Obscured AGN and XRB models

Obscured AGN and XRB modelsAndrea Comastri (INAF-OABologna-Andrea Comastri (INAF-OABologna-

Italy)Italy)Roberto Gilli (INAF-OABologna-Roberto Gilli (INAF-OABologna-Italy)Italy)

F. Fiore (INAF-OARoma-Italy)F. Fiore (INAF-OARoma-Italy)G. Hasinger (MPE-Garching- G. Hasinger (MPE-Garching- Germany)Germany)M. Brusa (MPE-Garching-M. Brusa (MPE-Garching-Germany)Germany)C. Vignali (Bologna University) C. Vignali (Bologna University) R. Della Ceca (INAF-OABrera-Italy)R. Della Ceca (INAF-OABrera-Italy)G. Malaguti (INAF-IASFBo-Italy) G. Malaguti (INAF-IASFBo-Italy)

SimbolX, May 15, 2007 2

Deep X-ray surveys have resolved some 80% of the XRB (below a few keV ) but “only” 50% > 6 keV and a few (1-2%) above 10 keV.

Wealth of X-ray and multiwavelength follow-up available -> possible to predict the missing population (Compton Thick AGN)

The missing population may provide an important contribution to the BH mass function SMBH/galaxy evolution, accretion rates, Eddington ratios, …

Deep X-ray surveys have resolved some 80% of the XRB (below a few keV ) but “only” 50% > 6 keV and a few (1-2%) above 10 keV.

Wealth of X-ray and multiwavelength follow-up available -> possible to predict the missing population (Compton Thick AGN)

The missing population may provide an important contribution to the BH mass function SMBH/galaxy evolution, accretion rates, Eddington ratios, …

SimbolX, May 15, 2007 3

SimbolX, May 15, 2007 4

Frontera+07Frontera+07astro-ph/0611228astro-ph/0611228

Model schemeModel scheme

• XRB flux “uncertain” , so use the more robust constraints below 10 keV (eg. source counts) to lock the properties (eg obs/unobs ratio, NH dist.) of the Compton Thin (log NH < 24) AGN

• Estimate the Compton Thin/Unobs. Ratio by comparing hard vs. soft XLF.

• Absorption distribution from X-ray counts.

• Include continuum slope dispersion.

• Add Compton thick AGN to fit the 30 keV bump

• Verify assumptions/make predictions on Compton Thick AGN

• XRB flux “uncertain” , so use the more robust constraints below 10 keV (eg. source counts) to lock the properties (eg obs/unobs ratio, NH dist.) of the Compton Thin (log NH < 24) AGN

• Estimate the Compton Thin/Unobs. Ratio by comparing hard vs. soft XLF.

• Absorption distribution from X-ray counts.

• Include continuum slope dispersion.

• Add Compton thick AGN to fit the 30 keV bump

• Verify assumptions/make predictions on Compton Thick AGN

SimbolX, May 15, 2007 6

Unabsorbed:logNH<21(plus Compton reflection) Compton-Thin:21<logNH<24

Compton-Thick:logNH>24

Mildly (log NH =24-25)(NGC 6240, Circinus)

Heavily (log NH >25)(NGC1068)

SimbolX, May 15, 2007 7

Best fit Best fit ratiosratios

~ 4 at low ~ 4 at low Log Lx < 44Log Lx < 44LuminositiesLuminosities

~ 1 at high~ 1 at highLog Lx > 44Log Lx > 44luminositiesluminosities

SimbolX, May 15, 2007 8

X-ray logN-logS

SimbolX, May 15, 2007 9

NH distribution

Thick

T h i n

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Radio loud AGN / Blazars contribute some 10% to the soft XRB (Galbiati et al 2004; Giommi et al 2006)

Normalizing to 1 keV for a range of slopes (0.5-0.7) a break or cut-off must be present around 1 MeV otherwise the soft-gamma-ray background would be exceeded

Radio loud AGN / Blazars contribute some 10% to the soft XRB (Galbiati et al 2004; Giommi et al 2006)

Normalizing to 1 keV for a range of slopes (0.5-0.7) a break or cut-off must be present around 1 MeV otherwise the soft-gamma-ray background would be exceeded

High energy cut-off 100-400 keV High energy cut-off 100-400 keV

SimbolX, May 15, 2007 11

hard X-ray surveys still miss the most obscured sources (do not sample the XRB peak)

Missing population: (numerous) moderate luminous, log NH > 23, z = 0.5-2 (Worsley+04,05, AC 04,05) and Compton Thick AGN (log NH > 24)

hard X-ray surveys still miss the most obscured sources (do not sample the XRB peak)

Missing population: (numerous) moderate luminous, log NH > 23, z = 0.5-2 (Worsley+04,05, AC 04,05) and Compton Thick AGN (log NH > 24)

Unresolved Background

AC 05 Worsley+05

SimbolX, May 15, 2007 12

70-75% of70-75% ofThe BeppoSAX/The BeppoSAX/

INTEGRALINTEGRAL10-40 keV10-40 keV

XRBXRBResolvedResolved

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Obscured AGN fraction vs sample limiting flux

ThickAll abs.

