Obscured and unobscured growth of Super-massive Black Holes

Francisco J. Carrera, X. Barcons, J. Bussons, J. Ebrero, M. Ceballos, A. Corral (IFCA, CSIC-UC, Spain)

&XMM-Newton Survey Science Centre

(S. Mateos, M. J. Page, M.G. Watson, J. Tedds, R. Della Ceca ...)

Extragalactic X-ray Surveys, Boston, November 6, 2006

Resolving the X-ray background:An XMM-Newton International

Survey (AXIS)

Definition of the AXIS survey (Carrera

et al 06) • 36 XMM-Newton target fields:

– Galactic latitude |b|>20 deg– X-ray observations with EPIC-pn

detector in FULL-FRAME-MODE– ~Avoided fields with bright and/or

extended targets– Good time intervals > 10 ksec– Available early on in the mission

• Solid angle ~4.8 deg2

• Using SAS v6.1.1 to produce final source list and products: – Exposure and background maps– Source detection– Spectra and calibration matrices

• Areas around target + OOT+ near the pn CCD gaps excluded

• Own empirical sentitivity maps from detected source parameters

• Very detailed source screening• Total of 1433 distinct X-ray

sources with detection likelihood >15 in any of 4 bands (see below)

NGC4291

Mrk 205

Soft0.5-2 keV

XID0.5-4.5

keV

Hard2-10 keV

Ultrahard4.5-7.5 keV

X-ray source counts (XMM-Newton & Chandra & ASCA)

The contribution to the X-ray background

ShallowMediumDeep Surveys

Medium surveysresolve the

brightest50% of the

X-raybackground

The XMM-Newton Medium Survey(XMS)

The XMS samples (Barcons et al.

07)

Name Band (keV)

Flux limit 10-14 cgs

# sources(unique)

# identified (fraction)

Soft XMS-S

0.5-2 1.5 210 (1) 200 (95%)

Hard XMS-H

2-10 3.3 159 (20) 132 (83%)

XID XMS-X

0.5-4.5 2.0 284 (56) 261 (92%)

Ultrahard XMS-U

4.5-7.5 - 70 (2) 60 (86%)

• Subset of AXIS:– 25 fields chosen for follow-up: 3.3 deg2

– Flux limited in Soft, Hard and XID

Optical identification of the XMS

• Optical imaging: g,r,i (SDSS), Z (Gunn), mostly at the INT/WFC to r~23-24mag

• Reliable & unique candidate counterpart in r/i for virtually all sources (< 5” or < 5)

• Optical spectroscopy– 50% from AXIS programme (WHT, TNG, NOT):

multi-fibre and long-slit spectroscopy– 20% from Calar Alto/3.5m long-slit spectroscopy– 15% from VLT/FORS2 long-slit spectroscopy– A few from AAT/2dF, SUBARU/FOCAS, and others

• Preliminary results from 2 XMM-Newton fields (~30 sources) in Barcons et al (2002)

The content of the XMS

10

12

14

16

18

20

22

24

26

28

0,1 1 10 100

0.5-4.5 keV flux / 10-14 erg cm-2 s-1

r o

r i o

r R

BLAGN

NELG

Gal

Star

Unid

4m spec lim

10m spec lim

Deep Medium Shallow

Breakdown of identified sources

XMS-S Soft

XMS-H Hard

XMS-X XID

XMS-U Ultrahard

Broad-line AGN

75% (148/200)

63% (83/132)

73% (190/261)

65% (39/60)

Narrow-line galaxies (AGN)

13% (27/200)

27%(35/132)

15% (39/261)

27% (16/60)

Absorption line galaxies+clust

4% (8/200)

7% (9/132)

4% (10/261)

5% (3/60)

Stars 8% (15/200)

2% (3/132)

8% (20/261)

0% (0/60)

Redshift distributionXMS-S

0

5

10

15

20

25

30

35

0 1 2 3 4

z

Nu

mb

er

Soft

XMS-H

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

z

Nu

mb

er

Hard

Peak of QSO distribution(z~1.5) well sampled.

Obscured population outto z~1 in Hard sample

Luminosities and redshiftsXMS-S

41

42

43

44

45

46

47

0 1 2 3

z

log

L (0.5

-2 k

eV

)

XMS-H

41

42

43

44

45

46

47

0 1 2 3

z

log

L (2-1

0 k

eV

)

Soft

Hard

QSO-2 @ z=2.2

All galaxies consistentwith hosting AGN

LX>1042 erg/s

QSOs

“Seyferts”

Tips for statistical identification

~90% Obscured AGN

90% unobscured AGN

Stars

HR2

log

(FH

ard

/Fop

t)

Obscured and Unobscured AGN

X-ray to optical ratio:

a marker for obscuration?

Soft•5% of sources with fX/fopt>10•30% of fX/fopt>10 obscured AGN

FX/Fopt >10

Hard

log

(FH

ard

/Fop

t)

•15% of sources with fX/fopt>10•~70% of fX/fopt>10 obscured AGN

log

(FS

oft/F

op

t)

FX(10-

14cgs)

FX(10-14cgs)

Optical colours

QSOsS+Irr

E+S0

10% of QSOsare red

QSOsS+Irr

E+S0

HardSoft

r-i

g-r g-r

#

Reddening

Fainter X-ray sources are redder?

FHard(10-14cgs)

r-i

Optical versus X-ray “colours”: Hard

Hard Softer

Harder sources are >90% obscured AGNSofter sources: Optically blue: unabsorbed AGN Optically red: mix of abs & unabs AGN

HR2

g-r

X-ray absorption vs obscuration: not equivalent

The XMS survey

•10% of type 1 AGN are absorbed(with NH<1022 cm-2) •>40% of type 2 AGN are absorbed

Mateos et al (2005)

The Lockman Hole survey

•15% (<30% at 3) of type 1 AGN are absorbed (with NH<1022 cm-2) •80% (>50% at 3) of type 2 AGN are absorbed. But 5/28 are unabsorbed

Mateos et al (2006)

Stacking analysis

• Procedure still being tested• Selecting X-ray spectra with >80cts• Unfolding with best fit Gal+Intrinsic abs. p.l.• Correcting for Galactic NH

• De-redshifting• Renormalizing using flux in 2-8 keV band• Averaging in final bins (≥500 cts)• Averaging AXIS:

– BLAGN (200 sources)– NELG (43)

• Much improved averaging AXIS+XMM-2dF (see Xu, Mateos):– BLAGN (549): =1.95±0.02 Fe line @6.5±0.2 keV EW=130±60 eV – NELG (113): =1.53±0.02 Fe line @6.6±0.4 keV EW=130±100 eV

AXIS+XMM-2dFBLAGN

AXIS+XMM-2dFNELGs

Averaging X-ray spectraCorral et al., in preparation

Conclusions

• On-going work• Brightest 50% of the X-ray background dominated by AGN.• Unobscured accretion dominates, but increasingly

important contribution from obscured objects.• X-ray absorption and optical obscuration not

equivalent:– 10% of type 1 AGN are X-ray absorbed– 15% of type 2 AGN are not X-ray absorbed

– 25% of fX/fopt>10 hard X-ray sources are type 1 AGN

– 10% of X-ray selected type 1 AGN have red colours

• Even at medium fluxes, an important fraction of the X-ray sources have optically faint and red optical counterparts.

• Most unIDed objects faint (r/i>21.5) and extended: NELGs• Preliminary results from average spectra show Fe lines

in both BLAGN and NELGs