X-ray X-ray spectroscopy spectroscopy of bright AGNof bright AGN

GiorgioGiorgio Matt & Stefano BianchiMatt & Stefano Bianchi (Dipartimento di Fisica, Università Roma Tre)(Dipartimento di Fisica, Università Roma Tre)

Bright AGNBright AGNWith bright AGN I mean sources with enough

photons to allow for a decent spectral analysis in the 0.2-4 (0.1-6) keV energy range

About 60000 AGN with more than

5000 counts (0.5-2 keV) will be detected by

WFXTWFXT

Population studies over very wide ranges Population studies over very wide ranges of the main parameters will be possibleof the main parameters will be possible

Optical coverage (SLOAN, etc) of the same fields will provide parameters like the mass of the BH

Some open problems (which can Some open problems (which can be addressed by WFXT)be addressed by WFXT)

• The nature of the soft X-ray emission in unobscured sources

• The properties of the warm absorber beyond the local Universe

• The IT effect at high z (>1) and L

The nature of the soft excessThe nature of the soft excess

The soft X-ray excess was first discovered in the EXOSAT spectrum of Mkn 841 (Arnaud et al. 1985).

The thermal discinterpretation of the

soft excess has problems: the derived temperatures are too high and always the

same (T M-1/4).

WFXTWFXT will stretch considerably the range of masses

probed. Its soft X-ray band will be

also very useful.

Mkn 841 (Petrucci et al.

2007)

The warm absorber beyind the The warm absorber beyind the LULU

Evidence for warm absorption in 50% of Seyferts.Usually outflowing (v ~ hundreds km/s).

Location, mass and energetics largely unknown.Dependence of ξ on L, Z, BH mass ??? WFXTWFXT !!

Blustin et al. 2005

The IT effect The IT effect

log(EWFe)=(1.73±0.03) + (-0.17±0.03) log(LX,44)

Bianchi et al. 2007

The Iwasawa-Taniguchi (a.k.a. X-ray Baldwin) effect is the anticorrelation between the EW of the iron line

(narrow core) and the X-ray luminosity (first discovered by Iwasawa & Taniguchi 1993)

The IT effect The IT effect The IT effect may be due to a decrease with L of the

covering factorof the reflecting matter (a similar effect has been found

by Maiolino et al. 2007 using infrared data). log(EWFe)=(1.73±0.03) + (-0.17±0.03) log(LX,44)

Bianchi et al. 2007

The IT effect The IT effect

Bianchi et al. 2007

log(EWFe)=(1.61±0.05) + (-0.19±0.05) log(Lbol/Edd)

The anti-correlation of the EW with the Eddington ratio

is highly significant

The IT effect The IT effect

log(EWFe)=(1.73±0.04) + (-0.07±0.04) log(LBH,8)

No significant dependence of the iron EW on the BH mass is instead found

The IT effect The IT effect

This effect is not well known at high luminosities

and it is probed only in the local Universe.

WFXT can expand enormously the range of L and of z probed.

Of course, the local Universe is forbidden…

Waiting for WFXT… where we Waiting for WFXT… where we are noware now

The XMM-Newton Bright Serendipitous Survey(Della Ceca et al. 2004; Caccianiga et al. 2008):

Flux-limited sample (~7x10-14 erg/s/cm2 in the 0.5-4.5 keV energy range)

400 sources (80% AGN)

X-ray selectionX-ray selection! Elusive AGN, etc.

Caccianiga et al. 2007

Type 2

Type 1

Waiting for WFXT… where we Waiting for WFXT… where we are noware now

CAIXA (Catalogue of AGN In the XMM-Newton

Archive) is a catalogue of pointed XMM observations of AGN in the public archive

up to March 2007 (Bianchi et al. 2009)

To be included in CAIXA, a source must have at

least 200 (0.5-2 keV) + 200 (2-10 keV) counts

In practice, most sources have more than a thousand counts.

Biased towards well-known sources. Undefined selection.

