Bibcode
Toloba, E.; Guhathakurta, P.; van de Ven, G.; Boissier, S.; Boselli, A.; den Brok, M.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Paudel, S.; Peletier, R. F.; Ryś, A.; Salo, H.
Referencia bibliográfica
The Astrophysical Journal, Volume 783, Issue 2, article id. 120, 12 pp. (2014).
Fecha de publicación:
3
2014
Revista
Número de citas
46
Número de citas referidas
43
Descripción
We present evidence for kinematically decoupled cores (KDCs) in two
dwarf early-type (dE) galaxies in the Virgo cluster, VCC 1183 and VCC
1453, studied as part of the SMAKCED stellar absorption-line
spectroscopy and imaging survey. These KDCs have radii of 1.''8 (0.14
kpc) and 4.''2 (0.33 kpc), respectively. Each of these KDCs is distinct
from the main body of its host galaxy in two ways: (1) inverted sense of
rotation and (2) younger (and possibly more metal-rich) stellar
population. The observed stellar population differences are probably
associated with the KDC, although we cannot rule out the possibility of
intrinsic radial gradients in the host galaxy. We describe a statistical
analysis method to detect, quantify the significance of, and
characterize KDCs in long-slit rotation curve data. We apply this method
to the two dE galaxies presented in this paper and to five other dEs for
which KDCs have been reported in the literature. Among these seven dEs,
there are four significant KDC detections, two marginal KDC detections,
and one dE with an unusual central kinematic anomaly that may be an
asymmetric KDC. The frequency of occurrence of KDCs and their properties
provide important constraints on the formation history of their host
galaxies. We discuss different formation scenarios for these KDCs in
cluster environments and find that dwarf-dwarf wet mergers or gas
accretion can explain the properties of these KDCs. Both of these
mechanisms require that the progenitor had a close companion with a low
relative velocity. This suggests that KDCs were formed in galaxy pairs
residing in a poor group environment or in isolation whose subsequent
infall into the cluster quenched star formation.
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