An Enigmatic 380 kpc Long Linear Collimated Galactic Tail

TL;DR

This paper reports the discovery and analysis of an exceptionally long, linear galactic tail extending over 380 kpc, formed possibly through a three-body interaction, with detailed spectroscopic confirmation of its kinematic properties.

Contribution

The study presents the first detailed analysis of a unique, extremely elongated galactic tail, combining observational data and proposing a novel formation scenario involving a three-body interaction.

Findings

Confirmed kinematic association of the tail with the Kite galaxy.

Measured a velocity gradient along the tail.

Discussed challenges to formation scenarios like ram pressure stripping and tidal interactions.

Abstract

We present an intriguing, serendipitously-detected system consisting of an S0/a galaxy, which we refer to as the "Kite", and a highly-collimated tail of gas and stars that extends over 380 kpc and contains pockets of star formation. In its length, narrowness, and linearity the Kite's tail is an extreme example relative to known tails. The Kite (PGC 1000273) has a companion galaxy, Mrk 0926 (PGC 070409), which together comprise a binary galaxy system in which both galaxies host active galactic nuclei. Despite this systems being previously searched for signs of tidal interactions, the tail had not been discovered prior to our identification as part of the validation process of the SMUDGes survey for low surface brightness galaxies. We confirm the kinematic association between various H$\alpha$ knots along the tail, a small galaxy, and the Kite galaxy using optical spectroscopy obtained with the Magellan telescope and measure a velocity gradient along the tail. The Kite shares characteristics common to those formed via ram pressure stripping ("jellyfish" galaxies) and formed via tidal interactions. However, both scenarios face significant challenges that we discuss, leaving open the question of how such an extreme tail formed. We propose that the tail resulted from a three-body interaction from which the lowest-mass galaxy was ejected at high velocity.