AGN OUTFLOWS

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AGN OUTFLOWS

• Observations and Physical Parameters
• Leah Simon
• Feb. 3, 2006

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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!

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Quasar Spectrum
Rodriguez-Hidalgo, private communication
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BALs

• V (FWHM)gt 3000 km/s
• Redshifts from quasar up 0.2c -gt winds!
• HiBALS high ionizations species
• CIV, NV, SiIV
• LoBALS low ionization species
• CII, MgII,

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NALs

• V spread (FWHM)lt 100-200 km/s
• CIV doublet resolvable
• V shift lt 5000 km/s -gt associated (probably part
  of quasar/host)

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Intrinsic AbsorptionStrong 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

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Variability
Rodriguez-Hidalgo, private communication
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Partial Coverage
Barlow, Hamann, Sargent, 1997
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Partial Coverage Cont.
Hamann, Sabra, 2004
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Intrinsic Absorption Weaker Indicators

• Chemical signatures
• Fine structure lines place density limits -gt
  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.

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Physical Parameters of Outflows

• Column density 1022 1025 cm-3
• Velocity 0 lt v lt 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

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Uncertainties in Interpretation

• Orientation Angle
• Possibly degenerate with ageevolution
• 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 n?/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)

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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)

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Comparison to BH accretion

• Probably Mdotoutflow Mdotaccretion
• Mass loss rate from accretion Lacc ? Mdot c2
• Mass loss rate in winds
• Very uncertain!

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References

• 1)T.A. Barlow, F. Hamann, W.L.W. Sargent, 1997
  astro-ph/9705048
• 2)D.M. Crenshaw, S.B. Kraemer, I.M. George, 2003
  ARAA, 41117
• 3)F. Hamann, B. Sabra, 2003 astro-ph/0310668
• 4)N. Murray, J. Chiang, 1995 ApJ 454 L105
• 5)N. Murray, J. Chiang, S.A. Grossman, G.M. Voit,
  1995 ApJ 451 498
• 6)D. Proga, J.M. Stone, T.R. Kallman, 2000 ApJ
  543 686
• 7)M. Urry, P. Padovani, 1995 PASP 107803
• 8)R.J. Weymann, R.F. Carswell, M.G. Smith, 1981
  ARAA, 1941