CIV RM OF RADIO-LOUD BROAD ABSORPTION LINE QUASARS

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					    RM OF RADIO-LOUD BROAD ABSORPTION LINE QUASARS
                                                     G. Bruni, K.-H. Mack, E. Salerno
                                                         IRA-INAF, Università di Bologna




                                    What are Broad Absorption Line (BAL) QSOs?
                                     ●   Broad absorption towards the blue wing of
                                                                                                                    How many?
                                     some UV emission lines, shifted up to ~ 0.2 c
                                                                                                                          ~15 %
                                                                                                                of the QSO population
                                                 ●   Absorption most probably intrinsic
                                                 ●   Al III, Mg II, Si IV, CIV
                            CIV                  ●   HiBALs (highly ionized species)                      How many radio loud?
                                                 ●   LoBALs (lowly ionized species)
                                                                                                                           ~15 %
                                                 ●   FeLoBALs (LoBALs + iron features)
                                                                                                            of the BAL QSO population



Models:
                                              BAL cloud
Current models try to explain the BAL
phenomenon through an orientative
scheme      (Elvis,  2000)      or   an       Inner jet
evolutionary scheme (Briggs et al.
1984, Becker et al. 2000). In the first
one, BALs are produced by an
accretion disk outflow, only when it
intercepts the observer's line of sight.
The second one includes these
objects in the framework of young or                       (Punsly, 1999)                                           (Elvis, 2000)
refueled QSOs, still expelling their
dust cocoon while transforming in
normal QSOs. A third model proposed              Radio – wavelength campaign:
by Punsly (1999) introduces a polar
outflow, present in a first evolutionary
                                                 ● Complete sample of 31 RL BAL QSOs + 31 comparison QSOs
phase, when non-magnetic vortices
                                                 ● Multi-frequency radio observations from 1.4 to 43 GHz (Effelsberg + VLA)
                                                 ● Continuum + polarisation
are present around the central black
hole.


Results:                                                                     BAL QSOs
● All unresolved at the VLA (<8 Kpc)
● ~ 50% Gigahertz peaked
● ~ 80% steep (between 10 and 22 GHz)

● Same polarisation as normal quasars

● Probably a particular orientation is present (only

~50% steep sources in comparison sample)                                   Comparison QSOs

RM values:
● Rotation Measures spread in a wide interval of values, from
Galactic (-34.08 rad/m2) to the second highest ever found
(-18350 rad/m2 – Benn et al. 2005).

● Except this one, values are similar for the comparison
sample.
                                                                                                                                              Bruni et al.
●We have embarked on a project to test whether such high                                                                                       (in prep.)

RMs are common in BAL QSOs or whether 1624+37 is a
peculiar object.                                                       References:                                  Acknowledgements:
                                                                       ●
                                                                         Becker at al., 2000, ApJ, 538, 72          This project is partly supported by
●RM is an important probe to test the AGN environment in BAL           ●
                                                                         Benn C.R. et al., 2005, MNRAS, 360, 1455   the European Union's Framework
QSOs. These values suggest that probably no particular                 ●
                                                                         Briggs et al., 1984, ApJ, 287, 549         Programme 7, Advanced Radio
physical conditions are present in these objects, so this can be
                                                                       ●
                                                                         Bruni et al., (in prep.)                   Astronomy     in    Europe,    grant
                                                                       ●
                                                                         Elvis M., 2000, ApJ, 545, 63               agreement no. 227290
another indication towards the orientative model.                      ●
                                                                         Punsly B., 1999, ApJ, 527, 624

				
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