Bibcode
Comerón, S.; Salo, H.; Knapen, J. H.; Peletier, R. F.
Bibliographical reference
Highlights on Spanish Astrophysics X, Proceedings of the XIII Scientific Meeting of the Spanish Astronomical Society held on July 16-20, 2018, in Salamanca, Spain, ISBN 978-84-09-09331-1. B. Montesinos, A. Asensio Ramos, F. Buitrago, R. Schödel, E. Villaver, S. Pérez-Hoyos, I. Ordóñez-Etxeberria (eds.) p. 104-109
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3
2019
Citations
0
Refereed citations
0
Description
The origin of thick discs in galaxies remains shrouded in mystery. A
variety of formation scenarios has been proposed. Here we aim to test
one such scenario where the thick disc stars are proposed to be accreted
from satellite galaxies. In this scenario, in at least some galaxies a
fraction of thick disc stars would rotate in a retrograde way, which
would cause a large thick disc velocity lag. Here, we compare the
rotation curves of the thin and the thick discs of eight edge-on
galaxies observed with MUSE at the VLT. We find that the velocity lags
of the thick discs are compatible with those expected from asymmetric
drift. If we consider the galaxies with thick disc rotation curves in
the literature, only one in about fifteen shows clear signs of an
accreted thick disc. Based on simulations in the literature we estimate
that if thick discs were accreted, at least one in six would show clear
signs of retrograde material. Thus, there is a growing tension between
the observations and the hypothesis that thick discs are made of
accreted stars.