Tidal mass loss in the Fornax dwarf spheroidal galaxy through N-body simulations with Gaia DR3-based orbits

¹ Consiglio Nazionale delle Ricerche – Istituto dei Sistemi Complessi, Via Madonna del piano 10, 50019 Sesto Fiorentino, Italy
² INFN – Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, Italy
³ Dipartimento di Fisica e Astronomia, sezione di Astrofisica e Scienze dello Spazio, Università di Firenze, Piazzale E. Fermi 2, 50125 Firenze, Italy
⁴ INAF – Firenze, Piazzale E. Fermi 5, 50125 Firenze, Italy
⁵ Dipartimento di Fisica e Astronomia Galileo Galilei, Università di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
⁶ INFN – Padova, Via Marzolo 8, 35131 Padova, Italy
⁷ INAF – Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁸ INAF – Bologna, via Gobetti 93/3, 40129 Bologna, Italy
⁹ Dipartimento di Fisica e Astronomia “Augusto Righi”, Alma Mater Studiorum - Università di Bologna, via Gobetti 93/2, 40129 Bologna, Italy

^★ Corresponding author; pierfrancesco.dicintio@cnr.it

Received: 1 July 2024
Accepted: 9 August 2024

Abstract

Aims. The Fornax dwarf spheroidal galaxy (dSph) represents a challenge for some globular cluster (GC) formation models, because an exceptionally high fraction of its stellar mass is locked in its GC system. In order to shed light on our understanding of GC formation, we aim to constrain the amount of stellar mass that Fornax has lost via tidal interaction with the Milky Way (MW).

Methods. Exploiting the flexibility of effective multi-component N-body simulations and relying on state-of-the-art estimates of Fornax’s orbital parameters, we study the evolution of the mass distribution of the Fornax dSph in observationally justified orbits in the gravitational potential of the MW over 12 Gyr.

Results. We find that, though the dark-matter mass loss can be substantial, the fraction of stellar mass lost by Fornax to the MW is always negligible, even in the most eccentric orbit considered.

Conclusions. We conclude that stellar-mass loss due to tidal stripping is not a plausible explanation for the unexpectedly high stellar mass of the GC system of the Fornax dSph and we discuss quantitatively the implications for GC formation scenarios.