Next Contents Previous  7.1. Search for correlations between
bars and AGN  There have been several observational works
revealing a correlation between nuclear activity and bars
(Dahari 1984, Simkin et al 1980, Moles et al 1995). But the
correlation is weak and depends on the definition of the
samples, their completion and other subtle effects. Near-
infrared images have often revealed bars in galaxies previously
classified unbarred, certainly due to gas and dust effects.
However, Seyfert galaxies observed in NIR do not statistically
have more bars nor more interactions than a control sample
(McLeod & Rieke 1995, Mulchaey & Regan 1997).  It is however
evident from observations that bars are efficient to produce
radial gas flows: barred galaxies have more H2 gas concentration
inside their central 500 pc than un-barred galaxies (cf Sakamoto
et al 1999). Also, the radial flows level out abundance
gradients in barred galaxies (Martin & Roy 1994).  Peletier et
al (1999) and Knapen et al (2000) have recently re-visit