1. 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

2. The NDWFS / XBoÖtes fields

3. 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.

4. 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=
Same evolution corrected absolute magnitude distribution over all redshifts (MR < -20.5) -> tracing same population

5. The stacked X-ray images

6. Evolution of X-ray Luminosity with Redshift
TOTAL
HARD
SOFT

7. 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

8. Extraction radius / off-axis distance

9. Results Redshift No. galaxies X-ray Counts (bkgd) X-ray Flux (bkgd)
10-16 ergs cm-2 s-1
X-ray Luminosity
1042 ergs s-1
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
1271
116 (32.25)
52 (13.25)
64 (19.0)
1.83±0.17 (0.51)
0.37±0.05 (0.09)
2.62±0.32 (0.77)
0.17 ± 0.02
0.036 ± 0.007
0.24 ± 0.05
1005
95 (30.75)
53 (12.5)
42 (18.25)
1.89±0.19 (0.61)
0.48±0.07 (0.11)
2.17±0.34 (0.94)
0.32 ± 0.06
0.093 ± 0.019
0.31 ± 0.10

10. Number counts

11. Tau distribution

12. MR distribution