SWIRE Science: Investigating the Active and Passive Universe on Large Scales Alberto Franceschini Padova University "SWIRE Science Team Meeting" IPAC, December 17-19, 2001

The SWIRE view on the Active Universe: AGN Contribution to the Infrared and X-ray Backgrounds [weighing the stellar vs. gravitational energy budget]

Summary The CIRB, recent results, comparison with XRB Ultimate energy sources for the BKGs: stellar emission and gravitational energy Physical properties of the CIRB sources: AGN vs. SB The X-ray diagnostics: deep IR/X-ray surveys Testing the origin of the XRB Prospects for SWIRE

The Global Background Radiation

COBE Discovery of the Cosmic Infrared Background (CIRB) (Puget et al. 1996; Hauser et al. 1998) λ=100 μ

The Infrared and Optical Background Radiations COBE HST  (IR)=40 nW/m  sr  (opt)=17 nW/m  sr

ULTIMATE ENERGY SOURCES XRB => mostly gravitational CIRB => mostly stellar? A solid limit: mass in local Massive Dark Objects (MDO's): M MDO ~ M * (M * : mass in spheroids Kormendy & Richstone ) How much energy out of this? η stellar ~10 -3, ε AGN ~0.5 ( limit) L AGN ~ ε/η L star ~ L star However : η stellar ~ (1-5) 10 -3, ε AGN ~ ( ), M MDO ~ (2-5) M * (Magorrian et al.)

A) 99% of the gravitational energy might be undetectable in X-rays because absorbed and re-radiated in the IR ~50% or more of the CIRB might be due to AGNs Relevant for the history of stellar formation (SF) B) XRB peak at 30 keV Compton-thick emission, implies that the 1-10 keV range covered by CHANDRA & XMM might not be appropriate at all to sample accretion processes Long-λ background critical for rather fundamental issues of cosmology: history of barion transformations in stars AGN unification, obscured quasar populations

M82 broad-band spectrum Log( ) [  ] Log L( ) (erg/s) Similarities of the CIRB/OPT. spectral shape and the typical StarBurst spectrum

SCUBA 850  survey of the CFRS 1415h field (Eales et al. 2000) 6.9x6.4 arcmin 19 sources above 3.5 mJy

LW3 z= Typical source spectra K-corrections LW3 15  LW2 6.7 

(Fadda et al. 2000)

15  differential counts (Euclidean normalized) by Elbaz et al. (1999) Contribution of faint ISO sources to the diffuse mid-IR background light

HDF-North image overlayed by the ISOCAM LW3 15  contours by Aussel et al arcmin

ISOCAM 15 μ image overlayed to the FORS2/VLT R-band image on the FIRBACK UDS field 2.7 arcmin

Evolution of the comoving luminosity density (Franceschini et al. 2001) Optical & X-ray AGNs UV-optical galaxies IR-starbursts

Correlations of the MIR and FIR fluxes => the global IR spectrum (Elbaz et al. 2001)

Bolometric luminosities of the faint ISO sources => only 30% are ULIRGs (L bol >10 12 L o )

The faint sources detected by ISO at 15  are responsible for the bulk of the CIRB background

ISO : tentative way to resolve the CIRB Appropriate z (z ~ 1) Easyly identified sources Good sampling of the part of the LF making the CIRB Large samples available Well-known z-distributions

First characterization of the CIRB sources LOW-RESOLUTION ISAAC OBSERVATIONS OF Ha+NII (Rigopoulou et al. 2000)

To summarize: 18 galaxies observed with H= H  detected in 15 (low-res) SFR(H  ) = 10 M/yr SFR(FIR) = 100 M/yr

HDF- South source 27 M= M o (H o = 60 Km/s) d=36 kpc HST I-band image

X-ray, IR and optical diagnosis of AGN vs. Starburst emission (Bassani et al. 2000)

X-ray vs. mm vs. optical (maps of A1835 and A2390) X-ray: CHANDRA optical: I-band mm: SCUBA 850  scale: 10 arcsec (Fabian et al. 2000) CHANDRA SCUBA

