A tale of two tails: insights from simulations into the formation of the peculiar dwarf galaxy NGC 1427A

Abstract

We present a scenario for the formation and the morphology of the arrow-shaped dwarf irregular galaxy NGC 1427A in the Fornax Cluster. This galaxy shows intriguing stellar and gaseous tails pointing in different directions for which alternative but not conclusive formation scenarios have been proposed in the literature. We performed N-body/SPH simulations of dwarf galaxies falling into a model of the Fornax cluster, exhibiting a jellyfish-like appearance while undergoing ram-pressure stripping. We noted that some of our models show interesting tail morphologies similar to that of NGC 1427A. In this way, the peculiar NGC 1427A structure can be studied using models whose stellar and neutral gas photometry and kinematics are in good agreement with the observed ones, without the need of invoking an interaction with a nearby galaxy. Thanks to the tails, we can identify the requirements for a galaxy to expose such a structure and assess the possible position and velocity of the galaxy in the cluster. This puts constraints on the orbit of the galaxy, its position in the cluster and the time since its pericentre passage. From the statistics of identified snapshots following our modelling, we found that the most likely position of the galaxy is around 200 kpc in front of the cluster centre, travelling towards the cluster with a velocity angle with respect to the line-of-sight direction of around 50 deg. This analysis can be useful in future observations of similar galaxies in clusters to characterise their position and velocity in the cluster and their formation.

13 pages, 16 figures. Accepted for publication in MNRAS

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• Star Cluster Formation and Survival in the First Galaxies
• The MeerKAT Fornax Survey II. The rapid removal of HI from dwarf galaxies in the Fornax cluster
• 1-DREAM: 1D Recovery, Extraction and Analysis of Manifolds in noisy environments
• The MeerKAT Fornax Survey -- I. Survey description and first evidence of ram pressure in the Fornax galaxy cluster
• More than a void? The detection and characterization of cavities in a simulated galaxy's interstellar medium