The Fornax3D project: Discovery of ancient massive merger events in the Fornax cluster galaxies NGC 1380 and NGC 1427

Autor(en)

Ling Zhu, Glenn van de Ven, Ryan Leaman, Annalisa Pillepich, Lodovico Coccato, Yuchen Ding, Jesús Falcón-Barroso, Enrichetta Iodice, Ignacio Martin Navarro, Francesca Pinna, Enrico Maria Corsini, Dimitri A. Gadotti, Katja Fahrion, Mariya Lyubenova, Shude Mao, Richard McDermid, Adriano Poci, Marc Sarzi, Tim de Zeeuw

Abstrakt

We report the discovery of ancient massive merger events in the early-type galaxies NGC 1380 and NGC 1427, members of the Fornax galaxy cluster. Both galaxies have been observed by the MUSE integral-field-unit instrument on the VLT as part of the Fornax3D project. By fitting recently developed population-orbital superposition models to the observed surface brightness, stellar kinematic, age, and metallicity maps, we obtain the stellar orbits, age, and metallicity distributions of each galaxy. We then decompose each galaxy into multiple orbital-based components, including a dynamically hot inner stellar halo component that is identified as the relic of past massive mergers. By comparing to analogs from cosmological galaxy simulations, chiefly TNG50, we find that the formation of such a hot inner stellar halo requires the merger with a now-destroyed massive satellite galaxy of 3.7_-1.5^+2.7 × 10¹⁰ M_⊙ (about one-fifth of its current stellar mass) in the case of NGC 1380 and of 1.5_-0.7^+1.6 ×10¹⁰ M_⊙ (about one-fourth of its current stellar mass) in the case of NGC 1427. Moreover, we infer that the last massive merger in NGC 1380 happened ∼10 Gyr ago based on the stellar age distribution of the regrown dynamically cold disk, whereas the merger in NGC 1427 ended t ≲ 8 Gyr ago based on the stellar populations in its hot inner stellar halo. The major merger event in NGC 1380 is the first one with both merger mass and merger time quantitatively inferred in a galaxy beyond the local volume. Moreover, it is the oldest and most massive merger uncovered in nearby galaxies so far.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Chinese Academy of Sciences (CAS), Max-Planck-Institut für Astronomie, European Southern Observatory (Germany), Instituto de Astrofísica de Canarias (IAC), Universidad de La Laguna, INAF - Osservatorio Astronomico di Padova, European Space Research & Technology Centre (ESA/ESTEC), Tsinghua University, Macquarie University, Armagh Observatory and Planetarium, University of Hertfordshire, Leiden University, Max-Planck-Institut für extraterrestrische Physik

Journal

Astronomy & Astrophysics

Band

664

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361/202243109

Publikationsdatum

08-2022

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/05e0267c-b0cc-49ea-a16f-c860e9685113