University of Oulu

P. Serra et al. Neutral hydrogen gas within and around NGC 1316, A&A 628, A122 (2019),

Neutral hydrogen gas within and around NGC 1316

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Author: Serra, P.1; Maccagni, F. M.1; Kleiner, D.1;
Organizations: 1INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, CA, Italy
2Netherlands Institute for Radio Astronomy (ASTRON), Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
3Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
4Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
5Department of Astronomy, Columbia University, New York, NY 10027, USA
6South African Radio Astronomy Oberservatory, Black River Park, 2 Fir Street, Observatory, Cape Town 7925, South Africa
7Department of Physics and Electronics, Rhodes University, PO Box 94, Makhanda 6140, South Africa
8INAF – Astronomical Observatory of Capodimonte, Salita Moiariello 16, 80131 Naples, Italy
9Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
10Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
11Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, 09042 Monserrato, Italy
12School of Physics and Astronomy, Cardi ff University, Queens Buildings, The Parade, Cardi ff CF24 3AA, UK
13Astronomy Research Unit, University of Oulu, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 13.1 MB)
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Language: English
Published: EDP Sciences, 2019
Publish Date: 2019-09-25


We present MeerKAT observations of neutral hydrogen gas (H I) in the nearby merger remnant NGC 1316 (Fornax A), the brightest member of a galaxy group which is falling into the Fornax cluster. We find H I on a variety of scales, from the galaxy centre to its large-scale environment. For the first time we detect H I at large radii (70–150 kpc in projection), mostly distributed on two long tails associated with the galaxy. Gas in the tails dominates the H I mass of NGC 1316: 7 × 108 M⊙– 14 times more than in previous observations. The total H I mass is comparable to the amount of neutral gas found inside the stellar body, mostly in molecular form. The H I tails are associated with faint optical tidal features thought to be the remnant of a galaxy merger occurred a few billion years ago. They demonstrate that the merger was gas-rich. During the merger, tidal forces pulled some gas and stars out to large radii, where we now detect them in the form of optical tails and, thanks to our new data, H I tails; while torques caused the remaining gas to flow towards the centre of the remnant, where it was converted into molecular gas and fuelled the starburst revealed by the galaxy’s stellar populations. Several of the observed properties of NGC 1316 can be reproduced by a ∼10:1 merger between a dominant, gas-poor early-type galaxy and a smaller, gas-rich spiral occurred 1–3 Gyr ago, likely followed by subsequent accretion of satellite galaxies.

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Series: Astronomy and astrophysics
ISSN: 0004-6361
ISSN-E: 1432-0746
ISSN-L: 0004-6361
Volume: 628
Article number: A122
DOI: 10.1051/0004-6361/201936114
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 679627; project name FORNAX). PK acknowledges being partially supported by the BMBF project 05A17PC2 for D-MeerKAT.
Copyright information: © ESO 2019.