Physical characterization of recently discovered globular clusters in
  the Sagittarius dwarf spheroidal galaxy II. Metallicities, ages and
  luminosities
  Globular clusters (GCs) are important tools to rebuild the accretion history
of a galaxy. There are newly discovered GCs in the Sagittarius (Sgr) dwarf
galaxy, that can be used as probes of the accretion event onto the Milky Way
(MW). Our main aim is to characterize the Sgr GC system by measuring its main
physical parameters. We build the optical and near-IR color-magnitude diagrams
(CMDs) for 21 new Sgr GCs using the VISTA Variables in the Via Lactea Extended
Survey (VVVX) near-IR database combined with the Gaia EDR3 optical database. We
derive metallicities and ages for all targets, using the isochrone-fitting
method and the RGB-slope and metallicity relation. The total luminosities are
calculated both in the near-IR and in the optical. We construct the metallicity
distribution (MD), the globular cluster luminosity function (GCLF), and the
age-metallicity relation for the Sgr GC system. We find 17 metal-rich GCs with
-0.9<[Fe/H]<-0.3, 4 metal-poor GCs with -2.0<[Fe/H]<-1.1 in the new Sgr GC
sample. Even though our age estimates are rough, we find that the metal-poor
GCs are consistent with an old population with an average age of ~13 Gyr, while
the metal-rich GCs show a wider age range, between 6-8 Gyr and 10-13 Gyr. We
compare the MD and the GCLF for the Sgr GC system with those of the MW, M31 and
Large Magellanic Cloud (LMC) galaxies. We conclude that the majority of the
metal-rich GCs are located within the main body of Sgr galaxy. We confirm that
the GCLF is not a universal distribution, since the Sgr GCLF peaks at fainter
luminosities than the GCLFs of the MW, M31 and LMC. The MD shows a
double-peaked distribution, and we note that the metal-rich population looks
like the MW bulge GCs. We compared our results with the literature concluding
that the Sgr progenitor could have been a reasonably large galaxy able to
retain the SNe ejecta, thus enriching its ISM.