Severgnini et al. (2000) => Sub-mm and X-ray emissions as two unrelated penomena

Modelling the IR SEDs of AGNs Radiative transfer modelling

IR spectra of a typical AGN (NGC 1068) with those of typical starbursts (M82, Arp220, Arp 244) and a mixed AGN/SB (NGC 6240) Elbaz et al. (2002)

NGC 1068 [Floch et al. 2001] [ISO CVF]

Entirely different spectral shapes for galaxies and Active Galactic Nuclei in the Mid-Infrared

Granato, Danese, Franceschini (1997) IR SEDs of Active Galactic Nuclei Models based on radiative transfer solutions

M82 IR spectrum fitted by AGN model

Image at 15 μ by ISO of the Lockman Hole (Fadda et al. (2001) Large square: shallow survey (0.7x0.7 deg.), small square: deep survey (20x20 arcmin) Inset: overlay of ISO and XMM (circle) on an I image

The problem of the origin of the flux: starburst or AGN ?

CHANDRA observation of the Hubble Deep Field North Brandt et al. (2001) (see Mushotzky et al. 2000, Hornschemeier et al ) S > (erg/cm 2 /s)

ISO & CHANDRA sources in the HDFN (Fadda et al. 2001)

Cross-correlation between ISO and CHANDRA in the HDFN

A JOINT ISO/XMM Deep Investigation in the Lockman Hole

XMM image by Hasinger et al. (2001) ISO image by Fadda et al. (2001)

IR and X-ray dapths in the Lockman and HDFN

STATISTICS ON ISO/XMM SOURCES IN THE LOCKMAN HOLE

X-ray vs. IR flux diagnostics

High X-ray luminosities =>>> they are type-II QSO

X-ray to IR spectral index as a function of the X-ray flux

AGN contribution to the CIRB: the ISO guess (<20%)

Contribution of ISO galaxies to the CIRB IGL 15 : contribution to CIRB in W/m 2 /sr at λ= 15 μ IGL 140 : contribution to CIRB in W/m 2 /sr at λ=140 μ R: ratio of νS ν at 140 and 15 μ C CIRB 140 = 25(+/-7) W/m 2 /sr at λ= 140 μ

New AGN statistics based on the mid-IR selection Assuming that unclassified X-ray sources are type-2 (supported by these data): – 7 AGN type-1 – 12 AGN type-2

Franceschini et al. (2001) ISO & XMM sources in common in the Lockman Hole area: type-II QSO originating the XRB

X-ray luminosity vs. optical color X-ray hardness ratio vs. optical color

Hardness-ratio HR=[H-S]/H+S] HR3: H=4.5-10, S=2-4.5 keV HR2: H=2-4.5, S= keV

Tests of the XRB synthesis model: a) bolometric luminosities of type-I vs. type-II objs. b) fractions of type-I vs. type-II

X-ray emissivity properties of faint ISO sources => 10% of sources show "AGN-type" X-ray activity

IR-selected AGNs ISO sources Where do the IR-selected AGNs contribute to the XRB? (cnt.)

The SIRTF "SWIRE" Survey SIRTF Wide-area IR Extragalactic Survey, Legacy Programme (C. Lonsdale and 18 co-investigators) ~ 70 square degree using all SIRTF photometric bands

A new AGN/Starburst diagnostic tool: the ISO LW3(15μ)/LW2(6.7μ) flux ratio AGN Starbursts

SWIRE Survey Fields Target RA Dec  100μ BKG E(B-V) Area(sq.deg.) XMM-LSS Chandra-S < Lockman Hole < Lonsdale Hole < ELAIS S < ELAIS N < ELAIS N <

CONCLUSIONS The CIRB background contains essential information not only on the history of SF, but also on the hystory of gas accretion, including obscured QSO phases Most of the XRB and CIRB now resolved into sources => combined X/IR info No clear-cut diagnostics for AGN/SB discrimination, two phenomena intimately connected and concomitant Only combined multi-λ approach may give answer with some confidence Preliminarly: XRB : gravitational energy CIRB : mostly stellar energy SWIRE: essential contribution to the investigation of hidden phases of gravitational accretion, by exploiting the large survey area, which is essential to detect substantial samples of type-II AGNs [NB: our ISO/XMM survey in Lockman detected only 14 type-II's over 220 sq.arcmin]