21 Aug 2014HEAD Meeting Chicago Revealing the heavily obscured AGN population with radio selection Wilkes, Kuraszkiewicz, Atanas, Haas, Barthel, Willner, Leipski, Worrall Birkinshaw, Antonucci,Ogle, U.T. Cobley & all Aim: to find ALL the AGN 21 Aug 2014HEAD Meeting Chicago 3CRR: Low-frequency, Radio-selected, Luminous (high L/L Edd ) AGN Selected at 178 MHz: isotropic emission 1 cm -2 L X /L R N H estimate for low S/N sources Juneau et al Edge-on Radio Core Fraction Face-on 21 Aug 2014HEAD Meeting Chicago X-ray Absorption vs. Radio Core-Fraction Strongly correlated Observed X-rays are consistent with orientation dependent obscuration of Unified Models Edge-onFace-on Radio Core Fraction 21 Aug 2014HEAD Meeting Chicago N H Distribution NLRG N H peaks at high values, >10 24 cm -2 Consistent with z 1 3CR sample Unification vs redshift Ratio or NL to BL radio sources ~ redshift 1:1 for z > 1 3:1 for 0.5 < z < 1 4:1 for z < 0.1 receding torus model, opening angle with L (Lawrence 1991) OR Unification excluding LERGs NERQUAM 23 Haystack Observatory Why Radio-selection? Most surveys do not find all the edge- on AGN Many 3CRR NLRGs fall outside AGN selection regions Low-frequency radio Selects on extended radio structure Orientation measure: core dominance Age estimate: radio size Caveat: only 10% of AGN are radio-loud Donley et al. (2011) Lacy et al. (2004) Spitzer IR AGN Selection