Dynamics and star formation activity of CG J1720-67.8 unveiled through integral field spectroscopy and radio observations

Abstract

CG J1720-67.8 is an ultra compact group of several galaxies with a low velocity dispersion, and displaying the hallmarks of mutual interaction and possible tidal dwarf galaxy formation. In hierarchical models, the system is a possible precursor to a massive elliptical galaxy. In this paper, we use new optical integral field spectroscopic and radio observations to investigate the evolutionary status of the group in more detail: global star-formation rates are estimated using H$\alpha$ and 1.4 GHz radio continuum measurements; H {\sc i} observations provide an upper limit to the global neutral gas content; optical broadband colours and spectra provide ages and stellar mass estimates for the tidal dwarf candidates; the bidimensional H$\alpha$ velocity field is used to trace the kinematics of the group and its members, which are compared with numerical simulations of galaxy encounters. The observations suggest a model in which multiple interactions have occurred, with the latest strong encounter involving at least two major components within the last 200 Myr. Debris from the encounter fuels ongoing star formation at the global level of $\sim 20$ M${}_{\odot }$ yr${}^{-1}$, with self-gravity within the tidal tail possibly providing a mechanism to enhance the star formation rate of the tidal dwarf candidates, with bursts of star-formation in clumps of mass $\sim 2\times 10^7$ M${}_{\odot }$ appearing within the last 10 Myr. The amount of time required for final merging of all group components remains uncertain.

arXiv comment22 pages, 16 figures. Accepted for publication in MNRAS

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Cited by in corpus (6)

• Massive star formation in Wolf-Rayet galaxies. V: Star formation rates, masses and the importance of galaxy interactions
• Star Clusters in the Tidal Tails of Interacting Galaxies: Cluster Populations Across a Variety of Tail Environments
• The K luminosity-metallicity relation for dwarf galaxies and the tidal dwarf galaxies in the tails of HCG 31
• A Comprehensive HST BVI Catalogue Of Star Clusters In Five Hickson Compact Groups Of Galaxies
• Interpreting the galaxy group CG J1720-67.8 through evolutionary synthesis models
• Past and Future of CG J1720-67.8: Constraints from Observations and Models