1. Observations and Physical Parameters Leah Simon Feb. 3, 2006
AGN OUTFLOWS
Observations and Physical Parameters
Leah Simon
Feb. 3, 2006

2. Absorption: Types
Unassociated/Associated: Redshift relative to quasar emission lines
Intrinsic/Extrinsic: Ejected from Quasar or part of host galaxy OR external to quasar
Broad Absorption Lines(BALs)/Narrow Absorption Lines(NALs) (mini-BALs): line widths FWHM
Outflows come from Intrinsic Lines of all types
Outflows occur in ~ 50% of all quasars!

3. Quasar Spectrum
Rodriguez-Hidalgo, private communication

4. BALs
V (FWHM)> 3000 km/s
Redshifts from quasar up ~0.2c -> winds!
HiBALS: high ionizations species
CIV, NV, SiIV
LoBALS: low ionization species
CII, MgII,

5. NALs V spread (FWHM)< 100-200 km/s CIV doublet resolvable
V shift < 5000 km/s -> associated (probably part of quasar/host)

7. Intrinsic Absorption: Strong Indicators
BALs
Large velocity widths
Within ~60,000km/s of quasar redshift
Variability: timescales of ~year(s)
Caused by continuum source variability affecting photoionized clouds
Or caused by cloud (outflow) motion across LOS
Partial coverage
Continuum source is small!
Cloud must be nearby if some continuum source can pass around cloud to our eye

8. Variability
Rodriguez-Hidalgo, private communication

9. Partial Coverage
Barlow, Hamann, Sargent, 1997

10. Partial Coverage Cont.
Hamann, Sabra, 2004

11. Intrinsic Absorption: Weaker Indicators
Chemical signatures
Fine structure lines place density limits -> intrinsic systems (probably) have higher densities
Requires low ionizations – not observed often
High Ionization and/or Metallicity - N(NV)/N(HI)
Line profiles: broad and smooth
Statistics: over-density of low-z (w/respect to quasar) NALs implies these are intrinsic
Properties observed in intrinsic NALs appear correlated with quasar properties (radio loudness, L etc.

12. Physical Parameters of Outflows
Column density ~1022 – 1025 cm-3
Velocity: 0 < v < 0.2c
Mass loss rate roughly correlated with line strengths
Mass loss due
to line driving:
Physical scale: calculate small region, however variability not observed on short enough time scales (~months) – something else is at work
Abundances and ionization levels

13. Uncertainties in Interpretation
Orientation Angle
Possibly degenerate with age+evolution
Needed to understand physical environment of QSO!
Age + Evolution
Shorter lifetimes allow a mixture of ages, evolutionary states at any given redshift
Lifetimes
Duty Cycle?
Shielding/self shielding Uinner nγ/n ~ 5 – 10
Set such that gas at inner edge of wind is at ionizations low enough to be pushed by UV flux (Murray + Chiang, 1995)

14. Acceleration Mechanisms
Radiation Pressure (Photoionization)
Line Driving – momentum from radiation field through line opacity
Expect vtransverse = small
Require very high L/LEdd
Thermal Pressure (Parker Wind)
Not strong enough
Requires Isothermal wind...
Magnetic Pressure (Magnetocentrifugal Driving)
'Beads on a string'
See John Everett (CITA)

15. Comparison to BH accretion
Probably Mdotoutflow ~ Mdotaccretion
Mass loss rate from accretion : Lacc= η Mdot c2
Mass loss rate in winds:
Very uncertain!

16. References
1)T.A. Barlow, F. Hamann, W.L.W. Sargent, astro-ph/
2)D.M. Crenshaw, S.B. Kraemer, I.M. George, ARAA, 41:117
3)F. Hamann, B. Sabra, 2003 astro-ph/
4)N. Murray, J. Chiang, 1995 ApJ 454: L105
5)N. Murray, J. Chiang, S.A. Grossman, G.M. Voit, ApJ 451: 498
6)D. Proga, J.M. Stone, T.R. Kallman, 2000 ApJ 543: 686
7)M. Urry, P. Padovani, 1995 PASP 107:803
8)R.J. Weymann, R.F. Carswell, M.G. Smith, ARAA, 19:41