de Lorenzo-Cáceres, A.; Sánchez-Blázquez, Patricia; Méndez-Abreu, J.; Gadotti, Dimitri A.; Falcón-Barroso, J.; Martínez-Valpuesta, I.; Coelho, Paula; Fragkoudi, Francesca; Husemann, Bernd; Leaman, Ryan; Pérez, Isabel; Querejeta, Miguel; Seidel, Marja; van de Ven, Glenn
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 4, p.5296-5314
Description
The formation of two stellar bars within a galaxy has proved challenging
for numerical studies. It is not yet clear whether the inner bar is born
via a star formation process promoted by gas inflow along the outer bar
or whether it is dynamically assembled from instabilities in a
small-scale stellar disc. Observational constraints to these scenarios
are scarce. We present a thorough study of the stellar content of two
double-barred galaxies observed by the MUSE TIMER project, NGC 1291 and
NGC 5850, combined with a two-dimensional multicomponent photometric
decomposition performed on the 3.6 μm images from S4G. Our
analysis confirms the presence of σ-hollows appearing in the
stellar velocity dispersion distribution at the ends of the inner bars.
Both galaxies host inner discs matching in size with the inner bars,
suggestive of a dynamical formation for the inner bars from small-scale
discs. The analysis of the star formation histories for the structural
components shaping the galaxies provides constraints on the epoch of
dynamical assembly of the inner bars, which took place >6.5 Gyr ago
for NGC 1291 and >4.5 Gyr ago for NGC 5850. This implies that inner
bars are long-lived structures.
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