SWIRE Science:Investigating the Active

and Passive Universe on Large Scales

Alberto FranceschiniPadova 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/msr (opt)=17 nW/msr

ULTIMATE ENERGY SOURCES

XRB => mostly gravitationalCIRB => mostly stellar?

A solid limit: mass in local Massive Dark Objects (MDO's):

MMDO ~ 2 10-3 M* (M* : mass in spheroids Kormendy & Richstone)

How much energy out of this?

ηstellar~10-3 , εAGN~0.5 (limit)

LAGN ~ 2 10-3 ε/η Lstar ~ Lstar

However: ηstellar~ (1-5) 10-3 , εAGN~ (0.1-0.5) , MMDO ~ (2-5) 10-3 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

M82broad-bandspectrum

Log() []

Log L() (erg/s)

Similarities of the CIRB/OPT. spectral shape and the typical StarBurst spectrum

SCUBA 850 survey of theCFRS 1415h field

(Eales et al. 2000)

6.9x6.4 arcmin19 sources above 3.5 mJy

LW3z=0

0.5

1

1.5

2

Typical sourcespectra

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 imageoverlayed by theISOCAM LW315 contours byAussel et al. 1999

2 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 (Lbol>1012 Lo)

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=19-22.5

•H detected in 15 (low-res)

•SFR(H) = 10 M/yr

•SFR(FIR) = 100 M/yr

HDF- South source 27M=3 1012 Mo (Ho = 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 CHANDRA SCUBA

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

Modelling the IR SEDsof 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 NucleiModels 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. 2000)

S0.5-2>5 10-17

(erg/cm2/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

IGL15: contribution to CIRB in W/m2/sr at λ= 15 μIGL140: contribution to CIRB in W/m2/sr at λ=140 μR: ratio of νSν at 140 and 15 μ

CCIRB140 = 25(+/-7) W/m2/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= 0.5-2 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.)

Table A-2: Expected SWIRE Performance:Noise and Sensitivity Estimates

Wavelength Cirrusnoise,1 #

(1 MJy/sr at100 m)

Extragalactic *Confusionnoise, 1

SWIREphotometricsensitivity,1

3.6 m 18 nJy 40 nJy 1.4 Jy4.5m 40 nJy 150 nJy 1.9 Jy5.8 m 60 nJy 150 nJy 5.5 Jy8.0 m 300 nJy 1 Jy 6.5 Jy24m 2.0 Jy 85 Jy 0.09 mJy70m 0.1 mJy 37 mJy 0.55 mJy160m 2.0 mJy 36 mJy 3.5 mJy # model of Gautier * derived fromFranceschini model confusion distribution

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 02 26 -04 30 -18 1.1 0.35 10Chandra-S 03 45 -30 -48 < 0.4 0.12 5Lockman Hole 10 40 57 +44 < 0.4 0.10 15Lonsdale Hole 15 10 56 +68 < 0.4 0.20 10ELAIS S1 00 35 -43 28 -43 < 0.4 0.12 15ELAIS N1 16 09 56 27 +74 < 0.4 0.10 10ELAIS N2 16 37 41 16 +62 < 0.4 0.11 5--------------------------------------------------------------------------------------

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 energyCIRB : 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]