Infrared spectroscopy of NGC 1068:
Probing the obscured ionizing AGN continuum
T. Alexander,
D. Lutz, E. Sturm, R. Genzel,
A. Sternberg, H. Netzer
Abstract:
The ISO-SWS 2.5-45µm infrared spectroscopic observations
of the nucleus of the Seyfert 2 galaxy NGC (see companion paper) are
combined with a compilation of UV to IR narrow emission line data to determine
the spectral energy distribution (SED) of the obscured extreme-UV continuum
that photoionizes the narrow line emitting gas in the active galactic nucleus.
We search a large grid of gas cloud models and SEDs for the combination that
best reproduces the observed line fluxes and NLR geometry. Our best fit model
reproduces the observed line fluxes to better than a factor of 2 on average
and is in general agreement with the observed NLR geometry.
It has two gas components
that are consistent with a clumpy distribution of dense outflowing gas in the
center and a more extended distribution of less dense and more clumpy gas
farther
out that has no net outflow. The best fit SED has a deep trough
at ~4
Ryd, which is consistent with an intrinsic Big Blue Bump that is partially
absorbed
by ~6×1019 cm-2 of neutral
hydrogen interior to the NLR.
Keywords: galaxies: individual (NGC 1068) -- galaxies:
Seyfert
Status:Status: ApJ accepted
Address: mailto:
tal@sns.ias.edu
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