontera Travel Grant: Multi-Scale Modeling of Accretion and Jets in Active Galactic Nuclei, WoU-MMA: Luminous Supermassive Black Hole Accretion Systems as High-Energy Neutrino Factories, Collaborative Research: NSF-BSF: WoU-MMA: Crossing the Chasm: From Compact Object Mergers to Cosmic Fireworks
OpenAlex ID: W4403704665