Tracing the Accretion History of the
Universe by stacking X-rays from
Red Galaxies in the NDWFS
Kate Brand, NOAO, Tucson
A. Dey, B. Jannuzi, M. Brown, J. Najita, C. Kochanek, C. Watson,
D. Fabricant, G. Fazio, W. Forman, P. Green, C. Jones, A. Kenter,
S. Murray, A. Vikhlinin, B. McNamara, J. Shields, M. Rieke
AAS, Denver, June 2004
The NDWFS / XBoÖtes fields
Summary
• Stacking analysis of X-rays from optically
selected galaxies to determine mean X-ray
properties and how this evolves.
• Wide field / deep multi-band optical data
• AGN / star formation.
The NDWFS red galaxy
population (Brown et al. 2003)
3316 red galaxies in 1.4 deg2 region selected
by model SED fitting to photometric data
Photometric redshifts, z= 0.3-0.9
Same evolution corrected absolute magnitude
distribution over all redshifts (MR < -20.5) ->
tracing same population
The stacked X-ray images
Evolution of X-ray Luminosity
with Redshift
HARD
TOTAL
SOFT
Future Work
• The full 9 deg2 -> ~ 7 x number of objects -> better number statistics
-Smaller errors
-Divide population into sub-populations
-Mean X-ray spectra
-Bimodality in number counts
• Stacking of X-rays in different optical populations
- AGN / Star formation
• Multi-wavelength data - deep radio / FIR - star formation rates
Extraction radius / off-axis distance
Results
Redshift
No.
X-ray
galaxies Counts
(bkgd)
X-ray Flux
X-ray
(bkgd)
Luminosity
10-16 ergs cm-2 s-1 1042 ergs s-1
0.3-0.5 0.5-10keV
0.5-2keV
2-10keV
1040
149 (26.5)
73 (10.5)
76 (16.0)
2.87±0.23 (0.51)
0.64±0.08 (0.09)
3.80±0.43 (0.80)
0.12 ± 0.01
0.028 ± 0.004
0.15 ± 0.02
0.5-0.7 0.5-10keV
0.5-2keV
2-10keV
1271
116 (32.25) 1.83±0.17 (0.51)
52 (13.25) 0.37±0.05 (0.09)
64 (19.0)
2.62±0.32 (0.77)
0.17 ± 0.02
0.036 ± 0.007
0.24 ± 0.05
0.7-0.9 0.5-10keV
0.5-2keV
2-10keV
1005
95 (30.75)
53 (12.5)
42 (18.25)
0.32 ± 0.06
0.093 ± 0.019
0.31 ± 0.10
1.89±0.19 (0.61)
0.48±0.07 (0.11)
2.17±0.34 (0.94)
Number counts
Tau distribution
MR distribution