Speaker
Beatriz Villarroel
(Dept. of Physics and Astronomy, Uppsala University)
Description
We have used the Sloan Digital Sky Survey (DR7) and Galaxy Zoo data to examine close neighbours to low-redshift Type-1 and Type-2 AGN. Our results show a strong color-distance relation for Type-2 AGN neighbours (but none for Type-1 AGN). We also see a trend in the ratio #Type-1/#Type-2 AGN neighbours to Type-2 AGN as a function of
projected distance.
Further, while 22% of the Type-1 AGN reside in spiral hosts only 12% of Type-1 AGN once they have a galaxy neighbour within 100 kpc. For the Type-2 AGN: 52% in spiral hosts, but in presence of a neighbour within 100 kpc ~ 58%. Also, for the Type-2 AGN the number of galaxies with uncertain morphologies decreases upon the presence of a neighbour.
This could suggest that Type-2 AGN are "fragile" states that transform into something else during merger.
We conclude that there are clear differences between Type-1 and Type-2 AGN neighbours and that the two types might be evolutionary connected.
Author
Beatriz Villarroel
(Dept. of Physics and Astronomy, Uppsala University)