Discovery of new globular clusters in the Sagittarius dwarf galaxy
  Context. Globular clusters (GCs) are witnesses of the past accretion events
onto the Milky Way (MW). In particular, the GCs of the Sagittarius (Sgr) dwarf
galaxy are important probes of an on-going merger. Aims. Our main goal is to
search for new GC members of this dwarf galaxy using the VISTA Variables in the
Via Lactea Extended Survey (VVVX) near-infrared database combined with the Gaia
Early Data Release 3 (EDR3) optical database. Methods. We investigated all
VVVX-enabled discoveries of GC candidates in a region covering about 180 sq.
deg. toward the bulge and the Sgr dwarf galaxy. We used multiband point-spread
function photometry to obtain deep color-magnitude diagrams (CMDs) and
luminosity functions (LFs) for all GC candidates, complemented by accurate
Gaia-EDR3 proper motions (PMs) to select Sgr members and variability
information to select RR Lyrae which are potential GC members. Results. After
applying a strict PM cut to discard foreground bulge and disk stars, the CMDs
and LFs for some of the GC candidates exhibit well defined red giant branches
and red clump giant star peaks. We selected the best Sgr GCs, estimating their
distances, reddenings, and associated RR Lyrae. Conclusions. We discover 12 new
Sgr GC members, more than doubling the number of GCs known in this dwarf
galaxy. In addition, there are 11 other GC candidates identified that are
uncertain, awaiting better data for confirmation.
