Dark mammoth trunks in the merging galaxy NGC 1316 and a mechanism of cosmic double helices

TL;DR

This paper studies dark, filamentary structures called mammoth trunks in galaxy NGC 1316, proposing a magnetized filament model to explain their shapes and similarities to elephant trunks in star-forming regions.

Contribution

It introduces a new model based on magnetized filaments to explain the morphology of mammoth trunks in elliptical galaxies, linking galaxy features to star formation structures.

Findings

Mammoth trunks are large, filamentary dark structures with V or Y shapes.

Many mammoth trunks show intertwined filaments, resembling twined structures.

The proposed model explains the shapes and formation of mammoth trunks using magnetized filaments.

Abstract

NGC 1316 is a giant, elliptical galaxy containing a complex network of dark, dust features. The morphology of these features has been examined in some detail using a Hubble Space Telescope, Advanced Camera for Surveys image. It is found that most of the features are constituted of long filaments. There also exist a great number of dark structures protruding inwards from the filaments. Many of these structures are strikingly similar to elephant trunks in H II regions in the Milky Way Galaxy, although much larger. The structures, termed mammoth trunks, generally are filamentary and often have shapes resembling the letters V or Y. In some of the mammoth trunks the stem of the Y can be resolved into two or more filaments, many of which showing signs of being intertwined. A model of the mammoth trunks, related to a recent theory of elephant trunks, is proposed. Based on magnetized filaments, the model is capable of giving an account of the various shapes of the mammoth trunks observed, including the twined structures.