AEGIS-X: Results from the Chandra
survey of the Extended Groth Strip
Elise Laird
A Georgakakis (NOA), K Nandra (PI: Imperial), J Aird
(Imperial), D Croton (Berkeley), K Bundy (U Toronto), A Coil
(Steward), C Pierce (UCSC), and the AEGIS team
All Wavelength Extra-Galactic International Survey
• Deep multiwavelength data
• Wide area (~0.5 -1.0 deg2)
• Keck/DEIMOS DEEP2
spectroscopy: >10,000
redshifts with R<24.1,
mainly 0.6<z<1.4
GALEX
Chandra
HST/ACS
Palomar
aegis.ucolick.org; Davis et al. (2007)
The X-ray Universe 2008, Granada
AEGIS-X survey
• 1.6 Ms over 0.67 deg2
(8 ACIS-I pointings)
• Flux limits (1% complete);
– SB (0.5-2 keV) 5.3 x 10-17 cgs
– HB (2-10 keV) 3.8 x10-16 cgs
• 1325 sources, selected
between 0.5 and 7 keV
• <1.5% spurious sources
• 0.79” astrometric accuracy
Laird et al. submitted to ApJS
The X-ray Universe 2008, Granada
AEGIS-X survey
• 1.6 Ms over 0.67 deg2
(8 ACIS-I pointings)
• Flux limits (1% complete);
AO9:
additional
1.8 Ms over
0.2 deg2
– SB (0.5-2 keV) 5.3 x 10-17 cgs
– HB (2-10 keV) 3.8 x10-16 cgs
• 1325 sources, selected
between 0.5 and 7 keV
• <1.5% spurious sources
• 0.79” astrometric accuracy
Laird et al. submitted to ApJS
Reduced data, data products, catalogues publicly available at
http://astro.imperial.ac.uk/research/aegis
The X-ray Universe 2008, Granada
AEGIS-X survey
---- L* at z=1
• Using Maximum Likelihood
technique to find secure
counterparts:
– optical: 76%, complete to
RAB=24.1, 6% spurious
matches
– IRAC 3.6m: 94% (of sources
with coverage), complete to
mAB=23.8, 1% spurious
matches
• Currently ~35% spectroscopic
completeness (with DEEP3 
60%)
Spectroscopy:
• Keck/DEEP2 (Davis et al. 2003)
• MMT (Coil et al. 2008)
The X-ray Universe 2008, Granada
800ks data
AGN formation models
“QSO mode”
Merger (QSO-mode) models
(e.g. Hopkins et al. 2005):
• gas rich major merger
• gas inflows trigger BH accretion &
starbursts
• dust/gas clouds obscure AGN
• AGN feedback sweeps away gas,
quenching SF and BH accretion
“Radio mode”
Weak AGN feedback models in
dense regions (e.g. Croton et
al. 2006; Bower et al. 2006):
• cooling flows in groups or clusters
  large cold-gas reservoirs at
galaxy centre
• weak AGN activity invoked to suppress
cooling flows by either heating of
mechanically sweeping away the gas
Hydra-A cluster,
McNamara et al. 2000
Kazantzidis
et al. 2005
The X-ray Universe 2008, Granada
Colour-magnitude relation
• Colour bimodality:
– Blue cloud: star-forming
– Red sequence: evolved
stellar pop
• Galaxy stellar mass builds
via mergers in blue cloud
• Rapid quenching RS
• Are AGN responsible for
quenching?
• Or for maintaining galaxies
on RS?
DEEP2 survey, 0.4<z<1.4; Willmer et al. 2006
Quenching
e.g. Strateva et al 2001; Bell et al 2004;
Faber et al 2007
The X-ray Universe 2008, Granada
Colour-magnitude relation for AGN
z=0.6-1.4; Nandra et al. 2007
The X-ray Universe 2008, Granada
Colour-magnitude relation for AGN
• Are AGN responsible for the
quenching?
• Obscured X-ray sources in
RED cloud: old stellar
populations
• X-ray surveys select AGN after
the quenching of the starformation
• Are there obscured AGN (in
star forming galaxies) below Xray detection threshold?
z=0.2-0.7
• Are obscured AGN found in
post starburst galaxies?
z=0.7-1.4
Coil et al. 2008
The X-ray Universe 2008, Granada
X-ray stacking results: 24m bright sample
 Stack X-ray emission of galaxies at different regions of CMD and in post
starburst galaxies
Georgakakis et al. 2008
• Hard signal around valley and in red sequence, C>–0.15
Stacked signal of 26 post starbursts:
• Obscured AGN associated with transition
galaxies
HR > 0.35.
<LX>~1041 ergs/s
• <Lx> = 1041 erg s-1
The X-ray Universe 2008, Granada
AGN host galaxy morphologies
0.2<z<1.4
LX>1042 erg s-2
65% E/S0/Sa
Massive, bulge dominated, red, evolved
hosts
Pierce et al. 2007
Gini coefficient: clumpiness; M20: central concentration
Abraham et al. 2003; Lotz et al. 2004
The X-ray Universe 2008, Granada
AGN stellar mass function
Hasinger et al. 2005
No Evidence for AGN hosts
“downsizing” in mass
Bundy et al. 2008
Accretion rate evolution?
Also Babic et al. 2007 for z<1 in CFD-S
The X-ray Universe 2008, Granada
Large scale structure
A. Coil
AGN: Massive galaxies tracing large scale structure
Also ECDF-S: Silverman et al. 2008; XBootes Murray et al. 2005; Hickox et al. 2008
The X-ray Universe 2008, Granada
AGN/Galaxy cross-correlation function
Split into 2 redshift bins: z=0.2-0.7 and z=0.7-1.4
X-ray AGN cluster like red galaxies, at z~0.5 and z~0.9
Relative bias of X-ray AGN to
galaxies:
z=0.7-1.4 red gals: 1.1 (0.1)
blue gals: 1.7 (0.1)
z=0.2-0.7 red gals: 1.1 (0.1)
blue gals: 1.4 (0.1)
Coil et al. 2006
Coil et al. 2008
The X-ray Universe 2008, Granada
AGN: relationship to groups
• Gerke et al. (2006) optical
spectroscopic groups
• 42% of X-ray AGN in groups
• Excess compared to general
population (~99%)
• Tentative excess relative to
matched galaxy population
(~91%)
• Tentative evidence that field
AGN more luminous than
group AGN (~98%)
Also Miyaji et al. 2007;
Silverman et al. 2008
Randomised optical
Randomised
optical
X-ray
X-ray
0.7< z< 1.4; Georgakakis et al. 2008
The X-ray Universe 2008, Granada
Conclusions
• Typical AGN at z~1 are in massive, red host galaxies
– Star formation has terminated or is terminating
– Many obscured AGN on red sequence
– Bulge dominated, mergers not main trigger
• Stellar Mass Function
– Flat, non-evolving, no downsizing in mass
• Large scale structure environment
– Dense environments (cluster like hosts)
– Around ~40% in groups
• Most black hole growth at z<1 not in “QSO mode”
The X-ray Universe 2008, Granada
AEGIS-X advertisement
• All reduced data and data products for AEGIS-X
released 1 May 2008.
• Processed other Chandra deep fields in same way
and reduced data, data products & source catalogues
also released
–
–
–
–
Chandra Deep Field North (2Ms)
Chandra Deep Field South (2Ms)
Extended Chandra Deep Field South (4 x 250 ks)
Also large area, shallow ELAIS-N1 and XBootes
surveys
http://astro.imperial.ac.uk/research/aegis
The X-ray Universe 2008, Granada