The nature and density of Spitzer selected X-ray absorbed AGN: Identification of sources with large MIR/Optical ratios in the XMM/SWIRE/ELAIS-S1 Fabio La Franca and N. Sacchi, S. Puccetti, F. Fiore, C. Gruppioni, C. Feruglio et al. Dipartimento di Fisica Universita` degli Studi ROMA TRE

QUESTIONS -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 or extrapolations (i.e. XLF)?

What do we know about the AGN evolution? A Luminosity Dependent Density Evolution (LDDE) for X-ray AGN is observed (e.g. Ueda+03; Fiore+03; La Franca+05; Barger+05; Hasinger+05; Gilli+07; Silverman+07; Della Ceca+08) Lower luminosity AGN peak at lower redshifts: DOWNSIZING (see models of galaxy and AGN formations) La Franca+05

What do we know about the AGN evolution? The fraction of absorbed AGN as function of LX and z INCREASE WITH THE REDSHIFT assumed *) DECREASE WITH LUMINOSITY Earlier evidences of a decrease of the fraction of absorbed AGN with luminosity from Lawrence & Elvis (1982), confirmed by Ueda et al. (2003). expected Fraction of Absorbed AGN La Franca+05 *) Assuming no luminosity and redshift dependences

The LX-z plane ~1x10-15@2Ms Many studies indicate that the majority of the sources with extreme F(24um)/F(R) (e.g. >1000) ratios are obscured/absorbed AGNs (see e.g. Martinez-Sansigre+05; Houck+05; Weedman+06; Brown+06; Polletta+06; Yan+07; Daddi+07; Fiore+08; Georgantopoulos+08…) ? X-ray stacking analysis of MIR selected AGNs allows to probe more distand, more absorbed, lower luminosity, regions of the LX-NH-z plane 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.

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: data AREA 0.6 deg2 (:0.5h, :-43.5o) IMAGING BVRIz (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 with VIMOS and FORS2@VLT Total~1500 Zs (R<24.5) (K, 3.6um and 24um sources) Catalogue of ~1700 24m sources with F24 > 0.280 mJy Redshift for 384 sources with R<24.2

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: SED templates fitting Red Power Law ~AGN1 (SED:1-6) Adapted from Polletta et al. (2007) ULIRG/Starburst (SED: 7-9) Seyfert2/AGN2 (SED:10-13) Spirals Star Forming (SED:14-20) Ellipticals (SED:21)

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Method: SED templates fitting (see Polletta et al. 2007) 1st choice 2nd choice 3rd choice AGN2 AGN1 χ2 best fit analysis Normal Normal SED

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 20% 43% 34% 3% Local relationship un-absorbed AGN What is the fraction/density of (possibly absorbed) AGN among these high MIR/O sources? 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 spectra 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 spectra TOTAL: 384 spectra 40% AGN2 (& AGN1) 60% ELG 56 spectra What about their SED? 82% of SED-PWL are optical AGN 93% of SED-ULIRG are optical ELG SED-Seyfert2: no preferences

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field X-ray stacking analysys of faint (R>22) high MIR/O sources X-ray detections and stacking (filled symbols) STACKED DATA 82% of OPT-AGN are X-ray absorbed AGN 85% of OPT-ELG are mildly X-ray absorbed with L2-10~1041-42 MID TERM SUMMARY: SED-PWL --> optical AGN(2) --> X-ray absorbed AGN SED-ULIRG --> optical ELG --> mildly absorbed low LX

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SED classification of high MIR/O sources Spec. and phot. redshifts Spec. and phot. redshifts 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 The sources with F24/FR>120 have z>0.6 and LogL24>44

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 strong star-forming galaxies

73% of large MIR/O (F24/R>120) sources Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field SOFT 0.3-1.5 keV HARD 1.5-6 keV R>25 SED-SEY2 SED-Red PWL X-ray properties of high MIR/O sources X-ray detections and stacking (filled symbols) 73% of large MIR/O (F24/R>120) sources are absorbed AGN What are their densities?…

Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Density of X-ray absorbed large MIR/O sources LogNH~22.3 LogNH~23.1 The density is compatible with the extrapolations coming from previous estimates at z~1 of the XLF of Compton thin AGN

? Looking for absorbed AGN in the XMM/SWIRE/ELAIS-S1 field Density of X-ray absorbed large MIR/O sources ~1x10-15@2Ms ? We have probed a one decade less luminous region at z~1 or a 0.7 larger redshift at LogL2-10~42.5

SUMMARY We have carried out optical spectroscopic identification of 56 sources with F24/R>120 and R<24.2. - The fraction of optically 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 XLF of Compton thin AGN.