BIB-VERSION:: AST-PP-v1.0
ID:: epreps.stsci//prep1215
ENTRY:: March 9, 1998
TITLE:: Jet Driven Motions in the Narrow Line Region of NGC 1068
SUBTITLE::
AUTHOR:: Axon, D.J. (1,2,3)
AUTHOR:: Marconi, A. (1,4,5)
AUTHOR:: Capetti, A. (6)
AUTHOR:: Macchetto, F.D. (1,2)
AUTHOR:: Schreier, E. (1)
AUTHOR:: Robinson, A. (7)
AFFIL:: (1) Space Telescope Science Institute 3700 San Martin Drive Baltimore, MD 21218, USA
AFFIL:: (2) Affiliated to the Astrophysics Division, Space Science Department, ESA
AFFIL:: (3) On leave from the University of Manchester
AFFIL:: (4) Dipartimento di Astronomia e Scienza dello Spazio Università di Firenze, Largo E. Fermi 5, I-50125, Italy
AFFIL:: (5) Osservatorio Astrofisico di Arcetri Largo E. Fermi 5, I-50125, Italy
AFFIL:: (6) Osservatorio Astronomico di Torino Strada Osservatorio 25 40025, Pino Torinese, Italy
AFFIL:: (7) Division of Physics and Astronomy, Department of Physical Sciences, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB,UK
DATE:: February 1998
JOURNAL:: To appear in: The Astrophysical Journal, Letters
SUBMITTED:: 5 August 1997
ACCEPTED:: 9 January 1998
OTHER_ACCESS::
COPYRIGHT:: Copyright 1998 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.
LANGUAGE:: English
ABSTRACT::
We have obtained HST FOC f/48 long-slit spectroscopy of the inner 4
arcseconds of the Narrow Line Region of NGC 1068 between
3500-5400Å with a spectral resolution of
1.78Å/pixel. At a spatial scale of 0."0287 per pixel these
data provide an order of magnitude improvement in resolution over
previous ground based spectra and allow us to trace the interaction
between the radio jet and the gas in the NLR. Our results show that,
within ± 0."5 of the radio-jet the emission lines are
kinematically disturbed and split into two components whose velocity
separation is 1500 km s-1.
The filaments
associated with the radio lobe also show a redshifted kinematic
disturbance of the order of 300 km s-1
which probably is a consequence of the expansion of the radio plasma.
Furthermore, the material enveloping the radio-jet is in a much
higher ionization state than that of the surrounding NLR gas. The
highest excitation is coincident with the jet axis where emission in
the coronal line of [FeVII] 
3769Å is detected
and the HeII 4686
Å is strong but where [OII] 3727 Å is depressed. This large
localized increase in ionization on the jet axis is accompanied by the
presence of an excess continuum. Because the electron density is
substantially larger in the jet compared to the surrounding NLR, these
results can only be explained if there is a more intense ionizing
continuum associated with the jet. This can be accomplished in a
variety of ways which include an intrinsically anisotropic nuclear
radiation field, a reduced gas covering factor or the presence of a
local ionization source.
The morphology, kinematics and, possibly, the ionization structure of
the NLR in the vicinity of the jet of NGC 1068 are a direct
consequence of the interaction with the radio outflow.
END:: epreps.stsci//prep1215