Mass Outflow in the Seyfert 1 Galaxy NGC 4151

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X-ray Grating Spectroscopy
X-ray Grating Spectroscopy of AGN
Mike Crenshaw Georgia State University

• Broad-band view
• X-ray spectral components
• Soft X-ray excess
• X-ray NLR
• X-ray warm absorber
• Fe K? (broad and narrow)
• The need for higher spectral resolution/sensitivit
  y

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Schematic Continuum SED for AGN
(hot dust)
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Components of X-ray Emission
Thermal component (or something else?)
Reflection of coronal X-rays by cold disk
Compton upscattering of disk photons by hot corona
(Fabian, 2006, AN, 327, 943)
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Soft X-ray Excess
XMM PNMOS
(Crummy, et al. 2006, MNRAS, 365, 1067)

• Seyfert 1s and quasars show a soft X-ray excess
  below 1 keV after subtraction of ? 1.7 ? 2.2
  power-law.
• Previously explained by a thermal component
  (e.g., low-temperature Comptonization of
  accretion disk photons).

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• But the excess has a fixed temperature (0.2
  keV), suggesting an atomic rather than continuum
  origin (Done Nayakshin, 2007, MNRAS, 377, L59)
• Relativistically broadened (blurred) emission
  lines from accretion-disk reflection (Crummy, et
  al. 2006).
• High-velocity outflows of ionized gas absorbing
  the 0.7 - 3 keV range (Done Nayakshin, 2007
  Chevallier, et al. 2006, AA, 449, 493).

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Narrow X-ray Emission Lines

• Another soft-excess contributor narrow X-ray
  emission lines
• ? Need high-resolution grating
  spectra to see their effect

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• Narrow radiative recombination continua (RRC)
  give temperatures of ? 10 eV ? photoionization
  dominates over collisional ionization (Guainazzi
  Bianchi, 2007, MNRAS, 374, 1290).
• In nearby Seyferts with obscured (NGC 1068) or
  temporarily faint (NGC 4151) central engines, the
  majority of the soft X-ray emission comes from an
  extended region roughly coincident with the NLR

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• In addition to photoionization, photo-excitation
  (resonance scattering) plays an important role in
  producing the observed emission lines.
• Turbulence can enhance this effect and boost
  resonance (r) lines, relative to intercombination
  (i) and forbidden lines in He-like triplets
  (Armentrout, et al. 2007, ApJ, astro/ph 0705.0628
  - see his poster)

Three-Component photoionization model for NGC
4151
Size lt 940 pc lt 0.9 pc lt 0.05

• Low is the extended X-ray NLR.
• Medium and High similar to the warm-absorber
  components in NGC 4151
• ( Kraemer et al. 2005, ApJ, 633, 693).
• ? A significant fraction of the X-ray emission
  lines comes from warm absorbers.

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X-ray Warm Absorbers
(George, et al. 1998, ApJS, 114, 73)

• ASCA detected O VII and O VIII absorption edges
  in 50 of Seyferts
• Seyferts with X-ray absorbers also have
  blueshifted UV absorption (Crenshaw et al. 1999,
  ApJ, 516, 750).
• Blueshifted absorption lines seen by Chandra and
  XMM confirm mass outflow (Kaspi et al. 2002, ApJ,
  574, 643).

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(Gabel, et al. 2003, ApJ, 583, 178)

• Similar velocity coverage for X-ray absorbers and
  multiple UV components.
• Mass outflow rates are comparable to accretion
  rates ( 0.01 M?/yr ).
• Do X-ray absorbers separate into multiple narrow
  components, or are they more like winds?

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Absorption Variability in X-rays
NGC 4151
(Kraemer et al. 2005, ApJ, 633, 693)

• X-ray absorption primarily from broad UV
  component at vr -500 km s-1.
• Deeper absorption in 2000 due to lower ionizing
  flux and larger NH.
• From variability, UV constraints absorber is at
  0.1pc with vT ? 2100 km s-1 (for a specific
  kinematic model, see Crenshaw Kraemer, 2007,
  ApJ, 659, 250).

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Hot Absorbers?

• Several studies find evidence for very
  highly-ionized absorbers, with U 10 - 100
  (Risaliti et al. 2005, ApJ, 630, L129).
• These hot absorbers tend to have large columns
  (NH ? 1023 cm-2), and could dominate the mass
  outflow rates, depending on their locations.

NGC 1365 Fe XXV and FeXXVI K? and K?
absorption at -5000 and -1000 km s-1 (Risaliti et
al. 2005)
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Relativistic Outflows?

• Two broad absorption-line (BAL) quasars show
  outflows of highly-ionized gas with vr up to
  0.4c (Chartas, et al. 2007, AJ, 133, 1349).
• Narrow-line outflows up to 0.2c have been
  claimed for a few non-BAL quasars (e.g., Pounds
  et al. 2006, 372, 1275), although this is more
  controversial (see McKernan et al. 2004, ApJ,
  617, 232 Kaspi Behar, 2006, ApJ, 636, 674).

Most of the high velocity/high ionization results
are from non-grating observations.
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Fe K? Emission
(Fabian, 2006, The X-ray Universe 2005, p. 463)

• Narrow component seen in many AGN -
  reflection from BLR, NLR, or torus
• Broad component fit with relativistic accretion
  disk model, velocity up to 0.4c
• Rest-frame line center at 6.4 keV - consistent
  with emission from cold disk.

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Broad Fe K? - Accretion Disk Models
Ultimate goal fit profile to get the black hole
spin (a) and accretion disk inclination
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Complications

• Strong narrow Fe K? contaminates the broad
  component.
• Grating observations are important for
  deconvolution.
• Broad Fe K? is often weak or absent (Reeves,
  2003, ASP, 290, 35).
• A systematic XMM study indicates broad Fe K?
  likely present in 75 of the Seyfert 1s studied
  (Nandra et al. 2006, 327, 1039).
• However, highly ionized absorption can mimic
  broad Fe K?
• Fe L-shell absorption on the left, Fe K
  edge/absorption lines on the right (Reeves et al.
  2004, ApJ, 602, 648 Turner et al. 2005, ApJ,
  618, 155).
• Once again, grating observations at high S/N
  would be helpful.
• Limited coverage at high energies makes it
  difficult to define the reflection component and
  therefore the continuum
• Suzaku observations are helpful.

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Suzaku Observations
MCG-6-30-15
XIS
HXD

• Broad Fe K? claimed in 6 of 7 Compton-thin
  Seyfert galaxies
• (Reeves et al. 2006, AN, 327, 1097)

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Transient, Narrow, and Moving
NGC 3516
(Turner et al. 2002, ApJ, 574, L123)
(Iwasawa et al. 2004, MNRAS, 355, 1073)

• NGC 3516 shows transient, narrow Fe K? emission
  (Turner et al. 2002).
• Fe K? periodically moves in energy between 5.7
  and 6.5 keV over 25 ks.
• Co-rotating flare model r 6 ? 17 rg, M 1 ?
  5 x 107 M? (Iwasawa et al. 2004)
• Mrk 766 also shows moving narrow lines with a
  period of 165 ks (Turner et al. 2006, AA,445,
  59).
• Fe K? and continuum flux are correlated,
  indicating reflection from accretion disk at
  several AU from the SMBH (Miller et al. 2006,
  AA, 453, L13).

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The End
OR, REALLY, JUST THE BEGINNING