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SUMMARY:The present-day growth rates of a large population of heavily obsc
 ured AGNs - Andy Goulding\, Durham University
DTSTART:20090916T093000Z
DTEND:20090916T094500Z
UID:TALK19864@talks.cam.ac.uk
CONTACT:Alexander Blustin
DESCRIPTION:Deep X-ray surveys have shown that the space density of high-l
 uminosity AGNs peaked at higher redshifts than lower luminosity AGNs\, sug
 gesting that the most massive SMBHs (M_BH approx 10^8^ - 10^9^ M_sun) grew
  first. The implication of these results is that the most rapidly growing 
 SMBHs in the local Universe should be of comparatively low mass (M_BH < 10
 ^7^ M_sun). We will show that this is indeed the case by providing X-ray a
 nd mid-IR spectral constraints of the most complete census of AGN activity
  to D<15 Mpc (Goulding & Alexander 2009). We find that ~50% of the AGNs in
  the local Universe are missed in even the most sensitive optical surveys\
 , and many of these AGNs host relatively low-mass SMBHs (M_BH approx 10^6^
  M_sun). Arguably\, the most direct method for measuring the true intrinsi
 c luminosity of the central source is through sensitive hard X-ray analyse
 s. By combining X-ray data from Chandra\, XMM-Newton\, Suzaku\, Swift and 
 Beppo-SAX with mid-IR spectroscopy from Spitzer-IRS we will show that thes
 e AGNs appear to be intrinsically luminous objects\, many of which are hea
 vily obscured at X-ray energies (< 10 keV). Furthermore\, we constrain the
  relative mass accretion rates\, and hence present-day growth rates of the
 se AGNs and conclude that AGNs hosting SMBHs with M_BH approx 10^6^ M_sun 
 are amongst the most rapidly growing in the local Universe. 
LOCATION:Sackler Lecture Theatre\, IoA
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