Binary neutron star merger offsets from their host galaxies. GW 170817 as a case study

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Main Authors: Gaspari, N., Stevance, H. F., Levan, A. J., Chrimes, A. A., Lyman, J. D.
Format: Preprint
Published: 2024
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author Gaspari, N.
Stevance, H. F.
Levan, A. J.
Chrimes, A. A.
Lyman, J. D.
author_facet Gaspari, N.
Stevance, H. F.
Levan, A. J.
Chrimes, A. A.
Lyman, J. D.
contents Aims. The locations of binary neutron star (BNS) mergers within their host galaxies encode the systemic kicks that these systems received in the supernova aftermath. We investigate how the galactic potential and the systemic kicks shape the offset distribution of BNS mergers with a case study of GW 170817 and its host NGC 4993. Methods. We derived dynamical constraints on the host potential from integral field spectroscopy with Jeans anisotropic modelling. We evolved the trajectories of synthetic BNSs from the BPASS code in the galactic potential, using two different kick prescriptions to investigate how the observed offsets might differentiate between these two possibilities. The simulation was repeated after swapping the host potential with that of a dwarf galaxy, to test the effect of the potential on the offsets. Results. The location of GW 170817 is entirely consistent with our predictions, regardless of large or small kicks, because the strong potential of NGC 4993 is only diagnostic of very large kicks. In galaxies of similar or greater mass, large offsets can constrain large kicks, while small offsets do not provide much information. In an old dwarf galaxy, on the other hand, small offsets can constrain small kicks, while large offsets would prevent host association.
format Preprint
id arxiv_https___arxiv_org_abs_2410_19480
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Binary neutron star merger offsets from their host galaxies. GW 170817 as a case study
Gaspari, N.
Stevance, H. F.
Levan, A. J.
Chrimes, A. A.
Lyman, J. D.
High Energy Astrophysical Phenomena
Aims. The locations of binary neutron star (BNS) mergers within their host galaxies encode the systemic kicks that these systems received in the supernova aftermath. We investigate how the galactic potential and the systemic kicks shape the offset distribution of BNS mergers with a case study of GW 170817 and its host NGC 4993. Methods. We derived dynamical constraints on the host potential from integral field spectroscopy with Jeans anisotropic modelling. We evolved the trajectories of synthetic BNSs from the BPASS code in the galactic potential, using two different kick prescriptions to investigate how the observed offsets might differentiate between these two possibilities. The simulation was repeated after swapping the host potential with that of a dwarf galaxy, to test the effect of the potential on the offsets. Results. The location of GW 170817 is entirely consistent with our predictions, regardless of large or small kicks, because the strong potential of NGC 4993 is only diagnostic of very large kicks. In galaxies of similar or greater mass, large offsets can constrain large kicks, while small offsets do not provide much information. In an old dwarf galaxy, on the other hand, small offsets can constrain small kicks, while large offsets would prevent host association.
title Binary neutron star merger offsets from their host galaxies. GW 170817 as a case study
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2410.19480