Intrinsic Absorption in Quasars: BALs & NALs

1. Intrinsic Absorption in Quasars:BALs & NALs Jonathan Trump February 11, 2007

2. Quasar Absorption Lines • Intrinsic • Caused by material in the AGN engine itself • Host • From gas in the host galaxy • Intervening • From an intervening galaxy This all has nothing to do with Type 2 AGN: we’re talking about absorption lines by diffuse gas, not global obscuration of the BLR by lots of dust!

3. Why Should We Care? • Dynamics • Mechanism for losing angular momentum? • Accretion disk as power source for winds • Effects on host? • Composition • Densities • Abundances • Unified Model • Evolution? Orientation?

4. Broad Absorption Line Quasars from Trump et al. 2006

5. Broad Absorption Line Quasars • Broadabsorption • Typically >1000 km/s • Up to ~20,000 km/s • Blueshifted from emission line • Typically few thousand km/s (~0.01c) • Up to ~60,000 km/s (0.2c) • Outflowing gas “wind” • High velocity dispersion • High velocity

6. The Zoo of BAL types from Reichard et al. 2003

7. Broad Absorption Line Quasars • High-Ionization BALs • CIV 1550 Å, also SiIV, NV, Lyα • ~15% of quasars • Low-Ionization BALs • MgII 2800 Å, also Al II, Al III • ~1-2% of quasars • FeLoBALs • FeII or FeIII (widespread) • <0.1% of quasars • Rarer objects: absorption in He, Balmer lines…

8. FeLoBALs (they’re weird) from Trump et al. 2006

9. FeLoBALs (they’re weird) from Hall et al. 2007 For more about FeLoBALs, see Hall et al. 2002, ApJ, 141, 267

10. [ ] ( ) 25000 km/s ò - 1 f v C ' dv 0 km/s Characterizing BALs • Balnicity Index (BI) • Weymann et al. 1991 • Limits width, min/max blueshift, depth • Absorption Index (AI) • Hall et al. 2002 • Less limiting than BI, includes mini-BALs • Characterization limited by S/N of spectra • BALQSOs are red, and LoBALs are redder • BALQSO fraction • Underestimated by all surveys: fainter, redder, obscured in X-rays • Typically saturated, but with partial coverage

11. What Causes BALs? • Evolution • Young quasars in a dusty cocoon • Especially considered for LoBALs • Orientation • Disk-driven wind in all quasars • Only visible in BALs because of orientation • Supporting evidence: Increased trough velocity with luminosity (Trump et al. 2006) • See models by Murray & Chiang 1998, Proga et al. 2000, etc.

12. from Elvis 2000

13. BALQSOs in Radio • LBQS (Weymann et al. 1991): surprising lack of radio-loud BALQSOs • SDSS (Reichard et al. 2003): same findings… • 10% of quasars are radio-loud, but only a few percent of BALQSOs are radio-loud • Supports orientation

14. BALQSOs in X-rays • From Brandt et al. 2000 • More UV absorption -> weaker in soft X-rays

15. BALQSOs in X-rays weaker X-rays -> harder spectrum Absorbed in soft X-rays only Gallagher et al. 2006

16. BALQSOs in IR • If BALQSOs are in a dusty cocoon, we’d expect stronger IR emission • Not the case! • Spitzer survey of Gallagher et al. 2007 find similar properties to normal QSOs • Occasionally, some narrow absorption in IR

17. BALs from Orientation Different absorption mechanisms originate at different scales from the central engine from Gallagher & Everett 2007

18. Narrow Absorption Lines from Wise et al. 2004 from Narayanan et al. 2004

19. Narrow Absorption Lines • In >20% of all quasars (Wise et al. 2004), but hard to ID because of S/N & host/intervening lines • Variability • Variable on the order of ~1 yr • Implies scales of <100 pc from the central source • > Intrinsic! • Really, the only way to determine intrinsic from host/intervening… but time-consuming

20. BALs & NALs: In Summary • BALs: big, broad, blueshifted absorption • High velocities & velocity dispersions require AGN engine • NALs: narrow, blueshifted absorption • High velocities & variability require AGN engine • Typically weaker in X-rays, radio • Mid-IR “normal” • Probably caused by orientation • Disk-driven winds • But LoBALs are tougher to explain…

21. BALs from Orientation from Gallagher & Everett 2007