Fabio La Franca

and N. Sacchi, S. Puccetti, F. Fiore, C. Gruppioni, C. Feruglio

et al.

Dipartimento di Fisica

The nature and density of Spitzer selected X-ray absorbed AGN:

Identification of sources with large Identification of sources with large MIR/Optical ratios in the MIR/Optical ratios in the XMM/SWIRE/ELAIS-S1XMM/SWIRE/ELAIS-S1

Universita` degli Studi ROMA TRE

-What is the fraction of AGN among the sources with large MIR/O?

-What is the fraction of absorbed AGN?

-Is the density of absorbed AGN compatible to other estimates orextrapolations (i.e. XLF)?

QUESTIONSQUESTIONS

What do we know about the AGN evolution?

A Luminosity Dependent Density Evolution(LDDE) for X-ray AGN isobserved(e.g. Ueda+03; Fiore+03; La Franca+05;Barger+05; Hasinger+05; Gilli+07; Silverman+07; Della Ceca+08)

Lower luminosity AGNpeak at lower redshifts:DOWNSIZING(see models of galaxy andAGN formations)

La Franca+05

*) Assuming no luminosity and redshift dependences

assumed *)

expected

What do we know about the AGN evolution?

The fraction of absorbed AGN as function of LX and z

DECREASE WITH LUMINOSITYEarlier evidences of a decrease of the fraction of absorbed AGN with luminosity from Lawrence & Elvis (1982), confirmed by Ueda et al. (2003).

INCREASE WITH THE REDSHIFT

Fract

ion o

f A

bso

rbed A

GN

La Franca+05

The LX-z plane

~1x10-15@2Ms

?

X-ray stacking analysis of MIR selected AGNsX-ray stacking analysis of MIR selected AGNsallows to probe more distand, more absorbed,allows to probe more distand, more absorbed,lower luminosity, regions of the Llower luminosity, regions of the LXX-N-NHH-z plane-z plane

Many studies indicate that the majorityof the sources with extremeF(24um)/F(R) (e.g. >1000) ratios areobscured/absorbed AGNs

(see e.g. Martinez-Sansigre+05; Houck+05;Weedman+06; Brown+06; Polletta+06; Yan+07; Daddi+07; Fiore+08; Georgantopoulos+08…)

However,1) these sources are so faint, that direct optical spectroscopic classifications

is available for very few of them;2) the density estimates are based on assumptions on the NH distribution.

AREA0.6 deg2 (:0.5h, :-43.5o)

IMAGINGBVRIz (PI Franceschini; Berta+06+08)

JK (PI Cimatti/Maiolino; Dias+08)

SWIRE (PI Lonsdale & Rowan-Robinson)(3.6, 4.5, 5.8, 8.0 and 24 μm)

X-ray (PI: Fiore) by XMM 4x100Ks (Puccetti+06)

Chandra x5 (Puccetti in prep)

SPECTROSCOPY(PI La Franca; Sacchi in prep)

~100 hours withVIMOS and FORS2@VLT

Total~1500 Zs (R<24.5) (K, 3.6um and 24um sources)

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: data

Catalogue of ~1700 24m sources with F24 > 0.280 mJy

Redshift for 384 sources with R<24.2

Seyfert2/AGN2 (SED:10-13) Seyfert2/AGN2 (SED:10-13)

ULIRG/Starburst (SED: 7-9)ULIRG/Starburst (SED: 7-9)

Spirals Star Forming (SED:14-20)Spirals Star Forming (SED:14-20)

Ellipticals (SED:21)Ellipticals (SED:21)

Red Power Law ~AGN1 (SED:1-6) Red Power Law ~AGN1 (SED:1-6)

Adapted from Polletta et al. (2007)

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: SED templates fitting

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: SED templates fitting

(see Polletta et al. 2007)

AGN2

AGN1

Normal

χ2 best fit analysis

1st choice

2nd choice 3rd choice

SED

Normal

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources

Local relationshipun-absorbed AGN

20%20%

4343%34%34%

3%3%

What is the fraction/densityof (possibly absorbed) AGNamong these high MIR/Osources?

First look at the OPT spectra…

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field OPTICAL VLT SPECTROSCOPY of faint (R>22) high MIR/O sources

TOTAL: 384 spectra

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field OPTICAL VLT SPECTROSCOPY of faint (R>22) high MIR/O sources

composite spectraTOTAL: 384 spectra

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field OPTICAL VLT SPECTROSCOPY of faint (R>22) high MIR/O sources

82% of SED-PWL are optical 82% of SED-PWL are optical AGNAGN93% of SED-ULIRG are optical 93% of SED-ULIRG are optical ELGELGSED-Seyfert2: no preferencesSED-Seyfert2: no preferences

composite spectraTOTAL: 384 spectra

40% AGN2 (& AGN1)

60% ELG

56 spectra

What about their SED?

X-ray detections and stacking (filled symbols)

STACKED DATA

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field X-ray stacking analysys of faint (R>22) high MIR/O sources

82% of OPT-AGN82% of OPT-AGNare X-ray absorbed AGNare X-ray absorbed AGN

85% of OPT-ELG85% of OPT-ELGare mildly X-ray are mildly X-ray absorbed withabsorbed withLL2-102-10~10~1041-4241-42

MID TERM SUMMARY:SED-PWL --> optical AGN(2) --> X-ray absorbed AGNSED-ULIRG --> optical ELG --> mildly absorbed low LX

Spec. and phot. redshiftsSpec. and phot. redshifts

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources

The sources with F24/FR>120 havez>0.6 and LogL24>44

Analysis for ∆z=0.6-1.3*

i.e.∆LogL24=44-45.5

*) At z>1.3 the sample is incomplete becouse of fainter R>25 unindentified sources

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field X-ray properties of low MIR/O sources

X-ray detections and stacking (filled symbols)

Low MIR/O sources show low LX and mild absorption,compatible with absorbed X-ray spectra of strongstar-forming galaxies

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field X-ray properties of high MIR/O sources

X-ray detections and stacking (filled symbols)

SOFT0.3-1.5 keV

HARD1.5-6 keV

R>25

SED-SEY2

SED-Red PWL

What are their densities?…

73% of large MIR/O (F24/R>120) sources are absorbed AGN

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Density of X-ray absorbed large MIR/O sources

The density is compatible with the extrapolations

coming from previous estimates at z~1of the XLF of Compton thin AGN

LogNH~22.3

LogNH~23.1

~1x10-15@2Ms

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Density of X-ray absorbed large MIR/O sources

?

We have probed a one decade less luminous region at z~1 or a 0.7 larger redshift at LogL2-10~42.5

-We have carried out optical spectroscopic identification of 56 sourceswith F24/R>120 and R<24.2.

- The fraction of optically classifiedoptically classified (or X-ray luminous) AGN is 40(45)%. SED-PWL --> optical AGN(2) --> X-ray absorbed AGN SED-ULIRG --> optical ELG --> mildly absorbed, low LX

-According to the X-ray stacking analysis, 73% of the sources are absorbed(22<LogNH<23.5) AGN with Log(L2-10)>42 cgs.

-Their density is compatible with the extrapolations at z~1 of the XLFof Compton thin AGN.

SUMMARY