1. Average Fe Kα emission from distant AGN
Amalia Corral
IFCA(Santander)/OAB(Milano)
M.J. Page: MSSL (UCL), UK
F.J. Carrera, X. Barcons, J. Ebrero: IFCA (CSIC-UC), Spain
S. Mateos, J.A. Tedds, M.G. Watson: University of Leicester, UK
A. Schwope, M. Krumpe: Astrophysikalisches Institut Postdam, Germany
X-ray Universe 2008, Granada, 27th May 2008

2. Introduction
Inclination angle
Maximum-rotating BH
Non-rotating BH
XRB (X-Ray Background) is known to be composed of discrete sources, most of them are AGN.
XRB synthesis models, ingredients:
- AGN intrinsic column density and acretion rate distribution and their evolution as a function of Luminosity and redshift.
- Average radiative efficiency of accretion onto Supermassive Black Holes -> Measure from Fe line relativistic profile.

3. Previous Results Local samples:
EW(relativistic) ~ eV (Guainazzi+06, Nandra+07)
Distant AGN -> average or stack many spectra together:
EW(relativistic) ~ 400 (type1) - 600(type2) eV
(Streblyanska+05,Brusa+05)

4. Our sample
AGN from the AXIS (An International XMM-Newton Survey) and XWAS (XMM-Newton Wide Angle Survey) medium surveys (average flux ~ 5x10-14 erg cm-2 s-1) .
Optical spectroscopic identifications (>80 counts keV):
Type 1 AGN: 606 sources
Type 2 AGN: 117 sources

5. Our sample Sample selection:
Individual spectra > 80 counts in keV

6. Averaging method
Fit an absorbed power law above 1 keV rest-frame and unfold the un-grouped spectra: best-fit model.
Correct for Galactic Absorption.
Shift to rest-frame.
Normalize using the 2-5 keV rest-frame band.
Rebin to 1000 final counts/bin.
Average.

7. Fit simple power law in 2-10 keV :
Results
Type 1 AGN > counts
Type 2 AGN ~ counts
Fit simple power law in 2-10 keV :
Type 1: Γ=1.92± Type 2: Γ=1.44±0.02

8. Broad relativistic profile not clearly present
Results
Type 1 AGN > counts
Type 2 AGN ~ counts
Broad relativistic profile not clearly present

9. Simulations
100 simulations (best-fit model) per real spectrum including Poisson counting noise and keeping the same 2-8 keV observed flux, exposure time and calibration matrices as for the real data.
Significance contours by removing the 32% (1σ level) and 5% (2σ level) extreme values.

10. Results ● Simulated continuum ▪ Average spectrum
·· 1σ confidence limit
-- 2σ confidence limit
▪ Average spectrum
● Simulated continuum

11. Results ● Simulated continuum ▪ Average spectrum
·· 1σ confidence limit
-- 2σ confidence limit
▪ Average spectrum
● Simulated continuum

12. Spectral fit Baseline model:
100-simulations continuum: mixture of absorbed power laws.
Narrow emission line.

13. Spectral fit – Type 1 AGN
Best-fit model: Baseline model plus neutral reflection:
Egaus = 6.36±0.05 keV
σgaus = 80±80 eV
EWgaus = 90±30 eV
i = 60±20º
R=0.5±0.20

14. Spectral fit – Type 1 AGN
Best-fit model: Baseline model plus neutral reflection:
Egaus = 6.36±0.05 keV
σgaus = 80±80 eV
EWgaus = 90±30 eV
i = 60±20º
R=0.5±0.20

15. EW(broad relativistic line) < 400 eV at 3σ confidence level
Spectral fit – Type 1 AGN
Best-fit model: Baseline model plus neutral reflection:
Egaus = 6.36±0.05 keV
σgaus = 80±80 eV
EWgaus = 90±30 eV
i = 60±20º
R=0.5±0.20
EW(broad relativistic line) < 400 eV at 3σ confidence level

