ULIRGs: ULIRGs: IR-Optical-X-ray IR-Optical-X-ray

propertiesproperties Valentina Braito

ULIRGs: ULIRGs: IR-Optical-X-ray propertiesIR-Optical-X-ray properties

• Results from XMM observations of 10 ULIRGs

• Searching possible multi wavelength diagnostics

• Results on L band observations

(P.I. Risaliti)

ULIRGs are a class of sources with ULIRGs are a class of sources with

LLIRIR>10>101212LL comparable to QSO luminosities.comparable to QSO luminosities.

BackgroundBackground

ULIULIRRGs are predominantly powered by Gs are predominantly powered by heavily heavily ddust enshrouded AGN or ust enshrouded AGN or

circumnuclear starburstscircumnuclear starbursts??ULIRGs classification strongly depends on the ULIRGs classification strongly depends on the

energy bandenergy band Starburst dominated ULIRGs revealing an obscured AGN when observed in the X-rays (i.e. NGC6240)

With this survey all the ULIRGs of Genzel sample With this survey all the ULIRGs of Genzel sample (complete at F(complete at F6060mm>5.4 Jy and L>5.4 Jy and LFIRFIR~10~101212LL ) )

will have X-ray datawill have X-ray data

AGN activity is present in 1/3 of the observed

sources

AGN-ULIRGs have hard X-ray luminosity lower than

typical QSO luminosity

We found 2 ULIRG with high X-ray luminosity &

deeply absorbed (Superantennae; Mkr231)

SB-ULIRGs have LX(2-10 keV) 1041-1042ergs/s

Main goals characterize the hard X-ray Main goals characterize the hard X-ray continuum continuum

investigate the presence of AGN investigate the presence of AGN activityactivity

Thermal emissionabsorbed power law (AGN) ~1.7-2or a flat power law (X-ray binaries)

E1-e-E/Ec Ec=8 keV

X Ray Spectral propertiesX Ray Spectral properties

X-ray & FIR emission X-ray & FIR emission

No evident correlation between X-ray thermal and FIR luminosity

No evident difference between SB and AGN ULIRGs

Thermal vs FIR luminosity

X-ray AGN-ULIRGs

X-ray SB-ULIRGs

X-ray & FIR emissionX-ray & FIR emission2-10 keV luminosity vs FIR luminosity

AGNAGN

SBSBX-ray AGN-ULIRGs

X-ray SB-ULIRGs

Our results confirm that for ULIRGs without a dominant AGN component, the 2-10 keV

emission is a good SFR indicator (Persic et al. 2004).

Arp 299

Comparison with local SBs

SB-ULIRGs

The observed hard X-ray emission can be used to highlight AGNs in LIRGs

X-ray & FIR emissionX-ray & FIR emission

X-ray AGN-ULIRGs

X-ray SB-ULIRGs

Optical-IR-X-rayOptical-IR-X-ray

Work in progress…

AGN REGIONSB REGION

Compton-thin

Compton-thick

Results from L band Results from L band spectroscopyspectroscopy

The waveband coverage allows

to determine of the 3-4 m continuum level

a correct estimate of the PAH strength

Broad absorption feature at 3.4m indicative of heavily absorbed AGN

PAH at 3.3m with low EW typical of AGN dominated sources

IRAS 19254-7245

P.I. Guido Risaliti

see poster by Risaliti for all the spectra

A possible dignostic diagram A possible dignostic diagram

PAH EW vs LIR

Risaliti et al. in prep

PURE SB

AGN

Composite SB AGN

vs PAH EW

AGN-dominated

SB-dominated

Conclusion and futureConclusion and future

• LX(2-10) keV as a SFR indicator or to preselect AGN in IR sources

• the Fx/FIR vs FOIII /FIR diagram allows to select heavily absorbed AGN in composite sources like ULIRGs

• check the peculiar sources in this diagram

• complete the Genzel sample (IRAS22491-1808 and IRAS 20100-4156) in L band

• spectra of the 4-5 brightest ULIRGs at 4-5 m