We consider the set of expanding maps of the circle which have a unique absolutely continuous invariant probability measure whose density is unbounded, and show that this set is dense in the space of expanding maps with the topology. This is in contrast with results for or maps, where the invariant densities can be shown to be continuous.
@article{bwmeta1.element.bwnjournal-article-smv120i1p83bwm, author = {Anthony Quas}, title = {Invariant densities for C$^1$ maps}, journal = {Studia Mathematica}, volume = {119}, year = {1996}, pages = {83-88}, zbl = {0858.58030}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv120i1p83bwm} }
Quas, Anthony. Invariant densities for C¹ maps. Studia Mathematica, Tome 119 (1996) pp. 83-88. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv120i1p83bwm/
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