Deconstructing double-barred galaxies in 2D and 3D. II. Two distinct groups of inner bars. (arXiv:1901.08881v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lorenzo_Caceres_A/0/1/0/all/0/1">A. de Lorenzo-Cáceres</a> (1, 2 and 3), <a href="http://arxiv.org/find/astro-ph/1/au:+Mendez_Abreu_J/0/1/0/all/0/1">J. Méndez-Abreu</a> (1, 2 and 3), <a href="http://arxiv.org/find/astro-ph/1/au:+Thorne_B/0/1/0/all/0/1">B. Thorne</a> (1, 4 and 5), <a href="http://arxiv.org/find/astro-ph/1/au:+Costantin_L/0/1/0/all/0/1">L. Costantin</a> (6 and 7) ((1) University of St Andrews, UK, (2) Instituto de Astrofísica de Canarias, Spain, (3) Universidad de La Laguna, Spain, (4) University of Oxford, UK, (5) Princeton University, USA, (6) Osservatorio Astronomico di Brera, Italy, (7) Universita di Padova, Italy)
The intrinsic photometric properties of inner and outer stellar bars within
17 double-barred galaxies are thoroughly studied through a photometric analysis
consisting of: i) two-dimensional multi-component photometric decompositions,
and ii) a three-dimensional statistical deprojection for measuring the
thickening of bars, thus retrieving their 3D shape. The results are compared
with previous measurements obtained with the widely used analysis of integrated
light. Large-scale bars in single- and double-barred systems show similar
sizes, and inner bars may be longer than outer bars in different galaxies. We
find two distinct groups of inner bars attending to their in-plane length,
resulting in a bimodal behaviour for the inner/outer bar length ratio. Such
bimodality is not related to the properties of the host galaxy or the dominant
bulge, and it does not show a counterpart in the dimension off the disc plane.
The group of long inner bars lays at the bottom end of the outer bar length vs.
ellipticity correlation, whereas the short inner bars are out of that relation.
We suggest that this behaviour could be due to either a different nature of the
inner discs from which the inner bars are dynamically formed, or a different
assembly stage for the inner bars. This last possibility would imply that the
dynamical assembly of inner bars is a slow process taking several Gyr to
happen. Finally, we have also explored whether all large-scale bars are prone
to develop an inner bar at some stage of their lives, possibility we cannot
fully confirm or discard.
The intrinsic photometric properties of inner and outer stellar bars within
17 double-barred galaxies are thoroughly studied through a photometric analysis
consisting of: i) two-dimensional multi-component photometric decompositions,
and ii) a three-dimensional statistical deprojection for measuring the
thickening of bars, thus retrieving their 3D shape. The results are compared
with previous measurements obtained with the widely used analysis of integrated
light. Large-scale bars in single- and double-barred systems show similar
sizes, and inner bars may be longer than outer bars in different galaxies. We
find two distinct groups of inner bars attending to their in-plane length,
resulting in a bimodal behaviour for the inner/outer bar length ratio. Such
bimodality is not related to the properties of the host galaxy or the dominant
bulge, and it does not show a counterpart in the dimension off the disc plane.
The group of long inner bars lays at the bottom end of the outer bar length vs.
ellipticity correlation, whereas the short inner bars are out of that relation.
We suggest that this behaviour could be due to either a different nature of the
inner discs from which the inner bars are dynamically formed, or a different
assembly stage for the inner bars. This last possibility would imply that the
dynamical assembly of inner bars is a slow process taking several Gyr to
happen. Finally, we have also explored whether all large-scale bars are prone
to develop an inner bar at some stage of their lives, possibility we cannot
fully confirm or discard.
http://arxiv.org/icons/sfx.gif
