632 Gaia Ultracompact Dwarf galaxy candidates

DOI

Tidally stripped galaxy nuclei and luminous globular clusters (GCs) are important tracers of the halos and assembly histories of nearby galaxies, but are difficult to reliably identify with typical ground-based imaging data. In this paper we present a new method to find these massive star clusters using Gaia DR2, focusing on the massive elliptical galaxy Centaurus A (Cen A). We show that stripped nuclei and GCs are partially resolved by Gaia at the distance of Cen A, showing characteristic astrometric and photometric signatures. We use this selection method to produce a list of 632 new candidate luminous clusters in the halo of Cen A out to a projected radius of 150kpc. Adding in broadband photometry and visual examination improves the accuracy of our classification. In a spectroscopic pilot program we have confirmed five new luminous clusters, which includes the 7th and 10th most luminous GC in Cen A. Three of the newly discovered GCs are further away from Cen A than all previously known GCs. Several of these are compelling candidates for stripped nuclei. We show that our novel Gaia selection method retains at least partial utility out to distances of ~25Mpc and hence is a powerful tool for finding and studying star clusters in the sparse outskirts of galaxies in the local universe.

Cone search capability for table J/ApJ/899/140/table2 (List of Gaia ultra compact dwarf (UCD) candidates)

Cone search capability for table J/ApJ/899/140/table3 (List of MIKE spectroscopic targets of Gaia-based UCD candidates)

Cone search capability for table J/ApJ/899/140/table4 (List of the 57 previously confirmed UCDs that were used to assess completeness in Figure 1)

Identifier
DOI http://doi.org/10.26093/cds/vizier.18990140
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJ/899/140
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/899/140
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/899/140
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/ApJ/899/140
Provenance
Creator Voggel K.T.; Seth A.C.; Sand D.J.; Hughes A.; Strader J.; Crnojevic D.,Caldwell N.
Publisher CDS
Publication Year 2021
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Galactic and extragalactic Astronomy; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy