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SUMMARY:Resolving AGN tori in the mid-infrared: a new unbiased probe of in
 trinsic accretion power - Poshak Gandhi\, Riken
DTSTART:20090916T094500Z
DTEND:20090916T100000Z
UID:TALK19865@talks.cam.ac.uk
CONTACT:Alexander Blustin
DESCRIPTION:We show that resolved mid-infrared (mid-IR) imaging of active 
 galactic nuclei (AGN) is an isotropic probe of their intrinsic luminositie
 s. We have obtained the largest sample to date of 8-m telescope diffractio
 n-limited mid-IR imaging of radio-quiet AGN (42 sources so far)\, using wh
 ich we find a strong correlation between mid-IR (12 micron) and intrinsic 
 X-ray (2-10 keV) luminosities. The relation holds true for Seyferts of all
  types\, including unobscured\, obscured\, as well as heavily Compton-thic
 k sources. Thus\, the mid-IR directly probes the intrinsic accretion power
  irrespective of obscuration\, and provides a new and accurate proxy of AG
 N luminosity (complementing other tools such as the forbidden [OIII]5007 e
 mission line). The relation may also be extended smoothly to the higher lu
 minosity quasar regime. Most star formation around the nuclei is resolved 
 out\, and the remaining unresolved mid-IR flux is dominated by the AGN alo
 ne. This enables clean estimates of bolometric luminosities to be derived 
 for the first time. The dispersion in the mid-IR:X-ray relation is tight e
 nough to provide sensitive discrimination between physical models of clump
 y vs. smooth dusty tori geometries. In addition\, our relation also provid
 es a simple pathway for estimating the intrinsic powers of Compton-thick A
 GN. 
LOCATION:Sackler Lecture Theatre\, IoA
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