Assigned ID: 734 ----- Attempting Submission 1 (Fri Mar 07 23:13:55 GMT 2008) ----- We propose to investigate at the highest possible angular resolution the nuclear excitation structure in > 150 nearby actively line-emitting galaxies, based on novel measurements of HST-STIS archival spectra. This sample offers the highest number statistics ever achieved for ~10 parsec resolution scrutiny of the power source of the ambiguous (and ubiquitous) $z \approx 0$ sources that are labeled as AGN yet do not present the usual hallmarks of an accretion-powered system. The data will be used to quantify line flux ratio gradients and isolate the spectrum from the central few tens of parsecs, allowing a more sensitive search for accretion signatures. We will be able to quantitatively test the validity of a potential H II -> Seyfert/Transition Object -> LINER evolutionary sequence, and offer crucial constraints for the true incidence of accretion activity at $z \approx 0$.

AGN/QUASARS 12 80000 12 mo. salary + ground-based observing false 0.0 0.0 false false false false false SUPPORTED