Download Presentazione di PowerPoint

Boston, November 2006
Extragalactic X-ray surveys
Spectral analysis of
X-ray sources in
the CDFS
Paolo Tozzi
0.3-1 keV
1-3 keV
3-7 keV
Detailed spectral analysis of
X-ray sources
Tozzi, Gilli, Mainieri et al. 2006, A&A, 451, 457
Rosati et al. 2002
National Geographic, Dec 2002
Deep X-ray Surveys: some open issues
The distribution of intrinsic absorption among AGN
Detection of Compton-Thick AGN
The unresolved fraction of the XRB at high energies
Compton thick candidates
NH vs redshifts for the whole sample
Detected fraction as a function of NH and z
z < 0.7
0.7 < z <1.5
z > 1.5
Sampling different luminosity and spectral population at different z
Selection effects are relatively easy to model in the X-ray band
NH histogram corrected for completeness
Corrected for completeness
and sources outside the
detectability region
<log(NH)> ~ 23.1
dispersion = 1.1
5% C-thick (14 reflection
+4 sources NH>1.5 1024 cm-2
density ~ 200 +- 50 deg-2
in agr w XRB model by
Gilli, Comastri, Hasinger
(2006)
NH distribution vs Optical Type
Whole sample (321)
QSOII (44)
Consistent with evolutionary sequence:
pre-QSO phase
C-thin absorbed QSO (QSOII @ high z)
unobscured QSO activity
quiescent spheroidal galaxy
Alexander et al. 2005; Stevens et al. 2005
Model: Granato et al. 2005
Whole sample (321)
Cthick candidates (14)
Part of the missing XRB is from
intermediate z strongly absorbed
moderate luminosity, possibly
C-thick sources, in a secondary,
relatively low-z phase of accretion
(see “downsizing” or antihierarchical behaviour)
The unresolved fraction increases
with the energy band
~50% not resolved
yet for E> 5 keV
(Worsley et al. 2004, 2005)
Missing XRB: NH=4.5 1023 cm-2 @ z=0.8
Compute the contribution of the absorbed sources to the XRB
NH > 1022 cm-2
NH > 1023 cm-2
Worsley et al. 2004
This work
After computing the skycoverage according to the spectral shape
of each source
CONCLUSIONS
Detailed X-ray Spectral Analysis of faint X-ray sources:
Towards an universal distribution of intrinsic absorption (selection
effects can be easily modelled in X-rays)
>~80% of the AGNs agree with simple unification models (TypeI/TypeII
Unobscured/Obscured corr.)
Evidence for strongly absorbed, C-thick sources @ z~1, and a substantial
QSOII population at z>~2
Part of the missing XRB is already observed in agreement with most
recent XRB synthesis models
C-thick candidates in IRAC/MIPS colors
Use secure spectral identifications in CDFS and CDFN
29 galaxies with good spectra in the CDFS and emission line ratios consistent with
starbursts or normal galaxies give the X-ray priors. A Bayesian approach allows
us to identify 74 galaxies in the CDFS and 136 in the CDFN (2 Ms)
Norman et al. 2004
SFR densities
XLF consistent with a PLE ~ (1+z)2.7
Consistent with an evolution of
SFR  (1+z)2.7 for 0<z<1.
Compilation from Tresse et al. 2002:
Gallego et al. 1995 (H)
Gronwall 1999
Hopkins et al. 2000
Pascual et al. 2001
Tresse et al. 2002
Sullivan et al. 2000
Norman et al. 2004
Lilly et al. 1996
Lines from 60 m
Saunders et al. 1990, Takeuchi et al. 2003
XLF of Star Forming Galaxies is a goal
for future X-ray missions (Con-X, XEUS)
K20 survey
Daddi et al. 2004
IR selected galaxies at z~2 with massive SF
Soft
Hard
Stacked image of 23 BzK galaxies; HR< -0.5 @ 2sigma ; L2-10~1042 erg/sec
SFR ~ 170 Myr-1 (4 higher than LBG). SFRD of 0.04 M⊙ /yr/Mpc3
We are witnessing the massive spheroid formation epoch
(the peak of just the low-z tail?)
Daddi et al. 2004
The evolution of the obscured fraction with redshift
This work
Ueda et al. 2003
Average NH artificially increases towards high-z
NH ~ 1020cm-2
150 and 80
net counts
Tozzi, Gili, Mainieri et al. 2006
Luminosity dependent density evolution:
downsizing or anti-hierarchical behaviour
Ueda et al 2003
Hasinger et al. 2005
Extended
CDFS
PI N. Brandt
~1000 sources
(Lehmer et al. 2005)
1Ms
+
4 X 240 ks
AGN Contribution to the hard XRB
90% resolved in 0.5-2 keV
93% resolved in 2-8 keV
AGN contribution
83% in 0.5-2 keV
95% in 2-8 keV
(Bauer et al. 2004)
CDFS (1Ms): XRB(S> 4.5×10 -16) = (1.70±0.15)×10 -11 erg s -1cm -2deg -2
CDFN (2Ms): XRB(S> 2 ×10 -16) = (2.07±0.15)×10 -11 erg s -1cm -2deg -2
The unresolved fraction increases
with the energy band
~50% not resolved
yet for E> 5 keV
(Worsley et al. 2004, 2005)
Missing XRB: NH=4.5 1023 cm-2 @ z=0.8
Worsley et al. 2004; 2005
Compute the contribution of the absorbed sources to the XRB
Worsley et al. 2004
This work
After computing the skycoverage according to the spectral shape
of each source