Bennert, Falcke, Schulz et al.: Size and Structure of Quasar NLRs
Size and Structure of the Narrow-Line Region of Quasars
Nicola Bennert1, Heino Falcke2, Andrew S. Wilson3, Hartmut Schulz1, Beverley J. Wills4
1Astronomisches Institut Ruhr-Universität Bochum,
Universitätsstrasse 150, D-44780 Bochum, Germany; email:
email@example.com; email: firstname.lastname@example.org
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany (email@example.com)
3Astronomy Department, University of Maryland, College Park,
MD 20742-2421 (firstname.lastname@example.org)
4Department of Astronomy and McDonald Observatory,
University of Texas at Austin, Austin, TX 78712, USA; email:
The Astrophysical Journal Letters (2002), in press
We have observed the narrow-line regions (NLRs) of the seven
brightest radio-quiet PG (or BQS) quasars (z < 0.5) with the Wide Field
and Planetary Camera 2 on board the Hubble Space Telescope (HST). Linear-ramp
filters were used to image the [OIII] lambda 5007 line
emission with 0.0455-0.1'' pixel resolution. We find that the NLRs are
very compact with typical extents of 2''-4''. Two quasars
show compact filamentary structures similar to Seyfert NLRs.
They may be related to radio outflows. Most interestingly, when
including a sample of Seyfert galaxies observed with HST, we
tentatively find that the size of the NLR is proportional to
the square root of the [OIII] luminosity. This is comparable to
the scaling found for the size of the broad-line region with
continuum luminosity, which has been interpreted in terms of a constant
photoionization parameter. The relation determined here connects the
NLR of radio-quiet quasars and Seyferts over three orders of
magnitude in [OIII] luminosity.
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