Flares, Warps, Truncations, and Satellite: The Ultra-thin Galaxy UGC 11859

TL;DR

This study investigates the structure of the ultra-thin galaxy UGC11859, revealing warps, flares, and truncations in its disk, and suggesting a possible interaction with a nearby faint galaxy, providing insights into galaxy evolution.

Contribution

First observational evidence linking disk truncations with flares in an ultra-thin galaxy, using deep imaging to analyze structural distortions and potential interactions.

Findings

Detected a warp on one side of the galaxy disk.

Identified a flare indicated by increasing scale height with radius.

Observed a sharp surface brightness break at 24 kpc, indicating truncation.

Abstract

The structure of the outskrits of galaxies provides valuable information about their past and evolution. Due to their projected orientation, edge-on isolated galaxies effectively serve as test labs in which to study the three-dimensional structures of galaxies including warps and flares, and to explore the possible sources of souch distortions. We analyzed the structure of the apparently isolated edge-on ultra-thin galaxy UGC11859 to look for the presence of disortions. The deep optical imaging observations we acquired with the GTC (Gran Telescopio Canarias) are used to derive the radial and vertical surface brightness profiles and g-r color radial profile. We find that the galaxy disk display a significant gravitational distortion. A warp is clearly detected on one side of the disk, and the galactic plane on both sides of the centre shows increasing scale height with increasing galactocentric radius, indicating the presence of a flare in the stellar distribution. The surface brightness profile of the disk shows a sharp break at 24 kiloparsecs galactocentric radius, and a steep decline to larger radii, and edge-on truncation, which we associate with the presence of the flare. The present study is the first observational support for a connection between truncations and flares. Just beyond the warped side of the disk a faint galaxy is observed within a small angular distance, identified as a potential interacting companion. Bases on ultra-deep g and r photometry we estimate that if the potential companion is at the same distance as UGC11859, the stellar mas of the satellite galaxy is approximately 6.33 log(MSol)