Probing AGN Populations at Redshifts 6 - 7+ with Large X-ray Surveys. Anton Koekemoer (Space Telescope Science Institute) + CDFS/GOODS-AGN (Alexander, Brandt, Bergeron, Conselice, Chary, Cristiani, Daddi, Dickinson, Elbaz, Grogin, Mainieri, Treister, Urry, ...) - PowerPoint PPT Presentation
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1
An
ton
Koe
kem
oer
(ST
ScI
)
Ext
raga
lact
ic X
-Ray
Su
rvey
s -
Cam
brid
ge, M
A, 6
Nov
200
6
Probing AGN Populations atRedshifts 6 - 7+ with Large X-ray Surveys
Anton Koekemoer (Space Telescope Science Institute)
Black holes in the context of reionization:May trace hierarchical dark matter halosProvide harder ionizing continuum than starsMay regulate galaxy growth / SFR via feedbackM- relation suggests intimate connection between
BH/galaxy formation and growth
Current knowledge:At z ~ 6 - 6.5, already have
supermassive BHs up toM ~ 3x109 Mo (Fan et al
2001+; Willott et al. 2003)High-luminosity end of
AGN LF evolves stronglyfrom z~6 to z~2; PLE isruled out (Fan et al. 2001+;Richards et al. 2006)
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An
ton
Koe
kem
oer
(ST
ScI
)
Ext
raga
lact
ic X
-Ray
Su
rvey
s -
Cam
brid
ge, M
A, 6
Nov
200
6
Instead of PLE, AGN appear to follow “downsizing” -- luminosity-dependent density evolution “LDDE” -- for X-ray LF (Ueda et al. 2003, Hasinger et al. 2005) and also for QSO LF (Richards et al. 2006):
– luminous AGN peak earlier (z~2-3)– fainter AGN peak more recently (z~1)(XLF; Hasinger et al.
2005)(QSO LF, Richards et al. 2006)
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An
ton
Koe
kem
oer
(ST
ScI
)
Ext
raga
lact
ic X
-Ray
Su
rvey
s -
Cam
brid
ge, M
A, 6
Nov
200
6
Questions:How do the most massive BHs form within < 1 Gyr?How does BH growth influence the M- relation?What is the ionizing budget of AGN integrated over the
LFbeyond z ~ 6, and its contribution to reionization?
(How) does obscured/unobsc. AGN ratio evolve at z > 6?
Our knowledge has been limited by the following:
only the top of the AGN LF has been studied at z ~ 6no AGN currently confirmed at z > 7
Approach:Set out to quantify the faint end of AGN LF at z ~ 6Search for more luminous AGN at z > 6 - 7
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An
ton
Koe
kem
oer
(ST
ScI
)
Ext
raga
lact
ic X
-Ray
Su
rvey
s -
Cam
brid
ge, M
A, 6
Nov
200
6
FOpt (mag)
log
FX (
erg
s-1cm
-2)
AGN
Require Wide+Deep X-ray / Optical / IR Surveys:
Depth probes faint/moderate-lum AGN to high zArea probes high-lum AGN at high z(Hard) X-rays penetrate obscuring torus, IR probes
rest-frame optical emission from AGN + host galaxy New part of parameter space:
Combined optical + X-ray depth allows wider exploration of FX/FOpt:
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An
ton
Koe
kem
oer
(ST
ScI
)
Ext
raga
lact
ic X
-Ray
Su
rvey
s -
Cam
brid
ge, M
A, 6
Nov
200
6
CDFS/GOODS-S+N survey:powerful combination of wide area and depth,