Dust in the Radio Galaxy and Merger Remnant NGC 1316 (Fornax A)

TL;DR

This study maps dust in NGC 1316 using submillimeter and infrared observations, revealing dust distribution linked to past merger activity and providing temperature estimates for dust components, with implications for future high-resolution studies.

Contribution

First detailed dust maps of NGC 1316 combining LABOCA and WISE data, linking dust distribution to merger history and estimating dust temperatures.

Findings

Dust emission detected in central 2 arcminutes

Evidence of past merger activity from dust and gas distribution

Cold dust temperature around 20 K, warm dust around 55 K

Abstract

We present dust maps of NGC 1316 (Fornax A), a well-studied early-type galaxy located in the outskirts of the Fornax cluster. We used the Large APEX BOlometer CAmera (LABOCA), operating at 870 micron with an angular resolution of 19.5 arcseconds on the Atacama Pathfinder EXperiment (APEX) 12m submillimeter telescope in Chile and the Wide-field Infrared Survey Explorer (WISE). WISE observes in four mid-infrared bands centered at 3.4, 4.6, 12 and 22 micron with angular resolutions ranging from 6 to 12 arcseconds. The WISE and LABOCA maps reveal emission from dust in the central 2 arcminutes of NGC 1316. The disturbed optical morphology with many shells and loops, the complex distribution of molecular gas and our dust maps are evidences of past merger activity or gas accretion in the galaxy. Combining the LABOCA flux measurement with existing mid- and far-infrared measurements, we estimate the temperature of the cold (~20 K) and warm (~55 K) dust components in the galaxy. This study will be extended to other southern radio galaxies and merger remnants. Those galaxies are good targets for future observations at higher angular resolution and sensitivity with ALMA to probe the interaction of the radio jets with the dusty molecular gas near active galactic nuclei.