12CO and 13CO J=3-2 observations toward N11 in the Large Magellanic
  Cloud
  After 30 Doradus, N11 is the second largest and brightest nebula in the LMC.
This large nebula has several OB associations with bright nebulae at its
surroundings. N11 was previously mapped at the lowest rotational transitions of
$^{12}$CO (J=1--0 and 2--1), and in some particular regions pointings of the
$^{13}$CO J=1--0 and 2--1 lines were also performed. Using ASTE we mapped the
whole extension of the N11 nebula in the $^{12}$CO J=3--2 line, and three
sub-regions in the $^{13}$CO J=3--2 line. The regions mapped in the $^{13}$CO
J=3--2 were selected based on that they may be exposed to the radiation at
different ways: a region lying over the nebula related to the OB association
LH10 (N11B), another one that it is associated with the southern part of the
nebula related to the OB association LH13 (N11D), and finally a farther area at
the southwest without any embedded OB association (N11I). We found that the
morphology of the molecular clouds lying in each region shows some signatures
that could be explained by the expansion of the nebulae and the action of the
radiation. Fragmentation generated in a molecular shell due to the expansion of
the N11 nebula is suggested. The integrated line ratios $^{12}$CO/$^{13}$CO
show evidences of selective photodissociation of the $^{13}$CO, and probably
other mechanisms such as chemical fractionation. The CO contribution to the
continuum at 870 $\mu$m was directly derived. The distribution of the
integrated line ratios $^{12}$CO J=3--2/2--1 show hints of stellar feedback in
N11B and N11D. The ratio between the virial and LTE mass (M$_{\rm vir}$/M$_{\rm
LTE}$) is higher than unity in all analyzed molecular clumps, which suggests
that the clumps are not gravitationally bounded and may be supported by
external pressure. A non-LTE analysis suggests that we are mapping gas with
densities about a few 10$^{3}$ cm$^{-3}$.
