The farUV break in quasar SEDs, dust

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The far-UV break in quasar SEDs, dust?
Luc Binette Sinhue Haro-Corzo Yair Krongold Anja
Andersen
Note the text accompanying this talk can be
found at astro-ph/0611011
Xian, October 2006
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correcting for intergalactic gas

• Telfer, Zheng , Kriss et al. derived a composite
  SED using 332 HST-FOS spectra of 183 quasars
• they corrected for the Lyman valley
• each spectrum was divided by the appropriate
  Transmission function
• comparison with SLOAN confirms strategy
  coincidence of the discontinuities with position
  of Ly? and Ly?

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problem composite SED too soft

• Korista et al. 1997 showed the difficulty of
  reproducing HeII, NV and CIV equivalent widths
  assuming a soft SED, similar to the Telfer
  composite
• photoionization models nowadays use a much harder
  SED
• SEDs that peak beyond 20eV

• analysis of X-ray and EUV spectra of 11
  individual quasars revealed that the soft X-ray
  excess does not correspond to an extrapolation of
  the far-UV powerlaw
• Haro-Corzo et al. (submitted)

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X-ray far-UV connection

• far-UV does not extrapolate smoothly into X-rays
• Haro-Corzo et al. (submitted)
• see poster 338

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principal
Eastman, MacAlpine, Richstone (1983)
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conclusions

• intrinsic crystalline C dust, promising
• polarization vs lambda
• should model scattering using transfer code
• René Goosmann
• optical reddening
• SMC-like dust?
• universal SED?
• Sinhue Haro Corzo et al. (submitted)
• atomic gas absorption
• in process (Ton 34)
• infrared re-emission
• rules out meteoritic flavor
• in progress Anja Andersen
• accretion disk photosphere
• accretion disk code needed
• accelerated outflow?
• speculative but tantalizing

GOAL to unmask the accretion disk (ionizing) SED
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1- extragalactic HI absorption (WHIM)
Binette et al. 2003, ApJ 590, 58
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A-intergalactic dust
Binette et al. 2005, ApJ 631, 661
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3- problem of accretion disk SED

• accretion disks predict break near Lyman limit
• but does not quite fit observed break of
  composite SED
• SED too soft to account for high ionization
  emission lines

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4-accelerated outflow

• see Eastman, MacAlpine Richstone (1983)
• gas condensations accelerated up to 0.8 c
• model should be modified
• need to blueshift break by 0.1c
• must produce a recovery in far-UV

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B- crystalline carbon dust grains

• Shang et al. (2005) explored SMC-like and ISM
  dust
• such dust does NOT fit UV break
• crystalline carbon grains
• extinction has sharp peak in the far-UV
• can fit UV break
• found in stellar disk
• formation processes
• nucleation of organic ice mixtures by UV
  photolysis (Kouchi et al. 2005)
• UV conversion of PAH clusters (Duley Grishko
  2001).

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fits UV break in individual quasar spectra

• example PG1148459
• assumes curve D3
• cubic nanodiamond grains only
• size distr. (a?3.5)
• range 3?200 Å
• Haro-Corzo et al. (submitted)

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examples of quasars consistent with an E-UV
recovery at 18.5 eV (670Å)

• extinction predicts a flux recovery in the
  extreme UV

1008
0232
1307
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Ton 34 extremely UV deficient

• Telfers sample, UV break 1100Å
• 2 spectral indices
• lt?NUVgt ?? ?0.7
• lt?FUVgt ?? ?1.7
• Ton 34
• extreme UV break
• ?NUV?0.3
• ?FUV?5.3 (TZ02)

línea ?FUV ?NUV
CB
disk
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big blue bump
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components encountered in quasar SEDs
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ton34 ngc5548

• HST-STIS
• (Crenshaw et al. 2003)
• warm absorber
• N(H)5 1020 cm-2
• T few 104 K