KMOS spectroscopic follow-up of 16 star cluster candidates in the Sagittarius dwarf galaxy

The Sagittarius (Sgr) dwarf spheroidal galaxy hosts several known globular clusters and numerous additional cluster candidates identified towards its crowded central regions. Establishing the nature of these candidates is difficult because apparent spatial and astrometric structure can arise from the underlying Sgr population. We investigated sixteen Minni stellar-cluster candidates with KMOS spectroscopy to determine whether the observed stars are compatible with Sgr and whether any candidate field shows evidence for a distinct stellar system. We analysed H-band KMOS spectra of 341 targets from the VVVX--GalCen Spectroscopic Survey, deriving radial velocities (RVs) and empirical metallicities. We compared these with an independent Sgr spectroscopic sample and used VVVX photometry and DR3 astrometry to test for localised stellar excesses relative to local control fields. Gaia Of the 341 KMOS targets, 256 (75%) have RVs within the adopted Sgr interval, and their metallicities broadly overlap the Sgr comparison population. No field shows statistically compelling kinematic evidence for a distinct system after accounting for the multiple examined candidates. Minni 329 shows the strongest spatial excess. However, this is not significant after multiple-testing correction and is not accompanied by significant central concentration. The KMOS targets predominantly trace the Sgr population, but Sgr compatibility alone does not confirm the individual candidates as distinct stellar clusters. None of the sixteen fields can be confirmed as a separate stellar system with the present data, although this does not establish that the original candidates are spurious. Deeper imaging and larger spectroscopic samples are required to determine their physical nature.