CAIXACAIXAA Catalogue of AGN in the XMM-A Catalogue of AGN in the XMM-Newton Newton ArchiveArchive

156 sources

All radio-quiet AGN in targeted XMM-Newton pn observations:

>200 counts in either of the (rest-frame) bands of 0.5-2 and 2-10 keV<1% pileup

log(R)<1 (quasar) – log(R)<2.4 and log(RX)<-2.755

(Seyfert)NH<2x1022 cm-2

6 and 20 cm fluxes (~100% of the catalog)Hβ FWHM (64% of the catalog): only from BLR

(<2000 km/s -> narrow-line objects)BH mass (52% of the mass)

Luminosity dependent bolometric correction (Marconi et al. 2004)

Bianchi et al. 2009Bianchi et al. 2009

Gen

era

l p

rop

ert

ies

Gen

era

l p

rop

ert

ies

<log(Lbol/LEdd)>≈-0.8

90 % with z<1

Sy

QSO

Powerlaw indexPowerlaw index

The average 2-10 keV spectral index for the whole catalogue is

1.73±0.04, with a large spread of σ = 0.45±0.03

Γ steeper in quasars (1.80±0.05, consistent with PG quasars:

Piconcelli et al., 2005) than in Seyferts (1.66±0.05). A Kolmogorov-

Smirnov test yields that the two populations are different at the 99%

level

The difference is even larger if we The difference is even larger if we consider narrow-line objects consider narrow-line objects

(1.94±0.07) with respect to broad-(1.94±0.07) with respect to broad-line objects (1.62±0.04). In this case, line objects (1.62±0.04). In this case,

a K-S test gives a NHP of 2x10a K-S test gives a NHP of 2x10-5-5

It is important to stress here that the photon indexes in CAIXA, in principle, are not the intrinsic ones, because we do not include a Compton

reflectionIt is possible that the different photon indexes found for different

populations in CAIXA do not only (or at all) reflect differences in the intrinsic Γ of the sources, but also in the amount of Compton reflection

BLS1

NLS1

Soft excessSoft excess

Hβ FWHM is correlated with the hard X-ray luminosity and anti-correlated with the ratio between the optical V and the X-ray fluxObjects with narrow-lines seems to be X-ray weaker than broad-

line objects

Soft excessSoft excess

If we replace the second power law with a thermal model, the soft excess in unobscured radio-quiet AGN is

characterized by a temperature which is constant across the range of luminosities and BH masses,

as already shown by several authors (Gierlinski & Done 2004; Crummy et al. 2006)

123 out of 156 sources need a second and steeper powerlaw to model the soft X-ray

emission

Correlations with BH massCorrelations with BH massThe strong correlation

between the X-ray luminosity

and the BH mass has a slope

flatter than 1, suggesting that high-luminosity

objects may be X-ray weak

A luminosity dependent bolometric

factor could explain this

result, but the one proposed by Marconi (2004) leads to a more-

than-linear relation

Interestingly, a linear

relation is recovered

using a bolometric correction based on

mdot (Vasudevan & Fabian 2008) or using the

radio luminosity

The iron linesThe iron lines The average EW of the neutral

(narrow) Kα iron line is around 80 eV, as expected

for Type 1 objects.

And, as said And, as said before, we before, we

confirmed the confirmed the IT effect!IT effect!

We do not find different

rates of detection for ionised iron

lines for narrow- and broad-line

objects

The iron linesThe iron linesBoth the Fe XXV and Fe XXVI lines are detected in 24 sourcesTheir EWs and the ratios between them are consistent with a

production in distant matter photoionised by the AGN, with large ionization parameters and large column densities (up to 1023 cm-2

for Fe XXV, larger for FeXXVI)

We cannot exclude a contribution from an ionised accretion disc for the larger EWs

ConclusionsConclusions

Thanks to XMM-NewtonXMM-Newton we have a decent idea of the X-

ray average properties of (unobscured) AGN in the Local

Universe.

WFXTWFXT will extend this to high luminosities and redshifts