Speaker: Stephanie Juneau, Univ. of Arizona, USA

Title: "Application of a New AGN Diagnostic to 70-micron Selected
Galaxies: Unveiling Compton-thick AGNs"

Abstract:
I will present a new excitation diagnotic that allows us to identify
the presence of active galactic nuclei (AGNs) in galaxies out to
redshift ~1. Our understanding of galaxy evolution relies on
disentangling the roles of star formation and AGN, two phenomena
affecting the fate of galaxies. Although it has become increasingly
clear that supermassive black holes are ubiquitous, the details of
their connection to their host galaxies remain open questions. For
instance, what fraction of SMBHs are actively accreting?  How does
that fraction relate to the rate of star formation? To address these
topics, I will describe a census of AGNs within 70-micron selected
galaxies from the Far-Infrared Deep Extragalactic Legacy survey
(FIDEL).  This population of galaxies includes the main contributors
to the star formation rate density at redshift ~ 1. We find that
although only ~10-12% of 70-micron galaxies with emission lines host a
strong, X-ray detected AGN, the AGN fraction reaches ~40% when
including systems with low-level activity.  Furthermore, the diagram
reveals AGNs that are misidentified in the most sensitive Chandra
X-ray observations (reaching 2 Msec in the GOODS-North field).  I will
show evidence that a large number of these "missed" AGNs are in fact
Compton-thick.