2025/07/18 by Eric Giunchi, Federico Marinacci, Giunchi, Eric +11 · 1 voice · 2 citations
Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.2507.13904
Recent JWST observations detected stellar clumps around the z=1.4 gravitationally lensed Sparkler galaxy (of stellar mass M_*∼ 109 M_\odot), with ages and metallicities compatible with globular clusters (GCs). However, most of their masses (>106 M_\odot) and sizes (>30 pc) are about 10 times those of GCs in the local Universe. To assess whether these clumps can evolve into GCs, we performed N-body simulations of their dynamical evolution from z=1.4 to z=0 (9.23 Gyr), under the effect of dynamical friction and tidal stripping. Dynamical friction is studied performing multiple runs of a clump system in a Sparkler-like spherical halo of mass M200≃ 5× 1011 M_\odot (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 also a Sparkler-like stellar disk. Dynamical friction causes the clumps with mass >107 M_\odot to sink into the galaxy central 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_\odot, implying the presence of uncommonly over-massive clumps at z=0. Tidal shocks by the stellar disk strip considerable mass from low-mass clumps, even though their sizes remain larger than those of present-day GCs. When the surviving clumps are corrected for tidal stripping, their mass distribution peak shifts to 2× 106 M_\odot, compatible with massive GCs. 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 form a nuclear star cluster. The remaining clumps are too large in size to be progenitors of GCs.