Micro-tidal disruption events in young star clusters

¹ Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB), c. Martí i Franquès 1, 08028 Barcelona, Spain
² Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (UB), c. Martí i Franquès 1, 08028 Barcelona, Spain
³ ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
⁴ Institut d’Estudis Espacials de Catalunya (IEEC), Edifici RDIT, Campus UPC, 08860 Castelldefels (Barcelona), Spain
⁵ School of Physics and Astronomy, Sun Yat-sen University, Daxue Road, Zhuhai 519082, China
⁶ CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area, Zhuhai 519082, China

^★ Corresponding authors: This email address is being protected from spambots. You need JavaScript enabled to view it. ; This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 8 August 2025
Accepted: 31 December 2025

Abstract

Context. Dense young star clusters (YSCs) are ideal environments for dynamical interactions between stars and stellar compact objects, such as black holes and neutron stars. In such dense environments, stars can undergo close encounters with black holes and fall within their tidal radius, resulting in tidal disruption. These events, known as micro-tidal disruption events (micro-TDEs), are transient phenomena with potential multi-messenger signatures.

Aims. We aim to quantify the nature, occurrence, and observational relevance of micro-TDEs across a wide range of cluster masses, densities, and metallicities through an extensive exploration of the parameter space.

Methods. We performed a suite of direct N-body simulations using the PETAR code, to which we implemented new prescriptions for modelling micro-TDEs. We constructed a set of realistic YSC models including primordial binaries based on the observed Milky Way population. Our simulations incorporate stellar and binary evolution, supernova kicks, and stellar winds using the BSE code, and they account for the Galactic tidal field via the GALPY library.

Results. We identified three primary dynamical channels for micro-TDE production: single star–single black hole encounters, binary-mediated interactions (including supernova-kick triggers), and interactions involving higher-order multiple systems such as hierarchical triples and quadruples as well as chaotic few-body interactions with more than three objects. Multiple encounters are the most efficient production channel and thus dominate the total production rate: ∼250–450 Gpc⁻³ yr⁻¹. Micro-TDEs from YSCs are expected to be detectable by upcoming surveys, particularly the Legacy Survey of Space and Time, with detection rates potentially up to hundreds per year. The gravitational wave signals expected from the micro-TDE peak in the deci-Hertz band, making them accessible to future instruments such as the Lunar Gravitational Wave Antenna and the Deci-Hertz Interferometer Gravitational wave Observatory.

Conclusions. Micro-TDEs emerge as promising multi-messenger sources, potentially offering unique insights into star cluster dynamics, stellar collisions, and the population of dormant stellar-mass black holes, through both electromagnetic and gravitational wave observations.