On accretion discs formed in MHD simulations of black hole–neutron star mergers with accurate microphysics
Abstract
Remnant accretion discs formed in compact object mergers are an important ingredient in the understanding of electromagnetic afterglows of multimessenger gravitational-wave events. Due to magnetically and neutrino-driven winds, a significant fraction of the disc mass will eventually become unbound and undergo r-process nucleosynthesis. While this process has been studied in some detail, previous studies have typically used approximate initial conditions for the accretion discs, or started from purely hydrodynamical simulations. In this work, we analyse the properties of accretion discs formed from near equal-mass black hole–neutron star mergers simulated in general-relativistic magnetohydrodynamics in dynamical spacetimes with an accurate microphysical description. The post-merger systems were evolved until 120 ms for different finite-temperature equations of state and black hole spins. We present a detailed analysis of the fluid properties and of the magnetic-field topology. In particular, we provide analytic fits of the magnetic-field strength and specific entropy as a function of the rest-mass density, which can be used for the construction of equilibrium disc models. Finally, we evolve one of the systems for a total of 350 ms after merger and study the prospect for eventual jet launching. While our simulations do not reach this stage, we find clear evidence of continued funnel magnetization and clearing, a prerequisite for any jet-launching mechanism.
Additional Information
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) ERM thanks Carolyn Raithel for helpful discussions. The authors thank the anonymous referee for useful comments on disc self-regulation. ERM gratefully acknowledges support from a joint fellowship at the Princeton Center for Theoretical Science, the Princeton Gravity Initiative, and the Institute for Advanced Study. The simulations were performed on the national supercomputer HPE Apollo Hawk at the High Performance Computing Center Stuttgart (HLRS) under the grant numbers BBHDISKS and BNSMIC. The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC at Leibniz Supercomputing Centre (http://www.lrz.de). LR gratefully acknowledges funding from HGS-HIRe for FAIR; the LOEWE-Program in HIC for FAIR; 'PHAROS', COST Action CA16214. DATA AVAILABILITY. Data are available upon reasonable request from the Corresponding Author.Attached Files
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Additional details
- Eprint ID
- 121220
- Resolver ID
- CaltechAUTHORS:20230501-297238000.38
- Princeton University
- Institute for Advanced Study
- Helmholtz Graduate School for Hadron and Ion Research
- CA16214
- European Cooperation in Science and Technology (COST)
- Helmholtz International Center for FAIR
- Created
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2023-05-25Created from EPrint's datestamp field
- Updated
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2023-05-25Created from EPrint's last_modified field