The dynamical evolution of the stellar clumps in the Sparkler galaxy

Recent James Webb Space Telescope observations detected a system of stellar clumps around the z ' 1:4 gravitationally lensed Sparkler galaxy (of stellar mass M_ _ 109M_) with ages and metallicities compatible with globular cluster (GC) progenitors. However, most of their masses (>106M_) and sizes (>30 pc) are about ten times those of GCs in the local Universe. Aims. To assess whether these clumps can evolve into GC-like objects, we performed N-body simulations of their dynamical evolution from z ' 1:4 to z = 0 (_9:23 Gyr) under the e_ect of dynamical friction and tidal stripping. Methods. We studied dynamical friction by performing multiple runs of a system of clumps in a Sparkler-like spherical halo of mass M200 ' 5 _ 1011M_, that was inferred from the stellar-to-halo mass relation. For the tidal stripping, we simulated resolved clumps orbiting in an external static gravitational potential including the same halo as in the dynamical friction simulations and a Sparkler-like stellar disc. Results. Dynamical friction causes the clumps with a mass greater than 107M_ to sink into the central galaxy regions, possibly contributing to the bulge growth. In absence of tidal stripping, the mass distribution of the surviving clumps (_40%) peaks at _5 _ 106 M_, implying the presence of uncommonly over-massive clumps at z = 0. Tidal shocks from the stellar disc strip considerable mass from low-mass clumps, but their sizes remain larger than those of present-day GCs. When the surviving clump masses are corrected for tidal stripping, their distribution peak shifts to _2 _ 106 M_, that is compatible with very massive GCs. Conclusions. Our simulations suggest that a fraction of the Sparkler clumps is expected to fall into the central regions, where they might become bulge fossil fragments or contribute to the formation of a nuclear star cluster. The remaining clumps are too large in size to be progenitors of GCs.