The Next Generation Virgo Cluster Survey (NGVS). XXVII. The Size and Structure of Globular Cluster Systems and Their Connection to Dark Matter Halos

• Published in: The Astrophysical journal 2024-05, Vol.966 (2), p.168
• Main Authors: Lim, Sungsoon, Peng, Eric W., Côté, Patrick, Ferrarese, Laura, Roediger, Joel C., Liu, Chengze, Spengler, Chelsea, Sola, Elisabeth, Duc, Pierre-Alain, Sales, Laura V., Blakeslee, John P., Cuillandre, Jean-Charles, Durrell, Patrick R., Emsellem, Eric, Gwyn, Stephen D. J., Lançon, Ariane, Marleau, Francine R., Mihos, J. Christopher, Müller, Oliver, Puzia, Thomas H., Sánchez-Janssen, Rubén
• Format: Article
• Language: English
• Subjects: Astrophysics; Color; Dark matter; Dwarf galaxies; Early-type galaxies; Galaxies; Galaxy dark matter halos; Galaxy formation; Globular clusters; Globular star clusters; Physics; Stars & galaxies; Stellar mass; Subpopulations; System effectiveness; Virgo Cluster; Virgo galactic cluster
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad3444

We study the size and structure of globular cluster (GC) systems of 118 early-type galaxies from the NGVS, MATLAS, and ACSVCS surveys. Fitting Sérsic profiles, we investigate the relationship between effective radii of GC systems ( R e ,gc ) and galaxy properties. GC systems are 2–4 times more extended than host galaxies across the entire stellar mass range of our sample (10 8.3 M ⊙ < M * < 10 11.6 M ⊙ ). The relationship between R e ,gc and galaxy stellar mass exhibits a characteristic “knee” at a stellar mass of M p ≃ 10 10.8 , similar to the galaxy R e –stellar mass relationship. We present a new characterization of the traditional blue and red GC color subpopulations, describing them with respect to host galaxy ( g ′ − i ′ ) color (Δ gi ): GCs with similar colors to their hosts have a “red” Δ gi , and those significantly bluer GCs have a “blue” Δ gi . The GC populations with red Δ gi , even in dwarf galaxies, are twice as extended as the stars, suggesting that formation or survival mechanisms favor the outer regions. We find a tight correlation between R e ,gc and the total number of GCs, with intrinsic scatter ≲0.1 dex spanning two and three orders of magnitude in size and number, respectively. This holds for both red and blue subpopulations, albeit with different slopes. Assuming that N GC,Total correlates with M 200 , we find that the red GC systems have effective radii of roughly 1%–5% R 200 , while the blue GC systems in massive galaxies can have sizes as large as ∼10% R 200 . Environmental dependence on R e ,gc is also found, with lower-density environments exhibiting more extended GC systems at fixed mass.