Physical characterization of recently discovered globular clusters in the Sagittarius dwarf spheroidal galaxy II. Metallicities, ages and luminosities
arXiv:2107.09987 · doi:10.1051/0004-6361/202141067
Abstract
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.
18 pages, 9 figures, accepted for publication in Astronomy & Astrophysics
References in corpus (33)
- Evidence for Two Early Accretion Events That Built the Milky Way Stellar Halo
- Is the SMC Bound to the LMC? The HST Proper Motion of the SMC
- The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation
- The VISTA Science Archive
- Near-IR properties of 24 Globular Clusters in the Galactic Bulge
- Reverse engineering the Milky Way
- A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: Variation of the Metallicity Distribution Function Along the Sagittarius Stream
- The chemical composition of red giant stars in four intermediate-age clusters of the Large Magellanic Cloud
- The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
- The last breath of the Sagittarius dSph
- The PAndAS Field of Streams: stellar structures in the Milky Way halo toward Andromeda and Triangulum
- Empirical photometric calibration of the Gaia Red Clump: colours, effective temperature and absolute magnitude
- An updated survey of globular clusters in M 31. I. Classification and radial velocity for 76 candidate clusters
- Chemical abundances in the nucleus of the Sagittarius dwarf spheroidal galaxy
- Reddening, Colour and Metallicity of the M31 Globular Cluster System
- Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour-magnitude diagrams
- No evidence of chemical anomalies in the bimodal turnoff cluster NGC 1806 in the LMC
- The search for multiple populations in Magellanic Clouds clusters - V. Correlation between cluster age and abundance spreads
- Double-diffusive erosion of the core of Jupiter
- A Comparison of Optical and Near-Infrared Colours of Magellanic Cloud Star Clusters with Predictions of Simple Stellar Population Models
- Ages of the Bulge globular clusters NGC 6522 and NGC 6626 (M28) from HST Proper-motion-cleaned Color-Magnitude Diagrams
- Analysis of the physical nature of 22 New VVV Survey Globular Cluster candidates in the Milky Way Bulge
- On the tidal tails of Milky Way globular clusters
- Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud: II. Relative ages and distances for six ancient globular clusters
- First Results from the KMOS Lens-Amplified Spectroscopic Survey (KLASS): Kinematics of Lensed Galaxies at Cosmic Noon
- Mass Evaporation Rate of Globular Clusters in a Strong Tidal Field
- Spectroscopic detection of multiple populations in the ~2 Gyr old cluster Hodge 6 in the LMC
- Integrated Light 2MASS IR Photometry of Galactic Globular Clusters
- Linking globular cluster formation at low and high redshift through the age-metallicity relation in E-MOSAICS
- Dynamical friction in multi-component evolving globular clusters
- AL 3 (BH 261): a new globular cluster in the Galaxy
- Two kinematically distinct old globular cluster populations in the Large Magellanic Cloud
- Discovery of new globular clusters in the Sagittarius dwarf galaxy