Presentazione di PowerPoint

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 - Accretion onto SMBH plays a
fundamental role in powering AGN 2 - In
radio loud AGN the energetic power is mainly
in relativistic jets 3 - The accreting
material may originate either from a thick torus
(obscured objects) or from the
InterGalactic Medium (IGM, unobscured objects)
4 - There is a connection between the
structure of the parent galaxy and the
nuclear activity ? We will
discuss these two main points A - What is
the relationship between the accretion power Pa
and the jet power Pj in AGN ? Can
the accretion alone support the jet power ?
B - There is some relation between
Pa and Pj , and the structure of the parent
galaxy ? We consider
unobscured objects with accretion from the IGM

- 2 -
3
Early type galaxies harbouring unobscured AGN
belong to two different classes depending on
their optical brightness profiles (1-5) Core
Sersic Galaxies (CSG) The inner
optical profile is flat Radio loud

Fig.1a X-ray emitters Major
mergings in the past Power Law Cusped Galaxies
(PCG) The inner optical profile is cusped Radio
quiet or silent X-ray emitters
Minor mergings in the past
Fig. 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 - s
correlation nB ,TB
density and temperature at the Bondi radius rB ,
deduced from
the X-ray properties of the IGM
Jet Power Pj a -
For bright objects and/or good enough data,
deduced from the cavities inflated by the
jets, detected in X-ray maps (7) b - For
weaker objects and/or poor data, deduced
exploiting the relation betwen Pj and
the radio luminosity Lr (8)
PJ Lr0.7
- 4 -



5
In these last years has been confirmed that the
accretion and jet powers are connected. In
particular the following strict correlation
between Pa and Pj has been found for a sample of
27 CSG (Fig. 2) (7,9,10), extracted from the
sample studied in (1) Log Pa 1.1 Log Pj
1.9 This implies - Almost a linear
dependence Pa ?? Pj - Pj 0.02 Pa ?
The jet power can be
supported by accretion
from the IGM

Fig. 2
Does a similar correlation hold also for PSG ?
Does the inner structure of the parent Galaxy,
and then its evolution, affect the Pa
Pj correlation ?
- 5 -
6
To test this point we referred to the sample of
PCG analyzed in (2) out the 23 objects of that
sample only for 9 galaxies Chandra X-ray data
were good enough for a reasonable estimate of Pa
In these objects the X-ray emission from the
IGM is quite weak with no evident cavities in
the Chandra maps Accordingly, instead to deduce
Pj from the radio emission we have considered
the radio luminosity as direct estimate of the
jet power considering the correlation (7)
Lr ?? Pj In the
following page we plot Lr vs Pa (Fig. 3) for
the two samples and report the results of the
statistical analysis where have considered the
properties of the CSG and PCG separately and as a
merged sinlge sample
- 6 -
7
CSG (27 objects) Log Pa 1.45 Log Lr
35.5 Pr 1.1 x 10-3

rms 0.94 CSG
PCG (36 objects) Log Pa 1.41 Log Lr 35.4
Pr lt 10-4

rms 0.93 PCG (9 objects) Pr 0.51
Pr Probability of no correl.

Fig. 3
For the CGS and CGS PCG samples the same
correlation basically holds but with quite a
large scatter of the data Any correlation
is found for PCG 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
1.52 Log LX 36.7 Pr 1.6 x 10-3, rms 0.73
CSG PCG Log Pa 1.18 Log 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 Pa has
a steeper slope X-ray excess for the
PCG
- 8 -

9

• Summary
• The correlation Pa - Lr holds 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 9 CSG, 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

10

• - This correlation is modified for the CSG PCG
  sample. This is the
• consequence of the X-ray excess in PCG we
  see in Figs. 3 and 4
• that they have LX lt 1042 erg/s (as for GSC)
  and at radio frequencies
• Lr lt 3 x 1038 erg/s
• - Again no correlation is found considering only
  PGS, 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

11
References 1)
Balmaverde B., Capetti A. AA 447, 97 (2006)
2) Capetti A., Balmaverde B. AA 453, 27
(2006) 3) Capetti A., Balmaverde B AA
469, 75 (2007) 4) Pellegrini S. ApJ
717, 640 (2010) 5) Kharb P., et al. AJ
143, 78 (2012) 6) Bondi H. MNRAS 112, 195
(1952) 7) Allen S. W., et al. MNRAS
372, 21 (2006) 8) Heinz S., et al. ApJ 658,
L9 (2007) 9)
Balmaverde B., et al. AA 486, 119 (2008)
10) Vattakunnel S., et al. AA 522, 89
(2010)
- 11 -