16. Spectral fit – Type 2 AGN
Model: Baseline model plus neutral reflection:
Egaus = 6.36±0.07 keV
σgaus = 80±60 eV
EWgaus = 70±30 eV
i < 80
R > 0.7

17. Spectral fit – Type 2 AGN
Model: Baseline model plus neutral reflection:
Egaus = 6.36±0.07 keV
σgaus = 80±60 eV
EWgaus = 70±30 eV
i < 80
R > 0.7

18. Spectral fit – Type 2 AGN Model: Baseline model plus Laor line:
Egaus = 6.36±0.07 keV
Elaor ~ 6.7 keV
σgaus = 80±60 eV
EWgaus = 70±40 eV
EWlaor ~ 300 eV
i ~ 60º

19. Spectral fit – Type 2 AGN Model: Baseline model plus Laor line:
Egaus = 6.36±0.07 keV
Elaor ~ 6.7 keV
σgaus = 80±60 eV
EWgaus = 70±40 eV
EWlaor ~ 300 eV
i ~ 60º

20. Neutral reflection and Relativistic line give the same fit
Spectral fit – Type 2 AGN
Model: Baseline model plus Laor line:
Egaus = 6.36±0.07 keV
Elaor ~ 6.7 keV
σgaus = 80±60 eV
EWgaus = 70±40 eV
EWlaor ~ 300 eV
i ~ 60º
Neutral reflection and Relativistic line give the same fit

21. Type 1 AGN: sub-samples
Number of counts 2-10 keV > 2x105 allow us to test evolution with different parameters by dividing the sample in 3 subsamples of equal quality (i.e. number of total counts): redshift, flux and luminosity.
We found no dependence for the emission features on redshift or flux.
Dependence on Luminosity -> Iwasawa- Taniguchi effect?

22. Type 1 AGN: sub-samples L(0.5-2 keV) (erg s-1) EW narrow line (eV)
1x1042 – 2x1044
190±50
2x1044 – 6x1044
150±80
6x1044 – 6x1046
50±40

23. Conclusions
Narrow emission line significatively detected in Type 1 and Type 2 AGN average spectra. E ~ 6.4 keV, EW ~ 100 eV.
Type 1 AGN: No compelling evidence of a Broad component in the average spectrum. Continuum features best represented by a reflection component. Relativistic line upper limit EW<400 eV (3σ confidence).
Iwasawa-Taniguchi effect for narrow line component marginally detected.
Type 2 AGN: Statistics insufficient to distinguish between a relativistic line and a reflection component.

24. Conclusions
Narrow emission line significatively detected in Type 1 and Type 2 AGN average spectra. E ~ 6.4 keV, EW ~ 100 eV.
Type 1 AGN: No compelling evidence of a Broad component in the average spectrum. Continuum features best represented by a reflection component. Relativistic line upper limit EW<400 eV (3σ confidence).
Iwasawa-Taniguchi effect for narrow line component marginally detected.
Type 2 AGN: Statistics insufficient to distinguish between a relativistic line and a reflection component.

25. Conclusions
Narrow emission line significatively detected in Type 1 and Type 2 AGN average spectra. E ~ 6.4 keV, EW ~ 100 eV.
Type 1 AGN: No compelling evidence of a broad component in the average spectrum. Continuum features best represented by a reflection component. Relativistic line upper limit EW<400 eV (3σ confidence).
Iwasawa-Taniguchi effect for narrow line component marginally detected.
Type 2 AGN: Statistics insufficient to distinguish between a relativistic line and a reflection component.

26. Conclusions
Narrow emission line significatively detected in Type 1 and Type 2 AGN average spectra. E ~ 6.4 keV, EW ~ 90 eV.
Type 1 AGN: No compelling evidence of a broad component in the average spectrum. Continuum features best represented by a reflection component. Relativistic line upper limit EW<400 eV (3σ confidence).
Iwasawa-Taniguchi effect for narrow line component marginally detected.
Type 2 AGN: Statistics insufficient to distinguish between a relativistic line and a reflection component.

27. THANK YOU