Massive star cluster formation and evolution in tidal dwarf galaxies

Abstract

Context. The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. Aims. We study star cluster formation in a tidal debris -including the vicinity of three tidal dwarf galaxies -in a massive gas dominated collisional ring around NGC 5291. These dwarfs have physical parameters which differ significantly from local starbursting dwarfs. They are gas-rich, highly turbulent, have a gas metallicity already enriched up to half-solar, and are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment. Methods. We use imaging from the Hubble Space Telescope using broadband filters covering the wavelength range from the nearultraviolet to the near-infrared. We determine the masses and ages of the cluster candidates by using the spectral energy distributionfitting code CIGALE, carefully considering age-extinction degeneracy effects on the estimation of the physical parameters. Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of ∼ 40%, comparable to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies and have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However one may speculate that similar objects at higher redshift, with higher star formation rate, might form some of the long lived globular clusters.

The GRIFFIN Project—Formation of Star Clusters with Individual Massive Stars in a Simulated Dwarf Galaxy Starburst

“…The red markers show observed values for the LMC(Goddard et al 2010;Baumgardt et al 2013;Chandar et al 2017) and the SMC(Goddard et al 2010;Chandar et al 2017). The black squares with errorbars are fromFensch et al (2019), the black circles fromChandar et al (2017) and the crosses collected from Goddard et al (2010), Adamo et al (2011), Silva-Villa & Larsen (2011), Annibali et al (2011), Cook et al (2012), Ryon et al (2014), Lim & Lee…”

The ultra-diffuse galaxy NGC 1052-DF2 with MUSE

“…Furthermore, old TDGs enter in the category of UDGs with their low central surface brightness and large effective radii (Duc et al 2014). Interestingly, we note that the cluster formation efficiency of TDGs, which is the fraction of SFR that happens in bound clusters, is seen to be very high (50%) compared to other systems (Fensch et al 2018). Last but not least, they inherit their metal-enrichment from the more massive host.…”

ALMA resolves giant molecular clouds in a tidal dwarf galaxy

“…For reference, the Hα contrast between the southern star-forming region and its surroundings (a factor of ∼8) is considerably higher than in the north-west. There are some scattered compact sources visible on the HST image towards the north of the TDG which might be young massive clusters (see Fensch et al 2019, for the efficient formation of clusters in TDGs). However, we also see similar knots towards the eastern side of NGC 3227, far from the TDG, making it likely that these compact sources coincide in position with the TDG simply due to projection, something that we cannot test further without spectroscopy.…”