ACCRETION AND JET POWERS IN NEARBY UNOBSCURED RADIO GALAXIES

1. ACCRETION AND JET POWERS IN NEARBY UNOBSCURED RADIO GALAXIES E. Trussoni(1),S. Vattakunnel(2), A. Capetti (1) (1)INAF - Osservatorio Astrofisico di Torino (2)INAF - Osservatorio Astronomico di Trieste ------------------------------------------- - 1 - A correlation has been found between the accretion and jet powers in a sample of unobscured radio galaxies (FR I and nearby low luminosity objects) showing a flattening of the optical brightness profiles in their central regions (core galaxies). The fraction of accreting power converted into kinetic energy is almost constant over 5 decades. We present the results of a similar analysis for a small sample of radio quiet objects showing a cusped power law inner brightness profile. In particular we discuss the possible correlation between the accretion and jet powers exploiting the multifrequency data available for these objects. The different properties of the core and power law samples are shortly discussed.

2. 1 - Accretiononto SMBH plays a fundamentalrole in powering AGN 2 - In radio loud AGN the energeticpowerismainly in relativisticjets 3 - The accreting material may originate eitherfrom a thicktorus (obscured objects) or from the InterGalactic Medium (IGM, unobscuredobjects) 4 - Thereis a connection between the structureof the parentgalaxy and the nuclearactivity  Wewilldiscussthesetwomainpoints: A - Whatis the relationshipbetween the accretionpowerPaand the jet powerPj in AGN ? Can the accretion alone support the jet power ? B - Thereis some relation betweenPa and Pj,and the structureof the parent galaxy ? Weconsiderunobscuredobjectswithaccretionfrom the IGM - 2 -

3. Earlytypegalaxiesharbouringunobscured AGN belongtotwodifferentclassesdepending on theiropticalbrightnessprofiles(1-5) CoreSersicGalaxies (CSG) The inneropticalprofileisflat Radio loudFig.1a X-rayemitters Major mergings in the past PowerLawCuspedGalaxies (PCG) The inneropticalprofileiscusped Radio quiet or silent X-rayemitters Minor mergings in the pastFig. 1b - 3 -

4. Accretion Power Pa Bondi model(6) for a spherical and steady accretion from the IGM Pa nB M2BH TB-3/2 MBH :mass of the SMBH, from the MBH - scorrelation nB,TB :density and temperature at the Bondi radius rB , deducedfrom the X-ray properties of the IGM Jet PowerPj a - Forbrightobjects and/or goodenough data, deducedfrom the cavitiesinflatedby the jets, detected in X-raymaps(7) b - Forweakerobjects and/or poor data, deducedexploiting the relation betwenPj and the radio luminosityLr(8) PJLr0.7 - 4 -

5. In these last years has been confirmed that the accretion and jet powers areconnected. Inparticular the following strict correlation between Pa and Pj has been found for a sample of 27CSG (Fig. 2)(7,9,10), extracted from the sample studied in (1): Log Pa = 1.1Log Pj – 1.9 This implies: - Almost a linear dependence: Pa Pj - Pj0.02Pa  The jet power can be supported by accretion from the IGM ~ Fig. 2 Does a similarcorrelationholdalsoforPSG ? Does the innerstructureof the parentGalaxy, and then itsevolution, affect the Pa – Pjcorrelation? - 5 -

6. Totest thispointwereferredto the sample ofPCGanalyzed in (2): out the 23objectsofthat sample onlyfor9galaxiesChandraX-ray data weregoodenoughfor a reasonable estimate ofPa In theseobjects the X-rayemissionfrom the IGM isquiteweakwith no evidentcavities in the Chandramaps Accordingly, insteadto deduce Pjfrom the radio emissionwehaveconsidered the radio luminosityasdirect estimate of the jet powerconsidering the correlation(7) Lr Pj In the followingpagewe plot Lrvs Pa (Fig. 3) for the twosamples and report the resultsof the statisticalanalysiswherehaveconsidered the propertiesof the CSG and PCGseparately and as a mergedsinlge sample - 6 -

7. CSG(27objects):Log Pa = 1.45Log Lr + 35.5; Pr = 1.1 x 10-3 rms = 0.94 CSG + PCG (36objects):Log Pa = 1.41Log Lr + 35.4; Pr < 10-4 rms = 0.93 PCG (9objects): Pr= 0.51 Pr:Probability of no correl. Fig. 3 For the CGS and CGS + PCGsamples the samecorrelationbasicallyholds butwithquite a largescatterof the data AnycorrelationisfoundforPCG alone - 7 -

8. As further test we have searched possible correlations with Pa of the core X-ray luminosities LX (Fig. 4) CSG:Log Pa = 1.52Log LX + 36.7;Pr = 1.6 x 10-3,rms = 0.73 CSG + PCG:Log Pa = 1.18Log LX + 37.8; Pr = 0.008, rms = 0.92 PCG:Pr = 0.87 Fig. 4 For CGS and PCG the results for LX and Lr vs Pa are very similar Discrepancy for the merged sample: the correlation between of LX and Pahas a steeper slope X-ray excess for the PCG - 8 -

9. Summary • The correlation Pa- Lrholds independently if we consider the CSG + PCG • sample or CSG alone, while no correlation emerges for PCG only • The low number of PCG (9) does not allow a definitive univocal • interpretation of our results (it is worth reminding however that in (7)a • strict connection Pa - Pj was found for a sample of only 9CSG, even • though with better data) • A reasonable conclusion is that the conversion process of accretion • power into jet kinetic energy is likely different in PGC and CSG. • On the other hand the few PCG have probably a small statistical weight • on the correlation of the CGS when they are included in the sample • - The correlation Pa– LX holds for CSG with the same slope as for Pa - • Lr, confirming that in these objects the emission at high and low • frequencies are related to the relativistic jet • - 9 -

10. - This correlation is modified for the CSG +PCG sample. This is the • consequence of the X-ray excess inPCG: we see in Figs. 3 and 4 • that they have LX < 1042 erg/s (as for GSC) and at radio frequencies • Lr < 3x1038 erg/s • - Again no correlation is found considering onlyPGS, confirming that the • accretion - jet relationship is different in the two classes of galaxies • - As main implication, while in CSG the accreting power is mainly • converted into jet power, which emits at various frequencies, in PCG • a relevant fraction is directly converted in X-ray emission (e.g. • through the accretion disk) • From the above arguments there are strong clues to argue that • the different evolution of these two classes of unobscured galaxies • play a relevant role in ruling the energetic processes between the • accretion and jets • - 10 -

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