  The triggering mechanisms for Active Galactic Nuclei (AGN) are still debated.
Some of the most popular ones include galaxy interactions (IT) and disk
instabilities (DI). Using an advanced semi analytic model (SAM) of galaxy
formation, coupled to accurate halo occupation distribution modeling, we
investigate the imprint left by each separate triggering process on the
clustering strength of AGN at small and large scales. Our main results are as
follows: i) DIs, irrespective of their exact implementation in the SAM, tend to
fall short in triggering AGN activity in galaxies at the center of halos with
$M_h>10^{13.5} h^{-1}M_{\odot}$. On the contrary, the IT scenario predicts
abundance of active, central galaxies that generally agrees well with
observations at every halo mass. ii) The relative number of satellite AGN in
DIs at intermediate-to-low luminosities is always significantly higher than in
IT models, especially in groups and clusters. The low AGN satellite fraction
predicted for the IT scenario might suggest that different feeding modes could
simultaneously contribute to the triggering of satellite AGN. iii) Both
scenarios are quite degenerate in matching large-scale clustering measurements,
suggesting that the sole average bias might not be an effective observational
constraint. iv) Our analysis suggests the presence of both a mild luminosity
and a more consistent redshift dependence in the AGN clustering, with AGN
inhabiting progressively less massive dark matter halos as the redshift
increases. We also discuss the impact of different observational selection cuts
in measuring AGN clustering, including possible discrepancies between optical
and X-ray surveys.
