The Variable UV

1
The Variable UV Intrinsic Absorption of Mrk 279
Jennifer E. Scott NRC/NASA/GSFC
N. Arav, J. Gabel (CASA/CU) G.
Kriss, J. Kim Quijano (STScI)
2
Mrk 279 Observations Summary
Date Instrument ksec
1999 Dec FUSE 61
2000 Jan FUSE 30
2002 Jan FUSE 37
2002 May FUSE 47
2002 May STIS/E140M 13
2002 May CXO/HETGS 114
2003 May FUSE 91
2003 May STIS/E140M 41
2003 May CXO/LETGS 340
Two sets of coordinated observations

• How do changes in emission components impact
  absorption profiles?
• Photoionization
• Effective Covering fraction
• (lines vs .continuum, or ILR vs. BLR )

3
Continuum Variability
Flux
Dec. 1999
May 2003
Jan. 2000
Jan., May 2002
Spectral index
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Mrk 279

• Seyfert 1 galaxy z0.0305
• Five velocity components of UV absorption
• Most likely intrinsic absorption -300 lt voutlt
  -200 km/s

Scott et al. 2004, Gabel et al. 2005
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Absorption Profile with Multiple Emission Sources
Each source i (continuum, BLR, etc.) contributes
Ri to total flux at pixel j
Effective covering fraction is a weighted sum of
individual covering fractions
Gabel et al. 2005, Scott et al. 2004
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Change in Lyman alpha absorption profile can be
explained by change in relative contribution of
continuum and BLR
No change in covering fraction or column density
necessary
Gabel et al. 2005
7
Global CNO Fits to 2003 Spectra
Gabel et al. 2005
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Relative contribution of emission lines is larger
in 2002 low flux state
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• Can changes in O VI, N V, and C IV be explained
  in a similar way?
• Use well-constrained 2003 covering fractions,
  column densities
• Try to reproduce 2002 profiles by
• Allowing the covering fraction of the
  intermediate line region (ILR) to be different
  from that of the BLR. (See emission profiles
  below)
• (2) Vary the column densities according to
  changes in the ionizing flux (photoionization
  models)

10
Relative contributions of ILR and BLR change with
continuum level
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Relative contributions of ILR and BLR change with
continuum level
12
Relative contributions of ILR and BLR change with
continuum level
13
Photoionization Models Spectral Energy
Distributions
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Photoionization Models 2002/2003 Column Density
Ratios
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O VI Compare 2002 profiles to variations on
2003 Cc, CBLR, N solutions
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N V Compare 2002 profiles to variations on
2003 Cc, CBLR, N solutions
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C IV Compare 2002 profiles to variations on
2003 Cc, CBLR, N solutions
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• For -300 lt vout lt -200 km/s absorption
• 2002 (low state) vs. 2003 (high state)
• O VI CILR 0, saturation -gt N(O VI)
  unconstrained
• N V
• CILR 0.5 CBLR, same N(N V) -or-
• 0 lt CILR lt 0.5 CBLR, larger N(N V) in 2002 vs.
  2003
• C IV
• C ILR C BLR, same N(C IV) -or-
• 0.5 CBLRlt C ILR lt C BLR, larger N(C IV) in 2002
  vs. 2003
• Problem with C III?

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Expect the column density to vary by a factor of
up to 1000 for observed changes in ionizing
flux. However, profile changes little,
particularly over -300 lt vout lt -200 km/s