An effective model for the tidal disruption of satellites undergoing minor mergers with axisymmetric primaries

Fuente: arXiv
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Autori principali: Varisco, Ludovica, Dotti, Massimo, Bonetti, Matteo, Bortolas, Elisa, Lupi, Alessandro
Natura: Preprint
Pubblicazione: 2024
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author Varisco, Ludovica
Dotti, Massimo
Bonetti, Matteo
Bortolas, Elisa
Lupi, Alessandro
author_facet Varisco, Ludovica
Dotti, Massimo
Bonetti, Matteo
Bortolas, Elisa
Lupi, Alessandro
contents According to the hierarchical formation paradigm, galaxies form through mergers of smaller entities and massive black holes (MBHs), if lurking at their centers, migrate to the nucleus of the newly formed galaxy, where they form binary systems. The formation and evolution of MBH binaries, and in particular their coalescence timescale, is very relevant for current and future facilities aimed at detecting the gravitational-wave signal produced by the MBH close to coalescence. While most of the studies targeting this process are based on hydrodynamic simulations, the high computational cost makes a complete parameter space exploration prohibitive. Semi-analytic approaches represent a valid alternative, but they require ad-hoc prescriptions for the mass loss of the merging galaxies in minor mergers due to tidal stripping, which is not commonly considered or at most modelled assuming very idealised geometries. In this work, we propose a novel, effective model for the tidal stripping in axisymmetric potentials, to be implemented in semi-analytic models. We validate our semi-analytic approach against N-body simulations considering different galaxy sizes, inclinations, and eccentricities, finding only a moderate dependence on the orbit eccentricity. In particular, we find that, for almost circular orbits, our model mildly overestimates the mass loss, and this is due to the adjustment of the stellar distribution after the mass is removed. Nonetheless, the model exhibits a very good agreement with simulations in all the considered conditions, and thus represents an extremely powerful addition to semi-analytic calculations.
format Preprint
id arxiv_https___arxiv_org_abs_2406_18652
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An effective model for the tidal disruption of satellites undergoing minor mergers with axisymmetric primaries
Varisco, Ludovica
Dotti, Massimo
Bonetti, Matteo
Bortolas, Elisa
Lupi, Alessandro
Astrophysics of Galaxies
According to the hierarchical formation paradigm, galaxies form through mergers of smaller entities and massive black holes (MBHs), if lurking at their centers, migrate to the nucleus of the newly formed galaxy, where they form binary systems. The formation and evolution of MBH binaries, and in particular their coalescence timescale, is very relevant for current and future facilities aimed at detecting the gravitational-wave signal produced by the MBH close to coalescence. While most of the studies targeting this process are based on hydrodynamic simulations, the high computational cost makes a complete parameter space exploration prohibitive. Semi-analytic approaches represent a valid alternative, but they require ad-hoc prescriptions for the mass loss of the merging galaxies in minor mergers due to tidal stripping, which is not commonly considered or at most modelled assuming very idealised geometries. In this work, we propose a novel, effective model for the tidal stripping in axisymmetric potentials, to be implemented in semi-analytic models. We validate our semi-analytic approach against N-body simulations considering different galaxy sizes, inclinations, and eccentricities, finding only a moderate dependence on the orbit eccentricity. In particular, we find that, for almost circular orbits, our model mildly overestimates the mass loss, and this is due to the adjustment of the stellar distribution after the mass is removed. Nonetheless, the model exhibits a very good agreement with simulations in all the considered conditions, and thus represents an extremely powerful addition to semi-analytic calculations.
title An effective model for the tidal disruption of satellites undergoing minor mergers with axisymmetric primaries
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2406.18652