The Fornax 3D project: dust mix and gas properties in the centre of early-type galaxy FCC 167

¹ Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
e-mail: sebastien.viaene@ugent.be
² Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium
³ Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, UK
⁴ School of Physics & Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK
⁵ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁶ Dipartimento di Fisica e Astronomia “G. Galilei”, Università di Padova, vicolo dell’Osservatorio 3, 35122 Padova, Italy
⁷ INAF – Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁸ Institut d’Astrophysique Spatiale, CNRS, Université Paris-Sud, Université Paris-Saclay, Bât. 121, 91405 Orsay Cedex, France
⁹ Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
¹⁰ Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85741 Garching bei München, Germany
¹¹ Instituto de Astrofísica de Canarias, C/ Via Láctea s/n, 38200 La Laguna, Tenerife, Spain
¹² Departamento Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
¹³ INAF – Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli, Italy
¹⁴ Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia
¹⁵ Australian Astronomical Observatory, PO Box 915, Sydney, NSW 1670, Australia
¹⁶ Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiapó, Chile

Received: 19 October 2018
Accepted: 14 December 2018

Abstract

Galaxies continuously reprocess their interstellar material. We can therefore expect changing dust grain properties in galaxies that have followed different evolutionary pathways. Determining the intrinsic dust grain mix of a galaxy helps in reconstructing its evolutionary history. Early-type galaxies occasionally display regular dust lanes in their central regions. Owing to the relatively simple geometry and composition of their stellar bodies, these galaxies are ideal to disentangle dust mix variations from geometric effects. We therefore modelled the various components of such a galaxy (FCC 167). We reconstructed its recent history and investigated the possible fate of the dust lane. Observations from MUSE and the Atacama Large Millimeter/submillimeter Array (ALMA) reveal a nested interstellar medium structure. An ionised-gas disc pervades the central regions of FCC 167, including those occupied by the main dust lane. Inward of the dust lane, we also find a disc/ring of cold molecular gas where stars are forming and HII regions contribute to the ionised-gas emission. Further in, the gas ionisation points towards an active galactic nucleus and the fuelling of a central supermassive black hole from its surrounding ionised and molecular reservoir. Observational constraints and radiative transfer models suggest the dust and gas are distributed in a ring-like geometry and the dust mix lacks small grains. The derived dust destruction timescales from sputtering in hot gas are short, and we conclude that the dust must be strongly self-shielding and clumpy or will quickly be eroded and disappear. Our findings show how detailed analyses of individual systems can complement statistical studies of dust-lane ETGs.