Expected Expected number of number of

sources per sources per SX fieldSX field

Gilli +07Gilli +07La Franca+05La Franca+05

Della Ceca Della Ceca

SimbolX, May 15, 2007 16

NGC5728 NGC5728

NGC4992 NGC4992

ScatteringScattering fraction ~ fraction ~ 2% 2%

Scattering fraction < Scattering fraction < 0.5 %0.5 %

See also See also Wilman et al. 2002Wilman et al. 2002

HyLIG HyLIG

SUZAKU OBSERVATION OFSUZAKU OBSERVATION OFMildly CT nearby galaxiesMildly CT nearby galaxies

AC+07 (astro-ph/0704.1253)AC+07 (astro-ph/0704.1253)

SimbolX, May 15, 2007 17

4 X4 X

Heavily Thick Heavily Thick

will not be well will not be well sampled by sampled by

deep hard X-raydeep hard X-raySurveys Surveys

SimbolX, May 15, 2007 19

Local Black Holes and AGN relics

Local Black Holes and AGN relics

Marconi et al. 2004 have shown that local BHs are relics of AGN activity by comparing:

the local BH mass function (from galaxy L/σ functions and MBH-Lbul/MBH-σe) the relic BHMF (from AGN luminosity function and continuity equation)

Importance of AGN LF: even

the hard (2-10 keV) XLF does not sample the whole AGN population.

Heavily obscured Compton-thick AGN are missing ...

Marconi et al. 2004 have shown that local BHs are relics of AGN activity by comparing:

the local BH mass function (from galaxy L/σ functions and MBH-Lbul/MBH-σe) the relic BHMF (from AGN luminosity function and continuity equation)

Importance of AGN LF: even

the hard (2-10 keV) XLF does not sample the whole AGN population.

Heavily obscured Compton-thick AGN are missing ...

Qso LF

Hard-X LF

Soft-X LF

SimbolX, May 15, 2007 20

Correction for Compton-Thick sources from XRB models wholeAGN pop considered

The only free parameters are the accretion efficiency and Eddington ratio

L = ε dM/dt c2

L = λ LEdd

Correction for Compton-Thick sources from XRB models wholeAGN pop considered

The only free parameters are the accretion efficiency and Eddington ratio

L = ε dM/dt c2

L = λ LEdd

SimbolX, May 15, 2007 21

Radiative Efficiency and Fraction of Eddington luminosity

Radiative Efficiency and Fraction of Eddington luminosity

Effect of changing scattering efficiency to compute pure reflection spectra of Compton-Thick sources

Effect of changing scattering efficiency to compute pure reflection spectra of Compton-Thick sources

2%

0.5%10%

Determine locus in ε-λ plane where there is the best match between local and relic BHMF!

ε=0.04-0.10 λ=0.08-0.5 which are consistent with common ‘beliefs’ on AGNs

Determine locus in ε-λ plane where there is the best match between local and relic BHMF!

ε=0.04-0.10 λ=0.08-0.5 which are consistent with common ‘beliefs’ on AGNs

CT space density degenerates with accretion efficiency and geometry of reflecting thick matter …

SimbolX, May 15, 2007 22

Obscured AGN and SMBH census:

observation strategies

Obscured AGN and SMBH census:

observation strategies1. A spectral survey of local CT Seyfert 2

galaxies previously discovered by BeppoSAX, INTEGRAL Swift and Suzaku. This should be accompanied by a volume limited survey of IR-bright or OIII-bright or … galaxies which have not shown strong X-ray emission below 10 keV, to search for highly CT objects.

2. A spectral survey of moderately obscured luminous QSOs discovered by XMM, Chandra up to z~1 (High luminosity)

3. Deep observations to search for faint mildly CT AGN + serendipitous survey (high redshift)

4. A survey of candidate CT AGN selected using their infrared emission (Spitzer/Herschel).

1. A spectral survey of local CT Seyfert 2 galaxies previously discovered by BeppoSAX, INTEGRAL Swift and Suzaku. This should be accompanied by a volume limited survey of IR-bright or OIII-bright or … galaxies which have not shown strong X-ray emission below 10 keV, to search for highly CT objects.

2. A spectral survey of moderately obscured luminous QSOs discovered by XMM, Chandra up to z~1 (High luminosity)

3. Deep observations to search for faint mildly CT AGN + serendipitous survey (high redshift)

4. A survey of candidate CT AGN selected using their infrared emission (Spitzer/Herschel).

SummarySummary A large fraction of the 10-40 keV XRB (2/3 - 3/4) will be resolved at a limiting flux of ~ 6 x 10-15 cgs

A major breaktrough is foreseen (compare with ROSAT and Chandra better than ASCA and BeppoSAX)

A large population of CT AGN (as large as Cthin ?) is waiting to be discovered by sensitive hard ( > 10 keV) X-ray observations

Statistically meaningful sample of the most obscured AGN over a broad range of fluxes and luminosities -> XLF and

evolution, SMBH assembly and distribution, geometry of obscuring/reflecting gas, …

A large fraction of the 10-40 keV XRB (2/3 - 3/4) will be resolved at a limiting flux of ~ 6 x 10-15 cgs

A major breaktrough is foreseen (compare with ROSAT and Chandra better than ASCA and BeppoSAX)

A large population of CT AGN (as large as Cthin ?) is waiting to be discovered by sensitive hard ( > 10 keV) X-ray observations

Statistically meaningful sample of the most obscured AGN over a broad range of fluxes and luminosities -> XLF and

evolution, SMBH assembly and distribution, geometry of obscuring/reflecting gas, …