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Fig. 4

image

Occurrence rate for different spectral types as a function of the density contrast. The upper panel shows that Transition objects are less abundant in high densities while LINERs show opposite trend. The middle and bottom panels show that strongly (solid line) accreting Transition objects (defined as L[OIII] >1039 erg s−1) are more sensitive to density contrast than weakly accreting (dashed line). This is compatible with the evolutionary sequence suggested by Constantin et al. (2008) with Transition objects transforming into LINERs.

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