Antlia Dwarf Galaxy: Distance, quantitative morphology and recent formation history via statistical field correction

Abstract

We apply a statistical field correction technique originally designed to determine membership of high redshift galaxy clusters to Hubble Space Telescope imaging of the Antlia Dwarf Galaxy; a galaxy at the very edge of the Local Group. Using the tip of the red giant branch standard candle method coupled with a simple Sobel edge detection filter we find a new distance to Antlia of 1.31 +/- 0.03 Mpc. For the first time for a Local Group Member, we compute the concentration, asymmetry and clumpiness (CAS) quantitative morphology parameters for Antlia from the distribution of resolved stars in the HST/ACS field, corrected with a new method for contaminants and complement these parameters with the Gini coefficient (G) and the second order moment of the brightest 20 per cent of the flux (M_20). We show that it is a classic dwarf elliptical (C = 2.0, A = 0.063, S = 0.077, G = 0.39 and M_20 = -1.17 in the F814W band), but has an appreciable blue stellar population at its core, confirming on-going star-formation. The values of asymmetry and clumpiness, as well as Gini and M_20 are consistent with an undisturbed galaxy. Although our analysis suggests that Antlia may not be tidally influenced by NGC 3109 it does not necessarily preclude such interaction.

Accepted for publication in MNRAS

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Cited by in corpus (6)

• An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS), I. Overview
• KAT-7 Science Verification: Using HI Observations of NGC 3109 to Understand its Kinematics and Mass Distribution
• A Plane of High Velocity Galaxies Across the Local Group
• Environments and Morphologies of Red Sequence Galaxies with Residual Star Formation in Massive Clusters
• Tidal interactions at the edge of the Local Group: New evidence for tidal features in the Antlia Dwarf Galaxy
• Dynamical History Of The Local Group In $\Lambda$CDM $\mathrm{II}$ $-$ Including External Perturbers In 3D