(Proposal ID) S12B-056

(PI) Akiyama, Masayuki

(Proposal Title)
Census of Active Super Massive Black Holes at z~2.0

(Abstract)
Revealing formation history of super massive black holes (SMBHs) of galaxies 
is one of big issues in galactic astronomy. We can quantitatively evaluate the 
accretion growth of SMBHs through investigating cosmological evolution of 
active black hole mass function (BHMF) and Eddington ratio distribution 
function (ERDF). Recently we construct BHMF and ERDF of broad-line AGNs at 
z~1.4 in Subaru XMM-Newton Deep Survey (SXDS) field. Their shapes are rather 
different from those in the local universe. The BHMF at z=1.4 indicates higher 
activity above 10^8 M_sun but lower activity below the mass range. The 
evolution shows "real" down-sizing of accretion activity among SMBHs. The 
evolution of ERDF from z=1.4 to 0 indicates the fraction of AGNs with 
Eddington-limited accretion is higher at higher redshifts. In order to extend 
the study to z~2 where the rapid growth of massive SMBHs is thought to be on-
going, we propose observations of broad MgII emission lines of 37 broad-line 
AGNs at redshifts between 1.68 < z < 2.33 in the SXDS. Adding 36 broad-line 
AGNs already with secure MgII width measurement, we can construct BHMF and 
ERDF at z~2 based on highly complete sample of 73 broad-line AGNs in the 
redshift range.