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AGN9, Ferrara 24-27 Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna A RADIO APPROACH TO BROAD ABSORPTION LINE QUASARS Gabriele Bruni (IRA-INAF, Univ.

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Presentation on theme: "AGN9, Ferrara 24-27 Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna A RADIO APPROACH TO BROAD ABSORPTION LINE QUASARS Gabriele Bruni (IRA-INAF, Univ."— Presentation transcript:

1 AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna A RADIO APPROACH TO BROAD ABSORPTION LINE QUASARS Gabriele Bruni (IRA-INAF, Univ. Bologna) K.-H. Mack (IRA-INAF) E. Salerno (IRA-INAF) ACTIVE GALACTIC NUCLEI IX 'Black holes and revelations' Ferrara Maggio 2010

2 Broad absorption towards the blue wing of some UV emission lines, shifted up to ~ 0.2 c CIV SiIV Most probably intrinsic HiBALs, LoBALs, FeLoBALs. How many? ~ 15 % Al III, Mg II, Si IV, C IV AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

3 BAL QSOs vs normal QSOs X-Rays: Emission intrinsically similar, BAL QSOs more absorbed (Green et al. 2001, Gallagher et al. 2007) Sub-mm, mm: No differences (Lewis et al. 2003, Willott et al. 2003, Priddey et al. 2007) Mid-IR: Similar properties (Gallagher et al. 2007) Optical: BALs more reddened, more highly polarized, UV absorption (Goodrich 1997, Krolik & Voit 1998) AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

4 Unification scheme of AGN AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

5 Explanations for the BAL phenomenon Elvis (2000) Orientation Scenario: AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

6 Explanations for the BAL phenomenon Orientation Scenario: PRO: Naturally explains why BAL/non-BAL QSOs are so similar Explains higher reddening/obscuration in BAL QSOs CONTRA: Explains higher polarisation (optical band) via resonant scattering Variety of radio spectral indices (Becker et al. 2000, Montenegro-Montes et al. 2008) Found both edge-on (FR II) and polar (strongly beamed) BAL QSOs (e.g., Gregg et al. 2006, Zhou et al. 2006) AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

7 Young or recently refueled quasars Explanations for the BAL phenomenon Evolutionary Scenario: PRO: Anticorrelation between radio-loudness and the BAL phenomenon (Gregg et al. 2006) Radio BAL QSOs are compact sources like CSS/GPS (Montenegro-Montes et al. 2008) CONTRA: Same cold and warm dust properties of BAL/non-BAL QSOs (Becker et al Gregg et al. 2000, Kunert-Bajraszewska & Marecki, 2007 – Willott et al. 2004) AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

8 Cross-over model (Punsly, 1999) Explanations for the BAL phenomenon Inner jet BAL cloud AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

9 Explanations for the BAL phenomenon Cross-over model: PRO: Naturally explains why BAL/non-BAL QSOs are so similar Explains higher reddening/obscuration in BAL QSOs Explain the anticorrelation between radio-loudness and the BAL phenomenon (Gregg et al. 2006) CONTRA: Same cold and warm dust properties of BAL/non-BAL QSOs (Becker et al Gregg et al. 2000, Kunert-Bajraszewska & Marecki, 2007 – Willott et al. 2004) Radio emission is an additional investigation tool! Radio Loud BAL Quasar AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

10 Pilot sample of 15 RL BALs (S 1.4 >15 mJy) Quite compact, ~ 50 mas ~ 1 kpc On average weakly polarised Convex-peaked spectra (some double-components) Weak variability Same α distribution on non-BAL QSOs (pro evolutionary scenario) Consistent with anticorrelation ν vs. LS peak (Montenegro-Montes PhD thesis) VLA (74 MHz – 43 GHz), Effelsberg (2 – 10 GHz), IRAM (NIR), VLBA (5 GHz, 8 GHz) AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

11 AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna Variability study Radio flux density variability can be used to constrain jet orientation since it can be interpreted as a sign of beaming jets oriented within a few degrees from the line of sight. No significant flux density variation occurred in these sources on time scales of at least 4 years (E. Salerno et al. in preparation) The sample was observed at several frequencies between 1.4 and 22 GHz Measurements of the flux densities were repeatedly performed between 2005 and Collected values were also compared with data available from literature.

12 New sample of 31 RL BALs + 31 comparison QSOs (S 1.4 >30 mJy) Radio continuum & polarisation (Effelsberg, IRAM, JCMT, VLA, WSRT, GMRT) Morphology & orientation (EVN, VLBA, global VLBI) polarisation: particle density & magnetic fields (Effelsberg, VLA) H I absorption & CO lines: gas component in the central engine environment (GMRT, WSRT, IRAM) Optical band: 36 nights at La Palma observatories in Ionization parameters and distance of the BAL region from the center (data still to be reduced...) Which is the right model? AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

13 Radio continuum & polarisation Effelsberg 100-m dish Very Large Array Observations during 2007, 2008, 2009 Polarisation and continuum at 2.6, 4.8, 8.3, 10.4 GHz 31 RL BALs + 31 comparison QSOs Observations performed in July 2009 (~40 hours) Polarisation and continuum at 1.38, 4.8, 8.4, 22, 43 GHz 31 RL BALs + 31 comparison QSOs AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

14 GMRT Observations in January 2010 Continuum at 244 & 610 MHz 6 brightest BALs of the sample Radio continuum & polarisation AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

15 Data reduction and analysis Fit of the spectra with an analytical function (Orienti et al. 2009) Determination of the peak frequency Evidence of low frequency components Both for comparison and BAL sample AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

16 Results Spectral characteristics Peak frequency of the synchrotron emission Spectral index 50% GPS, 50% low frequency flat, steep BALs ? AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

17 Results Polarimetry Polarisation percentage Rotation Measure Bruni et al. (in prep.) ~ 1-10%Similar to comparison Values similar to comparison BALs Comparisons AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

18 Conclusions BALs are all 43 GHz (VLA - C config.): Linear Size < 8 Kpc No particular orientation, only steep-spectrum majority Both GPS and low frequency peaked, old components in some cases Not extremely young radio jet No variability The most probable model is the Elvis one (but it must account for both steep and flat sources) Outflow must be present only in a short phase (15% of QSOs are BALs) AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

19 From VLBI data Future Work Morphology study Additional orientation study Magnetic field orientation Synchrotron ageing Old components VLA+Eff.+GMRT data AGN9, Ferrara Maggio 2010 Gabriele Bruni – IRA INAF, Univ. Bologna

20 ...Thank you!


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