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					          VLBI Observations of
          Nearby Radio Loud AGNs

                    Gabriele Giovannini
         Dipartimento di Astronomia, Bologna University
              Istituto di Radioastronomia - INAF

In collaboration with: E. Liuzzo – PhD Bologna Univ. + IRA - INAF
                      M. Giroletti – IRA - INAF Bologna
                      G.B. Taylor - UNM Albuquerque USA
              The Bologna Complete Sample
B2 and 3CR radio sources with z < 0.1

Being selected at low frequency it is not affected by
observational biases related to orientation effects.

Nearby sources: good linear resolution; high + low power

VLBI data are available for 78/95 sources
(arcsecond core > 5 mJy)

  The large scale morphology of observed sources is:
  50 FR I
  15 FR II
  12 compact sources:Bl_Lacs, CSO, CSS, flat spectrum
   1 Spiral
Two-sided sources on the pc scale are 30 % to be compared with
11% in PR sample and 4.6 % in the Caltech-Jodrell Bank survey

In a random oriented sample the probability that a source is
at an angle between θ1 and θ2 with respect to the line of sight is

           P(θ1,θ2) = cos(θ1) – cos(θ2)

the percentage of FR I + FR II is 65/78 = 80% corresponding to
θ > 35o-40o in agreement with unified models.

The percentage of two-sided sources is 30% corresponding to
angles > 70o.

Consistent with a j/cj ratio R ≤ 5 if jet velocity = 0.9 – 0.99c
-All FR II two-sided are NLR.

-Two-sided sources show low power radio cores.

- In most sources there is a good agreement between the pc-kpc
  scale jet orientation in agreement with the suggestion that
  large distortions seen in BL-Lac and BLAZAR sources are due
  to small intrinsic bends amplified by projection effects

-In all sources pc scale jets move at high velocity.
 No correlation has been found with core or total radio power
   3C192 z = 0.0597     arcsecond core: 8 mJy at 5 GHz

                                 VLBI phase reference mode
                                 Peak: 1.7 mJy/b
                                 noise: 0.05 mJy/b

   VLA B+C at 1.4 GHz
                                          10 pc
LS 200 kpc
3C 452 a NL FR II radio galaxy

                                 0331+39 a low power compact
                                 radio galaxy
    3C 338 a FR I radio galaxy
Sources with a faint radio core:
                            more complex structures

-- restarted activity
-- different orientation angle between pc and
   kpc structure
-- complex pc scale structure with no dominant core

A statistical problem or we are starting to study
sources with different properties?

Different ambient medium (e.g. galaxy cluster)
Is it important?

                                               10 pc

                            VLBI 20 cm
                            Phase ref. Mode
5 pc
                            Peak 24 mJy/b
                            Noise 0.07 mJy/b
       VLBI 6cm
VLBA 6 cm – phase ref. mode

                    Spectral index image between 6 and 20 cm
                    with VLBA
                                                     3C 310 VLA B+C
                                                     Linear size  300 kpc

                                        1.4 GHz
1.7 GHz
        In agreement with Gizani and
        Garrett (2002) 6th EVN Symp.

5 GHz

                5 pc                   Peak flux 1.3 mJy/b
                                       Noise 0.07 mJy/b
                       Jamrozy et al.


                      25 kpc

                                                Van Breugel et al. 1986
                                                VLA A+B at 20cm

100Myr                                  0836+29B 4C29.30
Jamrozy et al. 2007                     A galaxy merger
  Core – most compact
  only flat spectrum component

104 yrs

                                  1 kpc

          VLA – A array at 6 cm


                                          15 yrs

                              5 pc
                      1 kpc
                               70 yrs

Strong outburst after 1990

Jamrozy et al. 2007
3C 293
• The parsec scale jet morphology is the same in high (FR II) and
  low (FR I) power sources

• The pc scale morphology is in agreement with expectations
  from unified models

• There is a good agreement between the pc and kpc scale

• The pc scale jet velocity is highly relativistic in FR II and FR I
  sources. It is not related to the total or core radio power of the
  source. No correlation with the kpc scale structure.
• In some sources with a low power nuclear source we find a
  peculiar morphology: restarted activity and a complex mas scale
  structure not yet understood, misaligned with the kpc scale

• In a few sources a large symmetric Z shaped distortion occurs.
   Since these sources are oriented near to the plane of the sky, the
   distortion it is not amplified by projection effect.
   It could be due to the jet interaction with a rotating disk (3C 293).

Other possible environmental effects could be at work. In the future
we plan to consider also the host galaxy environment as traced by
X-ray emission, atomic or molecular absorption/emission.

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